Smart underwear, incorporating textrodes, to estimate the bladder volume: proof of concept on a test bench

Smart textiles, incorporating physiological sensors, are paving the way for remote and personalized healthcare. Indeed, their wearable sensors enable continuous and non-invasive monitoring of vital signs, such as an electrocardiogram (ECG), during patients' daily life without discomfort. Until now, most of the textile electrodes reported are ECG sensors to prevent heart disease. Nonetheless, the suitability of smart garments to tackle many other health conditions is still to be addressed. Around the world, millions of people are suffering from bladder dysfunctions such as urinary incontinence or retention. Hence the need to unobtrusively monitor their bladder content volume to improve their quality of life is evident. Most of the existing portable bladder scanners use ultrasounds to determine the bladder content volume. However bioelectrical measurements, such as electrical impedance tomography (EIT) or bioimpedance spectroscopy (BIS) have shown promising results. Also, textile electrodes have proven to be suitable for bioimpedance measurements in body composition analysis. In this study, smart underwear, integrating textile electrodes for bioelectrical measurements, has been designed and fabricated. The suitability of this smart structure for monitoring the bladder fullness has been evaluated on a test bench, including a pelvic phantom. A preliminary study has been done with conventional electrodes to determine the electrodes best location to sense the bladder filling. Then, the smart underwear, integrating two textile flexible electrodes on each thigh, was produced with the seamless technology on a circular knitting machine. The recordings of resistance variations, following the bladder filling with different solutions, with the developed underwear show similar trends as medical electrodes which is promising.