Multi-site monitoring of choline and glutamate using biosensor microprobe arrays in combination with CMOS circuitry

Biosensor microprobe arrays for the simultaneous in vivo detection of the neurotransmitters choline and L-glutamate are presented. Combined with a custom-developed CMOS chip, comprising 24 potentiostatic circuits, recordings can be performed at high signal-to-noise ratio in multiple areas of a rat´s brain in parallel. The functionalization to create selective enzyme electrodes is based on electrochemical deposition methods and can be obtained by using functions of a versatile CMOS circuitry chip. The result is a compact all-in-one system convenient for on-site measurement. Biosensors show good selectivity, sensitivities larger than 100 μA mM^-1 cm^-2, detection limits of less than 0.3 μM, and response times below 1 second.