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

Study Overview

• Status: Not yet recruiting
• Conditions: Neurogenic Lower Urinary Tract Dysfunction; Spinal Cord Injuries (SCI); Neurogenic Bladder (NB)
• Intervention / Treatment: Device: Wearable microwave Bladder Monitoring System

Detailed Description

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.

The study will enroll adult healthy volunteers and adult participants with SCI who use self-catheterization for bladder management. Following informed consent, participants with SCI may complete questionnaires related to bladder dysfunction and bladder-related quality of life, including the Neurogenic Bladder Symptom Score Short Form (NBSS-SF).

Participants will undergo bladder filling and voiding cycles during the study visit. At the beginning of the session, participants will be asked to void their bladder using their usual voiding or catheterization method. For participants in whom pregnancy is possible, urine pregnancy testing may be performed prior to RF measurements. Ultrasound bladder scans will be performed at empty and full bladder states and will serve as reference measurements for bladder volume estimation. Voided urine volumes will also be collected during voiding phases.

The MW bladder monitoring prototype will be placed externally on the lower pelvic region by study personnel. Up to six sensors may be used. Sensors will be secured using adhesive bandages or wrap-style fixation methods. No skin preparation, gels, or invasive procedures are required. MW measurements will be collected automatically approximately every five minutes while the bladder fills naturally. Participants may rest or perform sedentary activities during the measurement period. Measurements will continue until bladder fullness is reached or the participant requests to void. The bladder filling and emptying process may then be repeated for a second cycle during the same study visit.

Collected MW measurement data will be analyzed to investigate signal trends and the feasibility of the technology. Planned analyses include:

• Bladder fullness classification through comparison of MW signal trends between non-full and full bladder states;
• Bladder volume quantification using raw measurement data and reconstructed radar image data;
• Comparison of MW-based bladder volume estimates with ultrasound-estimated bladder volumes and voided urine volumes.

Exploratory analyses will evaluate signal trends across the measured frequency range to select optimal frequency points, measurement variability, and sex-based differences in MW measurements. Participant and clinician feedback surveys will additionally be used to assess device comfort, usability, and utility for bladder monitoring applications.

As a final remark, this pilot feasibility study is intended to generate preliminary clinical data supporting further development and optimization of wearable MW bladder monitoring technology and may support future larger clinical investigations aimed at improving bladder management for individuals living with bladder dysfunction, including neurogenic bladder associated with SCI. The investigational device is considered low risk. The device is non-invasive and uses low-power RF/MW signals for sensing and monitoring purposes only.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Emily Porter, Ph.D.; Phone Number: 37794 514-934-1934; Email: emily.porter@mcgill.ca
• Study Contact Backup: Name: Lysanne Campeau, Ph.D.; Phone Number: 24906 514-340-8222; Email: lysanne.campeau@mcgill.ca

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H4A 3J1
      • Centre for Innovative Medicine (CIM) - McGill University Health Centre (MUHC)
      • Contact: Emily Porter, Ph.D.; Phone Number: 37794 514-934-1934; Email: emily.porter@mcgill.ca
      • Principal Investigator: Emily Porter, Ph.D.
      • Principal Investigator: Lysanne Campeau, Ph.D.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Microwave Bladder Monitoring in Individuals with Spinal Cord Injury; Healthy participants and participants with spinal cord injury (SCI) who use self-catheterization for bladder management will undergo non-invasive microwave (MW)-based bladder monitoring during two bladder filling and voiding cycles. Up to six externally applied MW sensors will be positioned over the lower pelvic region to collect measurements associated with bladder filling. Measurements will be acquired approximately every five minutes while the bladder fills naturally. Ultrasound bladder scans and voided urine volumes will be used as reference measurements for bladder volume estimation and bladder fullness assessment. The study will evaluate the feasibility, usability, comfort, and preliminary performance of the wearable MW bladder monitoring system in both healthy participants and individuals with SCI.

Device: Wearable microwave Bladder Monitoring System; The investigational device is a non-invasive wearable microwave (MW) bladder monitoring system designed to monitor bladder filling and estimate bladder volume. The system uses low-power radio-frequency (RF) signals and externally applied sensors positioned over the lower pelvic region to collect electromagnetic measurements associated with bladder filling. Measurements will be collected approximately every five minutes during natural bladder filling cycles. The device is intended for investigational use only and does not provide therapeutic intervention or automated clinical decision-making.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean difference in microwave S-parameter magnitude between full and empty bladder states (dB)	Microwave S-parameter measurements collected during bladder filling and voiding cycles will be compared between empty and full bladder states. The outcome will be reported as the mean difference and standard deviation in S-parameter magnitude between full and empty bladder states across the measured frequency range, expressed in decibels (dB).	Through study completion, an average of 4-8 hours
Mean error of microwave-based bladder volume estimation (mL) relative to ultrasound bladder volume estimates and voided urine volume	Bladder volume estimates derived from microwave S-parameter measurements will be compared with ultrasound bladder volume estimates and voided urine volumes obtained during bladder filling and voiding cycles. The outcome will be reported as the mean difference and standard deviation between microwave-based bladder volume estimates and the corresponding reference measurements (mL).	Through study completion, an average of 4-8 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total score on the investigator-developed post-participation bladder monitor questionnaire	Participant perceptions of comfort, usability, and utility of the wearable microwave-based bladder monitoring system will be assessed using an investigator-developed post-participation questionnaire. Total scores range from 1 to 10, with higher scores indicating greater comfort, usability, and perceived utility of the device.	Day 1
Frequency points exhibiting the greatest difference in microwave S-parameter magnitude between full and empty bladder states (MHz)	For each participant, differences in microwave S-parameter magnitude between full and empty bladder states will be calculated across the 500-3000 MHz frequency range. The outcome will identify the frequency points and frequency ranges exhibiting the largest bladder-state-dependent signal differences. Analyses will be performed for the overall cohort and separately for male and female participants to assess sex-based differences in optimal frequency selection.	Through study completion, an average of 4-8 hours

Collaborators and Investigators

• Sponsor: McGill University Health Centre/Research Institute of the McGill University Health Centre
• Collaborators: Congressionally Directed Medical Research Programs
• Investigators: Principal Investigator: Emily Porter, Ph.D., McGill University; Principal Investigator: Lysanne Campeau, Ph.D., McGill University

Publications and helpful links

General Publications

• A. Farshkaran and E. Porter, "Importance of Sex-Based Modelling of the Pelvic Region for Microwave Medical Applications," 2022 IEEE MTT-S International Microwave Biomedical Conference (IMBioC), Suzhou, China, 2022, pp. 1-3, doi: 10.1109/IMBioC52515.2022.9790287. keywords: {Microwave technology;Biomedical equipment;Biological system modeling;Conferences;Scattering;Medical services;Physiology;bladder;microwave medical applications;pelvic region}
• A. Raterink, A. Farshkaran and E. Porter, "Microwave Reflection-based Bladder State Discrimination with Realistic Pelvic Models: Impact of Urine Conductivity and Volume," 2021 IEEE MTT-S International Microwave and RF Conference (IMARC), KANPUR, India, 2021, pp. 1-4, doi: 10.1109/IMaRC49196.2021.9714587. keywords: {Microwave antennas;Solid modeling;Shape;Bladder;Conductivity;Microwave theory and techniques;Dielectrics;bladder;microwave imaging;pelvic region model.}
• E. Porter, A. Raterink and A. Farshkaran, "Microwave-Based Detection of the Bladder State as a Support Tool for Urinary Incontinence [Bioelectromagnetics]," in IEEE Antennas and Propagation Magazine, vol. 64, no. 1, pp. 112-122, Feb. 2022, doi: 10.1109/MAP.2021.3129687. keywords: {Wireless communication;Ultrasonic imaging;Magnetic resonance imaging;Computed tomography;Wearable computers;Microwave devices;Monitoring}
• Farshkaran A, Fry A, Raterink A, Santorelli A, Porter E. Proof-of-Concept of Microwave-Based Bladder State Detection Using Realistic Pelvic Models. IEEE Open J Eng Med Biol. 2023 Aug 16;5:140-147. doi: 10.1109/OJEMB.2023.3305838. eCollection 2024.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): March 31, 2027

Study Registration Dates

• First Submitted: June 1, 2026
• First Submitted That Met QC Criteria: June 5, 2026
• First Posted (Actual): June 10, 2026

Study Record Updates

• Last Update Posted (Actual): June 10, 2026
• Last Update Submitted That Met QC Criteria: June 5, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Spinal Cord Injury; Neurogenic Bladder; Assistive Technology; Urology; Non-Invasive Monitoring; Neurogenic Lower Urinary Tract Dysfunction; Wearable Medical Device; Bladder Monitoring; Bladder Management; Microwave Sensing; Radio-Frequency Sensing; Bladder Fullness Detection; Bladder Volume Estimation; Pilot Feasibility Study
• Additional Relevant MeSH Terms: Urogenital Diseases; Neurologic Manifestations; Central Nervous System Diseases; Nervous System Diseases; Wounds and Injuries; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Trauma, Nervous System; Urinary Bladder Diseases; Spinal Cord Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Spinal Cord Injuries; Urinary Bladder, Neurogenic
• Other Study ID Numbers: 2025-10205; CDMRP-SC240005 (Other Grant/Funding Number: CDMRP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified microwave measurement data may be published. No personally identifiable participant information will be shared.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No