Artificial anal sphincter (AAS) is an in situ implanted device that acts as a treatment for fecal incontinence regardless of etiology by augmenting the incompetent sphincteric structures. However, AAS is impeded from becoming a valid therapy by its high rate of ischemic complication and malfunction. This article presents an original puborectalis-like artificial anal sphincter (PAAS) that features a low risk of ischemia necrosis and rectal perception remodeling. The device retains continence by reproducing the action, including the pulling and angulating the rectum, of the puborectalis muscle, which forms the anorectal angle and reduces the required clamping pressure. Three rectal pressure sensors were embedded to maintain the pressure exerted on the rectal wall in a safe range and to monitor the distention of the rectum. A series of in vitro studies were conducted with a porcine rectum, and this PAAS prototype manifested the ability of maintaining continence with a clamping pressure considerably lower than that required by other AAS devices. The pressure sensors exhibit good linearity, and the function of rectal perception remodeling has also revealed high reliability with a success rate of 93.3%.

This article presents a novel puborectalis muscle artificial anal sphincter system (PM-AASS) with the module of sensory perception for treating severe faecal incontinence (FI). Due to the implantable feature of PM-AASS, this system applied low-power design and the total energy consumption could drop to 48.8 Ah/d. To reduce the injury of intestine and the pressure exerted on intestine, the actuator, including the structure of tings and the robot mechanism, of PM-AASS was presented and the middle ring was optimised. To realise the sensory perception, the intestinal flexible pressure sensors, comprising the radial sensors and the axial sensors, were designed. The sensors calibration showed the R-square of each fitting line were above 0.998, which presented a high goodness of fit and indicated we could figure out the pressure value with the analogue voltage captured by MCU. Through the in-vitro experiment, the results that the radial sensors were more relevant to the occlusion threshold while the axial sensors had more effect on the alarm threshold could be concluded. The practicability of the PM-AASS was verified by the results of the in-vivo experiment, which showed that the PM-AASS had the effect of improvement to the anorectal internal pressure.