A 26.5 pArms Neurotransmitter Front-End With Class-AB Background Subtraction

This paper presents an analog front-end (AFE) for fast-scan cyclic voltammetry (FSCV) with analog background subtraction using a pseudo-differential sensing scheme to cancel the large non-faradaic current before seeing the front-end. As a result, the AFE can be compact and low-power compared to conventional FSCV AFEs with dedicated digital back-ends to digitize and subtract the background from subsequent recordings. The reported AFE, fabricated in a 0.18-mu m CMOS process, consists of a class-AB common-mode rejection circuit, a low-input-impedance current conveyor, and a 1st-order current-mode delta-sigma (Delta Sigma) modulator with an infinite impulse response quantizer. This AFE achieves an effective dynamic range of 83 dB with a state-of-the-art 39.2 pA(rms) input-referred noise when loaded with a 1 nF input capacitance (26.5 pA(rms) open-circuit) across a 5 kHz bandwidth while consuming an average power of 3.7 mu W. This design was tested with carbon-fiber microelectrodes scanned at 300 V/s using flow-injection of dopamine, a key neurotransmitter.

Automated summary

This paper presents an analog front-end (AFE) for fast-scan cyclic voltammetry (FSCV) that uses a pseudo-differential sensing scheme to cancel non-faradaic current and achieve a more compact and low-power design. The AFE achieves excellent performance in experimental tests.