title: A system for monitoring cardiac vibration, respiration, and body movement in bed.
abstract: We have developed a non-invasive system for monitoring cardiac vibrations, respiration and body movement of in-bed hospitalized patients and elderly people who need constant care. These physiological parameters are recorded by 40 kHz ultrasonic transmitter and receiver, which are installed into the bed mattress. The ultrasonic transmitter diffuses an ultrasonic wave into the mattress. The diffusion of the ultrasonic energy is changed by mattress shape variations, which modulate the amplitude of the received ultrasonic signal. The amplitude is also modulated by physiological parameters such as heart pulse, respiration and body movement. The received ultrasonic signal is demodulated by an envelope detection circuit, and the physiological parameters are detected by low, high and band pass filters.
authors.affiliation: Dept. of Electronics, Hiroshima Inst. of Technology, Hiroshima 731-5193, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Mukai
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Yonezawa
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Maki
authors.forename: Hidekuni
authors.initials: H
authors.lastname: Ogawa
authors.forename: Ishio
authors.initials: I
authors.lastname: Ninomiya
authors.forename: Kouji
authors.initials: K
authors.lastname: Sada
authors.forename: Shingo
authors.initials: S
authors.lastname: Hamada
authors.forename: Allen W
authors.initials: AW
authors.lastname: Hahn