Stable Electrocardiogram Measurement Using Capacitive-Coupled Electrodes*

In recent years, the number of traffic accidents attributable to human error has been increasing, and it is essential to monitor the biological state of drivers to avoid accidents. Biological sensors with skin contact are generally employed for such purposes, but using such skin-contact-based sensors in cars is challenging. To avoid skin contact, in this study, we focus on a capacitance-coupled electrode that can measure electrocardiogram (ECG) even when a person is wearing clothes. However, capacitance-coupled electrodes have a practical limitation in that the detection level of ECG differs between summer and winter. In addition, the detection level is unstable depending on the measurement environment and factors such as the number of layers of clothes worn. Based on experiments conducted in an in-vehicle environment, we propose a solution to the problem of overlapping clothing and a system that can acquire ECG by improving capacitive-coupled electrodes and analog signal processing circuits.