Development of High-Sensitivity Piezoresistive Sensors Based on Highly Breathable Spacer Fabric with TPU/PPy/PDA Coating

Abstract

In recent years, the research of flexible sensors has become a hot topic in the field of wearable technology, attracting the attention of many researchers. However, it is still a difficult challenge to prepare low-cost and high-performance flexible sensors by a simple process. Three-dimensional spacer fabric (SF) are the ideal substrate for flexible pressure sensors due to its good compression resilience and high permeability (5747.7 mm/s, approximately 10 times that of cotton). In this paper, Thermoplastic polyurethane/Polypyrrole/Polydopamine/Space Fabric (TPU/PPy/PDA/SF) composite fabrics were prepared in a simple in-situ polymerization method by sequentially coating polydopamine (PDA) and Polypyrrole (PPy) on the surface of SF, followed by spin-coating of different polymers (thermoplastic polyurethane (TPU), polydimethylsiloxane (PDMS) and Ecoflex) on the PPy/PDA/SF surface. The results showed that the TPU/PPy/PDA/SF pressure sensors prepared by spin-coating TPU at 900 rpm at a concentration of 0.3 mol of pyrrole monomer (py) and a polymerization time of 60 min have optimum sensing performance, a wide working range (0–10 kPa), high sensitivity (97.28 kPa−1), fast response (60 ms), good cycling stability (>500 cycles), and real-time motion monitoring of different parts of the body (e.g., arms and knees). The TPU/PPy/PDA/SF piezoresistive sensor with high sensitivity on a highly permeable spacer fabric base developed in this paper has promising applications in the field of health monitoring.

How Far for the Electronic Skin: From Multifunctional Material to Advanced Applications

“…Mechanical stimuli can change the distance or the overlapping area between the two electrodes, and the change of distance and area can convert into capacitance change to realize pressure sensing. The acquisition of high sensitivity requires flexible electrode materials and dielectric materials so that even Capacitive Sensors Air chambers into polydimethylsiloxane 0.01-0.03 kPa 0.82 kPa −1 31.2 ms >10 000 [111] All-fibrous multilayer nanostructure 0-135 kPa 0.32 V kPa −1 20 s >10 000 [74] Ionic liquid _ 8.21 kPa −1 8000 [112] MXene/P(VDF-TrFE-CFE) 0.04 to 88.89 kPa 16.0 kPa −1 229 ms ≈1500 [119] PSeD-U <2 kPa 2-10 kPa 0.16 kPa −1 0.03 kPa −1 _ 1000 [164] PVDF/NMP, micro-structured PDMS electrode 0-130 Pa 30.2 kPa −1 at 0.7 Pa 25 s 100 000 [113] Deformable ionic mechanotransducer array _ 2.65 nF kPa −1 47 ms 200 [121] LMs@PDMS 3.87% 0.46 kPa −1 _ _ [120] CB/PDMS 0-0.2 kPa 0.2-1.5 kPa 35 kPa −1 6.6 kPa −1 _ 100 [123] Ag NW/flower/Ag NW 0.6 Pa to 115 kPa 1.54 kPa −1 _ 5000 [165] Piezoresistive sensors MXene@fabric-based Up to 150 kPa 6.31 kPa −1 300 ms 2000 [166] Vertical graphene arrays 2.5 Pa to 1.1 MPa 2.14 kPa − 1 6.7 ms 2000 [138] Zinc oxide nanorod 0-100 kPa 0.095 kPa − 1 140 ms _ [144] Thermoplastic polyurethane/polypyrrole/polydopamine/space fabric 0-10 kPa 97.28 kPa −1 60 ms >500 [167] 3D poly(3,4-ethylenedioxythiophene) coated wrinkled nanofiber film 0-3 kPa 397.54 kPa −1 80 ms 16 500 [168] Graphene oxide self-wrapped Copper nanowire networks 0.1-15 kPa 0.144 kPa −1 150 ms 1000 [169] CNTs-UPy/PUa THF 0-6.1 kPa 8.7 kPa −1 40 ms 10 000 [93] Polyacrylonitrile, cellulose, and MXene 0-50 kPa 179.1 kPa −1 _ 10 000 [136] Carbon black/polyaniline nanoparticles/thermoplastic polyurethane fil 0-680% 0.03% 80 ms 10 000 [47] Serpentine Ti/Au metal traces 1-25 kPa 3.78 kPa −1 200 ms 10 000 [67] MXene nanosheets and Fe 3 O 4 nanoparticles 0-2.5 kPa 5.53 kPa −1 62.2 ms 2500 [41] Poly(vinyl alcohol)/poly(vinylidene fluoride) nanofibers spider web structure 0-135 kPa 0.48 V kPa −1 16 s _ [170] Silicon rubber thin film after Ag NW deposition and PEDOT:PSS coating 0-2 kPa 138.0 kPa −1 128 ms _ [140] Hair-epidermis-dermis aerogel electrode 100 Pa to 30 kPa 137.7 kPa −1 80 ms 10 000 [171] Cellulose/carbon nanotube fiber 0-400 kPa 9.364 kPa −1 <2 ms 10 000…”

Interfacial Sintering of PU/MXene Foam for Piezoresistive Sensor with Superior Sensitivity, Mechanical Performance, and Durability

“…Over the past few years, flexible pressure sensors have attracted widespread attention owing to the promising applications in wearable electronic devices, medical and healthcare detection, , human–computer interaction, , and so on. The sensing response mechanisms of pressure sensors include piezoelectric sensing, capacitive sensing, and piezoresistive sensing. − Piezoresistive sensors are common pressure sensors that convert external pressure into a signal of resistance change, which are widely used because of their simple preparation process, low manufacturing cost, and easy signal acquisition. − Particularly, piezoresistive sensing devices with superior comprehensive performance including high sensitivity, mechanical performance, and long-term stability are of crucial ambition as it comes to practical applications.…”

Highly Stretchable PPy/PDMS Strain Sensors Fabricated with Multi-Step Oxygen Plasma Treatment

“…To meet all these demanding conditions, many different stretchable conducting polymer materials of polypyrrole (PPy) [ 17 , 18 , 19 ], polyaniline (PANI) [ 20 , 21 , 22 ], and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) [ 23 , 24 ] have been intensively studied for their easy integration to flexible and human-skin friendly substrates such as polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU), and Ecoflex TM rubbers [ 25 , 26 , 27 ]. More specifically, these conducting polymers, which have recently started to be widely examined as strain sensor films, are subjected to respond to mechanical deformations which, in turn, alters their electrical characteristics, such as change in resistance, because of their reproducibility and stretchability.…”