关键词: 压力传感器, 聚二甲基硅氧烷, 多壁碳纳米管, 还原氧化石墨烯

Abstract: With the rapid development of the wearable electronic device industry all over the word, the related products have shown great commercial prospects. As the future growing trend of wearable electronic devices, flexible wearable electronics has gradually become the focus of research and application in various fields, especially in the textile field. Among them, as a key component of information interaction, the flexible pressure sensor has attracted much attention due to its broad application prospects in health detection, electronic skin, human-computer interaction, flexible touch screen and other fields. According to its sensing mechanism, flexible pressure sensors are generally divided into piezoresistive, capacitive and piezoelectric ones. In practical applications, sensitivity and stability are the key technical indicators of flexible pressure sensors.
In order to develop a flexible pressure sensor with high sensitivity and excellent stability, a composite porous capacitive flexible pressure sensor was prepared in this research with polydimethylsiloxane (PDMS) as the substrate, multi-wall carbon nanotubes (MWCNT) and reduced graphene oxide (rGO) as fillers. And the porous structure was formed through sugar particle template. The effects of single doping with MWCNT and composite doping with MWCNT and rGO on the sensitivity of the sensor were compared. The structure of PDMS sponge after doping in different ways and the influence of the doping concentration on the sensitivity were analyzed. The key sensing characteristics of the sensor, such as response time, hysteresis and cycle stability were tested. The feasibility of its application in intelligent wearable textiles was discussed. The results show that the blending doping with rGO can effectively improve the aggregation of MWCNT, improve the dispersible uniformity of the doped conductive medium, maintain the porous structure of PDMS sponge, and effectively improve the sensitivity of the pressure sensor. When the mass ratio of MWCNT to rGO is 1:1 and the doping concentration is 2.5%, the sensitivity of the rGO/MWCNT/PDMS composite flexible pressure sensor reaches the highest value. The sensitivity reaches 31.324 kPa-1 in the pressure range of 0~0.5 kPa, which is more than four times of the pure PDMS sponge, and more than twice of mono-doped MWCNT with the same mass ratio. At the same time, the flexible pressure sensor also shows fast response, minimal hysteresis error, good cycle stability and mechanical stability. The strain-stress curves of 300 and 500 cycles of cyclic compression at 30% deformation are basically consistent.
The intelligent insole designed and prepared by using the flexible pressure sensor shows good response feedback to different foot pressures, which can be used in intelligent sports shoes as a flexible pressure sensor unit for recording and analyzing athletes' running posture data, showing a broad application prospect in intelligent wearable products.

Key words: pressure sensor, PDMS, MWCNT, rGO