Poster V19 - Laser-Engraved Electrodes for High-throughput Electrochemical Analysis at the Point-of-care

Introduction: Biosensors measure the electrical, chemical, or biological reaction the target biomarker produces on the electrode's surface. [1] Their application has been implemented across various problems, such as diabetes, cardiovascular diseases, and infections. Furthermore, their reproducibility, ease of use, and cost efficiency have been highlighted during the COVID-19 pandemic. [2] Recently, biosensors with laser-induced graphene (LIG) based electrodes have gained recognition for their high electrical conductivity, microporous structure, and easy laser fabrication. [3] Similar to other microfabricated electrodes, the surface of LIG-based electrodes can be chemically activated to detect the target analyte at the point of care [2, 4-6]. Here, we present LIG-based electrochemical sensors to be integrated into a system with multiple detection chambers for high-throughput analysis of biomarkers at the point of care.

Materials and

Methods: The methodology we implemented was first to design the electrodes using AutoCAD 2024; the electrode design was inspired by commercially available screen-printed graphene electrodes and based on the literature. As for fabrication, we used commercially available 0.005" polyimide sheets from McMaster-Carr and the CO2 laser (BOSSLASER LS1630). The final parameters for the laser induction were a speed of 15 mm/s, a maximum and minimum power 8.0%, an interval 0.1 mm, and two pass counts. After the successful induction of the graphene, the electrode was encapsulated using encapsulant paste DuPont PE773 and a reflow oven (LPKF ProtoFLow S4). The template for the screen printing was fabricated using the CO2 laser and 0.001" acrylic sheet, and the paste was uniformly placed on the surface of the electrode and cured in the oven for 10 minutes at 150C. The reference electrode (Ag/AgCl) was deposited using silver nitrate-ammonia solution and 3.7% hydrochloric acid and benchtop electrochemical workstation CHI660E (CH Instruments). The encapsulation was characterized using Bruker DektakXT Surface Profiler, and the electrode was characterized using cyclic voltammetry.

Results, Conclusions, and Discussions: Various fabrication parameters were tested for the ideal graphene induction, and the selection of the best electrodes with the most reproducibility rate was Trial 21 (Table 1). The fabricated electrodes were tested for graphene conductivity using a standard multimeter. Multiple electrodes (Fig 2) demonstrated the same conductivity and surface profile. The cyclic voltammetry (CV) analysis of the produced electrode without silver analysis showed consistency and a standard CV curve. (Fig 3) Furthermore, differential pulse voltammetry (DPV) analysis with different potassium ferricyanide concentrations (0.5 mM, 1 mM, 2 mM, and 3 mM) was done to observe the difference it caused in the peak signal.

High throughput, cost-effective, and fast LIG-based electrodes were produced for a multi-system assay to detect different biomarkers for various disease diagnoses and progression analyses. The production of the electrodes demonstrated the ease of fabrication and reproducibility due to the step-forward approach and non-specialized materials and techniques employed.

Acknowledgements (Optional):