| Electrochemical biosensors transform biochemical reactions into electrical information through various electrode transducers. With their high sensitivity and specificity, electrochemical biosensors are ideal agents to detect many inorganic and organic substances. Recently, the microfabrication of biosensors has matured to the point where high density arrays can be generated. A microsystem comprised of such arrays and an integrated circuit (IC) suitable for sensor interrogation and information extraction enables the capabilities of electrochemical sensors to be employed in applications that require miniaturization, including point of care medical diagnostics and distributed safety and security monitoring. In such a microsystem, the interrogation IC must provide extremely high sensitivity, to read the weak response from the miniaturized sensors, and be capable of multi-channel simultaneous readout, to support high density (∼100 elements) arrays. This dissertation focuses on overcoming the challenges and limitations in electronics that impede the development of electrochemical microsystems. Specifically, this research targets electrochemical impedance spectroscopy, an essential assay technique for many sensor interfaces. Several possible architectures for multichannel impedance spectroscopy were explored in this dissertation. The key functional blocks, identified as an impedance extractor and digitizer and a wide frequency range quadrature signal generator, were designed, tested, and implemented within a prototype biosensor array system to validate the design. The results of this research pave the way for further development of ICs for electrochemical sensors and lay a solid foundation for future implementations of fully integrated electrochemical impedance microsystems. |
