Single-use ECG electrodes are used for conventional ECG tests during diagnosis or monitoring. It uses a sensitive element Ag / AgCl, a solid conductive and adhesive hydrogel, or a wet conductive gel for adhesion. The sensory element Ag/AgCl has better sensitivity, while the solid conductive, sticky, and wet hydrogel have very low impedance and do not cause irritation, sensitization, or cytotoxicity to the skin.