A wireless strain sensor system for bladder volume monitoring

A wireless strain sensor system has been designed to monitor the bladder volume in patients suffering from urinary incontinence. An interdigitated capacitive (IDC) strain sensor was micro-machined from a 127-μm thick brass shim with a laser system, followed by an encapsulation process to package the sensor in elastic polydimethylsiloxane (PDMS). A proof-of-concept passive telemetry platform was developed to employ the sensor in vivo and a commercial wireless module was utilized for networking and data recording. The system includes a transducer implant, an external wearable unit and a base station. The implant harvests electromagnetic energy from the external unit, supplies power to operate the sensor and transduces the sensor data back. The wearable unit processes and transfers the signals to the base station connected to a computer which continuously displays and records the strain sensor data on the bladder. The sensor was calibrated and the entire system was tested with a bladder phantom model. Results were promising and demonstrated the feasibility of our passive wireless strain sensing system for urinary incontinence management.