A Bistable Assistive Device for Wireless Control of a Dysfunctional Bladder Under Minimal Stress

A wireless system for real-time bladder volume sensing and timely voiding can manage underactive bladder (UAB) but should avoid imposing long-term stress on the bladder during application. Here, this work develops a flexible sensing-actuation system that incorporates a bistable pre-shaped polyether ether ketone (PEEK) layer for minimizing the bladder stress while maintaining a high voiding efficiency by a bistable shape memory alloy (SMA) spring actuator. The actuator achieves a repeatable voiding efficiency of 95–100% within 10 s, after which the pre-shaped PEEK layer is self-activated within 30 s due to its internal residual stress, releasing the actuator-imposed stress onto the bladder. The system's soft silver (Ag)-Ecoflex composite piezoresistive sensor monitors the bladder volume with low bladder tension. The presented bladder assistive system enables wireless real-time bladder status monitoring and initiation of voiding by the user for enhanced convenience. The system highlights the potential of this technology for prolonged usage without causing tissue damage due to excessive stress applied to the bladder during its operation.