The World's First Sterilizable Flexible Organic Transistor

Engineerblogger
March 7, 2012

Figure 1: A highly thermostable organic transistor manufactured on a thin plastic film. The team succeeded in building a low drive-voltage and a high thermostable organic circuit on a plastic film by using SAM molecule for the gate insulator, and high heat resistant semiconductors for semiconductor layer.

An international research team has succeeded in manufacturing on a polymeric film the world’s first flexible organic transistor that is robust enough under high temperature medical sterilization process. The study published online in Nature Communications on March 6, 2012.

In a serious aging society with a declining birthrate, electronics are increasing their importance in the health and medical area as more IT devices are being introduced. Upon this background, an expectation is getting higher on an organic transistor, which is a soft electronic switch. A flexible organic transistor can easily be manufactured on a biocompatible polymeric film, and this is the reason why it is expected to adopt it to a wearable health monitor without a stress, and/or implantable devices such as a soft pace maker. For practical implementation, it is crucial (1) to make the best use of its softness and biocompatibility, simultaneously (2) to decrease driving voltage down to a few V, and (3) to decrease the risk of infections by sterilization, for a security reason. Up until now, however, the existing organic transistors had huge obstacles towards the practical usage in the health and medical field. For example, typical driving voltage for displays is high (i.e. 20 to 80 V) and/or and it is not durable under high temperature sterilization.

The team has succeeded in manufacturing on a polymeric film an organic transistor that has high thermal stability and driving voltage of 2V at the same time. The new type organic transistor can be sterilized in a standard sterilization process (150 °C heat treatment) without being deteriorated in its electrical performances. The key to realize heat resistant organic transistor is in the forming technique of an ultrathin insulator film: The team develops a technique to form extraordinarily densely packed self-assembled monolayer (SAM) films, whose thickness is as small as 2 nanometers, on a polymeric film. This allows them to elevate substrate temperature up to 150 °C without creating pinholes through SAM films during the high temperature treatment. It is believed that ultrathin monolayer film like SAM degrades easily by thermal processes; however, it is unexpectedly demonstrated that densely packed SAM is stable at 150 °C or higher. This result is also proved by systematic characterization of crystallographic structures of SAM using a synchrotron radiation beam. Furthermore, by adopting a novel encapsulation layer comprising organic/metal composite materials and extremely thermally stable and high mobility organic semiconductors, the thermal stability of organic transistors is now improved up to 150 °C.

It should be benefited more from applying this heat-resistant organic transistor to long term implantable devices, or to some medical devices such as a smart catheter. With these applications, it is expected to broaden the usage of the transistor to medical apparatus such as thin film sensor that will detect tumors, inflammations, and or cancers.

The international team is led by Dr. Takao Someya, who is a professor of the University of Tokyo (President: Jyunichi Hamada, Ph.D.), a research director of ERATO (Exploratory Research for Advanced Technology) “Someya Bio-Harmonized Electronics Project” of Japan Science and Technology Agency (JST, President: Michiharu Nnakamura, D.Sc.), and a global scholar of Princeton University (President: Shirley M. Tilghman, Ph.D.), in collaborations with Associate Professor Tsuyoshi Sekitani of the University of Tokyo and Professor Yueh-Lin (Lynn) Loo of Princeton University. This joint research project was also carried out with the following institutions: Max Planck Institute for Solid State Research, Germany, National Institute of Standards and Technology, NIST, U.S., Hiroshima University, and Nippon Kayaku Co., Japan.

Background

In consequence of a serious declining birthrate and a growing proportion of elderly, information technology (IT) devices are rapidly introduced in the health and medical area. One of the good examples is the internet connection of a healthcare device between a patient’s home and a hospital. The internet allowed a doctor to monitor patience’s heart rates and weights away from his/her home. The miniaturization of medical apparatuses such as endoscopes succeeded in minimizing patients’ burdens and/or invasiveness. In this way, in the medical and the healthcare field, electronics are increasing their importance. Indeed, in the health and medical market, electronics are expected to grow 120% every year successively until 2015.

In this background, an organic transistor, which is a flexible electronic switch, attracts much attention because it is easily manufactured on a biocompatible polymeric film. A biocompatible organic transistor would be suitable for applications to a stress free wearable health monitoring system and implantable devices such as a soft pacemaker. For practical implementation, it is crucial (1) to make the best use of its softness and biocompatibility, simultaneously (2) to decrease driving voltage down to a few V, and (3) to decrease the risk of infections by sterilization, for a security reason. Up until now, however, the existing organic transistors had huge obstacles towards the practical usage in the health and medical field. For example, typical driving voltage for displays is high (i.e. 20 to 80 V) and/or and it is not durable under high temperature sterilization.

Results in details

The team has succeeded in manufacturing on a polymeric film an organic transistor that has world’s first 150 °C thermostability and simultaneously its driving voltage of 2V. The keys to realize the heat resistant organic transistor are (1) self-assembled monolayer (SAM) and (2) a sealing film, which are to be discussed later. The highly thermal stability that we had realized exploded the typical theory that an ultrathin monolayer film of nanometers in size was easily affected by heat. This result was also proved by the systematic analysis of precise crystallographic characterizations using a synchrotron radiation beam, which will be described in (3) in detail. Furthermore, the organic transistor has successfully been sterilized under a standard sterilization process (150 °C heat treatment) without being electrically deteriorated. This will be discussed in (4).

(1) Highly thermostable self-assembled monolayer (SAM) gate insulator

A key technology towards the development of sterilizable organic transistor is the 2-nm-thick ultrathin self-assembled monolayer (SAM) film. To reduce a thickness of a gate insulator film is known as the effective way to reduce the driving voltage of an organic transistor. From the security reasons, it is necessary to thin down a gate insulator film to a few nanometers thickness in order to reduce the driving voltage down to 2V. The team employed SAM film for a gate insulator in the past. They attempted to optimize manufacturing process of SAM from heat resistance point of view. As a result, by substantially improving crystalline ordering of densely packed SAM films on a polymeric film, they succeed in forming an insulator film that does not create pinholes, the cause of a leakage current, even under a high heat treatment. This becomes possible by optimizing plasma condition during the shaping process of aluminum-oxide thin films on top of the polymeric film, resulting in a way to avoid the film from being damaged during a plasma process.

(2) An encapsulation layer comprising organic and metal composite films

An improvement of thermal stability of a SAM gate insulator is not enough to accomplish the high thermal stability of an organic transistor. Normally, organic semiconductors that compose the channel layer in organic transistor are known to be easily degraded by heat. Thereby, an organic semiconductor, which is carefully chosen among heat resistant materials, is dinaphtho-thieno-thiophene (DNTT) in the experiment. Furthermore, after manufacturing an organic transistor, the transistor is completely covered by a flexible, heat-resistant encapsulation layer comprising organic and metal composite films (Figure 2). The encapsulation layer restrains DNTT from subliming with heat, and it prevents elements from substantial deterioration. Moreover, it is demonstrated that electronic characteristic of organic transistor remains practically unchanged even after dipped in the boiling water.

Figure 2: A schematic device structure (a) and a picture (b) of a thermally stable organic transistor. An organic transistor is covered with a flexible encapsulation layer that has both sealing characteristic as well as thermal stability.

(3) Structural characterization of nanometer-thick films by synchrotron radiation beams

The crystallographic structures of SAM films are examined. To be accurate, the gate insulator film used in the experiment consists of two layers, namely, 4-nm-thick aluminum-oxide and 2-nm-thick self-assembled monolayer. The thermal resistance of aluminum-oxide has been long known; however, there has been no report published on a structural analysis on SAM film, nor a report to prove structural stability of SAM film embedded in the devices at high temperature. This is because of the difficulty in analyzing the structure of such a thin SAM film with single molecular layer thickness using x-ray analysis.

The team attempted to precisely characterize crystallographic structures of a SAM film in order to evaluate the heat resistance of an organic transistor. Note that the thickness of a SAM film is as small as 2 nanometers. By using a synchrotron radiation beam, it is proven, for the very first time, to the best of our knowledge, that crystallographic structure of a SAM film exhibits any deterioration in molecular ordering even at 150 °C or higher temperature. This outcome unexpectedly overthrew what it had been believed that an ultrathin monolayer film of a few nanometers thinness must degrade easily by heat.

The analysis was carried out together with Professor Yueh-Lin (Lynn) Loo from Princeton University and a group at NIST, and a synchrotron radiation beam at Brookhaven National Laboratory is used.

(4) The creation of medical flexible electronics

The high thermostable organic transistors are capable of being sterilized without electrically deteriorated. The team evaluated elements’ heat resistance for three different standard heating sterilization processes that are widely used to sterilize medical apparatuses: they are (1) a heat treatment at a temperature of 150 °C for 20 seconds at atmospheric pressure, (2) a heat treatment at 2 atmospheric pressures, 121 °C for 20 seconds, and (3) a sterilization by boiling.

First, the thermal stability of the manufactured organic transistor is improved by annealing process at 160 °C, which is slightly high than the typical annealing temperature for sterilization. Second, bacteria are cultured on the above mentioned transistor. Finally, the number of bacteria and the electric characteristics are measured before and after the medical sterilization process. As a result, almost all the bacteria died off after the sterilization; however, electrical characteristics of the transistor are practically unchanged (a negligible level).

The team’s development in the past

Unlike the conventional inorganic materials, organic transistors are capable of making lightweight and mechanically flexible electronic devices, since they can be built on polymeric film by a low temperature processing. Organic transistors can be manufactured through printing process as well: This allowed a drastic cost reduction when making large area transistors, compared with those made with silicon. One of the major driving applications for organic transistors is e-paper. Up until now, Someya and his coworkers have intensively investigated the application of organic transistors to large-area sensors or large-area actuators. The team has shown the feasiblity of implementing organic transistors to large area electronics. A series of their achievements include a robot e-skin (2003), a sheet type scanner (2004), an ultrathin braille sheet display (2005), a wireless power transmission sheet (2006), a communication sheet (2007), an ultrasonic sheet (2008), a flash memory (2009).

Recently, organic transistors are longed to be implemented to medical and healthcare devices because of their biocompatibility. However, it is indispensable that those devices are sterilized. Therefore, it has been required that those organic circuits built on plastic films to be stable through heat treatment, and that they are driven with low voltage.

Someya and his coworkers have succeeded in making an organic transistor which stays undeteriorated after heating up to 150 °C in 2004. Though, a thick organic polymer that was used as an insulator film caused the driving voltage to be very high, and it was the reason why it did not suit for bio/medical usage. The team had attempted to build a few nm organic/inorganic materials on a plastic film using a molecular self-assembly, and they have finally proved the feasibility of heat resistance of SAM film for the first time.

In the last year, they invented a new medical electronics called “an intelligent catheter” using flexible organic transistor technique: the new narrow catheter is covered with a pressure sensor network (published in Nature Materials, UK in 2010). It was inevitable to develop a thermostable organic transistor so that the new catheter to be used practically at the hospitals. They finally overcame the barrier.

Outlook for the future

Organic transistors are mechanically flexible and expectedly biocompatible since they are made of soft organic electronic materials such as organic semiconductors. Attractive applications that are expected to be realized by flexible biocompatible organic transistors include “a wearable electronics” which reads out bio-information from outside of a skin, or “an implantable electronics” that directly extracts bio-information by implanting the electronics in a body. Indeed, Someya and his coworker also came up with applying the ultraflexible organic electronics to cover a narrow catheter. This opens a new path to the development of a thin film sensor that detects tumors, inflammations, early cancers. The invention will surely broaden the usage of the organic transistors as medical devices. Since a flexibility, a large coverage, and an electric stability are indispensable for implementation of these medical devices, the present invention will serve as the core technology when developing the future medical devices.

Up to this point, displays and solar cells have been considered as main driving applications of organic devices. Organic EL displays and organic flexible solar cells are implemented rapidly. However, they are only a glimpse of vast potentials that organic devices possess. Indeed, world’s researchers are competing in developing health and medical applications utilizing softness of organic devices. The team has led the field of flexible devices by achieving the world’s smallest minimum bending radius (100 µm). With the feasibility shown with these sterilizable, flexible organic transistors, the contribution will accelerate the researches on the medical applications.

Source: University of Tokyo via Brookhaven National Laboratory

Additional Information:

• The paper " Organic transistors with high thermal stability for medical applications" published online in Nature Communications on March 6, 2012

Robotic surgery popular, expensive, but is it more effective?

Medill Reports
March 7, 2012

Da Vinci surgeries like this one may not be any more effective than the cheaper traditional surgeries. Credit: Lisa Weidenfeld/MEDILL

The new Da Vinci surgical robot is a hit with patients, who request it for all kinds of procedures. But is it really more effective than traditional surgery -- or just more expensive? Some doctors argue that without much authoritative research, the Da Vinci robot is more a marketing tool than an improvement to surgery.

Surgeries performed with the new, high-tech, da Vinci robot use a narrower blade and provide greater precision than traditional open surgeries, which are performed with a scalpel. The machines are maneuvered by a surgeon operating the robotic arms from behind a nearby console.

There are 2,132 da Vinci systems world-wide, said Chris Simmonds, senior director of marketing services for manufacturer Intuitive Surgical, Inc. and that number is growing. But they do not come cheap. The machines each cost between $1.1 million and $2 million, with an additional cost of $100 thousand to $180 thousand for maintenance annually.

In a 2011 study from Johns Hopkins University about the marketing of the da Vinci robot, 41 percent of hospital websites included a description of robotic surgery, with 89 percent of those descriptions claiming clinical superiority. Despite this claim, only 2 percent of those hospitals made a specific comparison to open or laparoscopic surgery, which involves inserting a camera through an incision. The marketing for robotic surgery may win over more converts than the results of the surgeries.

“You start to see this is not just a trivial issue of exuberant marketing, but it is in some cases potentially inaccurate and really harmful, potentially harmful information, wrapped in the glitz and the glamor of a new technology,” said Gary Schwitzer, publisher of HealthNewsReview.org, a site devoted to reviewing media coverage of “medical treatments, tests, products and procedures.” Schwitzer has been reporting on health issues for more than 30 years.
To read more click here...

Printing Muscle: 3D printer creates human tissues that could help speed drug discovery

Engineerblogger
March 5, 2012
 

Credit: Frank Rogozienski/Wonderful Machine

In a small clean room tucked into the back of San Diego–based startup Organovo, Chirag Khatiwala is building a thin layer of human skeletal muscle. He inserts a cartridge of specially prepared muscle cells into a 3-D printer, which then deposits them in uniform, closely spaced lines in a petri dish. This arrangement allows the cells to grow and interact until they form working muscle tissue that is nearly indistinguishable from something removed from a human subject.

The technology could fill a critical need. Many potential drugs that seem promising when tested in cell cultures or animals fail in clinical trials because cultures and animals are very different from human tissue. Because Organovo's product is so similar to human tissue, it could help researchers identify drugs that will fail long before they reach clinical trials, potentially saving drug companies billions of dollars. So far, Organovo has built tissue of several types, including cardiac muscle, lung, and blood vessels.

Unlike some experimental approaches that have used ink-jet printers to deposit cells, Organovo's technology enables cells to interact with each other much the way they do in the body. They are packed tightly together and incubated, prompting them to adhere to each other and trade chemical signals. When they're printed, the cells are kept bunched together in a paste that helps them grow, migrate, and align themselves properly. ­Muscle cells, for example, orient themselves in the same direction to create tissue that can contract.

So far, Organovo has made only small pieces of tissue, but its ultimate goal is to use its 3-D printer to make complete organs for transplants. Because the organs would be printed from a patient's own cells, there would be less danger of rejection.

Organovo plans to fund its organ-­printing research with revenue from printing tissues to aid in drug development. The company is undertaking experiments to prove that its technology can help researchers detect drug toxicity earlier than is possible with other tests, and it is setting up partnerships with major companies, starting with the drug giant Pfizer.

Source: Technology Review

Heart-powered pacemaker could one day eliminate battery-replacement surgery

Engineerblogger
March 5, 2012

An artificial pacemaker from St. Jude Medical, with electrode.

A new power scheme for cardiac pacemakers turns to an unlikely source: vibrations from heartbeats themselves.

Engineering researchers at the University of Michigan designed a device that harvests energy from the reverberation of heartbeats through the chest and converts it to electricity to run a pacemaker or an implanted defibrillator. These mini-medical machines send electrical signals to the heart to keep it beating in a healthy rhythm. By taking the place of the batteries that power them today, the new energy harvester could save patients from repeated surgeries. That's the only way today to replace the batteries, which last five to 10 years.

"The idea is to use ambient vibrations that are typically wasted and convert them to electrical energy," said Amin Karami, a research fellow in the U-M Department of Aerospace Engineering. "If you put your hand on top of your heart, you can feel these vibrations all over your torso."

The researchers haven't built a prototype yet, but they've made detailed blueprints and run simulations demonstrating that the concept would work. Here's how: A hundredth-of-an-inch thin slice of a special "piezoelectric" ceramic material would essentially catch heartbeat vibrations and briefly expand in response. Piezoelectric materials' claim to fame is that they can convert mechanical stress (which causes them to expand) into an electric voltage.

Karami and his colleague Daniel Inman, chair of Aerospace Engineering at U-M, have precisely engineered the ceramic layer to a shape that can harvest vibrations across a broad range of frequencies. They also incorporated magnets, whose additional force field can drastically boost the electric signal that results from the vibrations.

The new device could generate 10 microwatts of power, which is about eight times the amount a pacemaker needs to operate, Karami said. It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute. That's well below and above the normal range.

Karami and Inman originally designed the harvester for light unmanned airplanes, where it could generate power from wing vibrations.

A paper on the research, titled "Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters," is published in the current print edition of Applied Physics Letters.

The research is funded by the National Institute of Standards and Technology and the Institute for Critical Technology and Applied Science at Virginia Tech.

Source: University of Michigan

Improving medical devices using computational modeling

Engineerblogger
Feb 20, 2012

Cardiovascular stent. Credit: ASME

To improve the design and testing of medical devices such as cardiovascular stents that are implanted in the human body, mathematical modeling techniques like computational fluid dynamics and finite element analysis (FEA) are being increasingly used these days in addition to traditional in-vitro techniques.

The Center for Devices and Radiological Health (CDRH) is a branch of the FDA responsible for the pre-market approval (PMA) of all medical devices, as well as overseeing their manufacturing, performance, and safety. The CDRH splits these devices into three main categories.

• Class 1 devices include everyday items such as battery-powered toothbrushes which are unlikely to cause serious consequences if they fail.

• Class 2 devices require an approval that is referred to as a "510(K)" after the relevant section of the Food, Drug and Cosmetic Act. The intent of this class is for companies who manufacture devices that already existed when the rules were first established.

• Class 3 devices require a full PMA. This class typically includes implantable medical devices that would cause serious risk of injury or even death if they did not function properly.

CDRH requires pre-market bench testing for most implanted materials and components to determine their potential for causing blood and tissue damage. Additionally, in-vitro testing is also important in determining the source of blood damage during adverse patient investigations that might occur post-market. However, uncertainty in the performance and use of the data can occur since standardized testing and reporting procedures for quantifying blood damage have not been established for evaluating many of these devices. The main reason is, due to the complexity of current blood trauma testing techniques, it has not been shown that preclinical evaluations of new devices using in-vitro laboratory testing have typically been good predictors of how they will perform in patient clinical trials, according to research conducted by the FDA.

Computer Modeling Techniques

For that reason, the FDA is actively involved in evaluating the differences between testing these devices and components with animal/human blood, and by exploring how flow-visualization and computational flow dynamic simulations can be used to validate and predict blood damage. One of the most widely used computer modeling techniques to simulate the flow of fluids and the physical forces acting on the fluid is known as computational fluid dynamics (CFD), a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. It is already being used to develop tests for blood-flow medical devices, such as ventricular assisted devices (VADs).

Another subset of computer modeling being used to support CFD studies is FEA. This model consists of knowing the detailed geometry of the device and the mechanical properties of the materials used to predict stresses and strains in solid structures and materials from the applied external forces and deformations. As with CFD, the method reduces costs by allowing virtual design and prototyping rather than actually building and testing each iteration of the device. FEA also can predict failures due to unknown stresses by showing problem areas and allowing designers to see more of the stresses calculated within the device

Computational modeling being used to test a cardiovascular stent. Image: Ozen Engineering

However, even though these computational models are proving very useful to demonstrate product reliability in FDA pre-market device applications, there have been limited studies carried out to adequately and systematically validate these techniques within a standardized procedure. This is particularly true in the final stage of predicting biological responses, such as comparing blood damage, or thrombus formation, to the purely physical results of the simulations, such as blood pressure, velocity, and shear stresses. Even the physical results generated by CFD are subject to considerable error as compared to experiment, as was recently demonstrated in a computational inter-laboratory study. In this study, computations of a relative hemolysis index (excessive blood cell destruction) of patients from the CFD simulations showed a great deal of scatter, which couldn't be fully explained.

ASME Interest

ASME has taken an interest in the standardization of these computation modeling techniques. The seed for a committee was nurtured during a 2008 FDA Workshop on Computer Methods for Cardiovascular Devices. As a result of feedback received from the workshop, it was determined to proceed with forming a new verification and validation (V&V) subcommittee that was application-specific to the medical device industry. The charter of this new committee, known as "V&V 40", was to provide procedures to standardize the verification and validation for the computational modeling of medical devices.

After two years of engaging the medical device industry through various forums, a panel of experts was assembled. Its main task initially involved putting together a comprehensive list of what the medical device industry needs, and in particular, how computer modeling can be used to support the design process. The first official meeting was held in April 2011 in conjunction with the Design of Medical Devices Conference at the University of Minnesota to review the in-depth analysis of the various V&V documents within the community.

The committee currently has a strong representation from experts on cardiovascular devices, but the group is looking to become better versed with expertise from other areas. It also is not clear where the boundaries of this committee lie. For example, it hasn't been decided on what specific medical devices the group should focus on and how to differentiate the work for a wide variety of devices, i.e., implantable versus non-implantable devices. However, the goals of the committee are clear, and are summed up by Ryan Crane, the committee secretary: "There is no question that through standardized computational modeling techniques, the design, testing, and regulatory review of medical devices or components will lead to improvements in efficacy and cost throughout the pre-market and post-market stages of the product's life cycle."

Source: ASME

Researchers find the healing properties of a spider’s web

Engineerblogger
Feb 20, 2012

Here is a close-up view of synthetic beads-on-a-thread. Credit: University of Akron

The study of spider webs has led to a discovery that will generate new kinds of medical sutures embedded with medication. The University of Akron scientists have developed a novel synthetic material similar to a specific kind of silk spun by an orb spider. The specific web design is known as BOAS because it looks like beads-on-a-string in a circular web. The beads are glue droplets. The replication of this design can potentially be used as strong and flexible sutures that contain medication embedded in these bead-like structures.

The researchers developed the new biocompatible thread after meeting with physicians who specialize in wound healing and who expressed the need for better material-related solutions to medical problems.

Novel material to aid healing
The scientists published their findings in the American Chemical Society journal Langmuir in an article titled Spider Silk Inspired Functional Microthreads and will present at two upcoming scientific conferences. The next step is to apply for funding to speed the commercialization process to create medical materials that can help heal injured tendons or tissue.

"We have been very interested in architecture of adhesives produced by spiders and were very intrigued to understand why spiders use the BOAS structure," says Vasav Sahni, UA polymer science graduate student and lead author of the article published in Langmuir.

Sahni and research team members Dr. Ali Dhinojwala, chair of the Department of Polymer Science and Maurice Morton Professor of Polymer Science, and Disha Labhasetwar, an NSF-REU student with the Department of Polymer Science created the BOAS replica by copying techniques used by spiders when they spin silk.

"We used fluid mechanics concepts to vary the size and spacing of the glue beads and mimicked the spider silk threads by using commercially available materials, such as nylon," Sahni says, adding that he and his colleagues designed and fabricated a specialized piece of equipment to develop the threads.

Glue releases medication
Rather than place individual glue drops on a string, the researchers' novel technique coats threads uniformly with glue. The glue forms waves, which morph into beads that create greater-than-average contact areas and also release energy, or adhesive strength, when peeled. The beads can potentially also create a structure in which medication can be placed and released.

Dhinojwala, Sahni and their research colleagues developed the biocompatible thread to address one of the needs identified in a pilot program with the Austin BioInnovation Institute in Akron (ABIA). The scientists shadowed medical experts at the Akron General Hospital wound clinic, the Akron Children's Hospital burn unit and Summa Health System, assessing needs and developing solutions.

The researchers plan to apply for a $25,000 ABIA grant to fund development of a prototype and hope to see it commercialized locally. The researchers say their simple and scalable technique allows for rapid and large-scale fabrication of the new adhesives.




Source: University of Akron

Additional Information:

• To read the abstract in the ACS "Spider Silk Inspired Functional Microthreads"  by Vasav Sahni, Disha V. Labhasetwar, and Ali Dhinojwala, published on December 7, 2011.

The Indispensable Biomaterial

Engineerblogger
Feb 17, 2012

Introduced in 2011, Biocoat’s HydroSleek coating for medical devices capitalizes on the low-viscosity properties of silicone elastomer. Through specialized construction, Biocoat was able to maximize lubricity performance without impinging on durability. Image: Biocoat Inc.

When we think of biomaterials used in medical devices or for surgery, polymers like polyethylene or similar plastics used in prosthetics or joint repair spring to mind. Or perhaps ceramics used in tooth fillings. Or, possibly, metals like stainless steel that are widely used in mechanical heart valves, stents, and joint replacements.

One of the oldest clinically applied biomaterials, however, is silicone. Its first recorded use as an implant was in 1946, when it was used to repair bile ducts; since then has been used in a tremendous array of medical applications, both in vivo and ex vivo. Silicone is also a polymer, but its specific backbone is built of repeating silicon-to-oxygen bonds. The material can be modified by linking silicon atoms to organic groups.

Cross-linking silicone produces an elastomer, and when it is chemically treated with silanes to enhance matrix integration, it becomes remarkably strong and resistant to tears. Today, silicone elastomers have advanced far beyond their best known application, breast implants, and have become one of the key enabling technologies for medical devices.

Silicone: Indispensable inside the body, and out
In February 2011, Biocoat Inc., Horsham, Pa., introduced its latest product, HydroSleek. Based on the company's HYDAK silicone coatings technology, HydroSleek has been engineered to be extremely slippery to liquids, particularly water, and is intended for medical device firms seeking to reduce surface friction for their devices.

A 21-year-old company, Biocoat was established by technology pioneered at Columbia University, New York, in the early 1980s. Chemist Ellington M. Beavers, PhD, and his team invented a method for immobilizing hyaluronan and other biopolymers. Hyaluronan or hyaluronic acid (HA) was first discovered in the 1930s, and until the 1970s was ingloriously described as a "goo" molecule. The human body has about 15 g of this material at any one time, and it acts as a natural coating around cartilage cells. It's also the naturally lubricating agent in synovial fluid, which separates most surfaces that slide against each other in tendon sheaths and joints.

Interest in HA has increased greatly in recent years with major clinical applications in ophthalmology, the treatment of degenerative joint disease, and adhesion prevention after surgery. Medical-grade HA is now produced globally in more than a dozen countries.

At Biocoat, HA was commercialized shortly after it was immobilized in Beavers’ laboratory. Since then, it has undergone a steady process of improvements. New additives and derivations have allowed Biocoat to make bioactive surfaces that can repel bacteria. HydroSleek is an example.

"The product is actually made possible by the primer coat, or basecoat, technology, which has been developed at Biocoat since 1991," says Josh Simon, senior product manager at Biocoat. "The basecoat is a proprietary polyacrylic co-polymer that uses isocyanate chemistry to reliably and consistently attach species that contain hydroxyl, carboxyl, and/or amine groups. This includes hyaluronic acid, which is the naturally occurring polysaccharide found in cartilage and blood, and in HydroSleek as well."

The basecoat/topcoat combination can be applied to a multitude of substrates, including nylon, silicone, PVC, and polyurethane. The total thickness of both layers can be as thin as 2 to 3 µm when dry, swelling to 10 µm when wet. The application process is the same as Biocoat's HYDAK coatings and is a relatively simple process using conventional coating equipment and curing ovens. Usually coatings are applied by dip-coating or cured with ultraviolet light.

"The coating has a coefficient of friction ranging from 0.01 to 0.05, after sterilization and aging. This is notable because most coatings lose performance after sterilization. This one does not," says Simon.

The main departure from previous coatings is that Biocoat has dealt with the traditional tradeoff between lubricity and durability. Usually, the more durable a coating is, the less lubricious it is, and vice versa. HydroSleek has all of the durability and lubricity of previous coatings, says Simon.

A year after its introduction, the coating has become popular with cardiovascular and neurovascular companies.

"Stent delivery catheters and neurovascular guidewires seem to be the most desired applications to date," says Simon. "However, this coating can be used in any of the applications of Biocoat's current customers, which range from intraocular lens cartridges to catheters used in the fertility industry."

 

Veryst Engineering, a contract design company, performs materials analysis and testing with an emphasis on biomaterials, such as silicone elastomers. One of their most important tools is finite-element software from vendors such as COMSOL, ANSYS, and Simulia. Image: Veryst Engineering

Computation analysis enables biomaterials
Biocoat has achieved market success through decades-long R&D regimens that resulted in successful products. But benchtop science is now giving way to materials design assisted by advanced computer-aided modeling solutions, such as finite-element analysis (FEA). Among biomaterials, elastomers are among the most challenging to design. An FEA solution must deal with highly non-linear material behavior and large deformations.

"We have worked extensively on silicone elastomers for various medical device manufacturers, so we are very familiar with their properties," says Jorgen Bergstrom, PhD, principal engineer at Veryst Engineering, Needham, Mass.

Veryst is a contract engineering and design firm that helps biomaterials manufacturers develop new products. It offers companies or universities the ability to mechanically test materials under a wide variety of formats and a range of environmental conditions, including tension and compression, bending, lap shear, hysteresis, creep, and volumetric compression. Most of these tests can be performed at temperatures from -80 to 280 C.

The company then feeds this data into FEA software from COMSOL, Burlington, Mass., to simulate the actions of materials such as polyethylene, stainless steel, and silicone. Because the bulk of Veryst's client base is in the biomaterials or medical device manufacturing business, engineers like Bergstrom have become familiar with the behavior of silicone.

This knowledge has been used by Veryst to create the PolyUMod library, a series of specialized modules that cover the four main categories of polymeric biomaterials: thermopolymers, thermosets, elastomers, and foams. Bergstrom himself created a model for elastomer while at the Massachusetts Institute of Technology, Boston. That module is now included in the PolyUMod library as the Bergstrom-Boyce model. Silicone is one of the most commonly used biomaterials, he says, although it has not been as thoroughly tested as polyethylene.

Silicone elastomer design requires the expertise provided by Veryst, Bergstrom continues, because they are physically complicated. The materials have a long, non-linear stretching capability, and FEA is one of the quickest ways engineers can predict how much a given formulation can be safely stretched, how much it continues to stretch when relaxed, and what its durability is over time. The PolyUMod tools help capture non-linear elastomeric behavior. The biggest challenge for engineers, Bergstrom says, is the long-term degradation of the material that occurs in some environments. Even in the laboratory, experimental data for how a given elastomer breaks down in biological environments is still quite poor.

However, Bergstrom anticipates this situation to improve. "Finite element [analysis] as a tool has been around for 30 years or more, but because biomaterials are complicated, it hasn’t been easy for design engineers to handle," says Bergstrom. In the last five to 10 years, however, he has seen a dramatic improvement in biomaterials reliability in part because of tools like FEA. "I think in the next five to 10 years we'll see even more of a marked improvement."

Source: R&D Magazine

Moving past trial and error: Applying math to design new materials and processes for drug manufacturing

MIT News
Feb 15, 2012

Richard Braatz. Photo: Dominick Reuter

Trial-and-error experimentation underlies many biomedical innovations. This classic method — define a problem, test a proposed solution, learn from failure and try again — is the main route by which scientists discover new biomaterials and drugs today. This approach is also used to design ways of manufacturing these new materials, but the process is immensely time-consuming, producing a successful therapeutic product and its manufacturing process only after years of experiments, at considerable expense.

Richard Braatz, the Edwin R. Gilliland Professor of Chemical Engineering at MIT, applies mathematics to streamline the development of pharmaceuticals. Trained as an applied mathematician, Braatz is developing mathematical models to help scientists quickly and accurately design processes for manufacturing drug compounds with desired characteristics. Through mathematical simulations, Braatz has designed a system that significantly speeds the design of drug-manufacturing processes; he is now looking to apply the same mathematical approach to designing new biomaterials and nanoscale devices.

“Nanotechnology is very heavily experimental,” Braatz says. “There are researchers who do computations to gain insights into the physics or chemistry of nanoscale systems, but do not apply these computations for their design or manufacture. I want to push systematic design methods to the nanoscale, and to other areas where such methods aren’t really developed yet, such as biomaterials.”

From farm to formulas

Braatz’s own academic path was anything but systematic. He spent most of his childhood on an Oregon farm owned by his grandfather. Braatz says he absorbed an engineer’s way of thinking early on from his father, an electrician, by examining his father’s handiwork on the farm and reading his electrical manuals.

Braatz also developed a serious work ethic. From the age of 10, he awoke early every morning — even on school days — to work on the farm. In high school, he picked up a night job at the local newspaper, processing and delivering thousands of newspapers to stores and the post office, sometimes until just before dawn.

After graduating from high school in 1984, Braatz headed to Alaska for the summer. A neighbor had told him that work paid well up north, and Braatz took a job at a fish-processing facility, driving forklifts and hauling 100-pound bags of fishmeal 16 hours a day. He returned each summer for four years, eventually working his way up to plant operator, saving enough money each summer to pay for the next year’s tuition at Oregon State University.

As an undergraduate, Braatz first planned to major in electrical engineering. But finding the introductory coursework unstimulating — given the knowledge he’d absorbed from his father — he cast about for another major.
To read more click here...

New nano-material combinations produce leap in infrared technology

Engineerblogger
Feb 15, 2012

ASU engineers are working on technological advances that promise to help enhance infrared photodetection used in sophisticated weapons and surveillance system, industrial and home security systems, medical diagnostics and night vision equipment for law enforcement and driving safety.  Photo by: Orkun Cellek/ASU

Arizona State University researchers are finding ways to improve infrared photodetector technology that is critical to national defense and security systems, as well as used increasingly in medical diagnostics, commercial applications and consumer products.

A significant advance is reported in a recent article in the journal Applied Physics Letters. It details discovery of how infrared photodetection can be done more effectively by using certain materials arranged in specific patterns in atomic-scale structures.

It’s being accomplished by using multiple ultrathin layers of the materials that are only several nanometers thick. Crystals are formed in each layer. These layered structures are then combined to form what are termed “superlattices.”

Photodetectors made of different crystals absorb different wavelengths of light and convert them into an electrical signal. The conversion efficiency achieved by these crystals determines a photodectector’s sensitivity and the quality of detection it provides, explains electrical engineer Yong-Hang Zhang.

The unique property of the superlattices is that their detection wavelengths can be broadly tuned by changing the design and composition of the layered structures. The precise arrangements of the nanoscale materials in superlattice structures helps to enhance the sensitivity of infrared detectors, Zhang says.

Zhang is a professor in the School of Electrical, Computer and Energy Engineering, one of ASU’s Ira A. Fulton Schools of Engineering. He is leading the work on infrared technology research in ASU’s Center for Photonics Innovation. More information can be found at the center’s Optoelectronics Group website.

Additional research in this area is being supported by a grant from the Air Force Office of Scientific Research and a new Multidisciplinary University Research Initiative (MURI) program established by the U.S. Army Research Office. ASU is a partner in the program led by the University of Illinois at Urbana-Champaign.

The MURI program is enabling Zhang’s group to accelerate its work by teaming with David Smith, a professor in the Department of Physics in ASU’s College of Liberal Arts and Sciences, and Shane Johnson, a senior research scientist in the ASU’s engineering schools.

The team is using a combination of indium arsenide and indium arsenide antimonide to build the superlattice structures. The combination allows devices to generate photo electrons necessary to provide infrared signal detection and imaging, says Elizabeth Steenbergen, an electrical engineering doctoral student who performed experiments on the supperlattice materials with collaborators at the Army Research Lab.

“In a photodetector, light creates electrons. Electrons emerge from the photodetector as electrical current. We read the magnitude of this current to measure infrared light intensity,” she says.

“In this chain, we want all of the electrons to be collected from the detector as efficiently as possible. But sometimes these electrons get lost inside the device and are never collected,” says team member Orkun Cellek, an electrical engineering postdoctoral research associate.

Zhang says the team’s use of the new materials is reducing this loss of optically excited electrons, which increases the electrons’ carrier lifetime by more than 10 times what has been achieved by other combinations of materials traditionally used in the technology. Carrier lifetime is a key parameter that has limited detector efficiency in the past.

Another advantage is that infrared photodetectors made from these superlattice materials don’t need as much cooling. Such devices are cooled as a way of reducing the amount of unwanted current inside the devices that can “bury” electrical signals, Zhang says.

The need for less cooling reduces the amount of power needed to operate the photodetectors, which will make the devices more reliable and the systems more cost effective.

Researchers say improvements can still be made in the layering designs of the intricate superlattice structures and in developing device designs that will allow the new combinations of materials to work most effectively.

The advances promise to improve everything from guided weaponry and sophisticated surveillance systems to industrial and home security systems, the use of infrared detection for medical imaging and as a road-safety tool for driving at night or during sand storms or heavy fog.

“You would be able to see things ahead of you on the road much better than with any headlights,” Cellek says.

The research team’s paper is reported on in the article “One giant leap for IR technology” on the LAB & FAB TALK website of Compound Semiconductor magazine.

Source: Arizona State University

Chemists Harvest Light to Create 'Green' Tool for Pharmaceuticals

Engineerblogger
Feb 10, 2012

Ryan Spencer Shinabery, Soumitra Maityand Nan Zheng (from left) have created a new, “green” method fordeveloping medicines. (Not shown: Mingzhao Zhu.)

A team of University of Arkansas researchers, including an Honors College undergraduate student, has created a new, “green” method for developing medicines. The researchers used energy from an ordinary 13-watt compact fluorescent light bulb to create an organic molecule that may be useful in the treatment of Alzheimer’s and other brain diseases. The finding, coauthored by Soumitra Maity, Mingzhao Zhu, Ryan Spencer Shinabery and Nan Zheng, is published in the current issue of Angewandte Chemie International Edition, one of the top journals in the field of chemistry.

“Our chemical reaction provides a new structure, a new building block for pharmaceutical companies that has not been available before,” said Zheng, an assistant professor of chemistry in the J. William Fulbright College of Arts and Sciences who leads the team. “It’s a very unusual scaffold, very lipophilic and non-polar, which is what you need to cross the blood brain barrier.”

Visible-light photocatalysis, or chemical reactions sparked by visible light, are rare in organic chemistry, because most organic compounds can’t readily absorb visible light. Instead, organic chemists typically rely on ultraviolet, or UV light, which has disadvantages.

“UV lights heat up very fast and waste a lot of energy. You’ll also get a sunburn if your skin is exposed,” said Shinabery, a senior honors chemistry student.

Postdoctoral student Mingzhao Zhu initiated the research with his effort to use light from a cheap, readily available light source – a supermarket light bulb, in this case, although sunlight would work just as well – to make an organic molecule useful to chemists. Using ruthenium, a metal that is active in the presence of visible light, as a catalyst, Zhu produced an unexpected and unstable organic molecule. Shinabery subsequently worked to identify the structure of the molecule.

“Spencer was able to reproduce the result and help us understand how the molecule was formed, which we needed to design a new reaction,” Zheng said.

Maity, also a postdoctoral student, led the way in developing the new reaction, which is green thanks to efficiency as well as use of visible light.

“All of the atoms are converted to the product. There is no waste, no additives or co-catalysts, which makes the reaction very clean and atom economical,” Maity said. Maity also succeeded in crystallizing one of the products, in effect sketching out its three-dimensional structure, which is critical should it be further developed in pharmaceutical applications.

Zheng and Maity are currently working on a new, even more powerful result: the use of a catalyst with visible light to create a carbon-nitrogen bond, one of the most common and important bonds used in pharmaceuticals and materials.

“People thought carbon-nitrogen bonds couldn’t be formed this way; this will change people’s perception of visible light photochemistry,” Zheng said.

“I am working at all hours,” Maity added. “I lose track of time, because the work is so exciting.”

As for Shinabery, he is writing up his contribution to the finding as his senior honors thesis and weighing multiple offers from top graduate schools.

Source: University of Arkansas

A 3D Printed Jawbone: Woman received an unusual implant

Engineerblogger
Feb 9, 2012

A computer model of the fitted 3D-printed jaw is shown next to an image of the manufactured part.  Credit BBC

I’ll set aside, for the moment, the question of whether 3-D printing can revolutionize manufacturing--a topic that Christopher Mims and Tim Maly have already taken up quite effectively in these web pages--and instead point my finger again to one incontrovertible fact: that the technology is yielding incredibly interesting applications. The latest? An 83-year-old Dutch woman has received a 3-D printed lower jaw.

This happened back in June, but was only announced now; the University of Hasselt in Belgium calls it (somewhat grandiosely) “a world première.” In June, the woman presented with a terrible infection of the lower jaw, or mandible, forcing doctors to surgically remove it. Traditionally, such a patient would simply have to endure life without a proper mandible, or perhaps submit to “complex microsurgical reconstruction” (more or less out of the question for an 83-year-old). And so her team of doctors decided it was time to try something new: a 3-D printed implant.

The implant was a coproduction of sorts, involving researchers from Hasselt, several other colleges, a Dutch company called Xilloc Medical (which handled the 3-D design), and another one called LayerWise (which managed the production).

The implant took just a few hours to print, according to the BBC, with a laser beam melting thin layers of titanium powder, one on top of the other. Thousands of layers were necessary to build the jawbone (33 layers translate to about 1 mm of height). The printed jaw then got a bioceramic coating, and was surgically attached to the woman in about four hours. Old-school reconstructive surgery would have taken 20 hours.

After just a day, the woman was talking and swallowing, and she was able to leave the hospital after four days. Her new jaw weighed about a third heavier than her old one, said the doctors, though they claim that won’t be too difficult to adjust to. Further surgery is planned to remove healing implants and to insert screw-in teeth.

A considerable amount of big talk accompanied the announcement--though admittedly, it seems that much of it was earned. The Hasselt surgeon who performed the operation, Jules Poukens, likened it to the first steps on the moon. “Doctors and engineers together around the design computer and the operation table: that’s what we call being truly innovative,” he also said.

This team was not the first to envision potentially transformative effects of 3-D printing on medicine. Surgeon Anthony Atala recently gave a TED talk on “printing a human kidney.” He’s already made some early prototypes.

But Ruben Wauthle, the medical applications engineer of LayerWise, cautioned to the BBC that we weren’t ready to print biomaterial just yet. “To print organic tissue and bone you would need organic material as your 'ink,’” he said. “Technically it could be possible - but there is still a long way to go before we're there.”

Source: Technology Review

DARPA researchers design eye-enhancing virtual reality contact lenses

Engineerblogger
Feb 6, 2012

Currently being developed by DARPA researchers at Washington-based Innovega iOptiks are contact lenses that enhance normal vision by allowing a wearer to view virtual and augmented reality images without the need for bulky apparatus. Instead of oversized virtual reality helmets, digital images are projected onto tiny full-color displays that are very near the eye. These novel contact lenses allow users to focus simultaneously on objects that are close up and far away. This could improve ability to use tiny portable displays while sill interacting with the surrounding environment.

Developed as part of DARPA’s Soldier Centric Imaging via Computational Cameras (SCENICC) program, SCENICC’s objective is to eliminate the ISR capability gap that exists at the individual Soldier level. The program seeks to develop novel computational imaging capabilities and explore joint design of hardware and software that give warfighters access to systems that greatly enhance their awareness, security and survivability.

Source:  DARPA

Robotics in healthcare: challenges and opportunities

Medical Design
Jan 27, 2012

RIVA compounding system installed in a hospital pharmacy.

The healthcare industry is unlikely to adopt robots unless the risk and the investment are small. Concrete evidence of success is needed before taking on the larger opportunities.

•  Why robots in healthcare

• Obstacles to adoption

• Meeting the requirements for success

With all the interest and money being directed towards robotics in healthcare, it may seem like there couldn’t be anything new to say. Everyone knows that robots are the future of healthcare, and it is generally recognized that an increasing number of people will need healthcare, with the impending retirement of “baby boomers” being only one reason, while the number of people providing that care is dropping. Still, we haven’t seemed to have been able to make the leap to mass utilization of robots in any area of the typical hospital. It’s not that there aren’t opportunities. Two factors that contribute to the lack of robots in healthcare are (1) the targeted areas are mission-critical and even modest problems would be catastrophic, and (2) the uncertainties of the robotic solutions outweigh the perceived benefits. Healthcare needs a pathfinder application in which the risk and the investment are small so that the industry can see some concrete evidence of success before taking on the larger opportunities.

Let’s consider a bit of history. The word ‘robot’ was first used by Karl Capek in his play “R.U.R.” (which stands for Rossum’s Universal Robots) that debuted in 1921. He derived the word from the Czech word robota and used it with reference to mechanical humanoids built to perform menial and repetitive tasks. While the play focused on how this intended purpose oppressed the robots, Capek was onto something: repetitive tasks are exactly the type of work where robots surpass humans.

When faced with a repetitive task that requires constant attention to detail, even the most diligent and dedicated human will make an occasional mistake. Once a robot is set up and programmed to perform a task, however, it will perform that task in exactly the same way each and every time without variation. This is not without its own problems, because most robots cannot accommodate even minor changes in the environment that a person would handle without even noticing a problem. An example would be a robot programmed to grip and pick up a soda can from a table while being unable to deal with a can that has fallen over on its side. A great deal of research has gone into making robots more aware or their surroundings and able to handle a limited amount of variation. These robots are neither simple nor cheap.

What may not be obvious is that we are surrounded by robots and use them continuously. In its simplest form, a robot is a device that performs one or more actions in response to one or more stimuli. While there may be a gray area somewhere along the spectrum between a mechanical typewriter and the autonomous vehicles of the DARPA Challenge, a workable definition of a robot is a device that incorporates a programmable processor wherein the actions of the device vary significantly depending on the input received. This excludes a toaster that uses a microprocessor to regulate the temperature of the heating element; however, the vending machine in the cafeteria and the ATM at your bank may qualify as robots. The self-parking cars built by Ford, Lexus, and Toyota definitely qualify as robots. It’s likely that many of the things that you use on a daily basis, from the inkjet cartridges in your printer to the car that you drive, were built on a production line that includes dozens if not hundreds of robots, each performing a specific task.
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"Open-source" robotic surgery platform going to top medical research labs

Engineerblogger
Jan 12, 2012

Team members posed with components of the Raven II surgical robotic systems developed in the Bionics Lab at the Baskin School of Engineering. From left to right: Zachary Wells (bioengineering undergraduate), Calvin Yoo (bioengineering undergraduate), lab director Jacob Rosen (associate professor of computer engineering), Ji Ma (postdoctoral researcher), Joshua Schloemer (economics undergraduate), Farhad Ighani (computer engineering undergraduate), and Kyle Fujisawa (computer engineering undergraduate). (Photo by Carolyn Lagattuta)

Robotics experts at UC Santa Cruz and the University of Washington (UW) have completed a set of seven advanced robotic surgery systems for use by major medical research laboratories throughout the United States. After a round of final tests, five of the systems will be shipped to medical robotics researchers at Harvard University, Johns Hopkins University, University of Nebraska, UC Berkeley, and UCLA, while the other two systems will remain at UC Santa Cruz and UW.

"We decided to follow an open-source model, because if all of these labs have a common research platform for doing robotic surgery, the whole field will be able to advance more quickly," said Jacob Rosen, associate professor of computer engineering in the Baskin School of Engineering at UCSC and principal investigator on the project.

Rosen and Blake Hannaford, director of the UW Biorobotics Laboratory, lead the research groups that developed the Raven II robotic surgery system and its predecessor, Raven I. A grant from the National Science Foundation funded their work to create seven identical Raven II systems. Hannaford said the systems will be shipped out from UW by the end of January. After they are delivered and installed, all seven systems will be networked together over the Internet for collaborative experiments.

Robotic surgery has the potential to enable new surgical procedures that are less invasive than existing techniques. For some procedures, such as prostate surgery, the use of surgical robots is already standard practice. In addition, telesurgery, in which the surgeon operates a robotic system from a remote location, offers the potential to provide better access to expert care in remote areas and the developing world. Having a network of laboratories working on a common platform will make it easier for researchers to share software, replicate experiments, and collaborate in other ways.

Even though it meant giving competing laboratories the tools that had taken them years to develop, Rosen and Hannaford decided to share the Raven II because it seemed like the best way to move the field forward. "These are the leading labs in the nation in the field of surgical robotics, and with everyone working on the same platform we can more easily share new developments and innovations," Hannaford said.

According to Rosen, most research on surgical robotics in the United States has focused on developing new software for various commercially available robotic systems. "Academic researchers have had limited access to these proprietary systems. We are changing that by providing high-quality hardware developed within academia. Each lab will start with an identical, fully-operational system, but they can change the hardware and software and share new developments and algorithms, while retaining intellectual property rights for their own innovations," Rosen said.

The Raven II includes a surgical robot with two robotic arms, a camera for viewing the operational field, and a surgeon-interface system for remote operation of the robot. The system is powerful and precise enough to support research on advanced robotic surgery techniques, including online telesurgery.

In addition to Rosen and Hannaford, UCSC postdoctoral researchers Daniel Glozman and Ji Ma, along with a group of dedicated undergraduate students working in Rosen's Bionics Lab, played a key role in developing the Raven II. Rosen and Glozman have also developed a Raven IV surgical robotics system, which includes four robotic arms and two cameras. The system enables collaboration between two surgeons working from separate locations and connected over the Internet.

Source: University of California - Santa Cruz

Optimized 3D inkjet printing process of hydrogels

Engineerblogger
Jan 10, 2012

Microdrop Printing of Hydrogel Bioinks into 3D Tissue-Like Geometries. Credit  EPFL

The group of Prof. Juergen Brugger (LMIS1 - Laboratoire de microsystèmes 1) demonstrates an optimized 3D inkjet printing process for structuring alginate into a tissue-like microvasculature capable of supporting physiological flow rates. Optimizing the reaction at the single-droplet level enables wet hydrogel droplets to be stacked, thus overcoming their natural tendancy to spread and coalesce. Live cells can be patterned using this process and it can be extended to a range of other hydrogels.

Source:  EPFL


Additional Information:

• "Microdrop Printing of Hydrogel Bioinks into 3D Tissue-Like Geometries" by Kris Pataky,Thomas Braschler, Andrea Negro, Philippe Renaud, Matthias P. Lutolf, and Juergen Brugger

ORNL technology could mean improved prosthesis fitting, design

Engineerblogger
Jan 4, 2012

ORNL biomedical engineers Boyd Evans and John Mueller are working to improve prosthetic fitting and design for young military amputees. (Photo: Jason Richards)

Soldiers returning from war who have lost a leg could lead a more active lifestyle with the help of a technology being developed by Oak Ridge National Laboratory researchers.

ORNL biomedical engineers Boyd Evans and John Mueller are perfecting a portable, wearable system to measure walking patterns that can be applied to real-world activities in a variety of settings.

"For example, if an amputee soldier wants to train and return to active duty, we need to understand how he or she would fare on a military training course, which you can't measure in a laboratory setting," said Evans, who leads the project.

Evans and Mueller are collaborating with Center for the Intrepid at Brooke Army Medical Center to improve prosthesis performance for young soldiers. Wounded soldiers tend to be between ages 18-25, need a prosthetic that will last a long time and are active so they are putting more stress on their healthy limb.

"Lower leg amputees in the military population are typically young, athletic and, besides their injuries, in top physical condition," Mueller said. "For this reason, most military patients want to remain active and in some cases return to active military duty. We are looking at how we can improve prosthesis fit, alignment and function."

Additionally, Evans and Mueller want to develop a gait analysis system that can be utilized outside of a confined laboratory setting. Typically, motion- capture gait analysis is performed in a large, multimillion dollar laboratory using controlled conditions and limited activities.

"The goal of our research is to use the recent advances made in video game technology to develop inexpensive tools for amputee rehabilitation," said Evans. "This will allow advanced rehabilitation techniques to both be used in smaller clinics and to be taken outside the clinic."

To monitor the motion and force of walking patterns, Evans and Mueller are collaborating with BAMC to utilize inertial measurement units and other sensors that can be strapped onto segments of a subject's leg, such as the thigh, calf and foot. The data collected from the IMU transfers to a computer, and algorithms calculate the motions and forces associated with specific joints.

To test the effectiveness of IMUs, Evans and Mueller use a robot leg, which has been programmed with data from a walking person. Evans and Mueller plan on going to the Gait and Motion Analysis Laboratory at Center for the Intrepid in a few months to test their system on a human subject with a prosthetic and healthy leg.

If the prosthesis is not fit or aligned correctly, it could affect a patient's walking patterns, resulting in "asymmetric" gait. These abnormal gait patterns can increase the stress on the healthy limb, leading to problems later in life such as arthritis.

"We have high expectations for this system once it is fully developed," Mueller said. "We think it will improve the prosthetic fitting and aligning process and help lower the risk of chronic joint disease in this group of wounded warriors."

A subset to this overall project, called "Using Kinect for Xbox 360 and Computer Vision to Analyze Human Gait," won the Siemens Competition for Math, Science and Technology in early December. The multi-camera Kinect is connected to a computer that uses body-tracking algorithms to measure how different parts of the leg move when someone's walking. Summer interns Cassee Cain and Ziyuan Liu, who worked with Evans and Mueller, received the top Siemens team award for their project.

Evans and Mueller's work represent an overall collaboration with Otto Bock Healthcare and the Center for the Intrepid at Brooke Army Medical Center. ORNL researcher Randy Lind is developing an advanced platform to measure the forces associated with motion, and researchers Nance Ericson and Ethan Farquhar are integrating the entire system to incorporate wireless data collection.

Source:  Oak Ridge National Laboratory

Where nanotechnology and medicine meet: Researcher shrinks medical tests, makes them more affordable

Canadian University Press
Jan 3, 2012

University of Alberta oncology professor Linda Pilarski, along with her research team, has created a microfluidic chip that can test for up to 80 different genetic markers of cancer. (photo courtesy Dammika Manage)

In a rural medical office, only the bare minimum of medical technology is either affordable or practical, and doctors rely on their own diagnostic skills rather than the expensive tests that doctors at urban centres can more easily access.

This can become a problem when a patient appears whose symptoms could represent a bad flu, but could also be indicative of cancer. In the absence of proper equipment from which many urban doctors benefit, rural patients can be misdiagnosed or mistreated due to the impracticality of running the gamut of tests on them.

Linda Pilarski, a University of Alberta oncology professor and Canada Research Chair in Biomedical Nanotechnology, has been working since 1998 to change this.

Researchers have made great strides in diagnostic tools for detecting the genetic abnormalities that lead to or signal cancers, but many of these remain solely the province of experimental labs because of practical impediments like the cost of equipment.

Aiming specifically to make clinical medicine easier and less expensive to conduct, Pilarski and her team have created a microfluidic chip about the size of a thumbnail that can test for up to 80 different genetic markers of cancer.

“Most of the things we were doing were much too complicated to do in a clinical lab,” Pilarski said. “Their technology has to be far more regulated than what we’re doing in the lab. It may be feasible [to use current experimental tests] in a big research hospital, but not in Stony Plains, in our little health care centre, for example.

“And with tests that are feasible, they’re feasible only because they study many samples at once.”

Acute lymphoblastic leukemia, for example, is a rare cancer that mostly affects children. When detected and treated early enough, it has an exceptionally high cure rate. But if left untreated, it can prove fatal in as little as a few weeks.
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The ROBOCAST Project: Robotic system for assisting neurosurgery

Engineerblogger
Dec 8, 2011

Robocast Plan. Credit: Robocast

 The ROBOCAST project focuses on robot assisted keyhole neurosurgery. This term refers to a brain surgery performed through a very small hole in the skull called burr hole. The reduced dimensions are the reason why it is called also “keyhole”.This surgery is carried out for several interventions, from endoscopy to biopsy and deep brain stimulation. Needles and catheters are inserted into the brain through the tiny hole for biopsy and therapy, including, among others the tasks of blood/fluid sampling, tissue biopsy, cryogenic and electrolytic ablation, brachytherapy, deep brain stimulation (DBS), diagnostic imaging, and a number of other minimally invasive surgical procedures. Related pathologies are tumours, hydrocephalus, dystonia, essential tremor, Parkinson’s Disease, Tourette Syndrome, clinical depression, phantom limb pain, cluster headache and epilepsy.

The ROBOCAST project outcome will be a system for the assistance of the surgeon during keyhole interventions on the brain. It will have a mechatronic part and an intelligence part. The mechatronic device will consist of a robot holding the instruments for the surgeon and inserting them in the brain with a smooth and precise controlled autonomous movement. The trajectory will be defined by the intelligence of the ROBOCAST system and will be approved by the surgeon, which is and remains the responsible of the outcome, before the insertion of the surgical instruments.

Source: Robocast

Additional Information:

• To read the Final Publishable Summary
• The Project Objectives
• The Robocast Challanges 

Everyday Prothetic Finger

Engineerblogger
Nov 28, 2011

X-Fingers surgical steel fingers.

In a former life, Dan Didrick fabricated cosmetic fingers. The key word in that phrase is cosmetic.

“The fingers were only a silicon cap that doesn’t bend,” Didrick said. “We call them Sunday fingers because you wear them to church or dinner and then throw them in a drawer for the week.”

Bedeviled by the cosmetic fingers’ shortcomings, he invented X-Finger, surgical steel fingers that move, flex, and grasp, just like the wearer’s original fingers.

“You can move them as quickly as you can move your prior finger; plus because it’s common to flex your finger from open to closed and the X Finger follows motion of a residual finger, there’s no learning curve,” Didrick said. “A patient can use the device right away after putting it on. They could immediately catch a tossed ball that they see from the corner of their eye.”





Along the 10-year path since his first prototype, Didrick patented the device—which uses no electronics—himself, sought and received coverage from all major medical insurers for the fingers, and taught himself computer-aided design (CAD). That last bit, he said, was the easiest.

A huge proportion of nonfatal accidental amputations involve fingers. The U.S. Bureau of Labor Statistics estimates that finger losses account for about 94 % of job-related amputations.

So Didrick—who got his start in prosthethics as a child, by using materials from his father’s dental office to make movie-quality monster masks—put his skills to use fabricating prosthetic fingers.






But his world, and his job, changed when he met a man who had lost several fingers in an accident and who was deaf. The loss of the fingers made it impossible to communicate in sign language.

“I started by actually carving components out of wood and assembling them into reciprocating series of components that, through leverages, force the mechanics in the shape of a finger to move from a straight to a bent position; from straight to a fist,” Didrick said.

Many amputees retain part of their finger. So the device, when fitted over the hand and the residual finger or fingers, lets a patient move his or her X-Finger by moving the residual finger from extended to bent.




X-Fingers, invented by Dan Didrick, are prosthetic fingers that can be manipulated by wearers through use of their residual finger or fingers. The device lets them regain full use of their finger or fingers.

“So I came up with the assembly, but I was just carving them out of wood,” Didrick said. “Then I started seeking out design engineers. That’s when I realized it can cost tens of thousands of dollars to have a design engineer create an assembly of this nature.”

Though he had majored in business in college, Didrick rose to this first challenge as he would rise to many others while launching X-Finger. He simply bought a CAD package—SolidWorks, from the company in Concord, MA—and quickly ran through the tutorial.

“Then I just started designing the components,” he said. “It only took about two weeks to get the first design. I shipped those to a manufacturer and they replicated them using an EDM machine and sent back components.”

Because all amputation cases are different, Didrick went on to develop what he called an erector set of parts that could be assembled into more than 500 different configurations. That number is likely much higher than 500, but “once I got that high, I became confused counting them,” he said.

The device is composed of stainless steel, with a plastic cap that sits on the tip of the finger and another bit of plastic that sits at the flange. This is covered with a thermoplastic cosmetic skin that is soft and resists tearing. Think of what an artificial fishing worm feels like and how it can stretch.

“We actually contacted a company that was doing a job for the military, and they’d formulated thermoplastic to the same durometer reading as human skin; so it’s almost eerie to touch it, in that it feels like skin,” Didrick said.

Each finger contains 23 moving parts, though depending on the complexity of the case—such as whether the wearer retains a residual finger or not—it could contain more. For those without residual fingers, a wire runs into the webbing between the fingers to receive open and flex impulses. The device is attached to the wrist and fitted over the hand and the residual fingers.

“It was really challenging replacing the ring and middle finger. The joint that controls those residual fingers is in your hand,” Didrick said. “But in this case it needs a probe that goes down into the webbing between the fingers to be controlled by that joint.

For those who have lost four fingers, the device allows the movement of the palm to control all the artificial fingers.

Post Engineering

Though he’d invented the world’s first active prosthetic finger (the passive type is the cosmetic ‘Sunday’ finger), Didrick, who now owns Didrick Medical of Naples, FL, was still an industry outsider.

He bought a book called Patent It Yourself by David Pressman (1979 McGraw-Hill and since updated) and spent a year writing his own patent.

Once the device was patented, FDA representatives and some online help taught him how to write a 513(d) document necessary for device evaluation. Didrick sent his evaluation to the agency and soon received a positive response. X-Fingers (the plural, used when the device contains more than one finger) had been registered with the FDA.

The next step was receiving insurance approval for the fingers. After he won approval from the FDA, he went on to get approval from all major insurance companies, which now cover X-Fingers.

“From there, the device began taking off. The need was great,” Didrick said. “Many amputees had been awaiting something like this.”

What’s little realized, he said, is how many children lose fingers. The largest group of people who lose fingers outside the workplace are children under five, who undergo finger amputation due to accidents like slamming them in a car door.

He also has learned that one out of 200 people will lose one or more fingers within their lifetime. That statistic takes into account people living all over the world.

“It’s not only machinists who lose fingers,” Didrick said.

Because his device is powered by the body, literally the wearer is flexing and bending his hand.

Many of Didrick’s customers pay a deposit in advance, which helps finance the four-employee company and it’s continued innovations.

What’s New and Next?

After his initial success, Didrick began routinely traveling to the Brooke Army Medical Center in San Antonio and to the Walter Reed Army Medical Center in Washington, DC, to fit wounded soldiers. He has also has fitted British soldiers with the device.

The U.S. Department of Defense asked him to design an artificial thumb, which he has also done. It’s not surprisingly called the X-Thumb.

He’s now at work on a thin glove that would enable those with paralyzed hands who retain some mobility in the wrist to use that mobility to control their hands.

Didrick is also trying to help children whose insurance companies deny them coverage because they grow out of their prosthetics too fast. The costs of producing children’s X-Fingers are high because of the variation in injuries and finger dimensions in smaller fingers and hands. He’s recently established the nonprofit 501(c)(3) organization, World Hand Foundation, to cover costs to provide X-Fingers for those who cannot afford to pay for them.

And he’s still using his original CAD package.

“If we needed the funds to hire a professional design team we’d never be able to do this,” Didrick said.

Source: ASME