Master of Sciences, Case Western Reserve University, 2019, EECS - Electrical Engineering

New research tools are essential to understanding neural control of the lower urinary tract (LUT) and could enable new treatments or neuroprosthesis to eliminate incontinence. Modern technologies enable real-time, catheter-free monitoring of bladder pressure, however variations in physiology among animals and people complicate interpretation of pressure data without bladder volume information. To date, no available technology achieves catheter-free, chronic monitoring of bladder volume. This thesis describes the design of a fully-wireless device for conductivity-corrected conductance measurements of fluid volume in a catheter-free system. The device consists of two electrodes, one sensing anode, and a microcontroller, and is small enough for surgical implantation within the bladder lumen. In-vitro benchtop testing demonstrated fluid volume prediction with <5mL mean error below 40mL and a worst-case mean error of 13mL near full-scale volume. These results indicate that conductance-based volume sensing of the urinary bladder is a feasible method for real-time catheter-free urine volume measurement.

Committee: Christian Zorman Dr. (Committee Chair); Margot Damaser Dr. (Committee Member); Soumyajit Mandal Dr. (Committee Member); Steve Majerus Dr. (Committee Member) Subjects: Biomedical Engineering; Electrical Engineering

Doctor of Philosophy, Case Western Reserve University, 2014, EECS - Electrical Engineering

This work describes the design and testing of a wireless implantable bladder pressure sensor suitable for chronic implantation in humans. The sensor was designed to fulfill the unmet need for a chronic bladder pressure sensing device in urological fields such as urodynamics for diagnosis and neuromodulation for bladder control. Neuromodulation would particularly benefit from a wireless bladder pressure sensor providing real-time pressure feedback to an implanted stimulator, resulting in greater bladder capacity while using less power. The pressure sensing system consists of an implantable microsystem, an external RF receiver, and a wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream, protecting both the device and the patient. The implantable microsystem consists of a custom application-specific integrated circuit (ASIC), pressure transducer, rechargeable battery, and wireless telemetry and recharging antennas. Because the battery capacity is extremely limited, the ASIC was designed using an ultra-low-power methodology in which power is dynamically allocated to instrumentation and telemetry circuits by a power management unit. A low-power regulator and clock oscillator set the minimum current draw at 7.5 µA and instrumentation circuitry is operated at low duty cycles to transmit 100-Hz pressure samples while consuming 74 µA. An adaptive transmission activity detector determines the minimum telemetry rate to limit broadcast of unimportant samples. Measured results indicated that the power management circuits produced an average system current of 16 µA while reducing the number of transmitted samples by more than 95% with typical bladder pressure signals. The wireless telemetry range of the system was measured to be 35 cm with a bit-error-rate of 10-3, and the battery was wirelessly recharged at distances up to 20 cm. A novel biocompatible (open full item for complete abstract)

Committee: Steven Garverick (Advisor); Swarup Bhunia (Committee Co-Chair); Margot Damaser (Committee Member); Pedram Mohseni (Committee Member); Christian Zorman (Committee Member) Subjects: Biomedical Engineering; Electrical Engineering