Implantable Biosensor for Brain Dopamine using Microwire-Based Electrodes

This paper systematically demonstrates the feasibility of wirelessly monitoring dopamine concentration in the brain with an implantable biosensor. The biosensor was realized using microwires, and then, the dopamine concentration was measured in-vitro ranging from 0.3 $\mu$M to 2 $\mu$M, corresponding to the physio-pathological concentration range in human brain. The obtained results were used to design and optimise a full-custom CMOS sensor interface for in-vivo dopamine monitoring. The key component of this interface is a potentiostat with a maximum power consumption of 10.24 $\mu$W in a 10kHz sampling frequency. The CMOS interface automatically subtracts the background current up to 2.34 $\mu$A. The obtained sensitivity in dopamine detection has been evaluated in 150$\mu$A/$\mu$M, with a Limit of Detection (LoD) of 33 nM, thus being suitable for dopamine monitoring in human brain.