Measurement of human body extension e.g. heartbeat or breathing - arranging stray field of capacitive sensor electrodes, which frequency modulate oscillator by body movement, near to metal foil sensor and forming resonant circuit, and coupling out signal via coil to mixer.

摘要

The electric field of a sensor capacitor, attached to the body either in conjunction with a coating or directly, is modulated in frequency by the extension. Its stray field is detected at few distances away from the body using a probe and converted into a signal by an electronic circuit connected to the probe via a cable (18). The signal is proportional to the extension. Two spaced conductors (2) forming the capacitor electrodes with an applied dielectric are arranged near the body so that the distance between the body's conducting surface and one electrode varies with the extension of the body to enable contactless measurement. The partial capacitors formed by the capacitor electrodes and body surface are connected in series. USE/ADVANTAGE - For use in monitoring vital functions of breathing and heartbeat and plethysmography of muscle contraction. Enables user-friendly, contactless measurement at low cost.