A Soft Robotic Design for Diabetic Amputee Pain Relief
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
