Ambulatory Device for Urinary Incontinence Detection in Female Athletes

Urinary incontinence (UI) has been known as a prevalent concern among parous and elderly women. However, recent studies have shown an unexpectedly high occurrence of UI in young physically fit female athletes who are actively participating in vigorous physical activities. Those study results motivated us to explore the relationship between daily intensive exercise and the occurrence of UI. As the first step to advance our understanding of this problem, an ambulatory device was developed for recording urological response to the intense force levels to which female athletes are subjected. The device consists of three types of wearable sensors, including 1) a +/– 25g tri-axial accelerometer, 2) a $360°$ biaxial inclinometer and 3) a urinary leakage detector or ULD. It also contains a compact data logger for real-time data recording with high frequency and precision (125 Hz, 16-bit A/D converter). The accelerometer and inclinometer help to determine the force levels developed in the body during physical activities at which urinary leakage occurs. Two types of ULD sensors have been designed: (1) copper lattice ULD, and (2) thermistor array ULD. Copper lattice ULD senses the UI based on the fact that urine drops reduce the resistance of the copper lattice resulting in a voltage change. The thermistor array ULD makes use of the finding that leaked urine is warmer than the surface of the skin, such that the integrated thermal components respond to urine leakage differently. In addition, a thermoelectric cooler is applied to produce a constant reference temperature. The entire device is small, lightweight, nonintrusive, and can be worn comfortably by subjects on their wrists or low back for at least 3 hours of continuous data recording. The test results from the recruited female athletes show that the three sensors can simultaneously record the intensity of activity and the corresponding urine leakage. However, for the copper lattice ULD, substantial sweat developed during the vigorous activity which produced an artifact and prevented the device from detecting the occurrence of urine leakage. The recently designed thermistor array ULD is less sensitive to sweat, resulting a more reliable sensor than is provided by the copper lattice ULD. The wearable sensor based device enables us to determine if urinary incontinence in female athletes occurs during vigorous physical activities or as a result of the fatigue caused by these activities. This conclusion facilitates the understanding of the mechanism of UI and assists trainers and coaches with the design of an appropriate training program that reduces the occurrence of UI in these female athletes.