Self-Calibrating Microfabricated Iridium Oxide pH Electrode Array for Remote Monitoring

摘要

The goal of this work is the development of microfabricatednelectrochemical sensing systems for environmental,nindustrial, and security applications requiring long-termnunattended operation. The specific advantages of thenmicrofabrication approach include the capability not onlynto miniaturize the size of the sensor platform but also toncreate an intelligent design including features such asnredundant sensing electrodes, on-chip reference andnauxiliary electrodes, and in situ electrode regenerationcalibration. The model system targeted here involvesncontinuous pH monitoring in drinking water at solid-stateniridium oxide electrodes. The microchips utilized consistnof a flow-through silicon platform (1 cm × 1.2 cm)ncontaining patterned gold electrodes onto which iridiumnoxide has been deposited electrochemically. To simulatendrinking water detection scenarios, sensors are integratedninto a flow system. Microfabricated designs include asnmany as 11 equivalent pH electrodes whose performancenwas evaluated for factors such as electrode-to-electrodenreproducibility, long-term drift, and response to expectedninterfering agents. With on-chip voltage treatment, absolutenpotentials measured for an electrode array are withinn(4 mV, with identical ((1 mV/pH unit) calibration slopes.nThis performance level is sustainable over weeks of usage.