A compact hybrid-multiplexed potentiostat for real-time electrochemical biosensing applications

Author-Highlights
• A multiplexed electrochemical readout must allow continuous working electrode biasing.
• A hybrid multiplexing architecture allows fulfilling predefined timing constraints.
• Accuracy of continuously biased multiplexed measurements was proven with experiments.

The architecture and design of a compact, multichannel, hybrid-multiplexed potentiostat for performing electrochemical measurements on continuously-biased electrode arrays is presented. The proposed architecture utilises a combination of sequential and parallel measurements, to enable high performance whilst keeping the system low-cost and compact. The accuracy of the signal readout is maintained by following a special multiplexing approach, which ensures the continuous biasing of all the working electrodes of an array. After sampling the results, a digital calibration technique factors out errors from component inaccuracies. A prototype printed circuit board (PCB) was designed and built using off-the-shelf components for the real-time measurement of the amperometric signal of 48 electrodes. The operation and performance of the PCB was evaluated and characterised through a wide range of testing conditions, where it exhibited high linearity (R2>0.999R2>0.999) and a resolution of 400 pA. The effectiveness of the proposed multiplexing scheme is demonstrated through electrochemical tests using KCl and [Fe(CN)6]3−[Fe(CN)6]3− in KCl solutions. The applicability of the prototype multichannel potentiostat is also demonstrated using real biosensors, which were applied to the detection of IgA antibodies.