Beginning with a comprehensive survey of existing semiconductor-based chemical microsensors and microsystems, this book proceeds to describe in detail CMOS technology-based chemical microsensor systems. The benefits of using CMOS technology for developing chemical microsensor systems and, in particular, monolithically integrated sensor systems comprising transducers and associated circuitry are laid out. Several successful realizations of such microsensor systems are presented. First, the fundamentals of the chemical sensing process itself will be elucidated, followed by a short description of microfabrication techniques and the CMOS substrate. Thereafter, a comprehensive overview of semiconductor-based and CMOS-based transducer structures and their applications is given. It is shown that CMOS-technology can be successfully used as platform technology to integrate microtransducers with the necessary driving and signal conditioning circuitry, and, in a next step, to develop monolithic multisensor arrays and fully developed microsystems with on-chip sensor control and standard interfaces. The book concludes with a brief outlook to future developments, such as interfacing cells with CMOS microelectronics.