Experimental results of two adaptive motion-artifact rejection and stabilization (MARS) techniques, namely, the acquisition-path-gain (APG) tracking and compensation and the negative input capacitance (NIC) neutralization, both prototyped in a dry-contact ECG sensor, are reported. The analog frontend (AFE) of the sensor is integrated in a 65-nm CMOS chip and the backend digital signal processing (DSP) is performed on a host PC. The MARS techniques help combat the distortion of recorded biopotentials due to voluntary and involuntary body movements, such as breathing and normal daily activities, and are suitable for deployment in wearable healthcare devices. Measurement results verify the efficacy of the reported MARS techniques. The CMOS AFE chip also achieves comparable performance with a few recently published works using dry-contact electrodes.