Wearable electrocardiogram (ECG) is attracting much attention for monitoring heart diseases in healthcare and medical applications. However, an imbalance usually exists between the contact resistances of sensing electrodes, so that a common mode noise caused by external electromagnetic field can be converted into the ECG detection circuit as a differential mode interference voltage. In this study, after explaining the mechanism of how the common mode noise is converted to a differential mode interference voltage, the authors propose a circuit with cadmium sulphide photo-resistors for cancelling the imbalance between the contact resistances and confirm its validity by simulation experiment. As a result, the authors found that the interference voltage generated at the wearable ECG can be effectively reduced to a sufficient small level.
Keywords: CdS; ECG detection circuit; biomedical electrodes; biomedical electronics; cadmium compounds; cadmium sulphide photoresistors; common-mode noise cancellation; contact resistances; differential mode interference voltage; diseases; electrocardiogram; electrocardiography; external electromagnetic field; healthcare; heart disease monitoring; medical applications; medical signal processing; patient monitoring; photoresistors; sensing electrodes; signal denoising; wearable ECG.