Facile fabrication of electrochemical ZnO nanowire glucose biosensor using roll to roll printing technique

Abstract

A three electrode electrochemical enzymatic biosensor consisting of ZnO nanowires was successfully fabricated using flexographic printing technique. The incorporation of ZnO nanowires at the working electrode provides advantages such as simple functionalization and high surface area for enhanced sensitivity. The flexographic printing technique allows ultra-high throughput and low cost mass production of devices due to the roll-to-roll nature of the technique. Therefore, the techniques developed here are prudent to the development of technologies capable of meeting the vast market demand for biosensing. Carbon electrodes, silver/silver chloride reference electrodes and ZnO seed layer precursors were directly printed onto a flexible plastic substrate through flexographic printing. The printing process was optimised to allow a suitable seed layer to be formed on the porous printed-carbon electrode to allow selective growth of ZnO nanowires using a hydrothermal growth method. The ZnO nanowires were subsequently functionalised with glucose oxidase, which was used in this work to form a glucose sensor as an exemplary use of the device. The fabricated nanowire electrochemical biosensing devices showed a typical sensitivity of 1.2 ± 0.2 µA mM-1 cm-2 with a linear response to the addition of glucose over a concentration range of 0.1 mM to 3.6 mM.

Roll‐to‐Roll Fabrication of Solution Processed Electronics

“…R2R flexographic coating of graphite pastes on paper at 60 m min −1 has been used to suppress the inherent luminescence from the substrate materials and to thus improve the sensitivity of sensors based on surface enhanced Raman scattering after liquid flame spray coating of silver nanoparticles on top . Electrochemical biosensors have been prepared by the R2R flexo printing of three functional layers (carbon electrodes, Ag/AgCl electrodes, and zinc oxide nanowire precursor) at rather low speeds (0.2–0.6 m min −1 ) on polyimide substrates . After appropriate functionalization of the nanowires with an enzyme and integration of pieces cut from the printed rolls, sensors could be prepared which were able to detect glucose down to a concentration of 46 μmol l −1 .…”

Recent Developments of Flexible and Stretchable Electrochemical Biosensors

“…However, their attractive attributes come at a high cost due to the cleanroom setup, multiple equipment acquisitions, complex processes, and the unique materials required [108][109][110]. Recent developments in advanced materials such as new ink formulations help promote the development of various printing technologies (Figure 4) [111][112][113][114][115]. These new developments partially address the challenges in high-cost lithographic approaches that also have compromised performance on rough or textured surfaces.…”

“…In the flexographic process, the surface of the anilox roller consists of engraved cells. The doctor blade helps to remove excess ink from the anilox; reproduced with permission from [112], Copyright 2017, Elsevier. By using a rotary printing press in the gravure printing, the image is engraved onto a cylinder; reproduced with permission from [113], Copyright 2018, American Chemical Society.…”

“…The other template-based printing methods also include flexography and gravure printing, where the ink is transferred to the substrate from a raised (flexography) or engraved (gravure) pattern on a roll. In flexography printing ( Figure 4b) [112], the ink is first transferred from a bath to an anilox roll. The anilox roll contains millions of tiny divots to take up the ink, which can bring the anilox roll in contact with the printing cylinder.…”

Recent Lipid Membrane-Based Biosensing Platforms

“…These nanowire nanocomposites have shown an excellent amperometric sensitivity to glucose (129 µA•mM −1 ), low detection limits (12 µM), good stability and reproducibility, and selectivity in the presence of common interferents. Recent works applied a roll-to-roll flexographic printing technique to construct a three-electrode electrochemical unit that consisted of ZnO NWs [89]. This unit exhibited a sensitivity of 1.2 ± 0.2 µA•mM −1 •cm −2 and the calibration graph was linear over the glucose concentration between 0.1 to 3.6 mM.…”