Process-property correlations in laser-induced graphene electrodes for electrochemical sensing

Arne Behrent,Antje J Baeumner,Paul Sippel,Christian Griesche

doi:10.1007/s00604-021-04792-3

Abstract

Laser-induced graphene (LIG) has emerged as a promising electrode material for electrochemical point-of-care diagnostics. LIG offers a large specific surface area and excellent electron transfer at low-cost in a binder-free and rapid fabrication process that lends itself well to mass production outside of the cleanroom. Various LIG micromorphologies can be generated when altering the energy input parameters, and it was investigated here which impact this has on their electroanalytical characteristics and performance. Energy input is well controlled by the laser power, scribing speed, and laser pulse density. Once the threshold of required energy input is reached a broad spectrum of conditions leads to LIG with micromorphologies ranging from delicate irregular brush structures obtained at fast, high energy input, to smoother and more wall like albeit still porous materials. Only a fraction of these LIG structures provided high conductance which is required for appropriate electroanalytical performance. Here, it was found that low, frequent energy input provided the best electroanalytical material, i.e., low levels of power and speed in combination with high spatial pulse density. For example, the sensitivity for the reduction of K3[Fe(CN)6] was increased almost 2-fold by changing fabrication parameters from 60% power and 100% speed to 1% power and 10% speed. These general findings can be translated to any LIG fabrication process independent of devices used. The simple fabrication process of LIG electrodes, their good electroanalytical performance as demonstrated here with a variety of (bio)analytically relevant molecules including ascorbic acid, dopamine, uric acid, p-nitrophenol, and paracetamol, and possible application to biological samples make them ideal and inexpensive transducers for electrochemical (bio)sensors, with the potential to replace the screen-printed systems currently dominating in on-site sensors used.Graphical abstract

Highlights

Low-cost, distributed electrochemical sensors can be used to address challenges in many fields of modern life, such as environmental monitoring, industrial manufacturing, and food production, and—most prominently—healthcare
Not much is known about the effect of energy input during the fabrication in correlation to electroanalytical performance, only anecdotal data are available describing obtainable micromorphologies
By systematically studying process parameters that influence the energy input and correlating it to micromorphologies, Raman, and especially electroanalytical characteristics, this knowledge gap was sought to be filled by the study

Summary

Introduction

Exemplary electrochemical biosensors for the measurement of blood glucose concentration have matured through decades of research and were successfully commercialized by several companies [1, 2]. These small disposable electrode strip sensors combined with a handheld glucose meter and supplied with a few microliters of blood from a pin-prick 159 Page 2 of 14. Examination of the created material via transmission electron microscopy (TEM), X-ray diffraction measurement (XRD), and Raman spectroscopy further reveal high similarity to few-layer graphene, confirming the sp carbon structures and giving rise to the name laser-induced graphene [6, 9]

Methods

Results

Conclusion