Electrochemical Sensor Fabrication via FDM 3D Printing and rGO Surface Modification
Authors: Dou Yan , Nian Qiong 
Published: August 2024

Abstract
Surface engineering of electrochemical sensors has become imperative to optimize their performance and address existing challenges. This research pivots to an innovative approach centered on surface engineering of electrochemical sensors through Fused Deposition Modeling (FDM) 3D Printing with reduced graphene oxide (rGO) modification. Utilizing a dual-extruder FDM printer, we prioritize surface characteristics by facilitating layered printing, allowing for the seamless package of copper-polyester electrodes within an insulated framework. This specialized printing method inherently engineers a distinct roughness onto the electrode surface, strategically enhancing its effective surface area for optimized electrochemical interactions. A subsequent strategic surface modification with casting rGO on the electrodes surface is pivotal in the sensor surface engineering. It not only protects the electrode from harmful copper oxidation and polyester degradation but also significantly reduces the charge transfer resistance between the electrode and the electrolyte. This advanced surface engineering method diverging from conventional techniques, such as chemical vapor deposition, which frequently necessitate intricate procedures and specific conditions, including elevated temperatures and high vacuum chambers. Furthermore, when comparing with other existing techniques, such as solution-phase inkjet/screen printings which mandate post-processing to eliminate undesired additives and improve conductivity, our proposed surface engineering process, particularly when amalgamated with drop casting, obviates these additives. This obviation directly eliminates the requisite for post-processing interventions, ensuring the resultant sensor’s purity and optimized performance. This innovative methodology enhances the efficiency of the production cycle, presenting potential for cost reduction. In this study, we assess the electrochemical implications of these manufactured electrodes when subjected to varying rGO concentrations for surface modification. Our findings indicate that the inherent roughness from the 3D printing process, coupled with a minimal rGO casting, accentuates surface roughness, thus increasing the effective surface area. After undergoing this surface engineering process, the sensor’s performance, as assessed by ferricyanide cyclic voltammetry (CV), displayed quasi-reversible characteristics, suggesting enhanced redox properties. The charge-transfer resistance, examined through electrochemical impedance spectroscopy (EIS), registers below 200 Ohms, resulting in amplified current signals. Such engineered surface attributes manifest superior electrochemical sensing capabilities, evidenced by hydrogen peroxide (H2O2) amperometry with a sensitivity of 156 μA/mMcm2. Over a series of tests conducted across a two-week period, sensors crafted using this surface engineering technique consistently exhibited stable current signals, underscoring the robustness and reliability of this process. Overall, this surface engineering in sensor fabrication through 3D printing showcases the potential for innovative developments in the fields like medical and biological research, food industry, environmental monitoring, and industrial processes. It also offers a blueprint for future innovations, promising a confluence of efficiency, adaptability, and precision in sensor development.