Harness-inspired and fully implantable electronic system for real-time urine volume monitoring

Patients with lower urinary tract dysfunction are often unable to sense urine volume. Implantable sensors are used to monitor bladder urine volume. Securing sensors to the bladder involves sutures or synthetic adhesives that are invasive to it. Inspired by the safety harness that can be attached to objects by straps, we propose the bladder electronic harness (E-harness) for urine volume monitoring. The E-harness is a non-stick 2-dimensional structure that can be wrapped around the bladder without harming it. It is also soft enough to put no extra pressure on the bladder when it expands. Integrated with soft strain sensors and a wireless system, the E-harness can conform to the bladder, can measure bladder liquid volume with high accuracy (∼0.16 mL), and does not fall off for 1 month. The size of the E-harness is easily adjustable and can be used on small animals such as mice and large animals such as pigs.