@article{discovery10185432, year = {2024}, journal = {Electrochimica Acta}, title = {An electroplated Ag/AgCl quasi-reference electrode based on CMOS top-metal for electrochemical sensing}, volume = {477}, note = {{\copyright} 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/).}, month = {January}, publisher = {Elsevier BV}, abstract = {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}, issn = {0013-4686}, url = {http://dx.doi.org/10.1016/j.electacta.2024.143780}, author = {Keeble, Lewis and Jaccottet, Arthur and Ma, Daryl and Rodriguez-Manzano, Jesus and Georgiou, Pantelis}, keywords = {CMOS, Reference electrode, Electroplating, Electrochemical, Electroless} }