Development and evaluation of sleep posture monitoring system by using body pressure distribution measuring sheet made of conductive knitting

In recent years, the number of senior citizens needing nursing care has been increasing rapidly. Pressure ulcer is a major health issue for such people. In this study, for early detection of pressure ulcer, we developed a monitoring system by using a fabric sensor sheet that can monitor the degree of progress of pressure ulcer daily. This sheet is made using conductive knitting, and it functions as a sensor for measuring body pressure distributions of a user sleeping directly on the sensor sheet. It does not disturb the movement of the user and has an advantage of superior breathability and flexibility in comparison with existing pressure sensors. Moreover, our new design comprises a laminar structure for the wiring of the device, for ease of use. We measured the sleep postures of six subjects using this system and monitored those clearly. For our experiment results, we used a deep neural network (DNN) to distinguish each sleep posture and used a support vector machine (SVM) to determine the positions that caused pressure ulcer the most. As a result of these examinations, we showed that it was possible to distinguish the sleep postures with a high accuracy of 98% or more, and it was also possible to identify the positions that caused pressure ulcer the most.