Stretchable Strain Sensors for Real-Time Bladder Volume Monitoring

Urinary incontinence (UI) is a prevalent condition that adversely affects quality of life, driving the need for innovative technologies for continuous bladder monitoring. In this study, we introduce a wrinkled metal (platinum and gold) strain sensor tailored for real-time bladder volume monitoring. This stretchable sensor is designed to provide robust and reliable performance for 5000 cycles with minimal hysteresis, and its mechanical properties match that of bladder tissue, enabling accurate monitoring during bladder filling and emptying. Our experimental results demonstrate that the sensor offers high sensitivity and stability, with a dynamic range of up to 230% strain, Young's modulus of 11.7-32 kPa, and a gauge factor (GF) of 2.9-4.7. The sensor's efficacy was validated through in vitro bladder phantom studies and ex vivo pig bladder experiments, where it consistently tracked bladder volume changes with a sensitivity of 4.60 mL^-1. The results suggest that the strain sensor is a promising candidate for robust, biocompatible bladder volume monitoring in patients with urinary disorders, offering an alternative to traditional methods by being more comfortable and biocompatible.