A novel flexible Ag/AgCl quasi-reference electrode based on silver nanowires toward ultracomfortable electrophysiology and sensitive electrochemical glucose detection

To miniaturize or integrate electrochemical devices, new types of nanoparticle-based Ag/AgCl quasi-reference electrodes (qREs) have been generated via screen printing and inkjet printing. However, their nanostructures and addition of binder materials produce unsatisfactory conductivity and sensitivity. Herein, a novel Ag/AgCl qRE with a nanowire-and-nanoparticle (NWP) structure is developed. The unique NWP-Ag/AgCl qRE is first generated by drop coating silver nanowires (AgNWs) on poly(dimethylsiloxane) (PDMS), followed by chemical chlorination. Because the nanowires form well-connected network, the novel NWP-Ag/AgCl qRE creates efficient charge transport paths as well as porous 3D structures that enable faster electrolyte percolation. The NWP-Ag/AgCl qRE reaches 95% stable potential fast (6.4 s) and is extremely stable (at least 8000 s continuous measurement and 6-month shelf life). The NWP-Ag/AgCl qRE on PDMS provides ultracomfortable tactile experience that is suitable for skin-contact electrophysiology. The NWP-Ag/AgCl qRE has also been successfully applied to the detection of glucose with a linear range of 1 μM–1900 μM. This study establishes a new printer-free Ag/AgCl qRE fabrication method with simple chemistry. Furthermore, the new method is a truly transformatively efficient and cost-effective approach with substantial industrial applications to electrophysiology and electrochemical device-making.