A SMA-actuated miniature pressure regulator for a miniature robot for colonoscopy

Abstract This paper describes a proportional minivalve actuated by shape memory alloy (SMA) actuators and designed primarily for application in semi-autonomous devices for endoscopy (colonoscopy, in particular). As compared to existing valves, the new minivalve exhibits favourable values of working pressure range (0–200 kPa), size, weight and response time. The mechanical structure and the fine proportional control of the minivalve are illustrated. Some innovative features which improve the overall performance of the minivalve (e.g. a waste conduit which increases thermal exchange) are analysed. Fluidic and thermal simulations of the minivalve are presented. Prototypes have been fabricated and tested. Experimental results compare favourably with the performance predicted by the theoretical model. A minivalve has been incorporated in a prototype miniature robot for colonoscopy and preliminarily used to control the locomotion parameters of the robot.