2026-04-06 ピッツバーグ大学
＜関連情報＞
- https://news.engineering.pitt.edu/stitching-precise-patterns—with-lasers/
- https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/admt.202502433
- https://pubs.acs.org/doi/10.1021/acsami.5c20377
レーザー誘起グラフェンのバイオセンサー向け小型化：開始点の空間制御と市販ポリマー上での側面選択的微細加工によるアプローチ Miniaturizing Laser-Induced Graphene for Biosensors by Spatial Control of Initiation and Side-Selective Microfabrication on Commercial Polymers
Soumalya Ghosh, Mirza Sahaluddin, Moataz Abdulhafez, May Yoon Pwint, Xinyan Tracy Cui, Mostafa Bedewy
Advances Materials Technologies Published: 29 December 2025
DOI:https://doi.org/10.1002/admt.202502433
ABSTRACT
Fabrication of porous graphene directly on polymers is crucial for many applications of flexible devices, including sensors, supercapacitors, and actuators. While printing methods can be used, they require the creation of inks followed by repeated printing steps and post-printing annealing. Hence, the one-step direct-write nature of the laser-induced graphene (LIG) process makes it an attractive alternative. Nevertheless, most previous work on LIG relied on continuous-wave CO2 lasers, which are largely limited to 100sµm resolution. Here, we develop a new approach that leverages a pulsed near-infrared (NIR) laser. Since polyimide absorbs far less strongly at 1064 nm than at CO2 laser wavelengths, LIG formation is substantially hindered. To overcome this challenge, we introduce a step of ink printing prior to laser patterning. Our approach enables fabricating lines as narrow as 40 µm on either the top or bottom surfaces. We utilize finite element modeling to explain the underlying mechanism of in situ LIG line thinning. This is critical for creating microelectrode arrays on flexible and implantable devices such as neural probes. Finally, we demonstrate high-sensitivity electrochemical sensing of dopamine for our miniaturized LIG down to 10 nM concentration with sensitivity of 0.369 µA cm−2 nM−1.
速度依存型逐次照射によるレーザー誘起グラフェンバイオセンサーのインピーダンス低減と感度向上 Lowering Impedance and Improving Sensitivity in Laser-Induced Graphene Biosensors via Speed-Dependent Sequential Irradiation
Moataz Abdulhafez,Elisa Castagnola,Mirza Sahaluddin,Giulia Baglieri,Golnaz N. Tomaraei,Soumalya Ghosh,Xinyan Tracy Cui,and Mostafa Bedewy
ACS Applied Materials & Interfaces Published: December 29, 2025
DOI:https://doi.org/10.1021/acsami.5c20377
Abstract
Laser-induced graphene (LIG) is a promising material platform for flexible bioelectronic devices, but further lowering its electrochemical impedance, without additives or postprocessing, is essential for scalable, implant-grade microelectrodes. Here, we introduce a speed-dependent sequential irradiation strategy that decouples the kinetically limited carbonization of the first lase from the higher-temperature graphitization induced during the second lase. We show that two passes at 49 mm/s reduce the electrochemical impedance by an order of magnitude compared to a single pass at 105 mm/s. Complementary structural and chemical characterization (Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy) reveals that relasing increases graphitic crystallinity, decreases heteroatom content, and generates a high-surface-area cratered morphology. Finite-element moving-heat-source simulations confirm that the second lasing pass produces markedly higher peak temperatures due to enhanced absorptance and reduced thermal diffusivity of the preformed LINC layer, providing quantitative thermodynamic support for the observed graphitization and controlled ablation. These combined effects enable robust, low-impedance microelectrodes capable of detecting dopamine concentrations below 25 nM using square-wave voltammetry. Importantly, this performance is not achievable using single-pass LIG. We further demonstrate seamless spatial control of the morphology on the same substrate, underscoring the versatility of the approach. Sequential CO2-laser irradiation therefore offers a scalable, additive-free pathway toward high-performance carbon microelectrode arrays for next-generation neural sensing and stimulation technologies.
