(154c) A Multi-Electrode Array Microbiosensor for Monitoring of Neurotransmitter Concentration Changes In Vivo

We are designing, producing, and implementing micromachined, multielectrode microprobes for the detection of neurotransmitters in near real-time in the brains of live rodents. Over 100 devices are constructed simultaneously on four-inch silicon wafers with two to five, micron-sized electrodes per probe using micro-electro-mechanical-systems (MEMS) fabrication technologies. One or more microelectrode sites per probe is chemically modified with permselective polymer films and immobilized glutamate oxidase for the electroenzymatic detection of glutamate. Another site is modified for use as an on-probe reference electrode. Glutamate is detected selectively with sub-second response time in the presence of the electroactive interferents, dopamine and ascorbic acid. In the anesthetized rat, these glutamate biosensors detect cortically-evoked glutamate release in the ventral striatum. In the freely moving rat, stress-induced glutamate release is detected in the dorsal striatum. Currently, these microprobes are being explored for use in the study of drug-seeking behavior in rodents. The microelectrode microsensors also may serve as a platform for the creation of multi-analyte (e.g., glutamate and dopamine) sensing devices useful for measurements in vivo.