The measurement of urine flow rate plays a crucial role in functional diagnosis. However, traditional weight transducer-based method can only offer single, random, and in-office measurement, which is further limited by psychological factors and external interferences. This work aims to develop a novel urinary flowmeter containing both a flexible pressure sensor and a micro-rotor to provide a portable home-use urine flow rate measurement with high precision.

The novel uroflowmeter adopts an integrated design, which is composed of a urine collection tube, a flexible pressure sensor, a micro-rotor, and a signal transceiver circuit, resulting in a compact and lightweight device. The flexible pressure sensor and the micro-rotor serve as the core detection units of the uroflowmeter. Specifically, the flexible pressure sensor is fabricated based on micro-nano processing technology, by embedding silver nanowires into a PDMS layer with a surface featuring a pyramid structure. The micro-rotor, on the other hand, is obtained through high-precision 3D printing. The sensor measures the pressure signals generated by the urine within the tube and then converts it into the cross-sectional area of the urine flow. The micro-rotor is responsible for measuring the urine flow velocity. By calculating the product of the cross-sectional area and flow velocity in real-time, accurate urine flow rate data can be obtained. Additionally, the device is equipped with Bluetooth wireless transmission capability, enabling real-time transmission of measurement data to the patient's smartphone.

Initial tests demonstrate that the uroflowmeter can accurately distinguish between different flow rates and exhibits good dynamic response characteristics. Further testing using a peristaltic pump to simulate four typical urination patterns: normal, intermittent, slow, and fluctuating, reveals a high degree of agreement between the flowmeter's measurements and the pump's output flow curves. The device accurately captures and reproduces the key features of each urination pattern. To address the issue of high-frequency noise interference identified during testing, a low-pass filter based on the FFT algorithm is introduced, effectively filtering out the noise and significantly improving measurement accuracy.

This study developed a novel Portable Urinary Flowmeter Based on Flexible Pressure Sensor and Micro-rotor. With adaptability to various urination modes and excellent accuracy, it can be applied to portable high-precision urine flow rate measurement for household use.

The novel urinary flowmeter designed in this study offers advantages such as portability, high detection accuracy, stable data output, and smart device compatibility. Its integrated structural design makes it more friendly for ambulatory monitoring of urine flow rate measurement. It also serves as a novel tool for virtual bladder diary recording of the circadian voiding pattern.

Continence 12S (2024) 101596
DOI: 10.1016/j.cont.2024.101596