1成果简介
应变传感器通过改变其电学特性来响应机械变形，近年来备受关注，尤其是那些可弯曲和可拉伸的传感器，因其可集成到可穿戴电子设备中而备受青睐。这种兴趣得益于新型纳米材料和微结构的最新进展。本文，上海机电学院Shengbin Cao等研究人员在《ACS Appl. Electron. Mater》期刊发表名为“
Polydimethylsiloxane/Graphene Conductive Composite Film Based Flexible Strain Sensor for Body Motion Detection”的论文，研究采用一种简单、高效且成本低廉的刮涂法，制备了基于聚二甲基硅氧烷/石墨烯（PDMS/G）导电复合薄膜的柔性应变传感器。
本研究探讨了不同石墨烯浓度（7%、11%、14%和21%）对传感器在不同条件下传感性能的影响。研究发现，当石墨烯浓度为7%时，柔性应变传感器的应力和应变在0–10%的应变范围内呈现线性关系，并在1 Pa至550 kPa的广泛应力范围内展现出优异的灵敏度。在重复小应变（1.5%）循环1000次的情况下，电阻相对变化（ΔR/R）保持稳定并展现出优异的稳定性。制备的柔性传感器还具有750 ms的快速响应时间和550 ms的恢复时间，且在0–6%应变范围内，电流幅度可在2000个循环后仍保持初始状态的75%。柔性应变传感器用于实际检测各种人类活动的多功能性已得到证实。它能够检测小应变（如脉搏搏动）和大应变活动（如肘部弯曲和膝盖屈曲）。基于PDMS/G导电复合薄膜的柔性应变传感器已通过人类活动监测及其他应用的验证。
2图文导读
图1. (a) Preparation of PDMS/G conductive composite film by the scratch coating method, (b) SEM image of conductive composite film at a graphene concentration of 7 wt %, and (c) photograph of the as-prepared flexible strain sensor.
图2. Observed (a, b) PDMS solutions and (c, d) PDMS/G films with solutions (a, c) before and (b, d) after removing bubbles. (e) Flexibility assessment of PDMS/G film and (f) before and (g) after encapsulation of prepared PDMS/G composite film. (h) Bulk XRD pattern and (i) SEM-EDX element distribution (inset is SEM image of the selected area) of the PDMS/G composite thin film with 7 wt % graphene loading.
图3. (a) Assembled detection system, strain–stress changes of films at (b) different graphene concentrations, and (c) various temperatures with a graphene concentration of 7%. Resistance change curves of sensors prepared at (d) varied graphene concentrations and (e) 7% graphene concentration in the strain range of 0–6%. (f) Resistance change rate during tensile/release cycles of the film at 7% graphene concentration. (g) DMA at tension mode of a 7% PDMS/G composite in the temperature range of 8.5–72 °C. (h) The resistivity of the film varies in the strain range of 0–15% at graphene contents of 7%, 14%, and 21%, (i) The time–resistance curves of graphene with 7% concentration under strain tension/release states of 2%, 5%, 10%, and 15%.
图4. (a) Working principle of the strain sensor. (b) Changes in sensor current amplitude under 4000 cycles of testing. (c) Strain tensile response recovery time. (d) Sensitivity test of sensor to index finger bending at different angles. (e) Repeatability and recovery of sensor operation after 1000 cycles of finger bending. (f) Enlarged view of selected red dashed-line boxed range in (e).
图5. Human body movement detection: (a) pulse signal on wrist, (b) extension and flexion at the fossa cubitalis, (c) knee bending, (d) underneath heel while walking, (e) swallowing action, (f) neck stretching/head lifting action, and clenching/relaxing fist (g) without and (h) with wearing gloves.
3小结
基于PDMS/G导电复合薄膜的柔性应变传感器采用刮涂法制备，该方法具有操作简便、效率高、成本低的特点。对不同石墨烯含量（7%、11%、14%和21%）的柔性应变传感器进行了机械和电气性能测试，以探讨不同石墨烯含量对传感器性能在不同场景下的影响。当石墨烯浓度为7 wt%时，柔性应变传感器的应力和应变在0–10%的应变范围内呈现线性关系，并在1 Pa至550 kPa的宽应力范围内展现出优异的灵敏度特性。在1000次1.5%应变循环下，电阻变化（ΔR/R）保持稳定，表明其具有优异的稳定性和可重复性。制备的柔性传感器具有750 ms的快速响应时间和550 ms的恢复时间。在2000次应变循环后，电流幅度仍能保持初始状态的75%。通过实际应用和检测各种人类活动，已证实柔性应变传感器具有多功能性。它既能检测微小应变（如脉搏搏动），又能检测较大应变活动（如肘部弯曲和膝盖屈曲）。PDMS/G柔性应变传感器在人类活动监测中的应用已得到验证。
文献：
https://doi.org/10.1021/acsaelm.5c00349
来源：材料分析与应用