Ultrasensitive and Highly Stable Resistive Pressure Sensors with Biomaterial-Incorporated Interfacial Layers for Wearable Health-Monitoring and Human–Machine Interfaces

Lou

et al. 2020

Sensors

Pressure sensors have been widely used in electronic wearable devices and medical devices to detect tiny physical movements and mechanical deformation. However, it remains a challenge to fabricate desirable, comfortable wearing, and highly sensitive as well as fast responsive sensors to capture human body physiological signs. Here, a new capacitive flexible pressure sensor that is likely to solve this problem was constructed using thermoplastic polyurethane elastomer rubber (TPU) electrospinning nanofiber membranes as a stretchable substrate with the incorporation of silver nanowires (AgNWs) to build a composite dielectric layer. In addition, carbon nanotubes (CNTs) were painted on the TPU membranes as flexible electrodes by screen printing to maintain the flexibility and breathability of the sensors. The flexible pressure sensor could detect tiny body signs; fairly small physical presses and mechanical deformation based on the variation in capacitance due to the synergistic effects of microstructure and easily altered composite permittivity of AgNW/TPU composite dielectric layers. The resultant sensors exhibited high sensitivity (7.24 kPa−1 within the range of 9.0 × 10−3 ~ 0.98 kPa), low detection limit (9.24 Pa), and remarkable breathability as well as fast responsiveness (<55 ms). Moreover, both continuously pressing/releasing cycle over 1000 s and bending over 1000 times did not impair the sensitivity, stability, and durability of this flexible pressure sensor. This proposed strategy combining the elastomer nanofiber membrane and AgNW dopant demonstrates a cost-effective and scalable fabrication of capacitive pressure sensors as a promising application in electronic skins and wearable devices.

Section: Introductionmentioning

confidence: 99%

Highly Sensitive, Breathable, and Flexible Pressure Sensor Based on Electrospun Membrane with Assistance of AgNW/TPU as Composite Dielectric Layer

Lou

et al. 2020

Sensors

“…[ 11–15 ] Among the different kinds of pressure sensors, piezoresistive pressure sensor demonstrates great application potential because of its fast response speed, simple structure, economical fabrication process and great stability. [ 16–20 ] Improvement of sensitivity of pressure sensors is critical for the high precision and ultrasensitive pressure detection, [ 21–25 ] which is however a challenging task because the key effect of device configuration on the sensitivity is always neglected.…”

Section: Figurementioning

confidence: 99%

Synergistic Resistance Modulation toward Ultrahighly Sensitive Piezoresistive Pressure Sensors

Yuan

Adv Materials Technologies

et al. 2020

In recent years, with the rapid development of prosthesis, [1,2] health monitoring, [3][4][5][6][7] and robot, [8][9][10] electronic skin has drawn huge research enthusiasm. Tactile sensation is one of the most significant functions of electronic skin, which mainly relies on pressure sensor to realize. [11][12][13][14][15] Among the different kinds of pressure sensors, piezoresistive pressure sensor demonstrates great application potential because of its fast response speed, simple structure, economical fabrication process and great stability. [16][17][18][19][20] Improvement of sensitivity of pressure sensors is critical for the high precision and ultrasensitive pressure detection, [21][22][23][24][25] which is however a challenging task because the key effect of device configuration on the sensitivity is always neglected.Until now, the commonly used strategy to improve sensitivity focuses on the development of different kinds of microstructure of active materials, but this strategy is still not effective enough to achieve ultrahigh sensitivity. [26][27][28] For example, Fang et al. replicated the lotus leaf surface onto the polydimethylsiloxane (PDMS) substrate to produce a structured layer and then sprayed graphene films as active electrodes, [29] which yields a sensitivity of 1.2 kPa −1 . Jong-jin Park et al. reported a sensor with sensitivity of 10.32 kPa −1 by introducing a pyramidical electrode consisting of a conductive polymer (PEDOT:PSS) and an aqueous polyurethane dispersion (PUD) elastomer blend. [30] Bao et al. prepared a new piezoresistive sensor with sensitivity up to 41.9 kPa −1 by preparing interconnected polypyrrole (PPY) hollow sphere structure through a multiphase synthesis technique. [31] These researches have significantly advanced the development of piezoresistive sensors, but still could not achieve ultrahigh sensitivity to meet the requirement of high precision and ultrasensitive detection. This is because the surface microstructure of active materials is not the only key factor for the improvement of sensitivity.To overcome the current obstacle and get ultrathigh sensitivity, it would be necessary to understand the basic working principle of piezoresistive pressure sensor, and further get the feasible solution. The basic electrical characteristics of piezoresistive sensor is similar, and the total resistance (R total ) of the device consists of two parts: the body resistance (R b ) Improvement of sensitivity of electrical piezoresistive sensors is critical for high-precision and ultrasensitive detection, which mainly depends on the modulation ability of total resistance of sensor under applied pressure. However, in most of the reported sensor devices, the contact resistance and body resistance (the key parts of total resistance of sensor) generally cannot be modulated simultaneously, which results in the limited sensitivity. In this work, an ultrahighly sensitive piezoresistive pressure sensor with an exquisitely designed structure is demonstrated, providing an uncomparable advantage of ...

“…Furthermore, a variety of microstructures, such as micro-pillars, hemispheres, and triangular pyramid have been introduced in fabrication of skin sensors to improve the performance of the skin sensors such as response time, detection limit, sensing range, and sensitivity. [12,[32][33][34][35] As an example, Cheng and co-workers demonstrated a pressure sensor with mimosa-inspired microstructures, achieving a high sensitivity up to 50.17 kPa-1 in the low pressure range of 0-70 Pa. However, the sensing range is below 1500 Pa and the sensitivity decreases to 1.38 kPa-1 beyond 70 Pa, which confines the sensor to tiny pressure detection.…”

Section: Introductionmentioning

confidence: 99%

Fingertip‐Skin‐Inspired Highly Sensitive and Multifunctional Sensor with Hierarchically Structured Conductive Graphite/Polydimethylsiloxane Foams

Sun

Zhao

Zhou

et al. 2019

Adv Funct Materials

175

151

Recently, skin sensors have obtained considerable attentions for potential applications in skin prosthetics, healthcare monitoring, and humanoid robotics. In order to further extend the practical applications, a dynamic broad range response with excellent sensitivity is important for skin sensors in sensing pressure, which eventually simplify the sensing system devoid of extra signal processing. On the other aspect, skin sensors with multifunctional sensing