Development of a Soft Pneumatic Actuator System Based on Flexible Force Sensor for Lower Limb Compression Therapy

The use of a soft pneumatic actuator (SPA) in compression therapy to enhance blood circulation shows potential because of its unique proactive bio-mechanical force delivery mode and wide range of pneumatic pressure control. This work presented new insights into the model-experiment method using mathematical simulation and flexible force sensor array (FFSA) to explore the bio-mechanical force delivery mechanism of a newly developed SPA and offer accurate pressure for lower limb compression therapy. Multichambered bladders were incorporated in the SPA system as key components to exert pressure on the lower limb, and the FFSA visualized the skin pressure on a software interface. Pressure signals were transiently collected by differential sensors and FFSA using the data acquisition unit and then transmitted to a computer software via Bluetooth module to build the interface pressure feedback and control subsystem. According to the interface pressure variation, the SPA system could automatically adjust the air pressure in bladders to generate suitable bio-mechanical force for compression therapy. Results revealed that the sensors-based SPA system could generate rhythmic (intermittent) bio-mechanical force, which could be transformed by FFSA and visualized in a morphological interface pressure mapping from quantitative and qualitative perspectives. This study provided an evidence-based technical guidance for a new SPA system design which could delivered controllable and precise dynamic pressure to affect the lower limb during compression therapy.