Soft pneumatic actuator with an embedded flexible polymeric piezoelectric membrane for sensing bending deformation

Soft actuators have been used for various robotic applications, such as flexible soft muscles, actuators, grippers, and wearable devices. Soft actuators help handle delicate and fragile objects; moreover, they are used in medical rehabilitation devices to ensure safer human interaction. Soft actuators actuated by pneumatic pressure are the most utilized due to their compliant and straightforward operations. A soft pneumatic actuator (SPA) deforms when applying pneumatic pressure, where the deformation energy is generated. The present work uses a bending-type SPA to harness its bending energy based on the piezoelectric effect. The focus is on developing a novel SPA embedded with a piezoelectric membrane (SPA-P), which is the combination of a flexible conducting polymer nanocomposite (CPNC) membrane entrapped within the silicone rubber body of the SPA. The CPNC consists of a dielectric polyvinylidene fluoride matrix, conducting carbon nanofibers for charge transport, and ionic liquid for providing extra ions and flexibility using the solvent casting technique. The experimental study of SPA-P showed a significant voltage change when actuating with the pneumatic pressure, which can be utilized to control SPA by providing feedback voltage corresponding to the deformation during bending. Finally, the proposed SPA-P has been tested for the medical application of human finger rehabilitation.