A 128-ch Area-Efficient Neurochemical-Sensing Front-End for FSCV Recordings of Dopamine

Neurochemical recordings rely on electrochemical reactions of electroactive neurotransmitters such as dopamine, serotonin, and norepinephrine. This electrochemical technique allows for highly sensitive monitoring of neurotransmitters in the brain. Traditionally, single-channel carbon-fiber microelectrode (CFE) recordings have been considered the gold standard method. However, an alternative approach involves the use of a microelectrode array, which enables high spatiotemporal resolution imaging of electroactive neurotransmitters. To enable neurochemical imaging using a microelectrode array, the development of a high-density current-sensing microchip is necessary. Here, a neurochemical microchip is introduced, featuring a 128-channel current sensing front-end capable of supporting 128 parallel neurochemical measurements. The designed amplifier array employs a highly scalable resistive feedback transimpedance amplifier design. This design allows for a large neurochemical dynamic range of ± 5 μA with a noise performance as low as 0.22 nARMS. The presented current sensing front end is validated by electrochemical detection of dopamine, by fast-scan cyclic voltammetry (FSCV) at 400 V/s, using an external carbon-fiber electrode in an electrochemical flow cell.