Flexible Multimodal Sensors Based on Fibrous Porous Networks of Multiwalled Carbon Nanotubes and Polydimethylsiloxane for Sensing and Distinguishing Vertical and Shear Force

Abstract

Wearable sensors are one of the key components in applications such as motion monitoring, smart medical care, and human-computer interaction systems. In the present work, we focus on the simultaneous improvements of flexible sensors in both performance and functionality. Here, with a porous fiber network of multi-walled carbon nanotubes (MWCNTs)−polydimethylsiloxane (PDMS) as an active layer, a flexible pressure sensor with ultra-high sensitivity and superior capability of identifying transverse shear force and temperature signals is designed and constructed. The fibral MWCNTs−PDMS piezoresistive layer was formed with a scouring pad (SP) fiber network as skeleton, and the PDMS thin layer formed by self-assembly can effectively increase the initial resistance. Attributing to the unique compressibility of the fibral porous network and the adjustable nanoscale contacts, the MWCNT-PDMS/SP sensor exhibits a wide detection range (0−360 kPa), and in particular, an ultra-high sensitivity (84,818.2 kPa −1 when <100 pa). Beyond the highly sensitive characteristics, the sensor also has a high shear-force sensitivity (GF = 6.15 under 0.05 N). The sensor can still maintain a relatively stable performance even after operating for more than 10,000 pressure cycles, showing as a potential candidate for the applications of electronic skin, intelligent robots, etc.

Recent developments in stretchable and flexible tactile sensors towards piezoresistive systems: A review

“…Here, carbon allotropes have shown better performances, among which the MWCNT sensor fabricated has delivered 84818.2 kPa À1 of sensitivity. 258 From these figures, it may be concluded that each material category has the potential to be applied to tactile sensors with interesting values of GF/sensitivity.…”

“…In both these figures, materials are categorized in the order of the discussion in the material selection section. On the x axis, four sections are shown for metallic materials, 63,64,196,210,211,215,[250][251][252] carbon allotrope, 26,66,149,152,221,222,[252][253][254][255][256][257][258] conductive polymer and hydrogel, 153,237,240,[259][260][261] and composite of materials. 178,224,239,[262][263][264] The discussed articles are arranged in ascending order of the GF/sensitivity, whereas the y-axis shows the actual value.…”

Transient Flexible Multimodal Sensors Based on Degradable Fibrous Nanocomposite Mats for Monitoring Strain, Temperature, and Humidity

“…Recently, flexible multimodal sensors responsive to multiple stimuli (humidity, temperature, etc.) in addition to mechanical stimuli are increasingly being investigated. − However, most of the flexible devices are still based on nondegradable polymer materials. − E-waste has enormous environmental pollution risks similar to traditional polymer materials and e-waste pollution of conventional inorganic electronic devices. − Therefore, the development of green flexible devices utilizing degradable materials has been an urgent subject.…”

Design and Analysis of Porous Elastomeric Polymer Based on Electro-Mechanical Coupling Characteristics for Flexible Pressure Sensor

“…Flexible sensors based on elastomeric polymers have gained significant interest across a range of fields such as robotics [ 1 , 2 ], healthcare [ 3 , 4 ], traffic monitoring [ 5 ], human motion detection [ 6 , 7 ], and intelligent tire technology [ 8 , 9 , 10 ] owing to their exceptional flexibility and ductility. Flexible capacitive pressure sensors stand out due to their stability and low power consumption [ 11 , 12 ].…”