ManyComplementary Metal-Oxide-Semiconductor (CMOS) of the electrochemical sensing devices introduced in the previous chapters rely on external instruments such as potentiostats or electrometers. For simultaneous multiplexed detection of multiple analytes and bio/chemical imaging, it is crucial to integrate sensors, microfluidic components, and circuitry for sensor operation, signal acquisition, and processing using CMOS-MEMS technology. Electrochemical sensors offer strong potential for CMOS integration owing to their structural simplicity. This on-chip integration minimizes signal path length, reducing noise and eliminating the need for external shielding, such as Faraday cages. Since their emergence in the 1980s, these devices have advanced substantially, enabling applications such as large-scale DNA sequencers, chemical imaging devices, and implantable pharmaceutical chips. These devices fall into two categories: (1) large-scale integrated sensor arrays with multiplexers for high-throughput data acquisition and chemical imaging. These arrays support applications such as label-free DNA detection, real-time PCR monitoring, and nanopore- and ISFET-based genome sequencing. In addition, electrochemical imaging allows for high spatial resolution and real-time monitoring of electrochemical species in biological systems, with applications including neurotransmitter imaging, cell counting, wound healing studies, and biofilm analysis. (2) Ultra-miniaturized, wireless, fully self-contained electrochemical sensor systems. These devices, some injectable through syringe needles, integrate all necessary circuitry onto chips with footprints under 1 mm2, offering promising solutions for continuous in vivo health monitoring and drug integration.