Ultralow-power data compression for implantable bladder pressure monitor: Algorithm and hardware implementation

Urinary incontinence, overactive bladder, and other dysfunctions of the lower urinary tract are conditions which affect millions worldwide, imposing a high financial burden and greatly affecting quality of life. Diagnosis of these conditions can be facilitated by monitoring bladder activity over time. Recent work has demonstrated the feasibility of device implantation for chronic bladder pressure monitoring, which can help to improve existing diagnostic techniques. For wireless implants, a significant portion of the implant power consumption results not from pressure sensing, but rather from data transmission. In this paper, we present a novel algorithm which is designed to perform efficient, on-chip compression of bladder pressure data with tunable quality, resulting in significant overall power savings. We validate our approach by applying the algorithm to prerecorded bladder pressure data from 14 human subjects, and demonstrate high average compression ratios (~5x), leading to similar reductions in transmission power draw, with low reconstruction error (RMSE
≈
1.09). An ultralow-power hardware implementation of the proposed algorithm is obtained by synthesizing the design with TSMC 0.18 μm technology, yielding an area of 1.34 mm
²
and average power of 2.3 nW using low power design techniques. To our knowledge, this is the first example of dedicated on-chip compression for bladder pressure data designed for an ultralow-power biomedical implant.