シート型電極マトリックスのインピーダンス変化を用いた排尿量推定システム

抄録

We developed a system in which an electrode matrix sheet is placed on the bedding to detect electrically urination of bedridden elderly patients without installation of special sensors in disposable diapers. The sensing device is an electrode matrix sheet consisting of 165 square copper electrodes arranged in 11 rows vertically and 15 horizontally. The system consists of an AC power supply, the electrode matrix sheet, and a resistor of 100 kΩ (for output detection) connected in series. The system can be represented as an AC circuit with a resistor and a capacitor connected in series. The output was the voltage at the resistor. It was possible to depict how simulated urine spread in the disposable diaper as the change in capacitive reactance in the electrode matrix sheet. The output was inversely proportional to the number of electrodes in the area with absorption of the simulated urine. It was also possible to estimate the amount of simulated urine regardless of the direction of spread on the sensing device. We investigated the relationship between the amount of simulated urine and the output voltage of the system using a three-dimensional buttock model. The experimental results showed that detection of urine from outside the disposable diaper was possible if the amount at the first urination was 200mL or more. The results of this experiment, showed that the output tended to increase logarithmically as the amount of simulated urine increased within the range of 200-1,000mL.