Time-based Sensor Interface for Dopamine Detection

This paper describes the design of an integrated sensor interface for dopamine detection. The sensor interface circuit fabricated in 65 nm CMOS technology utilizes a time-based analog-to-digital conversion circuit built around a ring oscillator. The circuit supports a wide input current range of±1.2 µA and sampling rate of 1 - 20 kHz, enabling sub-second detection of neurochemicals within the supported current range. Measured results with physiologically relevant dopamine concentration of 500 nM demonstrate the ability of the sensor interface circuit to detect oxidation and reduction current peaks, which provides information about the release times and redox potentials of the neurochemical. This chemical information is essential in neurostimulation treatment of neurological and neurodegenerative diseases.