Electrochemical multi-analyte point-of-care perspiration sensors using on-chip three-dimensional graphene electrodes

Abstract

Multi-analyte sensing using exclusively laser-induced graphene (LIG)-based planar electrode systems was developed for sweat analysis. LIG provides 3D structures of graphene, can be manufactured easier than any other carbon electrode also on large scale, and in form of electrodes: hence, it is predestinated for affordable, wearable point-of-care sensors. Here, it is demonstrated that LIG facilitates all three electrochemical sensing strategies (voltammetry, potentiometry, impedance) in a multi-analyte system for sweat analysis. A potentiometric potassium-ion-selective electrode in combination with an electrodeposited Ag/AgCl reference electrode (RE) enabled the detection of potassium ions in the entire physiologically relevant range (1 to 500 mM) with a fast response time, unaffected by the presence of main interfering ions and sweat-collecting materials. A kidney-shaped interdigitated LIG electrode enabled the determination of the overall electrolyte concentration by electrochemical impedance spectroscopy at a fixed frequency. Enzyme-based strategies with amperometric detection share a common RE and were realized with Prussian blue as electron mediator and biocompatible chitosan for enzyme immobilization and protection of the electrode. Using glucose and lactate oxidases, lower limits of detection of 13.7 ± 0.5 μM for glucose and 28 ± 3 μM for lactate were obtained, respectively. The sensor showed a good performance at different pH, with sweat-collecting tissues, on a model skin system and furthermore in synthetic sweat as well as in artificial tear fluid. Response time for each analytical cycle totals 75 s, and hence allows a quasi-continuous and simultaneous monitoring of all analytes. This multi-analyte all-LIG system is therefore a practical, versatile, and most simple strategy for point-of-care applications and has the potential to outcompete standard screen-printed electrodes.

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

“…Laser-induced graphene was studied as an alternative, carbonaceous material for electrochemical (bio)sensing applications. Its promising characteristics described by us earlier [15,16] indicate that it may be not only an alternative but a superior transducer material for electrochemical point-of-care sensors. 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.…”

“…Fenzl et al used pyrenebutyric acid to couple a thrombin aptamer to the LIG matrix and demonstrated that it can be successfully used in an aptasensor [15]. Also, recent work from our lab describes a combination of amperometry-, potentiometry-, and impedance-based sensors made from LIG for the measurement of lactate, potassium, and conductivity in sweat [16]. Other groups have modified DLW-created carbon electrodes with copper nanoparticles alone or in combination with diamine oxidase to detect glucose or biogenic amines respectively [17,18].…”

Lab-on-a-chip technologies for food safety, processing, and packaging applications: a review

“…Nanotechnology could offer a possible path for development of precise and accurate sensors by facilitating design of novel materials and enabling selective surface modification. In recent years, materials like graphite, graphene (Shahdeo et al 2020 ; Bauer et al 2021 ), carbon nanotubes (Sobhan et al 2020 ), and chitosan (Lin et al 2020 ) have shown promising results for the development of lab-on-a-chip devices and their scale-up. Further, scale-out strategies must also be explored to achieve higher throughput in production.…”

Electrochemical Response of Glucose Oxidase Adsorbed on Laser-Induced Graphene

“…As concerns the enzymatic biosensors, LIG modified with electrodeposited Pt NPs was explored to detect glucose by the amperometric response when H 2 O 2 , as a by-product of the enzymatic reaction, is oxidized by the Pt NPs [ 16 , 17 ]. Another example relies on the immobilization of Prussian blue, as electron mediator, on LIG electrodes to detect glucose oxidation by the enzyme [ 18 ]. LIG was also explored for the detection of the biomarkers AA, UA and DA [ 4 , 19 , 20 ], and for the sensing of thrombin [ 21 ] and urea [ 22 ] using specific biorecognition elements.…”