Radio-frequency (RF) Bladder Monitor

The goal of this pilot feasibility study is to evaluate a wearable microwave (MW)-based bladder monitoring system in adult volunteers and those with spinal cord injury (SCI) who use self-catheterization for bladder management. The study aims to learn whether the device can monitor bladder filling and estimate bladder volume non-invasively. The main questions the study aims to answer are: 1. Can the MW-based monitoring system distinguish between non-full and full bladder states? 2. How accurately do MW-based bladder volume estimates agree with ultrasound bladder scans and voided urine volumes? 3. Is the wearable monitoring system feasible, comfortable, and usable for individuals with SCI? Participants will: 1. Complete questionnaires about bladder symptoms and quality of life 2. Wear up to six non-invasive MW sensors on the lower pelvic region 3. Undergo two bladder filling and voiding cycles during the study visit 4. Have MW measurements collected approximately every five minutes during bladder filling 5. Undergo ultrasound bladder scans and bladder volume measurements for comparison 6. Complete a post-study usability and comfort survey

Inclusion Criteria: * Age \> 18 * Able/willing to sit (or stand) in place for the time it takes for bladder to fill once. * No implanted devices * Able to toilet/void independently * No pregnancy Exclusion Criteria: * Age \< 18 * Implanted devices (e.g., pacemakers) * Unable to toilet without assistance * Unable to stay relatively still for the time it takes bladder to fill once * Pregnancy