Faustino Lucas C, Cunha João P C, Cantanhêde Welter, Kubota Lauro T, Gerôncio Everson T S
Department of Chemistry, Federal University of Piauí - UFPI, Teresina, PI, 64049-550, Brazil.
Department of Chemistry, State University of Piauí - UESPI, Teresina, PI, 64002-150, Brazil.
Mikrochim Acta. 2023 Jul 31;190(8):338. doi: 10.1007/s00604-023-05920-x.
Pencil drawing is one of the simplest and most cost-effective ways of fabricating miniaturized electrodes on a paper substrate. However, it is limited by the lack of reproducibility regarding the electrode drawing process. A 3D-printed pencil holder (3DPH) is proposed here for simple, reproducible, and low-cost hand-drawn fabrication of paper-based electrochemical devices. 3DPH was designed to keep pressure and angulation of the graphite mine constant on the paper substrate using a micromechanical pencil regardless of the user/operator. This approach significantly improved the reproducibility and cost of making reliable pencil-drawn electrodes. The results showed high reproducibility and accuracy of the 3DPH-assisted electrodes prepared by 4 different operators in terms of sheet resistance and electrochemical behavior. Cyclic voltammetric (CV) curves in the presence of [Fe(CN)] redox probe showed only 3.9% variation for the anodic peak currents of different electrodes prepared by different operators when compared with electrodes prepared without the 3D-printed support. SEM analyses revealed a more uniform graphite deposition/design of the electrodes prepared with 3DPH, which corroborates the results obtained by CV. As a proof of concept, 3DPH-assisted pencil-drawn graphite electrodes were employed for dopamine detection in synthetic saliva, showing a proportional increase in anodic peak current at 0.12 V vs. carbon pRE with increasing dopamine (DA) concentration, with a detection limit of 0.39μmol L. Moreover recovery was in the range 93-104% of DA (4-7% RSD) in synthetic saliva for three different concentrations, demonstrating the reliability of the approach. Finally, we believe this approach can make pencil-drawn technology more robust, accessible, reliable, and inexpensive for real on-site applications, especially in hard-to-reach locations or research centers with little investment.
铅笔绘图是在纸质基底上制造微型电极最简单且最具成本效益的方法之一。然而，电极绘制过程缺乏可重复性限制了它的应用。本文提出了一种3D打印铅笔架（3DPH），用于简单、可重复且低成本地手工绘制纸基电化学装置。3DPH的设计目的是，无论使用者/操作人员如何，使用微型机械铅笔在纸质基底上保持石墨笔芯的压力和角度恒定。这种方法显著提高了制作可靠的铅笔绘制电极的可重复性和成本。结果表明，由4名不同操作人员制备的3DPH辅助电极在薄层电阻和电化学行为方面具有很高的可重复性和准确性。在存在[Fe(CN)]氧化还原探针的情况下，循环伏安（CV）曲线显示，与未使用3D打印支撑制备的电极相比，不同操作人员制备的不同电极的阳极峰值电流变化仅为3.9%。扫描电子显微镜（SEM）分析显示，用3DPH制备的电极的石墨沉积/设计更均匀，这证实了CV获得的结果。作为概念验证，3DPH辅助的铅笔绘制石墨电极被用于合成唾液中多巴胺的检测，结果表明，相对于碳伪参比电极，在0.12 V时阳极峰值电流随多巴胺（DA）浓度增加呈比例增加，检测限为0.39μmol L。此外，对于合成唾液中三种不同浓度的DA，回收率在93-104%范围内（相对标准偏差为4-7%），证明了该方法的可靠性。最后，我们相信这种方法可以使铅笔绘制技术在实际现场应用中更加强健、易用、可靠且廉价，特别是在难以到达的地点或投资很少的研究中心。
