Microfluidics-based soft robotic prostheses promise relief for diabetic amputees


WASHINGTON, June 28, 2022 – Every 30 seconds, a leg is amputated somewhere in the world due to diabetes. These patients often suffer from neuropathy, a loss of sensation in the lower limbs, and are therefore unable to detect damage resulting from an ill-fitting prosthesis, leading to limb amputation.

In Biomicrofluidicsby AIP Publishing, Canadian scientists unveil their development of a new type of prosthesis using soft robotics based on microfluidics that promises to significantly reduce skin ulcerations and pain in patients who have undergone amputation between the ankle and the knee .

More than 80% of lower limb amputations worldwide are the result of diabetic foot ulcers, and the lower limb is known to swell at unpredictable times, causing 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 must manually change the liners, but the neuropathy causing poor sensation makes this difficult and may lead to further damage to the remaining limb.

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

The scientists started with a newly developed device using pneumatic actuators to adjust the pressure of the prosthetic socket. This initial device was quite heavy, limiting its use in real-life situations.

To solve this problem, the group has developed a way to miniaturize the actuators. They designed a microfluidic chip with 10 integrated pneumatic valves to control each actuator. The complete system is controlled by a miniature air pump and two solenoid valves which supply air to the microfluidic chip. The control box is small and light enough to be worn with the prosthesis.

Medical personnel with extensive experience with prosthetic devices were part of the team and provided a detailed map of the desired pressures for the prosthetic socket. The group made extensive measurements of the contact pressure delivered by each actuator and compared them to the desired pressure for a working prosthesis.

All 10 actuators were found to produce pressures within the desired range, suggesting that the new device will perform well in the field. Future research will test the approach on a more accurate biological model.

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

– This press release was provided by the American Institute of Physics

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