i-Flow: Design and evaluation of a wearable uroflowmeter with non-invasive low power bio-impedance sensing

Urological problems involving lower urinary tract symptoms (LUTS) such as urinary frequency, urgency, nocturia, and urine volume have a significant impact on patient health and quality of life. At present, clinical uroflowmeter tests and a urination frequency-volume chart (FVC) or bladder diary is recommended for monitoring the symptoms and the efficacy of treatment. However, these solutions are intermittent, needing high user compliance, repeated visits to the clinic and are inconvenient, especially for elderly patients. Such limitations lead to misdiagnosis and an inability to personalise treatments. This work proposes i-Flow, a low-power bio-impedance sensing system enabling wearable uroflowmetry. To demonstrate the effectiveness of the proposed solution, a preliminary dataset has been collected from 6 healthy subjects. Furthermore, the dataset acquired with a developed wearable system has been used to design a low-complexity, lightweight bladder voiding measurement algorithm and evaluates the overall hardware-software performance. In addition, repeatability tests on a single subject with multiple voiding instances (n=5) were conducted. The experimental evaluation demonstrates high-performance bladder voiding estimation with the total end volume (TEV) error for multi-subject voiding instances to be 38.4±18 ml. While the TEV error for repeated measures with a single subject was 21.7±15 ml for five voiding instances. The presented system for recording bladder voiding achieves an unobtrusive, comfortable and reliable method for automated recording of the frequency of voiding, the total voided volume and urine flowrate. Thus providing a means of conducting uroflowmetry tests in at-home settings while also maintaining a digital bladder diary devoid of human lapses. Such a system has the ultimate goal of assisting in diagnosis and personalizing treatment of LUTS.