Highly Sensitive Capacitive Flexible Pressure Sensor Based on a High-Permittivity MXene Nanocomposite and 3D Network Electrode for Wearable Electronics

Abstract

With the fast development of consumer electronic and artificial intelligence equipment, flexible pressure sensors (FPSs) have become a momentous component in the application of wearable electronic, electronic skin, and human–machine interfacing. The capacitive FPS possesses the merits of low energy consumption, high resolution, and fast dynamic response, so it is ideal for mobile and wearable electronics. However, capacitive FPS is vulnerable to electromagnetic interference and parasitic capacitance due to its low sensitivity. Microstructure or porous dielectric materials have been applied to improve the sensitivity of the capacitive FPS, but the high sensitivity is just limited to a narrow region. In this work, we propose a different strategy that incorporates a high-permittivity MXene nanocomposite dielectric with a 3D network electrode (3DNE) to improve the sensing performance of the capacitive FPS. Thanks to the high permittivity of the dielectric layer and hierarchical deformation of the electrode, the fabricated capacitive FPS exhibits a high sensitivity of 10.2 kPa–1 in the low pressure range (0–8.6 kPa) and still maintains a relatively high sensitivity of 3.65 kPa–1 with a near-linear response in a wide pressure range (8.6–100 kPa). In addition, the capacitive FPS can withstand over 20,000 times pressure loads without significant signal damping. Furthermore, the working mechanism of the capacitive FPS is illustrated by the finite element analysis (FEA) method and theoretical calculation. The application potential of the sensor in wearable electronics was demonstrated by human pulse wave monitoring and pressure mapping tests with a 4 × 6 sensor microarray.

Recent Progress in Ti3C2Tx MXene-Based Flexible Pressure Sensors

“…75 In addition, researchers used sponges or foams as skeletons, impregnated MXene solutions to attach them to the skeletons, or used chitosan as an adhesive. 77,78 Hydrogel Flexible Pressure Sensors. The method is to blend MXenes with other polymers (polyvinylpyrrolidone, poly (3,4-ethylenedioxythiophene), poly(4-styrenesulfonate), polydopamine, and others) using MXene surface groups to interact with the polymers and then using a polymerization reaction to form the hydrogel.…”

“…The reduction self-assembly method uses the active group components in the compound to interact with MXenes to form a self-assembled gel and then enhances the conductivity of the material by reduction . In addition, researchers used sponges or foams as skeletons, impregnated MXene solutions to attach them to the skeletons, or used chitosan as an adhesive. , …”

MXene-containing pressure sensor based on nanofiber film and spacer fabric with ultrahigh sensitivity and Joule heating effect

“…Meanwhile, higher compression stresses from 12 to 35 kPa are also measured, but the DR/R 0 (%) (DR/R 0 , DR ¼ R-R 0 , the resistances with and without pressure, respectively) value reaches the maximum at 15 kPa around 1.44 M of 29,397.97 kPa À1 , a very much higher sensitivity than most previous reported works. 34,[60][61][62][63][64][65][66][67] (shown in Table 2), and in particular is more stable than the most hydrogels 68 and polymers. 61,64,[69][70][71] However, the sensitivity dropped after 15 kPa, mainly because the compression distance was smaller so that new conductive interconnections and paths cannot be produced, corresponding to Figures 3(c) and (d).…”

“…34,[60][61][62][63][64][65][66][67] (shown in Table 2), and in particular is more stable than the most hydrogels 68 and polymers. 61,64,[69][70][71] However, the sensitivity dropped after 15 kPa, mainly because the compression distance was smaller so that new conductive interconnections and paths cannot be produced, corresponding to Figures 3(c) and (d). As a result, the fit sensitivity of the MPS was as displayed in Figure 3(e), showing a good linear compression effect, high sensitivity and large sensing range.…”

Porous Polydimethylsiloxane Elastomer Hybrid with Zinc Oxide Nanowire for Wearable, Wide-Range, and Low Detection Limit Capacitive Pressure Sensor

“…Unlike conventional composites or a sole type of material, polymer-based nanocomposites may offer considerable enhancement in thermal, electrical, optical, chemical, or mechanical properties. Among them, a variety of nanostructures with highly conductive [14][15][16], dielectric [17][18][19], piezoelectric [20][21][22], triboelectric [23][24][25], photo-responsive [26][27][28], or stress-sensitive [10,[29][30][31] properties have been studied for flexible pressure sensors because of their potential in amplifying stress/strain sensing capability for human motion detection, health diagnosis, and electronic skin.…”