Advances in Nanomaterials Integration in CMOS-Based Electrochemical Sensors: A Review

The monolithic integration of electrochemical sensors with instrumentation electronics on semiconductor technology is a promising approach to achieve sensor scalability, miniaturization, and increased signal-to-noise ratio. Such integration requires postprocess modification of microchips (or wafers) fabricated in standard semiconductor technology [e.g., complementary metal–oxide–semiconductor (CMOS)] to develop sensitive and selective sensing electrodes. This review focuses on the postprocess fabrication techniques for the addition of nanomaterials to the electrode surface, a key component in the construction of electrochemical sensors that has been widely used to achieve surface reactivity and sensitivity. Several CMOS-compatible techniques are summarized and discussed in this review for the deposition of nanomaterials such as gold, platinum, carbon nanotubes, polymers, and metal oxide/nitride nanoparticles. These techniques include electroless deposition, electrochemical deposition, liftoff, microspotting, dip-pen lithography, physical adsorption, self-assembly, and hydrothermal methods. Finally, this review is concluded and summarized by stating the advantages and disadvantages of these deposition methods.