Fabrication of Three-Dimensional Woodpile Cerium Oxide Nanostructure Via Solution-Based Soft Nanoimprint Lithography for Enzymatic Glucose Sensor

Abstract

Fabrication of ultra-high surface area electrodes can improve sensitivity for analyte detection. Here we report a scalable method for producing three-dimensional, nanoscale woodpile structures of cerium oxide for use in glucose sensors. A CeO2 nanoparticle based ink was used to directly pattern 500 nm wide grid structures via a solution-based soft nanoimprint lithography technique. The residual layer of the imprinted pattern was minimized by optimization of CeO2 concentration, speed and time of spin coating. Multi-layered woodpile structures of CeO2 were then achieved by a layer-by-layer imprint strategy. To prevent defects at the intersection of the layers, titanium diisopropoxide bis(acetylacetonate) was added as a binder. SEM data revealed that three-dimensional woodpile cerium oxide structures were successfully fabricated over a large areas. Then, an enzymatic glucose sensor was fabricated by printing such a CeO2 woodpile structure on a gold-coated substrate. Cyclic voltammetry and chronoamperometry were applied for detecting glucose in PBS buffer solution (50 mM, pH 7.0, 25 °C). Experimental data showed the sensitivity of glucose sensors can be improved by increasing the number of layers. The tetralayer CeO2 glucose sensors exhibited high sensitivity (8.2 µA mM-1 cm-2), short response time (1-2 s) and long linear range (0.02 mM-2.0 mM). These results indicated the three-dimensional woodpile structure of CeO2 is a promising material for high sensitivity biosensors.