Key aspects of achieving this stable performance include the electrodes and the implant packaging, however, this chapter focuses on the electronics aspects. In depth reviews and recent developments of recent electrode development can be found in [29,45,71,90,114] and of packaging can be found in [35,96,98,104,108]. There are also basic architectural challenges involved in scaling-up to hundreds or thousands of channels -for instance floating electrodes (i.e., with wires between the electrodes and electronics)