Wearable vibrating device may help with freezing of gait in Parkinson’s
Prototypes as shoe sole aims to restore nervous system's feedback loop
Researchers at Virginia Commonwealth University have developed prototypes of wearable devices that use pressure sensors and vibrations to address freezing of gait, a hallmark symptom of Parkinson’s disease.
One such device is a specialized shoe sole equipped with sensors. These sensors detect changes in pressure as the wearer takes a step, and respond by sending vibratory signals to the top of the foot, allowing for adjustments in gait and balance.
“It could be that if it vibrates, the patient knows, OK, I’m having trouble walking, so I’ll take bigger steps, slow down or turn a different direction,” Ingrid Pretzer-Aboff, PhD, a study co-author and a professor in the School of Nursing at Virginia Commonwealth, said in a university news story.
The device’s development is detailed in the study “A synchronized event-cue feedback loop integrating a 3D printed wearable flexible sensor-tactor platform,” published in Biosensors and Bioelectronics.
Parkinson’s disrupts central and peripheral nervous system’s feedback loop
The somatosensory system is a network of nerve cells that allows people to sense touch, temperature, pain, vibration, and body position.
To initiate body movement, nerve cells in the central nervous system (CNS), comprising the brain and spinal cord, send signals via nerves that extend from the CNS into the limbs, or the peripheral nervous system. At the same time, somatosensory nerves in the limbs send signals back to the brain to provide information on pressure, vibration, weight, and limb positions. This so-called feedback loop is essential for maintaining balance and facilitating movement.
“The brain is constantly talking to the peripheral nervous system, including the sensors in the fingertips and feet,” said Phillip Glass, the study’s first author and a PhD candidate at the university.
However, Parkinson’s disrupts the feedback loop between the CNS and the peripheral nervous system. This leads to the common disease motor symptom of freezing of gait, a sudden inability to move despite the intention to walk.
Researchers at Virginia Commonwealth have developed a wearable, vibrating technology that may restore that feedback loop, potentially improving gait, balance, and motor skills in people with Parkinson’s or conditions related to the peripheral nervous system.
Pretzer-Aboff’s early work focused on using vibrations to help Parkinson’s patients regain motor control. The initial prototypes were large and difficult to manage.
“Patients felt that the old vibrators were bulky, heavy and not comfortable,” said Daeha Joung, PhD, the study’s senior author and an assistant professor of physics at the university. “Patients want to have something subtle, flexible and small.”
With the help of 3D printing, the team has developed a more flexible and comfortable product that uses many small vibration devices instead of one or two large, available models.
Each wearable device functions through a simple feedback mechanism. When a user takes a step, pressure is applied to 3D-printed sensors composed of carbon nanotubes situated on the sole of the shoe. A similar process occurs when gripping an object with the hand via sensors on the surface of a glove.
Sensors send signal that causes device to vibrate, much like a cellphone
These pressure sensors transmit an electrical signal to adjacent vibrating devices known as solenoids, which trigger a magnet within the solenoid to vibrate, much like a cellphone would. Worn on a different part of the body, these vibrating devices alert the user to the increase in pressure.
The setup is distinct for the feet and hands. When a person takes a step, pressure is applied to the sole of the shoe, activating sensors that send vibratory signals to the top of the foot. When gripping an object with the glove, vibrations are felt on a glove worn on the other hand, with signals sent via Bluetooth.
While those vibrations alert wearers to the change in pressure from weight, gait, and grip, they may also affect the somatosensory system.
“If it’s having a neurostimulation effect, it could be that it’s really activating the receptors in the skin and traveling up to the brain, and then alerting the patient to what they’re doing,” Pretzer-Aboff said.
Beyond helping Parkinson’s patients, the devices could be adapted for people with other disorders related to the peripheral nervous system, or to help those with prosthetic legs prevent falls by sending vibrations to the upper leg.
The team is seeking a patent to move beyond prototypes into wearable, commercially available devices. In the short term, they want to work with Parkinson’s patients at Virginia Commonwealth in further refining them.
“The implementation of these devices, combined with the event-cue feedback loop, demonstrates potential in revitalizing impaired peripheral nerves, enhancing prosthetic capabilities, and improving tactile perception in individuals with restricted nervous system function,” the researchers wrote.
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