Design, fabrication, and evaluation of a wearable pneumatic module for pressing and torsional massage

Abstract

Massage-related mechanotherapy relies on mechanical stimuli such as compression, stretch, and shear. However, most flexible pneumatic massage devices mainly generate radial compression and have limited ability to provide controllable tangential or torsional stimulation. This study presents a wearable pneumatic module for upper-limb massage that integrates radial pressing and circumferential torsional rubbing. The dual counter-rotating pneumatic architecture balanced the internal torque while rubbing, allowing it to be worn without external fixation. A rigid–soft prototype was fabricated using SLA-printed structures and heat-pressed TPU airbags and characterized in no-load and on-arm tests with one healthy volunteer. Estimated contact pressure between module and skin was linearly related (R² = 0.9531) to input pressure in effective range of 10–30 kPa. Quasi-static torsion tests showed pressure–angle slopes of 0.2754 and 0.1605 deg/kPa under no-load and on-arm conditions, respectively. Dynamic on-arm torsion tests generated a mean peak-to-peak twist range of 14.28 deg. The results present the feasibility of integrated pneumatic pressing and torsional rubbing.