Flexible capacitive pressure sensor based on multi‐walled carbon nanotube electrodes

Abstract

Flexible pressure sensors offer the advantages of flexibility, low cost, and easy to large area fabrication, and they have wide applications in many fields. This work proposes a flexible capacitive pressure sensor that exhibits a sandwich-like structure, a good performance, and a simple process. Multi-walled carbon nanotube (MWNT) is used to fabricate the two electrodes of the sensor because this low cost material possesses good mechanical and electronic properties. Meanwhile, MWNT naturally forms numerous micro-nano structures that can enhance the sensitivity of a sensor. In addition, the dielectric layer of the sensor composed of parylene C (poly(chloro-p-xylylene)) is sandwiched between the two electrodes. The experimental results show that the pressure sensor demonstrates high sensitivity and a rapid response. The average sensitivity is 1.33 kPa-1 at a pressure that ranges from 0 to 758 Pa and the response time reach to millisecond level. Given that low cost, good property and simple process, the sensor has wide application prospects in electronic skins, health monitoring devices, and other wearable electronic products.

Flexible capacitive and piezoresistive pressure sensors based on screen-printed parylene C/polyurethane composites in low-pressure range

“…Due to the viscoelastic nature of Parylene C, PU and PMMA, the response time, relaxation time and detection limit are high when compared to other sensors. Compared to the PAC-based study by Shao et al [46], the linearity range is quite wide with 0-17.5 kPa but the sensitivity is ten times lower. Compared to the results of Wang et al [45], the linearity range is half the value of our result.…”

Ti3C2Tx MXene-Based Flexible Piezoresistive Physical Sensors

“…Currently, graphene, carbon nanotubes (CNTs), silver nanowires (AgNWs), and polypyrrole can be used as sensing materials for pressure sensors. − However, due to limitations of the production process, graphene prepared by CVD deposition has poor hydrophilicity, which limits the operability. There can be some improvement through postsynthesis restoration, but this increases the cost of application and the complexity of production.…”

Review on Conductive Polymer/CNTs Nanocomposites Based Flexible and Stretchable Strain and Pressure Sensors

“…SIMAX glass acts as the insulating dielectric layer between the electrodes constituting the pressure sensor. Similarly, Shao et al [ 93 ] demonstrates the use of MWCNT as a conductive material for the electrodes of a parallel plate capacitive pressure sensor. The electrodes are made flexible using utilizing polydimethylsiloxane (PDMS) as a substrate and coating it will a solution of MWCNTs dispersed in alcohol by ultrasonication.…”

“…Such sensor structures mainly focus on patterning the dielectric layer by different technique like lithographic patterning of micro pillars in PDMS, sandwiching the dielectric layer as two parts and deposition of PDMS in a wrinkled mold. Though all approaches present a good sensitivity and pressure range, the structures with insulating dielectric material that utilizes CNTs as the electrode material shows sensitivity only in a small range such as 20% in 0.01–1 N [ 96 ] and 1.33 kPa −1 in 0–758 Pa [ 93 ]. While the sensor with a CNT-PDMS conductive layer exhibits pressure sensitivity comparatively higher-pressure range at 8.3 kPa −1 in 0–3.5 kPa [ 12 ].…”