Noninvasive Ambulatory Monitoring of the Electric and Mechanical Function of Heart with a Multifunction Wearable Sensor

A multifunction wearable noninvasive ambulatory monitoring sensor based on Electrocardiogram (ECG) and Impedance Cardiography (ICG) has been designed, fabricated and tested. The electric function (with ECG) and mechanical function (with ICG) of the heart can be monitored simultaneously and continuously. Based the RR serials computed from ECG waveform, the sympathetic and parasympathetic function of the automatic nervous system can also be monitored at the same time. The physical activity is monitored with a 3-axis accelerometer and a 3-axis gyroscope chip on the sensor board. The physical activity data is very important because heart rate and cardiac output etc has different standard value under different movement intensity conditions. Hemodynamic parameters such as stroke volume (SV), cardiac output (CO) and cardiac index (CI) can be estimated according to Kubicek Formula by extracting characteristic points and characteristic periods of the ICG Signal. CI is CO divided by body surface area. CI is comparable among people because it is not influenced by the body height and body weight. The detection accuracy has also been validated with a commercial patient monitor from Mind Ray company, the correlation coefficient is 0.83.