Development of a Soft Growing Actuator for Automated Cystoscope Insertion

This study presents the first prototype of an insertion mechanism designed to reduce pain during cystoscope insertion. Traditional cystoscopy often causes discomfort as the cystoscope rubs against the urethral wall and its tip impacts the curved urethra. To address this issue, this study focuses on developing a “painless” automatic insertion mechanism for cystoscopy in the urethra, prostate, and bladder using a soft growing actuator. The paper introduces a compact soft growing actuator made from a low-friction material capable of inverted growth. The prototype actuator extended to a maximum length of 140 mm in just 0.10 seconds, with no significant variation in the elongation-time relationship when air pressure was applied at 70–90 kPa. The prototype successfully guided a cystoscope- like wire from the urethral entrance to the bladder within an S- tube that replicates the scale and curvature of the human urethra. These findings suggest that the proposed cystoscope insertion mechanism, utilizing a soft growing actuator, has the potential to enable automated cystoscopy for rapid and painless examination of the human urethra.