基於表面改質與快速熱退火結合水膠介面整合之雷射誘導石墨烯電極性能提升研究

Abstract

近年來，柔性電子與可攜式生醫感測技術快速發展，使低成本、大面積且具可撓性的導電電極受到高度關注。雷射誘導石墨烯（Laser-Induced Graphene, LIG）具有製程快速、可直接圖案化與適合軟性基板整合等優點，然而其導電性、製程穩定性以及液態環境下之界面反應表現仍可能限制其於生醫感測貼片中的應用。因此，本研究旨在建立一套以 CO2 雷射製備 LIG 並結合後處理與水膠介面層之系統性流程，以作為後續生醫應用的相關基礎。 本研究首先於聚醯亞胺薄膜（Polyimide, PI）上製備 LIG，並透過雷射功率與掃描速度之參數調控，建立適合作為後續處理與比較之基準製程條件。接著，利用 Flash Joule Heating（FJH）快速熱退火處理，促進 LIG 碳網絡的結構重組並改善導電路徑，使片電阻降低約 57%，同時提升整體導電性。另一方面，採用低損傷氧電漿進行表面改質，在盡量避免破壞導電骨架的前提下，引入含氧官能基以提升表面能與親水性，改善 LIG 與水溶液之界面作用。除上述後處理製程外，本研究亦導入 Chitosan 水膠作為貼片介面層之製備與塗佈流程，藉由酸性溶液溶解 Chitosan 並以 NaOH 中和誘導成膠，使水膠能覆蓋於 LIG 指定反應區域，提供貼附皮膚與潮濕環境下所需的保濕與界面接觸條件，作為後續傷口感測貼片整合之材料基礎。 電化學量測結果顯示，經後處理後之 LIG 電極於循環伏安法（Cyclic Voltammetry, CV）中展現較高的氧化還原電流響應，並於電化學阻抗頻譜（Electrochemical Impedance Spectroscopy, EIS）中呈現較低的界面電荷轉移阻抗與較高的界面電容特性。此結果說明 FJH 退火與低損傷氧電漿改質可分別從導電結構與表面界面兩方面改善 LIG 電極表現，並使其於液態電化學環境中具備較佳的反應能力與訊號表現。 整體而言，本研究證實透過雷射製程參數最佳化、FJH 快速熱退火、低損傷氧電漿改質，並結合 Chitosan 水膠介面層之導入，可有效提升 LIG 電極之導電性與界面活化程度，並為後續應用於生醫皮膚傷口感測貼片之可撓式電極提供材料與製程基礎。

In recent years, the rapid development of flexible electronics and portable biomedical sensing has driven growing interest in low-cost, large-area, and mechanically compliant conductive electrodes. Laser-induced graphene (LIG) offers advantages such as rapid fabrication, direct patternability, and compatibility with soft substrates; however, its electrical conductivity, process stability, and interfacial electrochemical performance in liquid environments may limit its application in biomedical sensing patches. Therefore, this study aims to establish a systematic process flow that combines CO2 laser fabrication of LIG with post-treatments and a hydrogel interfacial layer for the biomedical applications. LIG was first fabricated on polyimide (PI) films, and baseline process conditions suitable for subsequent treatments and comparisons were determined by tuning laser power and scan speed. Flash Joule heating (FJH) was then employed as a rapid annealing method to promote structural reorganization of the LIG carbon network and improve conductive pathways, resulting in an approximately 57% reduction in sheet resistance and enhanced electrical connectivity. In parallel, low-damage oxygen plasma surface modification was applied to introduce oxygen-containing functional groups while minimizing damage to the conductive framework, improving surface energy, hydrophilicity, and interfacial interactions with aqueous solutions. In addition to these post-treatments, a chitosan hydrogel was introduced as the patch interfacial layer. Chitosan was dissolved under acidic conditions and gelled via NaOH neutralization, enabling uniform coverage over the designated LIG reaction region to provide moisture retention and stable interfacial contact in humid environments, supporting future integration into wound-sensing patches. Electrochemical measurements showed that post-treated LIG electrodes exhibited higher redox current responses in cyclic voltammetry (CV), along with lower interfacial charge-transfer resistance and more pronounced capacitive characteristics in electrochemical impedance spectroscopy (EIS). Overall, the integration of laser process optimization, FJH rapid annealing, low-damage oxygen plasma modification, and a chitosan hydrogel interfacial layer effectively improves both conductivity and interfacial activation of LIG electrodes, providing a material and process foundation for flexible electrodes in biomedical skin wound-sensing patches.