Fabrication and Characterization of a Balloon Actuator Array for Haptic Feedback in Robotic Surgery

Robot-assisted surgery is characterized by a total loss of haptic feedback, requiring surgeons to rely solely on visual cues. A pneumatically-driven balloon actuator array, suitable for mounting on robotic surgical master controls, has been developed to provide haptic feedback to surgeons. The actuator arrays consist of a molded polydimethylsiloxane substrate with cylindrical channels and a spin-coated silicone film that forms the array of balloons. Preliminary human perceptual studies have demonstrated that balloon diameters greater than $1.0mm$ may provide effective haptic feedback to the index finger. Before conducting further human perceptual tests, refinements of the fabrication process and performance data of the actuator are required. Balloons with diameters ranging between $1.5mm$ and $4.0mm$ were fabricated with film thicknesses of $200μm$ and $300μm$⁠. Inflation pressure versus balloon deflection tests and cyclic actuation tests were performed to characterize each balloon type. The results demonstrated a high linearity between inflation pressure and balloon deflection $(R2>0.93)$ and negligible hysteresis effects between inflation and deflation over $100,000cycles$⁠. The studies indicated that $300μm$ films are optimal for $3.0mm$ and $4.0mm$ diameter balloons, and $200μm$ films are optimal for $1.5mm$⁠, $2.0mm$⁠, and $2.5mm$ diameter balloons. Due to its compact size and high performance, the described pneumatic actuator can provide sensory input that is otherwise unavailable during robotic surgery.