Multi-target detection of neurochemicals is crucial to elucidate brain chemical signaling interplay. We describe in this paper an efficient experimental method to detect 2 types of neurotransmitters and the subsequent implementation of a dedicated potentiostat custom circuit. The experimental method is based on a biosensor performing constant-potential amperometry for an efficient detection of neurotransmitters, such as dopamine and glutamate, using a Carbon-nanotube (CNT)-based multi-working electrode sensor, which offers high sensitivity and selectivity. The custom CMOS time-based potentiostat circuit, designed to accommodate the detection of a wide variety of neurochemicals, is used as transducer. The proposed design is characterized through post-layout simulations, showing a wide dynamic input current range of 20 pA to 800 nA, and an input referred noise of 0.13 pA/√Hz. The circuit dissipates 56 μW for a minimum sampling frequency of 1.25 kHz. Circuit performances fully satisfies the requirements for the developed dopamine and glutamate sensors. The proposed biosensor configuration can be extended to the detection of a large number of neurochemicals.