Low power noise immune circuit for implantable CMOS neurochemical sensor applied in neural prosthetics

In this manuscript, we present the features and describe the operation of a low power, noise immune circuit for a CMOS based neurochemical sensor for implantable neural prosthetics. This microsystem consists of a single ended low noise low power amplifier and an integrator, in addition to a 10-bit first order sigma delta Analog to Digital Converter (ADC). Using electrochemical techniques, it senses picoscale to microscale current which corresponds to micro molar neurotransmitter concentration and converts the measurement to a 10-bit digital code. Combining amperometry and fast-scan cyclic voltammetry electrochemical technique results in a sensor with a high selectivity while having elevated temporal resolution. The microsystem consumes 120.85 μW which is the lowest reported brain implant and biosensor power consumption. This circuit is designed in CMOS 0.18 μm technology. Integration is an averaging operation and provides significant noise immunity. The low noise characteristics of our design make this device suitable for the noisy environment often encountered in-vivo.