Department of Electrical Engineering, Indian Institute of Technology Hyderabad, Hyderabad, 502285, India.
Nanotechnology. 2017 Mar 3;28(9):095501. doi: 10.1088/1361-6528/aa5845. Epub 2017 Jan 10.
This paper reports a new type of electronic, recoverable skin-like pressure and strain sensor, produced on a flexible, biodegradable pencil-eraser substrate and fabricated using a solvent-free, low-cost and energy efficient process. Multi-walled carbon nanotube (MWCNT) film, the strain sensing element, was patterned on pencil eraser with a rolling pin and a pre-compaction mechanical press. This induces high interfacial bonding between the MWCNTs and the eraser substrate, which enables the sensor to achieve recoverability under ambient conditions. The eraser serves as a substrate for strain sensing, as well as acting as a dielectric for capacitive pressure sensing, thereby eliminating the dielectric deposition step, which is crucial in capacitive-based pressure sensors. The strain sensing transduction mechanism is attributed to the tunneling effect, caused by the elastic behavior of the MWCNTs and the strong mechanical interlock between MWCNTs and the eraser substrate, which restricts slippage of MWCNTs on the eraser thereby minimizing hysteresis. The gauge factor of the strain sensor was calculated to be 2.4, which is comparable to and even better than most of the strain and pressure sensors fabricated with more complex designs and architectures. The sensitivity of the capacitive pressure sensor was found to be 0.135 MPa.To demonstrate the applicability of the sensor as artificial electronic skin, the sensor was assembled on various parts of the human body and corresponding movements and touch sensation were monitored. The entire fabrication process is scalable and can be integrated into large areas to map spatial pressure distributions. This low-cost, easily scalable MWCNT pin-rolled eraser-based pressure and strain sensor has huge potential in applications such as artificial e-skin in flexible electronics and medical diagnostics, in particular in surgery as it provides high spatial resolution without a complex nanostructure architecture.
本文报道了一种新型的电子可恢复的类皮肤压力和应变传感器，它基于一种柔性、可生物降解的铅笔橡皮擦基底，采用无溶剂、低成本和节能的工艺制造。多壁碳纳米管 (MWCNT) 薄膜作为应变传感元件，使用滚轮和预压缩机械压力机在铅笔橡皮擦上进行图案化。这会在 MWCNT 和橡皮擦基底之间产生高界面键合，从而使传感器能够在环境条件下实现可恢复性。橡皮擦不仅用作应变传感的基底，还用作电容压力传感的介电层，从而省去了电容式压力传感器中至关重要的介电层沉积步骤。应变传感的转换机制归因于 MWCNTs 的弹性行为和 MWCNTs 与橡皮擦基底之间的强机械互锁引起的隧道效应，这限制了 MWCNTs 在橡皮擦上的滑动，从而最大限度地减少了滞后。应变传感器的应变系数计算为 2.4，与使用更复杂设计和结构制造的大多数应变和压力传感器相当，甚至更好。电容压力传感器的灵敏度被发现为 0.135 MPa。为了展示传感器作为人工电子皮肤的适用性，将传感器组装在人体的各个部位，监测相应的运动和触觉。整个制造过程是可扩展的，可以集成到大面积上以绘制空间压力分布。这种低成本、易于扩展的 MWCNT 针滚橡皮擦基压力和应变传感器在柔性电子和医疗诊断等领域的人工电子皮肤应用中具有巨大的潜力，特别是在手术中，因为它提供了高空间分辨率，而无需复杂的纳米结构架构。
