The measurement of the urine flow rate is one of the most commonly used tests in urology. Weight sensor-based instruments are currently the main methods for this measurement. However, the specific detection environment and heavy instruments required by this method reduce the comfort and portability of the measurement, resulting in random deviation and inaccuracy of the results. Therefore, this study intends to construct a novel uroflowmeter based on flexible pressure sensor to realize portable and highly urine flow measurements.

The novel uroflowmeter in this work consists of three components: an arc-shaped tube, a flexible pressure sensor, and the signal measurement circuit, which is compact and lightweight. The flexible pressure sensor is placed at the outlet of the circular tube, and the pyramid micron structure is used as the core sensitive unit of the sensor, so as to respond to the small pressure signal generated by the trace amount of urine. The piezoresistive signals generated by urine on the unit area of the sensor can be converted into the cross-sectional area and velocity of urine at the moment, and the instantaneous urine flow rate can be measured finally. The resulting signal can be transmitted to the patient's mobile phone via an external Bluetooth device to enable portable urine flow rate detection.

Simulated urinary flow with five different cross section diameters (e.g., 1.6mm, 2.4mm, 3.2mm, 4.8mm and 6.4mm) were used to flow through the sensor, and we found that the resistance value of the sensor changed significantly. The results showed that the flexible pressure sensor had good resolution and stable current output in flow rate monitoring, and the resistance results decreased with the increase of the simulated urine volume.  In addition, the sensor's signal curves was bell-shaped, consistent with the normal urination curve. By comparing the sensor detection curve with the original data of voiding functional diseases in the database, portable and accurate assessment of different voiding functional diseases can be achieved.

The above results indicate that the uroflowmeter based on flexible pressure sensor in this work can distinguish the water flow with dynamic diameter change and has good dynamic characteristics.

In summary, we have designed a flexible pressure sensor-based uroflowmeter with simple structures, high detection accuracy and stable data output. It shows great potential in portable, home-based urine flow rate detection and preliminary voiding functions assessment. Future clinical evaluation in normal person and patients is still needed to justify its regular use.

Continence 7S1 (2023) 100919
DOI: 10.1016/j.cont.2023.100919