npj Flexible Electronics: 激光诱导石墨烯柔性可拉伸电子器件

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聚酰亚胺（PI）是激光诱导石墨烯技术应用中最常见的前驱体材料，基于PI薄膜的LIG器件，受限于较大的面内刚度，在可穿戴柔性电子设备领域，受到相当程度的应用限制。本文将PI颗粒分散到具有良好可拉伸性能的聚二甲基硅氧烷（PDMS）中，得到了可用于制备LIG的可拉伸柔性基底。通过激光切割平台，在复合材料表面原位制备LIG，利用LIG随基底在形变过程中引起的电阻变化，可以制备可拉伸LIG应变传感器。

图1. 作为可穿戴电子设备的可拉伸LIG传感器在健康监测、动作捕捉和人机交互方面的应用

文中系统地分析了在PI/PDMS复合材料基底上，复合材料的配比和LIG的制备参数对其电学性能造成的影响（包括激光功率、频率、扫描速度和分辨率）。总结了相关的经验公式，用于方便地调控LIG的电阻以满足电子器件的需要。相对于转印技术得到的可拉伸LIG柔性电子器件，复合材料基底具有重复使用能力，可以在同一位置多次地写入LIG。提高了器件制备的容错率和复合材料的循环使用率。文中通过以下应用，展示了基于PI/PDMS复合材料基底的可拉伸LIG传感器高灵敏度、可拉伸性、和可定制化的特点，在健康监测、动作捕捉和人机交互领域具有潜在的应用价值。柔性基底与皮肤贴合度良好，位于声带处的LIG传感器可以根据声带振动程度，对不同的单词发音做出响应。并可以根据LIG在器件发生拉伸/压缩时的电阻增减，识别头部的运动状态。贴合在手腕处的传感器，可以记录到清晰的脉搏信号，准确的记录被测志愿者的心率。此外，由于可以在复合材料任意位置通过激光诱导直接生成图案化石墨烯，柔性复合材料可以直接被制成可穿戴器件。因此PI/PDMS复合材料能满足定制化需要，文中展示了将复合材料制备成可穿戴手套，分别在每根手指关节处制备LIG传感器，可用于整个手掌的手势反馈。上使用自主设计的单片机系统，实现了LIG传感器对LIG驱动器的远程操控。

相关研究成果近期以发表于npj Flexible Electronics (2022) 26，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。

图2. 可循环使用的高灵敏度，大量程可拉伸LIG传感器

A soft and stretchable electronics using laser-induced graphene on polyimide/PDMS composite substrate

Hao Wang, Zifen Zhao, Panpan Liu, Xiaogang Guo

The one-step fabricated laser-induced graphene (LIG) has the advantages of low cost, patterning of various desired geometries, and high sensitivity. The LIG-based sensor is of increasingly important in wearable electronics, health monitors, and motion captures. However, the robustness of substrates imposes certain constraints on their applications in the devices that require the remarkable stretchability. In this paper, the substrate composed of PDMS and PI particles is proposed to serve as the platform to manufacture graphene under the irradiation of infrared laser beam. Ascribing to the inherent soft and stretchable attributes of the PI/PDMS composite substrate, the LIG-based sensors show the capability to fit complex 3D configurations or to bear a mechanical tension over 15%. Notably, the fluence of the laser is experimentally and theoretically determined as the only principle to characterize the formation of conductive LIG on PI/PDMS composite substrate, greatly facilitating the selection of the allowable laser scanning parameters (i.e., the laser power, the frequency, the scanning speed and the dots per inch (DPI)) to form the desired LIG-based devices. Three demonstrations are conducted to highlight the superiority and the potential of this soft and stretchable LIG-based system in wearable electronics and soft robots.

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