Category: Implants and Prostheses

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Brain-computer Interfaces Deemed Safe for Long-term Use

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Patient with complete spinal cord injury walking at EPFL Campus after 5 months of rehab. ©NeuroRestore Jimmy Ravie

For people with paralysis caused by neurologic injury or disease, brain-computer interfaces (BCIs) can potentially restore mobility and function by transmitting neural data to external devices such as mobility aids, which have already shown promise in trials.

Although implanted brain sensors, the core component of many brain-computer interfaces, have been used in neuroscientific studies with animals for decades and have been approved for short term use (< 30 days) in humans, the long-term safety of this technology in humans is unknown.

New results published in Neurology from the BrainGate feasibility study, the largest and longest-running clinical trial of an implanted BCI, suggest that these sensors’ safety is similar to other chronically implanted neurologic devices, with skin irritation around the implant interface.

This new report from a Massachusetts General Hospital (MGH)-led team, examined data from 14 adults with quadriparesis from spinal cord injury, brainstem stroke, or ALS who were enrolled in the BrainGate trial from 2004 to 2021 through seven clinical sites in the United States.

Participants underwent surgical implantation of one or two microelectrode arrays in a part of the brain responsible for generating the electrical signals that control limb movement. With these “Utah” microelectrode arrays, the brain signals associated with the intent to move a limb can then be sent to a nearby computer that decodes the signal in real-time and allows the user to control an external device simply by thinking about moving a part of their body.

The authors of the study report that across the 14 enrolled research participants, the average duration of device implantation was 872 days, yielding a total of 12 203 days for safety analyses. There were 68 device-related adverse events, including 6 device-related serious adverse events.

The most common device-related adverse event was skin irritation around the portion of the device that connects the implanted sensor to the external computer system. Importantly, they report that there were no safety events that required removal of the device, no infections of the brain or nervous system, and no adverse events resulting in permanently increased disability related to the investigational device.

“This interim report demonstrates that the investigational BrainGate Neural Interface system, which is still in ongoing clinical trials, thus far has a safety profile comparable to that of many approved implanted neurologic devices, such as deep brain stimulators and responsive neurostimulators,” says lead author Daniel Rubin, MD, PhD.

“Given the rapid recent advances in this technology and continued performance gains, these data suggest a favorable risk/benefit ratio in appropriately selected individuals to support ongoing research and development,.” said Rubin.

Leigh Hochberg, MD, PhD, director of the BrainGate consortium and clinical trials and the article’s senior author emphasised the importance of ongoing safety analyses as surgically placed brain-computer interfaces advance through clinical studies.

“While our consortium has published more than 60 articles detailing the ever-advancing ability to harness neural signals for the intuitive control of devices for communication and mobility, safety is the sine qua non of any potentially useful medical technology,” says Hochberg.

“The extraordinary people who enroll in our ongoing BrainGate clinical trials, and in early trials of any neurotechnology, deserve tremendous credit. They are enrolling not to gain personal benefit, but because they want to help,” said Hochberg.

Source: Massachusetts General Hospital

Categories : Implants and Prostheses Metabolic DisordersTags :

Artificial Pancreas Successfully Trialled for Type 2 Diabetes

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Diabetes - person measures blood glucose
Photo by Photomix Company from Pexels

Cambridge scientists have successfully trialled an artificial pancreas for use by patients living with type 2 diabetes. They report in Nature Medicine that the device doubled the amount of time patients were in the target range for glucose compared to standard treatment and halved the time spent experiencing high glucose levels.

The artificial pancreas developed by University of Cambridge researchers combines an off-the-shelf glucose monitor and insulin pump with an app developed by the team, known as CamAPS HX. This app is run by an algorithm that predicts how much insulin is required to maintain glucose levels in the target range.

The researchers have previously shown that an artificial pancreas run by a similar algorithm is effective for patients living with type 1 diabetes, from adults through to very young children. They have also successfully trialled the device in patients with type 2 diabetes who require kidney dialysis.

Today, in Nature Medicine, the team report the first trial of the device in a wider population living with type 2 diabetes (not requiring kidney dialysis). Unlike the artificial pancreas used for type 1 diabetes, this new version is a fully closed loop system, whereas patients with type 1 diabetes need to tell their artificial pancreas that they are about to eat to allow adjustment of insulin, for example, with this version they can leave the device to function entirely automatically.

The researchers recruited 26 patients who were randomised to one of two groups – the first group would trial the artificial pancreas for eight weeks and then switch to the standard therapy of multiple daily insulin injections; the second group would take this control therapy first and then switch to the artificial pancreas after eight weeks.

The team used several measures to assess how effectively the artificial pancreas worked. The first was the proportion of time that patients spent with their glucose levels within a target range of between 3.9 and 10.0mmol/L. On average, patients using the artificial pancreas spent two-thirds (66%) of their time within the target range, compared to control (32%).

A second measure was the proportion of time spent with glucose levels above 10.0mmol/L. Over time, high glucose levels raise the risk of potentially serious complications. Patients taking the control therapy spent two-thirds (67%) of their time with high glucose levels — this was halved to 33% when using the artificial pancreas.

Average glucose levels fell from 12.6mmol/L when taking the control therapy to 9.2mmol/L while using the artificial pancreas.

The app also reduced levels of a molecule known as glycated haemoglobin, or HbA1c. Glycated haemoglobin develops when haemoglobin, a protein within red blood cells that carries oxygen throughout the body, joins with glucose in the blood, becoming ‘glycated’. By measuring HbA1c, clinicians are able to get an overall picture of what a person’s average blood sugar levels have been over a period of weeks or months. For people with diabetes, the higher the HbA1c, the greater the risk of developing diabetes-related complications. After the control therapy, average HbA1c levels were 8.7%, while after using the artificial pancreas they were 7.3%.

No patients experienced dangerously-low blood sugar levels (hypoglycaemia) during the study. One patient was admitted to hospital while using the artificial pancreas, due to an abscess at the site of the pump cannula.

Dr Charlotte Boughton from the Wellcome-MRC Institute of Metabolic Science at the University of Cambridge, who co-led the study, said: “Many people with type 2 diabetes struggle to manage their blood sugar levels using the currently available treatments, such as insulin injections. The artificial pancreas can provide a safe and effective approach to help them, and the technology is simple to use and can be implemented safely at home.”

Dr Aideen Daly, also from the Wellcome-MRC Institute of Metabolic Science, said: “One of the barriers to widespread use of insulin therapy has been concern over the risk of severe ‘hypos’ — dangerously low blood sugar levels. But we found that no patients on our trial experienced these and patients spent very little time with blood sugar levels lower than the target levels.”

Feedback from participants suggested that participants were happy to have their glucose levels controlled automatically by the system, and nine out of ten (89%) reported spending less time managing their diabetes overall. Users highlighted the elimination of the need for injections or fingerprick testing, and increased confidence in managing blood glucose as key benefits. Downsides included increased anxiety about the risk of hypoglycaemia, which the researchers say may reflect increased awareness and monitoring of glucose levels, and practical annoyances with wearing of devices.

The team now plan to carry out a much larger multicentre study to build on their findings and have submitted the device for regulatory approval with a view to making it commercially available for outpatients with type 2 diabetes.

Source: University of Cambridge

Categories : Antibiotics Implants and ProsthesesTags :

Injectable Hydrogel Treats Infections from Hip and Knee Replacements

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Source: Pixabay CC0

In APL Bioengineering, researchers report on an injectable hydrogel that treats infections around hip and knee replacement prosthetics without the problems caused by current treatments. Testing showed that the gel inhibits common bacteria and promotes tissue regrowth.

After hip and knee replacement surgeries, pathogenic bacteria can adhere to the surface of the joint prosthesis and form a dangerous biofilm. Gold standard clinical methods use potent antibiotics and further surgery, including removal of infected tissue and transplantation of new tissue, to treat these infections. However, these strategies run into problems with hyper-resistant bacteria caused by the abuse of antibiotics, persistent damage caused by tissue removal, difficulties in obtaining tissue donors, and toxicity and immune system complications.

A team from Shanghai Jiao Tong University School of Medicine created ablack phosphorus-enhanced antibacterial injectable hydrogel to re-establish biological barriers in soft tissue and suppress persistent infections. The gel has a porous structure, excellent injectability, and rapid self-healing properties.

“It is important to explore a new strategy for treatment of infected soft tissue wounds because it is directly related to prognosis,” said author Ruixin Lin. “We aspire to develop a simpler, safer method to help more patients avoid suffering and help more doctors make the right choices.”

In vitro tests showed the hydrogel had good stability and low toxicity to tissue cells. Irradiating the gel with near infrared light causes it to release silver ions. This process was highly efficient at inhibiting the common bacteria S. aureus.

“Furthermore, an in vivo infected wound model showed that the hydrogel could not only inhibit the persistent infection of the wound, but also accelerate the deposition of collagen fibres and angiogenesis, thereby realizing the repair of the natural barrier of soft tissue,” said Lin.

The novel hydrogel provides a safe and feasible synergistic antibacterial strategy for infected soft tissue healing. The team believes that it solves current clinical problems, such as stubborn infections caused by antibiotic resistance, and provides new ideas for minimally invasive treatment. They hope to see it used in the clinic after conducting sufficient studies on its underlying mechanisms.

Source: American Institute of Physics

Categories : Implants and Prostheses Pain ManagementTags : 1 Comment

Do Spinal Cord Stimulators Live up to Pain Relief Expectations?

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Photo by Cottonbro on Pexels

A comparison of spinal cord stimulators (SCS) revealed that the implants only offer a notable benefit within the first year of use, while also being associated with a high risk of adverse effects – nearly one in five, and a similar number requiring device revision or removal.

In this propensity-matched comparative effectiveness research analysis of 7560 insured individuals published in JAMA Neurology, treatment with SCS was not associated with a reduction in use of opioids, pain injections, radiofrequency ablation, or spine surgery at two years.

The study used administrative claims data, including longitudinal medical and pharmacy claims, from 2020–2021. Patients with incident diagnosis codes for failed back surgery syndrome, complex regional pain syndrome, chronic pain syndrome, and other chronic postsurgical back and extremity pain were included in this study.

Patients were an average age of 63.5 years and 59.3% were female. Among matched patients, during the first year, patients treated with SCSs had higher odds of chronic opioid use (adjusted odds ratio [aOR], 1.14) compared with patients treated with CMM but lower odds of epidural and facet corticosteroid injections (aOR, 0.44), radiofrequency ablation (aOR, 0.57), and spine surgery (aOR, 0.72).

During the second year, these beneficial effects disappeared. Compared to CMM there were no significant differences with SCS use in:

  • chronic opioid use (aOR, 1.06),
  • epidural and facet corticosteroid injections (aOR, 1.00)
  • radiofrequency ablation (aOR, 0.84)
  • spine surgery (aOR, 0.91)

Overall, 226 of 1260 patients (17.9%) treated with SCS experienced SCS-related complications within 2 years, and 279 of 1260 patients (22.1%) had device revisions and/or removals, which were not always for complications. Total costs of care in the first year were $39 000 higher with SCS than CMM and similar between SCS and CMM in the second year.

In an accompanying editorial, Prasad Shirvalkar, MD, PhD, and Lawrence Poree. MD, PhD, MPH conclude: “The findings appear to belie the popular belief that SCS may result in reduced opioid medication usage or overall fewer physician visits in the years immediately following device implant.”

They continue: “Notably, a formal cost-utility analysis was not done, and therefore caution is advised not to interpret these results as an argument against the therapeutic effectiveness of SCS for reducing symptoms or improving daily function. After all, there is surely some intrinsic social value to alleviating symptoms and improving individual function that may justify health care costs for chronic pain, just as in the practical treatment of cancer or heart disease.”

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Non-toxic Liquid Metal Breaks Down Aluminium Medical Implants

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Photo by Louise Reed on Unsplash

By taking advantage of a phenomenon that is usually an engineering headache, MIT researchers have designed a liquid metal to safely disintegrate metal medical implants and drug depots when they are not needed anymore.

In their work published in Advanced Materials, the researchers showed that aluminium biomedical devices can be disintegrated by exposing them to a liquid metal known as eutectic gallium-indium (EGaIn). In practice, this might work by painting the liquid onto staples used to hold skin together, for example, or by administering EGaIn microparticles to patients.

According to the researchers, disintegrating metal devices in this way could eliminate the need for surgical or endoscopic removal procedures.

“It’s a really dramatic phenomenon that can be applied to several settings,” says senior author Giovanni Traverso, assistant professor of mechanical engineering at MIT and a gastroenterologist at Brigham and Women’s Hospital. “What this enables, potentially, is the ability to have systems that don’t require an intervention such as an endoscopy or surgical procedure for removal of devices.”

Breaking down metals

For several years, Traverso’s lab has been working on ingestible devices that could remain in the digestive tract for days or weeks, releasing drugs on a specific schedule.

Most of those devices are made from polymers, but recently the researchers have been exploring the possibility of using metals, which are stronger and more durable. However, one of the challenges of delivering metal devices is finding a way to remove them once they’re no longer needed.

Right now, removing the staples can actually induce more tissue damage

Vivian Feig, MIT POSTDOC & First Author

To create devices that could be broken down on demand inside the body, the MIT turned to liquid metal embrittlement. This process has been well-studied as a source of failure in metal structures, including those made from zinc and stainless steel. It is why metal liquids such as mercury are not allowed on aircraft.

“It’s known that certain combinations of liquid metals can actually get into the grain boundaries of solid metals and cause them to dramatically weaken and fail,” says first author Vivian Feig, an MIT postdoc. “We wanted to see if we could harness that known failure mechanism in a productive way to build these biomedical devices.”

One room-temperature liquid metal that can induce embrittlement is gallium. For this study, the researchers used eutectic gallium-indium, an alloy of gallium that scientists have explored for a variety of applications in biomedicine as well as energy and flexible electronics.

For the devices themselves, the researchers chose to use aluminium, which is known to be susceptible to embrittlement when exposed to gallium.

Gallium weakens solid metals such as aluminium in two ways. First, it can diffuse through the grain boundaries of the metal – border lines between the crystals that make up the metal – causing pieces of the metal to break off. The MIT team showed that they could harness this phenomenon by designing metals with different types of grain structures, allowing the metals to break into small pieces or to fracture at a given point.

Gallium also prevents aluminium from forming a protective oxide layer on its surface, which increases the metal’s exposure to water and enhances its degradation.

The MIT team showed that after they painted gallium-indium onto aluminium devices, the metals would disintegrate within minutes. The researchers also created nanoparticles and microparticles of gallium-indium and showed that these particles, suspended in fluid, could also break down aluminium structures.

On-demand disintegration

While the researchers began this effort as a way to create devices that could be broken down in the gastrointestinal tract, they soon realised that it could also be applied to other biomedical devices such as staples and stents.

To demonstrate GI applications, the researchers designed a star-shaped device, with arms attached to a central elastomer by a hollow aluminium tube. Drugs can be carried in the arms, and the shape of the device helps it be retained in the GI tract for an extended period of time. In a study in animals, the researchers showed that this kind of device could be broken down in the GI tract upon treatment with gallium-indium.

The researchers then created aluminium staples and showed that they could be used to hold tissue together, then dissolved with a coating of gallium-indium.

“Right now, removing the staples can actually induce more tissue damage,” Feig says. “We showed that with our gallium formulation we can just paint it on the staples and get them to disintegrate on-demand instead.”

The researchers also showed that an aluminium stent they designed could be implanted in oesophageal tissue, then broken down by gallium-indium.

Currently, oesophageal stents are either left in the body permanently or endoscopically removed when no longer needed. Such stents are often made from metals such as nitinol, an alloy of nickel and titanium. The researchers are now working to see if they could create dissolvable devices from nitinol and other metals.

“An exciting thing to explore from a materials science perspective is: Can we take other metals that are more commonly used in the clinic and modify them so that they can become actively triggerable as well?” Feig says.

Initial toxicity studies in rodents showed that gallium-indium was non-toxic even at high doses. However, more study would be needed to ensure it would be safe to administer to patients, the researchers say.

Source:

Categories : Cardiovascular Disease Implants and ProsthesesTags :

A New Pacemaker that Works with Light, not Electricity

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Pacemakers regulate the heartbeats of people with chronic heart diseases like atrial fibrillation and other forms of arrhythmia. However, pacemaker implantation is an invasive procedure, and the lifesaving pacing the devices provide can be extremely painful. Pacemakers also can only be used to treat a few specific types of disease.

In Science Advances, researchers describe their new pacemaker design that uses light and optogenetics that could be implanted with a less invasive procedure, also causing less pain in operation. As well as triggering cardiac neurons with light, the new design can also be powered by light, removing the need for a battery which has to be surgically replaced.

The study was helmed by researchers in the Gutruf Lab, led by biomedical engineering assistant professor and Craig M. Berge Faculty Fellow Philipp Gutruf.

Currently available pacemakers work by implanting one or two leads, or points of contact, into the heart with hooks or screws. If the sensors on these leads detect a dangerous irregularity, they send an electrical shock through the heart to reset the beat.

“All of the cells inside the heart get hit at one time, including the pain receptors, and that’s what makes pacing or defibrillation painful,” Gutruf said. “It affects the heart muscle as a whole.”

The device Gutruf’s team has developed, yet to be tested in humans, would use a digitally created mesh that would send much more targeted signals.

Modifying cardiac neurons to respond to light

Optogenetics modifies cells, usually neurons, to make them responsive to light. This technique only targets cardiomyocytes, the cells of the muscle that trigger contraction and make up the beat of the heart. This precision will not only reduce pain for pacemaker patients by bypassing the heart’s pain receptors, it will also allow the pacemaker to respond to different kinds of irregularities in more appropriate ways. For example, during atrial fibrillation, the upper and lower chambers of the heart beat asynchronously, and a pacemaker’s role is to get the two parts back in line.

“Whereas right now, we have to shock the whole heart to do this, these new devices can do much more precise targeting, making defibrillation both more effective and less painful,” said Igor Efimov, professor of biomedical engineering and medicine at Northwestern University, where the devices were lab-tested. “This technology could make life easier for patients all over the world, while also helping scientists and physicians learn more about how to monitor and treat the disease.”

To ensure the light signals can reach many different parts of the heart, the team created a design that involves encompassing the organ, rather than implanting leads that provide limited points of contact.

The new pacemaker model consists of four petallike structures made of thin, flexible film, which contain light sources and a recording electrode. The petals, specially designed to accommodate the way the heart changes shape as it beats, fold up around the sides of the organ to envelop it, like a flower closing up at night.

“Current pacemakers record basically a simple threshold, and they will tell you, ‘This is going into arrhythmia, now shock!'” Gutruf said. “But this device has a computer on board where you can input different algorithms that allow you to pace in a more sophisticated way. It’s made for research.”

Because the system uses light to affect the heart, rather than electrical signals, the device can continue recording information even when the pacemaker needs to defibrillate. In current pacemakers, the electrical signal from the defibrillation can interfere with recording capabilities, leaving physicians with an incomplete picture of cardiac episodes. Additionally, the device does not require a battery, which could save pacemaker patients from needing to replace the battery in their device every five to seven years, as is currently the norm.

Gutruf’s team collaborated with researchers at Northwestern University on the project. While the current version of the device has been successfully demonstrated in animal models, the researchers look forward to furthering their work, which could improve the quality of life for millions of people.

Source: University of Arizona

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Silver Lining for Titanium Implants Reduces Infection Risk

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Photo by Mehmet Turgut Kirkgoz on Unsplash

A novel method of coating titanium implants for orthopaedic and trauma surgery promises to reduce infection complications, according to a paper published in Langmuir: The ACS Journal of Fundamental Interface Science.

Infection remains a major complication when implants such as screws and plates are embedded into people during procedures like joint replacement surgery and spinal fusion surgery. Most infections occur because the devices’ titanium implant surfaces have poor antibacterial and osteoinductive properties, despite titanium possessing the highest biocompatibility of all metals.

Assistant Professor Rahim Rahimi at Purdue University has developed a process which immobilises silver onto the implant surfaces of titanium orthopaedic devices to improve their antibacterial properties and cellular integration. The process can be implemented onto many currently utilised metal implant surfaces.

The antibacterial efficacy of laser-nanotextured titanium surfaces with laser-immobilised silver was tested against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The surfaces retained efficient and stable antimicrobial properties for more than six days. The laser-nanotextured titanium surfaces also provided a 2.5-fold increase in osseointegration properties compared with a pristine titanium implant surface.

“The first step of the two-step process creates a hierarchical nanostructure onto the titanium implant surface to enhance the bone cells’ attachment,” A/Prof Rahimi said. “The second step immobilises silver with antibacterial properties onto the titanium implant surface.

“The technology allows us to not only immobilise antibacterial silver compounds onto the surface of the titanium implants but also provide a unique surface nanotexturing that allows better settle attachment mineralisation.

“These unique characteristics will allow improving implant outcomes, including less risk of infection and fewer complications like device failure.”

A/Prof Rahimi said the traditional method to address infections caused by implanted orthopaedic devices often utilises antibiotics or other surface modifications that have their own associated complications.

“Long-term antibacterial protection is not possible with these traditional drug coatings because a large portion of the loaded drug is released in a short time,” Rahimi said. “There also is often a mixture of microbes that are found in implant-associated infection; it is essential to choose a bactericidal agent that covers a broad spectrum.”

Source: Purdue University

Categories : Implants and Prostheses Metabolic DisordersTags :

A Soft Robotic Design for Diabetic Amputee Pain Relief

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Proof-of-concept rendering (left) and photo (right) of the prototype of the new microfluidics-enabled soft robotic prosthesis for lower limb amputees.
Credit: Waterloo Microfluidics Laboratory at University of Waterloo

Diabetic amputations often involve neuropathy, and patients detect damage resulting from an ill-fitting prosthesis, leading to further amputation. To solve this, in Biomicrofluidics, scientists described a new type of prosthetic using microfluidics-enabled soft robotics that reduces skin ulcerations and pain in patients who have had an amputation between the ankle and knee.

More than 80% of lower-limb amputations are due to diabetic foot ulcers, and the lower limb is known to swell at unpredictable times, resulting in volume changes of 10% or more.

Typically, the prosthesis used after amputation includes fabric and silicone liners that can be added or removed to improve fit. The amputee needs to manually change the liners, but neuropathy leading to poor sensation makes this difficult and can lead to more damage to the remaining limb.

“Rather than creating a new type of prosthetic socket, the typical silicon/fabric limb liner is replaced with a single layer of liner with integrated soft fluidic actuators as an interfacing layer,” said author Carolyn Ren, from the University of Waterloo. “These actuators are designed to be inflated to varying pressures based on the anatomy of the residual limb to reduce pain and prevent pressure ulcerations.”

The scientists started off with pneumatic actuators to adjust the pressure of the prosthetic socket, but it was quite heavy.

To reduce weight, the group miniaturised the actuators, designing a microfluidic chip with 10 integrated pneumatic valves to control each actuator. The full system is controlled by a miniature air pump and two solenoid valves that provide air to the microfluidic chip. The control box is small and light enough to be worn as part of the prosthesis.

Prosthetics experts provided a detailed map of desired pressures for the prosthetic socket. The group carried out extensive measurements of the contact pressure provided by each actuator and compared these to the desired pressure for a working prosthesis.

All of the actuators produced the right pressures suggesting the new device will work well in the field, with the next step being a more accurate biological model.

The group plans additional research to integrate pressure sensors directly into the prosthetic liner, perhaps using newly available knitted soft fabric that incorporates pressure sensing material.

Source: American Institute of Physics

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Partially Paralysed Man Uses Robotic Arms to Feed Himself

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Photo by Tara Winstead on Pexels

Recent advances in neural science, robotics, and software have enabled scientists to develop a robotic system that responds to muscle movement signals from a partially paralysed person relayed through a brain-machine interface. Human and robot act as a team to make performing some tasks a piece of cake.

Two robotic arms – a fork in one hand, a knife in the other – flank a seated man, who sits in front of a table, with a piece of cake on a plate. A computerised voice announces each action: “moving fork to food” and “retracting knife.” Partially paralysed, the man makes subtle motions with his right and left fists at certain prompts, such as “select cut location”, so that the machine slices off a bite-sized piece. Now: “moving food to mouth” and another subtle gesture to align the fork with his mouth.

In less than 90 seconds, a person with very limited upper body mobility who hasn’t been able to use his fingers in about 30 years, just fed himself dessert using his mind and some smart robotic hands.

A team led by researchers at the Johns Hopkins Applied Physics Laboratory (APL), in Laurel, Maryland, and the Department of Physical Medicine and Rehabilitation (PMR) in the Johns Hopkins School of Medicine, published a paper in the journal Frontiers in Neurorobotics that described this latest feat using a brain-machine interface (BMI) and a pair of modular prosthetic limbs.

Also sometimes referred to as a brain-computer interface, BMI systems provide a direct communication link between the brain and a computer, which decodes neural signals and ‘translates’ them to perform various external functions, from moving a cursor on a screen to now enjoying a bite of cake. In this particular experiment, muscle movement signals from the brain helped control the robotic prosthetics.

A new approach

The study built on more than 15 years of research in neural science, robotics, and software, led by APL in collaboration with the Department of PMR, as part of the Revolutionizing Prosthetics program, which was originally sponsored by the US Defense Advanced Research Project Agency (DARPA). The new paper outlines an innovative model for shared control that enables a human to manoeuvre a pair of robotic prostheses with minimal mental input.

“This shared control approach is intended to leverage the intrinsic capabilities of the brain machine interface and the robotic system, creating a ‘best of both worlds’ environment where the user can personalise the behaviour of a smart prosthesis,” said Dr Francesco Tenore, a senior project manager in APL’s Research and Exploratory Development Department. The paper’s senior author, Tenore focuses on neural interface and applied neuroscience research.

“Although our results are preliminary, we are excited about giving users with limited capability a true sense of control over increasingly intelligent assistive machines,” he added.

Helping people with disabilities

One of the most important advances in robotics demonstrated in the paper is combining robot autonomy with limited human input, with the machine doing most of the work while enabling the user to customize robot behavior to their liking, according to Dr David Handelman, the paper’s first author and a senior roboticist in the Intelligent Systems Branch of the Research and Exploratory Development Department at APL.

“In order for robots to perform human-like tasks for people with reduced functionality, they will require human-like dexterity. Human-like dexterity requires complex control of a complex robot skeleton,” he explained. “Our goal is to make it easy for the user to control the few things that matter most for specific tasks.”

Dr Pablo Celnik, project principal investigator in the department of PMR said: “The human-machine interaction demonstrated in this project denotes the potential capabilities that can be developed to help people with disabilities.”

Closing the loop

While the DARPA program officially ended in August 2020, the team at APL and at the Johns Hopkins School of Medicine continues to collaborate with colleagues at other institutions to demonstrate and explore the potential of the technology.

The next iteration of the system may integrate previous research that found providing sensory stimulation to amputees enabled them to not only perceive their phantom limb, but use muscle movement signals from the brain to control a prosthetic. The theory is that the addition of sensory feedback, delivered straight to a person’s brain, may help him or her perform some tasks without requiring the constant visual feedback in the current experiment.

“This research is a great example of this philosophy where we knew we had all the tools to demonstrate this complex bimanual activity of daily living that non-disabled people take for granted,” Tenore said. “Many challenges still lie ahead, including improved task execution, in terms of both accuracy and timing, and closed-loop control without the constant need for visual feedback.”

Celnik added: “Future research will explore the boundaries of these interactions, even beyond basic activities of daily living.”

Source: Frontiers

Categories : Cardiovascular Disease Implants and ProsthesesTags :

Deep Nerve Stimulation Controls Blood Pressure

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Blood pressure cuff
BP cuff for home monitoring. Source: Pixabay

A study published in Frontiers in Neuroscience demonstrated that blood pressure and renal sympathetic nerve activity (RSNA) can be controlled by bioelectronic treatment. RSNA is often increased in hypertension and renal disease.

Using a custom-wired electrode, Professor Mario Romero-Ortega previously reported that deep peroneal nerve stimulation (DPNS) elicits an acute reduction in blood pressure. The current study, advances that work, focusing on his development of a small implantable wireless neural stimulation system and exploration of different stimulation parameters to achieve a maximum lowered response.

Prof Romero-Ortega integrated a nerve stimulation circuit less than a millimetre in size, with a novel nerve attachment microchannel electrode that can be implanted into small nerves, while enabling external power and DPNS modulation control.

Using this implantable device, his team demonstrated that systolic blood pressure can be lowered 10% in one hour and 16% two hours after nerve stimulation.

“Our results indicate that DPNS consistently induces an immediate and reproducible arterial depressor effect in response to electrical stimulation of the deep peroneal nerve,” reported Prof Romero-Ortega.

While pharmacological treatments are effective, blood pressure remains uncontrolled in 50–60% of resistant hypertensive subjects. Unfortunately, despite the use of multiple antihypertensive drugs in combination, blood pressure remains poorly controlled in 50–60% of the hypertensive population and approximately 12–18% of them develop resistant hypertension, defined as blood pressure greater than 140/90 mmHg despite the use of antihypertensive drugs.

“In this study, DPNS induced an initial increase in RSNA during the first 2–3 seconds, followed by a reduction in renal activity and mean arterial pressure, despite the increase in heart rate,” said Prof Romero-Ortega. “The observed activation of the RSNA during the DPNS was not expected since its activity is associated with hypertension.”

Source: University of Houston