Cleveland, Ohio, and Chicago, Illinois – Scientists at the University of Chicago and Case Western Reserve University have found a way to produce realistic sensations of touch in two human amputees by directly stimulating the nervous system.

The study, published Oct. 26, 2016, in Science Translational Medicine (STM), confirms earlier research on how the nervous system encodes the intensity, or magnitude, of sensations. It is the second of two groundbreaking publications this month by University of Chicago neuroscientist Sliman Bensmaia, PhD, using neuroprosthetic devices to recreate the sense of touch for amputee or quadriplegic patients with a "biomimetic" approach that approximates the natural, intact nervous system.

On Oct. 13, 2016, in a separate publication from STM, Bensmaia and a team led by Robert Gaunt, PhD, from the University of Pittsburgh, announced that for the first time, a paralyzed human patient was able to experience the sense of touch through a robotic arm that he controls with his brain. In that study, researchers interfaced directly with the patient's brain, through an electrode array implanted in the areas of the brain responsible for hand movements and for touch, which allowed the man to both move the robotic arm and feel objects through it.

The new study takes a similar approach in amputees, working with two male subjects who each lost an arm after traumatic injuries. In this case, both subjects were implanted with neural interfaces, devices embedded with electrodes that were attached to the median, ulnar and radial nerves of the arm. Those are the same nerves that would carry signals from the hand were it still intact.

"If you want to create a dexterous hand for use in an amputee or a quadriplegic patient, you need to not only be able to move it, but have sensory feedback from it," said Bensmaia, who is an associate professor of organismal biology and anatomy at the University of Chicago. "To do this, we first need to look at how the intact hand and the intact nervous system encodes this information, and then, to the extent that we can, try to mimic that in a neuroprosthesis."

Recreating different sensations of intensity
The latest research is a joint effort by Bensmaia and Dustin Tyler, PhD, the Kent H. Smith Professor of Biomedical Engineering at Case Western Reserve University, who works with a large team trying to make bionic hands clinically viable. Tyler's team, led by doctoral student Emily Graczyk, systematically tested the subjects' ability to distinguish the magnitude of the sensations evoked when their nerves were stimulated through the interface. They varied aspects of the signals, such as frequency and intensity of each electrical pulse. The goal was to understand if there was a systematic way to manipulate the sensory magnitude.

Earlier research from Bensmaia's lab predicted how the nervous system discerns intensity of touch, for example, how hard an object is pressing against the skin. That work suggested that the number of times certain nerve fibers fire in response to a given stimulus, known as the population spike rate, determines the perceived intensity of a given stimulus.

Results from the new study verify this hypothesis: A single feature of electrical stimulation – dubbed the activation charge rate – was found to determine the strength of the sensation. By changing the activation charge rate, the team could change sensory magnitude in a highly predictable way. The team then showed that the activation charge rate was also closely related to the evoked population spike rate.

Building neuroprosthetics that approximate the natural nervous system
While the new study furthers the development of neural interfaces for neuroprosthetics, artificial touch will only be as good as the devices providing input. In a separate paper published earlier this year in IEEE Transactions on Haptics, Bensmaia and his team tested the sensory abilities of a robotic fingertip equipped with touch sensors.

Using the same behavioral techniques that are used to test human sensory abilities, Bensmaia's team, led by Benoit Delhaye and Erik Schluter, tested the finger's ability to distinguish different touch locations, different pressure levels, the direction and speed of surfaces moving across it and the identity of textures scanned across it. The robotic finger (with the help of machine learning algorithms) proved to be almost as good as a human at most of these sensory tasks. By combining such high-quality input with the algorithms and data Bensmaia and Tyler produced in the other study, researchers can begin building neuroprosthetics that approximate natural sensations of touch.

Without realistic, natural-feeling sensations, neuroprosthetics will never come close to achieving the dexterity of our native hands. To illustrate the importance of touch, Bensmaia referred to a piano. Playing the piano requires a delicate touch, and an accomplished pianist knows how softly or forcefully to strike the keys based on sensory signals from the fingertips. Without these signals, the sounds the piano would make would not be very musical.

"The idea is that if we can reproduce those signals exactly, the amputee won't have to think about it, he can just interact with objects naturally and automatically. Results from this study constitute a first step towards conveying finely graded information about contact pressure," Bensmaia said.

This article has been republished from materials provided by University of Chicago Medical Center. Note: material may have been edited for length and content. For further information, please contact the cited source.

Research paper: Dustin J. Tyler et al. The Neural Basis of Perceived Intensity in Natural and Artificial Touch. Science Translational Medicine, 2016; DOI: 10.1126/scitranslmed.aaf5187

Source: Case Western Reserve University & University of Chicago

Washington, DC – Stroke and spinal cord injury patients often require gait rehabilitation to regain the ability to walk or to help strengthen their muscles. Wearable "robot-assisted training" is quickly emerging as a method that helps improve this rehab process.

In a major advance, researchers from Beihang University in China and Aalborg University in Denmark have designed a lower-limb robot exoskeleton – a wearable robot – that features natural knee movement to greatly improve patients' comfort and willingness to wear it for gait rehab.

As the team reports this week in Review of Scientific Instruments, from AIP Publishing, their robotic exoskeleton is intended to help stroke patients strengthen their physical fitness, aid the rehabilitation training of paralyzed patients, or to assist those who need help performing daily activities.

Exoskeleton robots aren't new – they've been studied extensively and many designs have focused on lower limbs. This team's approach focused instead on the knee joint, one of the most complex mechanical systems within the human body and a critical player during gait.

The knee joint's motion is actuated by several skeletal muscles along its articular surfaces, and its center of rotation moves. The researchers wondered if a parallel mechanism similar to skeletal muscles would be useful for designing a bionic knee joint.

"Our new design features a parallel knee joint to improve the bio-imitability and adaptability of the exoskeleton," explained Weihai Chen, a professor at Beihang University's School of Automation Science and Electrical Engineering, in Beijing, China.

Specifically, the team's exoskeleton taps a hybrid serial-parallel kinematic structure consisting of a 1-degree of freedom (DOF) hip joint module and a 2-DOF knee joint module in the sagittal plane. And a planar 2-DOF parallel mechanism helps to fully accommodate the motion of the human knee -- enabling rotation and relative sliding.

Movement transparency is critical when wearing a robot for gait rehab. In other words: When wearing the exoskeleton, its movement should be synchronized and consistent with a patient's natural movement.

"If not, it exerts extra forces on the human joint," Chen said. "And this extra force causes patient discomfort and unnatural movements."

So the team focused on bionic mechanical design to achieve this goal.

"To improve the transparency of the robot, we studied the structure of the human body, then built our model based on a biometric design of the lower limb exoskeleton," Chen continued.

This design is the first known use of a parallel mechanism at the knee joint to imitate skeletal muscles. "Our design goes beyond solving the transparency problem in the knee joint – and it's a simple structure," Chen added. "Unlike most previous exoskeletons, which simplified the knee joint as a pin joint, ours provides 2 DOF to make the exoskeleton's movement consistent with a patient's natural movement."

As far as its applications, the exoskeleton's main role will be to help stroke or spinal cord injury patients with their rehab.

"We plan to streamline it to be wearable and to provide a comfortable training experience," Chen said. "Our team is also developing virtual reality games to help make the training process more enjoyable."

The team is exploring controlling their exoskeleton via patients' electromyography (EMG) signal – which records electrical activity produced by skeletal muscles – so that they'll be more actively involved in their training.

"We can obtain the movement intention from a patient's electroencephalogram (EEG) – brain signals – and use it to directly control the exoskeleton," Chen explained. "These improvements should enable easy control and make the exoskeleton act as part of the human body."

The next step for the team is to collaborate with hospitals, because testing the robot out with patients can provide critical feedback from patients and doctors.

"We'd also like to commercialize it in the near future, so we'll be working to make the robot's appearance fancier and enhancing the user interface to be more user friendly," Chen noted.

Source: American Institute of Physics

Boston, Massachusetts – Implanted medical devices such as left ventricular-assist devices for patients with heart failure or other support systems for patients with respiratory, liver or other end organ disease save lives every day.  However, bacteria that form infectious biofilms on those devices, called device-associated infections, not only often sabotage their success but also contribute to the rampant increase in antibiotic resistance currently seen in hospitals.

As reported in Biomaterials, a team led by Joanna Aizenberg, Ph.D., and Elliot Chaikof, M.D., Ph.D., at the Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied Sciences at Harvard University, as well as the Beth Israel Deaconess Medical Center (BIDMC), has created self-healing slippery surface coatings with medical-grade teflon materials and liquids that prevent biofilm formation on medical implants while preserving normal innate immune responses against pathogenic bacteria.

The technology is based on the concept of slippery liquid-infused porous surfaces (SLIPS) developed by Aizenberg, who is a Wyss Institute Core Faculty member, Professor of Chemistry and Chemical Biology and the Amy Smith Berylson Professor of Materials Science at SEAS. Inspired by the carnivorous Nepenthes pitcher plant, which uses the porous surface of its leaves to immobilize a layer of liquid water, creating a slippery surface for capturing insects, Aizenberg previously engineered industrial and medical surface coatings that are able to repel unwanted substances as diverse as ice, crude oil and biological materials.

“We are developing SLIPS recipes for a variety of medical applications by working with different medical-grade materials, tuning the chemical and physical features of these solids and the infused lubricants to ensure the stability of the coating, and carefully pairing the non-fouling properties of the integrated SLIPS materials to specific disturbing factors, contaminating environments and performance requirements,” Aizenberg says. “Here we have extended our repertoire of materials classes and applied the SLIPS concept very convincingly to medical-grade teflon, demonstrating its enormous potential in implanted devices prone to bacterial fouling and infection.”

First, the team searched ex vivo for the teflon material that would work best with a selection of compatible lubricants to provide a long-lived repellent surface against a common device-associated bacterial strain. The most advantageous teflon-lubricant combinations had to preserve the anti-bacterial activity of innate immune cells that provide the natural first-line response against invading bacteria. The winning material was ‘expanded polytetrafluoroethylene’ (ePTFE). Used in prosthetic grafts for cardiovascular reconstruction, mesh for hernia repair, as well as implants in a wide variety of reconstructive surgery, ePTFE tested well with lubricants with proven acceptable safety profiles.

Moving to a rodent model, the team compared bacterial and tissue responses to implanted hernia meshes with or without a SLIPS surface after infecting the animals with Staphylococcus aureus.

“SLIPS coatings yielded extremely favorable responses in vivo:  they resisted infection by bacteria and were associated with considerably less infiltrating immune cells and inflammatory abscesses than non-coated ePTFE,” said Chaikof, who is a Wyss Institute Associate Faculty member, Chairman of the Roberta and Stephen R. Weiner Department of Surgery and Surgeon-in-Chief at BIDMC.

“At present, patients who receive implants for the repair, reconstruction or replacement of diseased or damaged organs or tissues or otherwise depend upon temporary life sustaining support systems, often require antibiotics at the time of implantation to keep the risk of bacterial infection at bay.  SLIPS coatings one day could obviate the widespread use of antibiotics, minimize the development of antibiotic resistant microorganisms, and enhance the capacity of temporary or permanent artificial devices to resist infection,” Chaikof says.

“This new study by Joanna and Elliot exemplifies the Wyss Institute model in which collaborations between basic scientists focused on industrial applications and clinicians working in the medical area are fostered in a way that can lead to unexpected developments – in this case, one that has the potential to have a major positive impact in the clinical setting,” states Don Ingber, M.D., Ph.D., Founding Director of the Wyss Institute, Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

Previous medical SLIPS applications include coatings that can repel bacteria and blood from small medical implants, tools and surgical instruments that are made of steel or, more recently, coatings that help keep the glass surfaces of endoscopy and bronchoscopy lenses free from highly contaminating body fluids and thus transparent during procedures.

Source: Wyss Institute

Rockville, Maryland – The global wearable medical device market is valued at just more than $13.2 billion for 2016, per Kalorama Information. The wearable technology industry, in general, is continuing to expand and healthcare is no exception. In fact, healthcare is among the fastest growing segments for wearables due to the overwhelming need to monitor diseases and aging populations. The healthcare market research firm's report, “The Market for Wearable Devices,” examines the global market, providing market size and forecasts.

Wearable devices are no longer just focusing on one measurement – such as the number of steps taken in a day – but are focusing on a variety of bodily measurements such as heart rate, breathing, blood pressure and many others. Advances in wearable medical devices include new miniaturized sensors; peripherals; real-time measurements and interactions, wireless communication, sort-and-analyze features, portability and data transfer capabilities.

"Sales in the lifestyle and fitness segment dominate the market," says Bruce Carlson, Publisher of Kalorama Information. "But we shouldn't count out other applications – the diagnostics and monitoring segment is making a strong showing as well. Long term, these devices will go beyond fitness."

Devices for lifestyle, diagnostics, therapeutics, injury prevention comprise market
The medical device market includes products in four segments:

Lifestyle and fitness – The wearable lifestyle and fitness devices segment is the most advanced category of the wearable medical devices market. Included in this category are fitness trackers, activity trackers, and sports trackers. Personal health monitoring has been a large contributor to this arena and continues to blend the lines between medical devices and lifestyle devices. Although many of the lifestyle and fitness devices are not technically medical devices, the U.S. Food and Drug Administration (FDA) has defined them as general wellness devices.

Diagnostics and monitoring – Wearable diagnostic and monitoring devices are non-invasive devices that provide valuable health information. The diagnostic and monitoring segment of wearable medical devices represent an exciting opportunity for industry participants and includes devices that perform glucose monitoring; cardiovascular monitoring and event recording; pregnancy, obstetrics, fetal and infant monitoring; neurological monitoring, such as electroencephalogram (EEG) tests; and sleep monitoring devices.

Therapeutic – Wearable systems that monitor disease states and track health activity, store data and deliver feedback therapy are the next frontier in personalized medicine and healthcare. These include respiratory therapy, insulin management, pain management devices.

Injury prevention and rehabilitation – Wearable injury prevention and rehabilitation devices are non-invasive devices that provide valuable health information. The injury prevention and rehabilitation segment includes body motion, wearable sensing garment, fall detection, and other wearable injury prevention and rehabilitation devices.

Looking to the future
There are many issues facing this industry. Some issues are helping to propel the market; while other issues may retard growth moving forward. Kalorama Information expects the industry will work through the issues and enjoy strong growth in the future.

New wireless and Bluetooth technologies, improved infrastructure, and patient familiarity with wireless devices are all combining to advance sales and use of new technologies in wearable medical devices. Patients are now more comfortable with using monitoring devices, then having a hub send the data to their healthcare provider via telephone, mobile phone, wireless, PC, or other connection. Although technology is the mainstay of advancements in healthcare, there are times when the pace of technological achievements runs faster than they can be utilized and not all industries embrace change equally. Though the medical community sometimes lags in IT area advancements, manufacturers in this field have been working diligently to engineer systems that make it easier for patients and physicians to incorporate wearable medical devices into their daily routine.

The "Market for Wearable Devices" focuses on products in the four main market segments, providing market size and forecasts for 2012-2021 and sales distribution by region (North America, Europe, Asia Pacific, and ROW market overviews) for each. The report discusses as well the market drivers and benefits associated with the adoption of wearable devices in the healthcare industry, as well as some significant market challenges.

There are a vast number of companies offering some form of wearable advanced feature: wireless/remote health monitoring technologies, patient data processing applications and equipment, and applications and equipment that transfer patient monitoring data to EMRs. The “Market for Wearable Devices” profiles companies that are among those providing leading products and some of the most interesting new technologies, including Philips, Dexcom, Medtronic, Bioness, Fitbit, and Apple.

Source: Kalorama Information