Su Feng-Chun, Huang Han-Xiong
Lab for Micro Molding and Polymer Rheology, The Key Laboratory of Polymer Processing Engineering of Ministry of Education, South China University of Technology, Guangzhou 510640, China.
ACS Appl Mater Interfaces. 2023 Dec 6;15(48):56328-56336. doi: 10.1021/acsami.3c13930. Epub 2023 Nov 21.
A strategy is proposed herein for preparing a flexible switching piezoresistive pressure sensor, which has a bridge-like structure and inverted micropyramids (IMPs) on its lower conductive substrate. The sensor substrates were prepared by injection compression molding (an industrial manufacturing process) using thermoplastic polyurethane (TPU; an industrial grade polymer). The designed bridge-like structure enables the sensor to obtain a pressure threshold. The flexibility of upper and lower TPU substrates allows them to contact quickly when pressed, and so the sensor exhibits a fast response (as short as 2 ms) and can respond to both static force and dynamic force (up to 50 Hz frequency), which are prominent for the sensor made from TPU. The sensor exhibits less bending-sensitive performance, which is attributed to the conformality of the upper and lower substrates and lower strain on the lower substrate with the IMP under bending. The sensor can amplify signal response at the monitoring limit (the relative resistance change is up to 46%). It can achieve a higher sensitivity in different low-pressure ranges by changing the gap of the bridge-like structure. Moreover, the sensor can obviously and steadily respond to an additional very low pressure under preloading and exhibits good durability performance. As the sensor has a pressure threshold similar to the human pain perception process, a pain-perception-mimetic glove that can identify the external mechanical stimuli but reduces the interference of finger bending is prepared, displaying potential applications of the flexible switching sensor in intelligent wearable protectors.
本文提出了一种制备柔性开关压阻式压力传感器的策略，该传感器具有桥状结构，其下部导电基板上有倒金字塔微结构（IMPs）。传感器基板采用热塑性聚氨酯（TPU；一种工业级聚合物）通过注射压缩成型（一种工业制造工艺）制备。设计的桥状结构使传感器能够获得压力阈值。上下TPU基板的柔韧性使它们在受压时能快速接触，因此该传感器具有快速响应（短至2毫秒），并且能响应静态力和动态力（频率高达50赫兹），这对于由TPU制成的传感器来说很突出。该传感器表现出较低的弯曲敏感性能，这归因于上下基板的保形性以及弯曲时下部带有IMPs的基板上的应变较小。该传感器在监测极限时能放大信号响应（相对电阻变化高达46%）。通过改变桥状结构的间隙，它可以在不同的低压范围内实现更高的灵敏度。此外，该传感器在预加载下能明显且稳定地响应额外的极低压力，并表现出良好的耐用性能。由于该传感器具有与人类疼痛感知过程相似的压力阈值，制备了一种能识别外部机械刺激但减少手指弯曲干扰的仿疼痛感知手套，展示了柔性开关传感器在智能可穿戴防护设备中的潜在应用。
