WSEAS Transactions on Electronics
Print ISSN: 1109-9445, E-ISSN: 2415-1513
Volume 7, 2016
Low-Power Measurement of Contact Impedance in Dry Electrocardiography
Authors: , ,
Abstract: This paper reports the design of an improved circuit for monitoring the quality of contact of un-gelled electrodes with a patient’s skin in the measurement of the ECG. The circuit is intended to be incorporated into a monitor used prior to and during childbirth to measure the mother’s heart rate. The revised design uses commercially available low-power technology to implement the circuit with a reduction in the power consumption by a factor of more than 40 over a previous design [13,14]. The circuit measures electrode contact impedance and activates a visual alarm when the contact impedance of either electrode rises above 100kΩ. The impedance is measured using a signal injected through the electrodes at a frequency of 5kHz. The resulting signal present at the amplifier input at this frequency is then extracted and processed before threshold detection of the signal level which is used to indicate whether or not the quality of contact with the electrodes is acceptable for the purposes of heart rate measurement. The circuit operates at a current of 700μA drawn from a 3.3V supply which gives a power consumption of 25mW.
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Pages: 65-78
WSEAS Transactions on Electronics, ISSN / E-ISSN: 1109-9445 / 2415-1513, Volume 7, 2016, Art. #9