This book presents the development of amplifiers designed specifically for the detection of biopotential signals. A refresher on op-amp-based amplifiers is presented in the context of the amplification of bio-potentials. Projects for this chapter include chloriding silver electrodes high-impedance electrode buffer array pasteless bioelectrode single-ended electrocardiographic (ECG) amplifier array body potential driver differential biopotential amplifier instrumentation-amplifier biopotential amplifier and switched-capacitor surface array electromyographic amplifier.