Developing an Untethered Soft Robot for Finger Rehabilitation

Sustaining a high-intensity rehabilitation routine is challenging for many, especially for less privileged populations with limited resources. Using robots for rehabilitation could potentially lower the barriers to accessing rehabilitation therapy and promote a more sustainable recovery process for patients in need. In this paper, we present a novel concept of an untethered soft robot designed to be used in finger rehabilitation. This soft robot is actuated by heat and, therefore, untethered from external tubes, valves, or pumps, which many other existing soft robots require to operate. In our soft robot design, a phase-changing material (PCM) is sealed inside an elastomer structure. As heat is applied, the PCM changes phase from liquid to gas, and the pressure inside the elastomer structure increases to cause the bending of the elastomer structure. To identify the best PCM to suit our design goals, we conducted preliminary experiments for our PCM-embedded soft robot prototypes made with various candidate PCMs. Although promising results mimicking human finger movement were observed for all prototypes tested, compared their bending responses with a benchmark pneumatic soft robot system, we conclude that NovecTM 7000 Engineering Fluid would be the most suitable PCM for our soft robot as an untethered finger rehabilitation device due to its desired operating conditions.