The objective of this work is the implementation of on-chip, built-in intelligent control (2-point self-calibration/self-diagnosis) of dissolved oxygen microsensor by using an integrated electrochemical actuation microsystem. The development of intelligent and autonomous biochemical microsensor is in infant stage. A novel protocol needs to be developed to overcome the signal instability caused by drift of baseline and degradation of sensitivity. We propose to use an electrochemical actuation mechanism (water electrolysis) to accomplish this novel functionality. A water electrolysis microsystem (microchambers, microelectrodes, and microchannels) will be designed to provide two critical functions. First, the electrolytes saturated with the electrochemically generated dissolved gases serve as the calibrants for an integrated microsensor (two-point procedure with oxygen-saturated and oxygen-depleted electrolytes). Secondly, the electrochemically generated bubbles provide a driving force of the bidirectional microfluidic manipulation for the sampling/dispensing of sample solution. A microsystem including an amperometric dissolved oxygen microsensor and a water electrolysis microactuator is prepared by microfabrication technology. Their performances will be characterized in terms of the actuation signal (duration and amplitude) and the geometries of microfluidic components. The self-calibration/self-diagnosis capability is expected to significantly improve the accuracy and reliability of the biochemical sensors during continuous use and to make the in situ decision- making process viable in biological and medical monitoring. INTELLECTUAL MERITS OF PROPOSED ACTIVITY The electrochemical actuation is an emerging field in the MEMS-based microsensor technologies. The proposed method is the first approach to accomplish the functional integration (built-in intelligence) combined with the structural integration of biochemical sensor/actuator (miniaturization). The electrolysis actuation is applicable to improve performances of other enzymatic microsensors that utilize the oxidase enzyme reaction and to accomplish intelligent optical biosensing system. The same method can achieve the microfluidic actuation without the complicated MEMS-based structures. This system integration of both microsensors and microactuators is anticipated to advance current biomicrosystem technology towards innovative instrumentation for autonomous and minimally-attended biochemical monitoring. BROADER IMPACTS RESULTING FROM THE PROPOSED ACTIVITY The PI has a joint appointment in the Departments of Electrical & Computer Engineering and Biological Sciences at the University of Missouri-Rolla (UMR). The primary responsibility of the PI is to bridge the gap between the disciplines by initiating the campus-wide interdisciplinary research activities and by educating the students from both departments. The UMR is a member of LS-MoAMP (The Louis Stokes Missouri Alliance for Minority Participation) program and runs WIES (Women in Engineering and Science Program). The proposed research will be a valuable resource to expedite these activities through the involvement of students from various academic departments and from underrepresented groups.
