Fabrication and Performance of Graphene Flexible Pressure Sensor with Micro/Nano Structure

Abstract

Laser-induced graphene (LIG) has been widely used in flexible sensors due to its excellent mechanical properties and high conductivity. In this paper, a flexible pressure sensor prepared by bionic micro/nanostructure design and LIG mass fraction regulation is reported. First, prepared LIG and conductive carbon paste (CCP) solutions were mixed to obtain a conductive polymer. After the taro leaf structure was etched on the surface of the aluminum alloy plate by Nd:YAG laser processing, the conductive polymer was evenly coated on the template. Pressure sensors were packaged with a stencil transfer printing combined with an Ecoflex flexible substrate. Finally, the effects of different laser flux and the proportion of LIG in the composite on the sensitivity of the sensor are discussed. The results show that when the laser flux is 71.66 J·cm−2 and the mass fraction of LIG is 5%, the sensor has the best response characteristics, with a response time and a recovery time of 86 ms and 101 ms, respectively, with a sensitivity of 1.2 kPa−1 over a pressure range of 0–6 kPa, and stability of 650 cycle tests. The LIG/CCP sensor with a bionic structure demonstrates its potential in wearable devices.

Applications of Graphene-Based Materials in Sensors: A Review

“…More importantly, compared with traditional films, inorganic nanostructures are easier to combine with flexible materials [51]. Nanomaterials, carbon nanofibers, carbon black, and graphene are often combined with elastomers such as polydimethylsiloxane (PDMS), eco flex, and rubber to make polymer composite sensors [52]. Based on this premise, we found that graphene is a two-dimensional nanostructured material that can be synthesized in a large area [48,53,54].…”

“…The research of flexible pressure sensors mainly changes the microstructure of the conductive layer of the sensor to improve the sensing performance of the sensor [52,55]. The following will introduce specific examples of several graphene flexible pressure sensors to reflect the role of graphene materials in flexible pressure sensors.…”

“…Due to the rapid development of laser direct writing technology, more researchers use laser-assisted technology to obtain graphene on flexible carbon substrate [52]. Among various high-performance composite graphene materials, laser-induced graphene (LIG) has been widely used in the field of flexible pressure sensors in recent years because of its simple preparation, low cost, and large area [52,56]. Some researchers mixed LIG and conductive carbon slurry to prepare the conductive mixture and made a pressure sensor by laser processing technology.…”

“…Then, by changing the ratio of laser flux to LIG in the composite, the sensitivity of the LIG/CCP sensor with a bionic structure is analyzed to determine the optimal laser flux and LIG mass fraction. The analysis of experimental results shows that LIG nanostructures have the function of repairing conductive network defects and can improve the sensitivity of the sensor in a certain range [52,57].…”

“…Flexible pressure sensor. (a1) Manufacturing process diagram of LIG/CCG sensor[52] (b1) Preparation process of a sensor made of conical microstructure PDMS substrate and double layer graphene[58]; (c1) Sensitivity curve of the sensor with and without conical microstructure[58]; (d1) Structure and enlarged details of electronic skin[59]; (e1) Size and photos of electronic skin[59].…”