Physical Science and Engineering Division (PSE), COHMAS Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Institute of Materials Technology and Engineering, Chinese Academy of Sciences , 1219 Zhongguan West Road, Ningbo 315201, China.
ACS Appl Mater Interfaces. 2017 Sep 20;9(37):32184-32191. doi: 10.1021/acsami.7b05467. Epub 2017 Sep 8.
Polydimethylsiloxane (PDMS)-based flexible films have substantiated advantages in various sensing applications. Here, we demonstrate the highly sensitive and programmable thermal-sensing capability (thermal index, B, up to 126 × 10 K) of flexible films with tunable sandwiched microstructures (PDMS/cracked single-walled carbon nanotube (SWCNT) film/PDMS) when a thermal stimulus is applied. We found that this excellent performance results from the following features of the film's structural and material design: (1) the sandwiched structure allows the film to switch from a three-dimensional to a two-dimensional in-plane deformation and (2) the stiffness of the SWCNT film is decreased by introducing microcracks that make deformation easy and that promote the macroscopic piezoresistive behavior of SWCNT crack islands and the microscopic piezoresistive behavior of SWCNT bundles. The PDMS layer is characterized by a high coefficient of thermal expansion (α = 310 × 10 K) and low stiffness (∼2 MPa) that allow for greater flexibility and higher temperature sensitivity. We determined the efficacy of our sandwiched, cracked, flexible films in monitoring and switching flexible devices when subjected to various stimuli, including thermal conduction, thermal radiation, and light radiation.
基于聚二甲基硅氧烷（PDMS）的柔性薄膜在各种传感应用中具有显著的优势。在这里，我们展示了具有可调夹心微结构（PDMS/裂纹单壁碳纳米管（SWCNT）薄膜/PDMS）的柔性薄膜在受到热刺激时具有高灵敏度和可编程的热传感能力（热指数 B 高达 126×10 K）。我们发现，这种优异的性能源于薄膜结构和材料设计的以下特点：（1）夹心结构允许薄膜从三维到二维面内变形；（2）通过引入微裂纹降低了 SWCNT 薄膜的刚度，这使得变形更容易，并促进了 SWCNT 裂纹岛的宏观压阻行为和 SWCNT 束的微观压阻行为。PDMS 层的特点是具有较高的热膨胀系数（α=310×10 K）和较低的刚度（约 2 MPa），这使得其具有更大的灵活性和更高的温度灵敏度。我们确定了我们的夹心、裂纹、柔性薄膜在监测和切换各种刺激下的柔性设备时的效果，包括热传导、热辐射和光辐射。
