Sensing Method of Patient’s Body Movement Without Attaching Sensors on the Patient’s Body Evaluation of “Scratching Cheek,” “Turning Over and Scratching Back,” and “Scratching Shin”

摘要

Medical specialists hardly pay attention to scratching as a disease, and thus, few measurement methods of scratching behavior and frequencies have been considered. Scratching can yield serious mental and physical problems. This paper describes a monitoring method for scratching and turning over motions during sleep, using a sensor without a power supply. The method is based on the piezoelectric effect. Piezo-ceramic devices are placed under the legs of a bed. When a subject lies on the bed, body movements occur. Small body movements can occur because of heart beats, while breathing, scratching, and other physiological phenomena. Significant body movements occur while changing positions during sleeping or while moving out of the bed. The proposed method detects these body movements, including the scratching. Here, we aimed at investigating how clearly the proposed method discriminates scratching from the other motions and extracts the scratching period. To validate the proposed method, we carried out experiments and evaluated three cases involving the scratching motion. In Case 1, the subject scratches one's right cheek with right hand; in Case 2, the subject scratches one's back after turning over; in Case 3, the subject scratches one's left shin with right foot. The results showed that the proposed method, using this simple device, can detect scratching, turning over, and their occurring periods with a comparable degree of accuracy to the conventional video camera recording method. Furthermore, the sensor could record a signal during the night, under real conditions, when a subject sleeps on the equipped bed.