复合材料柔软性对倒金字塔微结构阵列传感器性能的影响

采用模压成型方法制备了2种柔软性不同的热塑性聚氨酯/短切碳纤维/碳纳米管(TPU/SCF-CNT)复合材料复制物, 其表面上具有倒金字塔微结构阵列, 内部有SCF与CNT共同构成的导电通路. 将复合材料复制物和相应的复合材料平整片封装成柔性传感器. 结果表明, 压力作用下传感器内复制物和平整片之间的接触电阻因倒金字塔底棱的形变而显著降低. 对使用柔软性较高的复合材料封装的传感器, 虽然其相对迟滞稍大, 但压力作用下倒金字塔底棱形变量较大, 且复制物和平整片内导电通路增加量较大, 因此其在0~2.5 kPa的线性区内具有较高的灵敏度(0.32 kPa^?1). 制备的2种传感器均具有快速响应特性, 且能在500 s(约1580次)的循环压缩/释放测试(峰值压力约3 kPa)中保持较稳定的电阻响应. 研究表明, 利用模压成型的表面倒金字塔结构复合材料复制物封装成的柔性压力传感器具有良好的传感性能.

Effect of Flexibility of Composites on Performances of Sensors with Micro-structured Inverted Pyramid Arrays

Two kinds of thermoplastic polyurethane/short carbon fiber/carbon nanotube（TPU/SCF-CNT） composites with different flexibilities were prepared by an extruder. By using compression molding， the replicas with micro-structured inverted pyramid arrays on the surfaces were molded from the two composites with the conductive paths comprised by SCF and CNT. Then two kinds of flexible sensors were prepared by assembling the composite replica with the corresponding composite flat plate face-to-face. It was demonstrated that the contact resistance between the replica and flat plates of the sensor under pressure was significantly reduced due to the deformation of the bottom edges of the inverted pyramid. Although the sensor assembled by using the more flexible composite had a slightly larger hysteresis coefficient， it exhibited a higher sensitivity（0.32 kPa^?1） in the linear region of 0—2.5 kPa， which is attributed to the larger deformation of the bottom edges of the inverted pyramid and the increased conductive paths inside the composite under pressure. Both sensors exhibited short response times stemming from rapidly changing contact resistance caused by the deformation of the bottom edges of the inverted pyramid. In addition， the sensors prepared in this work maintained a relatively stable resistance response during 500 s（approximately 1580 cycles） of cyclic compression/release tests（under a peak pressure of ca. 3 kPa）. The results demonstrated that it is feasible to fabricate higher performance flexible sensors with inverted pyramid arrays on the sensing element prepared by compression molding.