%0 Journal Article
%@ 0013-4686
%A Keeble, Lewis
%A Jaccottet, Arthur
%A Ma, Daryl
%A Rodriguez-Manzano, Jesus
%A Georgiou, Pantelis
%D 2024
%F discovery:10185432
%I Elsevier BV
%J Electrochimica Acta
%K CMOS,  Reference electrode,  Electroplating,  Electrochemical,  Electroless
%T An electroplated Ag/AgCl quasi-reference electrode based on CMOS top-metal for electrochemical sensing
%U https://discovery.ucl.ac.uk/id/eprint/10185432/
%V 477
%X The integration and mass-production of reference electrodes for CMOS-based electrochemical sensing systems  pose a challenge for the accessibility and commercial-viability of such devices. In this paper, a method of  electroplating an Ag/AgCl quasi-reference electrode using CMOS top-metal as a base is presented for the first  time. The aluminium bond-pad of a CMOS microchip was zincated, an electroless nickel immersion gold layer  applied, and a thick silver layer electroplated and chemically chlorinated. The resulting reference electrode was  able to provide a stable potential with a drift rate of 0.3 mV/h for up to 18 h. This validates the approach of a  fully electroplated bond-pad reference electrode, which offers simplified post-processing and greater scalability  of production. Further work towards an entirely electroless process is envisaged
%Z © 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).