Design and implmtation of Optoisolation circut of E.C.G machine using 650nm diode laser

Abstract

Electrical safety and more explicityly, patient shock hazard associated with the use of biomedical electronic equipments has become controversial and embrassing subject and become a continuously growing problem. Great majority of electric accidends involve a current pathway through the victime from one upper limb to the feet or to the opposite upper limb. So various effects of the electric current on the muscles along its pathway,as well as its effectcs on the heart as it passes through the chest.So ECG must not produce a direct electrical connection between the subject and ground. Electrical isolation is provided using transformer isolation , capacitive isolation, or optical isolation coupling techniques. in this work, ECG signal was transmitted via an optical amplitude modulated transmitter and the signal decoded at the receiver,to achieve patient’s safety against electrical hazards (Micros hock and leakage current), using diode laser at the end of the patient’s circuit and photodetector at the portion of the circuit connected to the ac power line and ground.