Nanoporous and wrinkled electrodes enhance the sensitivity of glucose biosensors

Three-dimensional electrodes improve the performance of biosensors by increasing their surface area to volume ratio, decreasing the analyte diffusion time, and/or improving analyte access or capture at the electrode. We demonstrate a rapid and facile method based on electroless deposition and polymer-induced wrinkling for creating three-dimensional multi-lengthscale electrodes. This all solution-processing method enables the structure of the electrodes to be tuned by inducing continuous or nanoporous wrinkled surfaces. The surface area and analytical sensitivity of the electrodes are tuned by varying the electroless deposition duration, with the nanoporous and wrinkled electrodes demonstrating the highest surface area and analytical sensitivity compared to their wrinkled and planar counterparts. The nanoporous and wrinkled electrodes developed here combine critical lengthscales ranging from the nanoscale to the macroscale by including nanoscale pores, microscale wrinkles and sub-millimetre-scale electrode footprints, and demonstrate a surface area enhancement of more than 5 times compared to the all-solution-processed planar electrodes. These electrodes were applied to glucose sensing, and their response was measured using three classes of electrochemical techniques: cyclic voltammetry, chronoamperometry, and pulsed amperometric detection. When using cyclic voltammetry, these electrodes enable enzyme-free glucose sensing with a sensitivity of 591 μA/mM.cm2 in alkaline solutions. This sensitivity is preserved when analysing solutions having a physiologically-relevant concentration of Cl− ions, and is reduced to 38 μA/mM.cm2 when analysing solutions having a neutral pH.