Development of Unconstrained Bio-signals Sensing Devices by Piezo Ceramic

Abstract

This paper describes a novel noninvasive, unconstrained and unconscious bio-signals sensing bed. The sensing bed detects heartbeat, respiration, body movement and posture change of a person laying or sleeping on the bed. These bio-signals provide not only the basic medical information but also the sophisticated sleeping condition information. Thus it can be used to monitor health condition of healthy persons spending their home at night as well as the patient persons in hospital. Further it can detect the emergent change in the physical condition at home and/or hospital. The basic device used in the sensing is the piezo-ceramics bonded to the stainless steel plate which is sandwiched by floor and four feet of a bed. Thus no special bed is required. The devices detect the bio-signals above generated as mechanical vibrations. The device has the wide dynamic range and high SN ratio so that it can detect from the micro-vibration due to heartbeat to the change in the force acted when a person rides on the bed wit out saturation. It clearly detects the heartbeat and respiration as well as it detects how a person on the bed moves. The devices can be applied to variety of health monitoring including sleep and medical application for diseases for the circulatory system and those accompanied with itchy.