School of Optical and Electronic Information and ‡Innovation Institute, Huazhong University of Science and Technology , 1037 Luoyu Road, 430074 Wuhan, China.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):41078-41086. doi: 10.1021/acsami.7b14501. Epub 2017 Nov 13.
Highly sensitive strain sensors that can detect small strain are in high demand in the fields of displays, robotics, fatigue detection, body monitoring, in vitro diagnostics, and advanced therapies. However, resistive-type sensors that are composed of electrically conductive sensing films coupled with flexible substrates suffer from the limits that their gauge factors (GFs) at small strains (e.g., 0.1-1%) are not high. Herein, through frictional direct-writing of graphite rod on the composite paper substrates, we produced strain sensors with extremely high gauge factor at small strains. The sensors exhibited a gauge factor of 9720 at a small strain of 0.9%, minimum strain detection up to 0.05%, strain resolution of 0.05%, response time of 40 ms, and high stability (>5000 bending-unbending cycles). Compared with the literature results so far, our sensors hold the highest GF value at small strains. Such high sensitivities are due to the precise control of narrow two-dimensional percolative conductive pathway, which means the content of conductive graphite sheets is close to the conductive percolation threshold. The strain sensors have a rapid response to microdeformation changes and can monitor various structural changes, including human motion, through facilitative and effective installation of device designs.
高度灵敏的应变传感器能够检测微小的应变，在显示、机器人、疲劳检测、身体监测、体外诊断和先进治疗等领域有很高的需求。然而，由导电传感膜与柔性基底结合而成的电阻式传感器存在一个局限，即在小应变（例如 0.1-1%）下的应变系数（GF）不高。在此，我们通过在复合纸基底上直接摩擦石墨棒，制造出在小应变为 0.9%时具有极高应变系数的应变传感器。该传感器在小应变为 0.9%时的应变系数为 9720，最小应变检测低至 0.05%，应变分辨率为 0.05%，响应时间为 40ms，稳定性高（>5000 次弯曲-非弯曲循环）。与迄今为止的文献结果相比，我们的传感器在小应变下具有最高的 GF 值。这种高灵敏度是由于对狭窄二维渗流导电通路的精确控制，这意味着导电石墨片的含量接近导电渗流阈值。应变传感器对微变形变化有快速响应，并可以通过方便有效的设备设计安装来监测各种结构变化，包括人体运动。
