High accuracy and sensitivity differential potentiostat with amplifier-based error cancellation feedback loop

We present a low-current, high sensitivity and high linearity biosensor dedicated to neurotransmitter detection. The design is based on a fully-differential amplifier for enhanced sensitivity and wide dynamic range. Moreover, an error cancellation loop composed of high gain and rejection ratio amplifiers subtracts the voltage drop created by the sense resistor, thus enabling the use of high resistance values for low current sensing with no adverse effect on the biosensor´s dynamic range; as a result, the sensitivity of the circuit is considerably improved. Implementing this biosensor with discrete components led to a current sensitivity of 10 nA, an accuracy of 0.1 % and a CMRR of 83 dB.