Radio-frequency (RF) Bladder Monitor

Spinal cord injury (SCI) presents significant long-term challenges for affected individuals, among which bladder dysfunction is a leading concern. Neurogenic lower urinary tract dysfunction (NLUTD), commonly referred to as neurogenic bladder dysfunction, may result in urinary retention, incomplete bladder emptying, urinary incontinence, urinary tract infections (UTIs), bladder distension, urinary reflux, renal complications, and reduced quality of life. Current bladder management approaches, including clean intermittent catheterization (CIC), indwelling catheterization, and external collection methods, may be associated with substantial time burden, complications, excessive bladder filling or incomplete emptying, and poor adherence. Studies have also shown that improving bladder function remains one of the highest rehabilitation priorities among individuals with SCI.

This study investigates the feasibility of a wearable radio-frequency (RF)-based bladder monitor operating in the microwave (MW) frequency range for non-invasive bladder monitoring and bladder volume estimation. The proposed system is intended to measure and track bladder volume and may ultimately support future development of discreet alerts indicating when the bladder is appropriately full and it is time to void. RF/MW sensing approaches provide several potential advantages for bladder monitoring applications because they are non-invasive, low-cost, safe for repeated use within established exposure limits, and compatible with wearable device designs.

Previous computational and experimental studies investigating RF/MW approaches for bladder-state detection have demonstrated proof-of-concept feasibility; however, many earlier studies relied on simplified anatomical models and limited experimental conditions. More recent work by the investigators demonstrated bladder-state discrimination using realistic anatomical pelvic models and preliminary measurements in healthy volunteers. This study includes measurements in both healthy volunteers and individuals with SCI who self-catheterize.

The objectives of the study are:

i) to provide a clinical proof-of-concept demonstration of MW bladder monitoring and bladder volume quantification; and ii) to provide data regarding the short-term functionality, utility, and comfort of the wearable MW bladder monitoring prototype.