This paper presents a proof of concept for noncontact and noninvasive bladder volume sensing in patients suffering from Neurological Lower Urinary Tract Dysfunction (NLUTD) caused by spinal cord injuries. The study investigates the feasibility of utilizing Frequency Modulated Continuous Wave (FMCW) radar as the underlying sensing modality. An algorithm for spectral data analysis is proposed to map radar measurements to bladder volume and is evaluated through MATLAB simulations. Additionally, time domain simulations of a tissue model are conducted to further assess the proposed spectral data analysis algorithm and demonstrate the feasibility of the sensing modality. The effectiveness of the sensing modality is demonstrated through a proof-of-concept measurement setup using an ex-vivo porcine bladder model, which is incrementally filled with saline solution in 200 ml portions. The results of the proposed spectral data analysis on the measured reflected waveforms reveal a strong correlation between the shift in peak frequency and the bladder volume in the model. These findings provide evidence supporting the potential of FMCW radar as a reliable and noninvasive method for continuous bladder volume monitoring.

In wearable optical sensing applications whose target tissue is not superficial, such as deep tissue oximetry, the task of embedded system design has to strike a balance between two competing factors. On one hand, the sensing task is assisted by increasing the radiated energy into the body, which in turn, improves the signal-to-noise ratio (SNR) of the deep tissue at the sensor. On the other hand, patient safety consideration imposes a constraint on the amount of radiated energy into the body. In this paper, we study the trade-offs between the two factors by exploring the design space of the light source activation pulse. Furthermore, we propose BASS, an algorithm that leverages the activation pulse design space exploration, which further optimizes deep tissue SNR via spectral averaging, while ensuring the radiated energy into the body meets a safe upper bound. The effectiveness of the proposed technique is demonstrated via analytical derivations, simulations, and in vivo measurements in both pregnant sheep models and human subjects.