New Wearable Reroutes Lost Sensation, Restores Stability
An interdisciplinary team of researchers developed a wearable “sensory substitution” system that translates foot pressure into high-tech patterns of heat and vibration they can feel elsewhere.
By Audra Davidson
Misjudge a curb or miss a step on the stairs, and there is a split second of panic as your foot doesn’t land when you expect it to. That brief loss of pressure can be enough to throw off your balance entirely.
Matthew Flavin, assistant professor in electrical engineering and lead author of the study, holds the flexible haptic device. (Photo courtesy Maxwell Guberman)
For most, that heart-pounding uncertainty ends the moment the foot finds solid ground. But for many individuals living with conditions like stroke or spinal cord injury (SCI), that sense of disconnect is a permanent reality.
“These conditions of course have a huge effect on our ability to move around and be independent—but the other side of it is the sensory feedback that we lose,” said Matthew Flavin, an assistant professor in the School of Electrical and Computer Engineering at Georgia Institute of Technology (Georgia Tech) in Atlanta. “Most rehabilitation treatments primarily focus on restoring movement, but “even if you have motor control, if you can’t feel when your foot’s touching the ground, it can be really hard for you to move around safely.”
In a new study published in Proceedings of the National Academy of Sciences, Flavin and an interdisciplinary team of researchers introduce a way to bridge this gap: a wearable “sensory substitution” system that translates foot pressure into high-tech patterns of heat and vibration they can feel elsewhere.
The system uses high-resolution pressure-sensing insoles designed by the team, which are placed inside a user’s shoes to record how their weight shifts in real-time. This data is streamed via Bluetooth to a flexible, skin-conformable array of haptic receivers worn on the forearms, a part of the body that often retains sensation in SCI. The receivers give quick pressure feedback through vibration, while also alerting the user to longer-term pressure “hotspots” through heat.
“One of the limitations of a lot of approaches in haptics is that you’re having to map a missing sense onto a completely different sense,” said Flavin. “We’re keeping the type of information that we’re missing, which is the distribution of pressure, and we’re just basically putting it on a different part of their body.”
Rerouting the lost sensation was key to making the device intuitive to learn. Participants were able to correctly identify the “feel” of the ground through their arms with high accuracy within a mere two-hour session. When tested with a small group of participants with stroke or SCI, the wearable significantly improved standing balance and led to steadier walking.
“What’s encouraging about these early results is that participants appeared to use the feedback in ways that supported balance and walking,” said John Rogers, a materials science and engineering professor at Northwestern University who collaborated on this study. “Our study suggests that providing pressure information through another part of the body could be a practical path for helping people compensate for lost sensation.”
While vibration provides immediate feedback for walking and balance, the team views the thermal feedback as a tool for long-term health. Heat is a slower, low-frequency signal that could alert patients to pressure hotspots, potentially preventing diabetic foot ulcers or pressure injuries for those who are bedridden or use wheelchairs.
The small, lightweight system is completely untethered, making it suitable for use during daily activities in and outside the clinic. It’s also highly adaptable to different injury types, which is ideal for conditions as variable as stroke, SCI, and diabetic neuropathy. Placement of the haptic receivers can be adjusted based on where a patient has the most sensation, and the sensitivity of the insoles can be tailored to each patient.
As a member of several of Georgia Tech’s Interdisciplinary Research Institutes—the Institute for Neuroscience, Neurotechnology, and Society, the Institute for Robotics and Intelligent Machines, and the Parker H. Petit Institute for Bioengineering and Biosciences—Flavin credits the project’s success to an interdisciplinary effort and deep engagement with clinicians and patients.
“This reinforces the importance of really engaging with your stakeholders very early on,” said Flavin. “If you’re not continually refining that concept with those stakeholders, you quickly find that they might be looking for something that your device isn’t delivering.”
With new funding from the National Science Foundation (NSF), the team is now working to make the technology even smaller and more reconfigurable, moving closer to a standard wearable for daily clinical use.
Audra Davidson is Research Communications Program Manager for Georgia Tech’s Institute for Neuroscience, Neurotechnology, and Society (INNS).
This article originally appeared in Georgia Tech Research News on the Georgia Tech College of Engineering website.
Tech Engineers to Develop a New Catheter to Improve Heart Procedures
A research team of Georgia Tech engineers is working to develop a new kind of catheter designed to give doctors clearer, real-time insight during these life-saving procedures.
By Tracie Troha
When patients undergo procedures to open blocked heart arteries, precision matters. Even small imperfections in placing a stent can affect blood flow and long-term health.
Now, a research team led by F. Levent Degertekin, Regents’ Entrepreneur, George W. Woodruff Chair in Mechanical Systems, and professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech, is working to change that with a new kind of catheter designed to give doctors clearer, real-time insight during these life-saving procedures.
Backed by a four-year, $2.2 million National Institutes of Health Research Project (R01) grant, the project aims to develop a microcatheter that combines high-resolution imaging with precise pressure sensing in a single device.
Personal Inspiration and A Long-Term Vision
Degertekin’s motivation for improving these procedures is deeply personal.
“My brother is an interventional cardiologist,” he said. “It turned out that the ultrasound imaging technologies I’ve been working on were especially suited to address the needs of cardiologists like him.”
That connection helped shape more than two decades of research focused on catheter-based imaging technologies for the heart.
Hidden Problems After Successful Procedures
Each year, more than a million patients in the United States undergo procedures to open blocked coronary arteries. While interventions such as angioplasty and stent placement are routine, they are not always perfect.
Research shows that 24% of patients have residual issues, even when imaging suggests success. In some patients, blood flow is not fully restored, which can lead to complications or additional procedures.
Even small imperfections in placing a stent can affect blood flow and long-term health.
To mitigate these risks, a Georgia Tech research team is aiming to develop a microcatheter that combines high-resolution imaging with precise pressure sensing in a single device. (Image courtesy Georgia Tech)
“Nearly one in five cases are complex, and the results are not optimal,” Degertekin explained. “The blood flow is not restored as desired, and there are still pressure drops at the lesion sites.”
Part of the problem lies in how procedures are currently evaluated. Physicians primarily rely on X-ray imaging (fluoroscopy), which shows anatomy but not how well blood is flowing. Measuring that requires additional devices, which adds time, cost, and risk.
A Single Device Providing Multiple Insights
Degertekin’s team is addressing this gap by combining two critical capabilities into one ultra-small catheter: intravascular ultrasound imaging to visualize the artery, and fractional flow reserve sensing to measure blood flow and pressure.
By integrating both functions, the device allows physicians to assess both structure and function at the same time.
“With a single catheter providing both anatomical and physiological information, potential issues can be detected and resolved during the same procedure, reducing the complications,” Degertekin said.
The approach could minimize procedure time and reduce radiation exposure and risk to the patient.
Powered by Silicon Innovation
At the heart of the new device is advanced silicon microelectronics technology.
Using techniques similar to those found in computer chips, the team is integrating ultrasound transducers, pressure sensors, and electronic circuits onto a single silicon platform. This allows the creation of a catheter that is only 800 micrometers in diameter, or less than a millimeter, with nearly 100 tiny transmitters and receivers that are all connected with only eight cables. It’s an engineering feat made possible by combining sensing and electronics on the same chip.
“Only with this small size can one measure pressure accurately in narrow arteries without blocking blood flow,” Degertekin said.
A Collaborative Effort Across Disciplines
The project brings together a multidisciplinary team spanning engineering and medicine, including collaborators from Emory University and Kennesaw State University.
Team members include Yue Chen, associate professor in the Wallace H. Coulter Department of Biomedical Engineering; Shaolan Li, assistant professor in the School of Electrical and Computer Engineering; Coskun Tekes, associate professor of computer engineering at Kennesaw State University (KSU); and William “Bill” Nicholson, M.D., director of interventional cardiology at Emory University.
“This is truly a multidisciplinary project,” Degertekin said. “It requires integrated circuit design, microfabrication, catheter design, and real-time signal processing and beamforming expertise on the engineering side, each of which is a specialization by itself and covered by the Georgia Tech and KSU faculty members.”
Degertekin added that Nicholson’s experience designing and commercializing coronary catheters has been especially valuable in shaping the device for real-world use.
From Lab to Clinic
Over the next four years, the team will design, build, and test the catheter system, moving from benchtop validation to animal studies.
“If we can demonstrate that this technology can perform imaging and pressure sensing as well as the currently separate individual devices in an animal study at the end of the project, that would be a great success,” Degertekin said.
The next steps would include scaling up manufacturing and clinical trials. Encouragingly, some of the underlying fabrication techniques are already used in commercial medical devices, helping lower barriers to translation.
Transforming the Future of Heart Care
Looking ahead, Degertekin believes this technology could have a significant impact, especially in complex cases involving multiple blockages or chronic total occlusions, which can be especially challenging and time-consuming.
“It can potentially improve clinical outcomes, especially for complex interventions,” he said. “The catheter also has special features to help cross chronic total occlusions, which can lead to hours-long procedures.”
By enabling physicians to make better decisions in real time, the technology could lead to safer procedures, fewer complications, and better long-term outcomes for patients.
Eventually, innovations like this could redefine interventional cardiology, making procedures more successful the first time.
Tracie Troha is a writer/editor with Georgia Tech’s George W. Woodruff School of Mechanical Engineering’s communications team.
This article originally appeared on the Woodruff School of Mechanical Engineering’s website.