Highly Sensitive P(VDF-TrFE)/BTO Nanofiber-Based Pressure Sensor with Dense Stress Concentration Microstructures

Abstract

Flexible pressure sensors demonstrate promising potential in human–machine interfaces, wearable devices, and implantable electronics. In this study, a highly sensitive pressure sensor was developed, comprising a polyimide substrate with a high-density micropyramid array (HD-μPA), an active piezoelectric component of poly­(vinylidenefluoride-co-trifluoroethylene) [P­(VDF-TrFE)]/barium titanate (BTO) nanofiber mat, and silver nanowires (AgNWs) as the top electrode. A mold for imprinting of polyimide HD-μPA was fabricated by an ultraprecision microgroove fly cutting process, which can obtain μPA with a higher density than the mold fabricated by anisotropic wet etching of silicon. The piezoelectric output of the HD-μPA-based pressure sensor was approximately 1.7 times higher than that of the sensor with a flat substrate. The improved sensitivity of the sensor was attributed to the stress concentration effect of HD-μPA and elastic modulus mismatch between the polyimide HD-μPA and the P­(VDF-TrFE)/BTO nanofiber mat. A pressure detection limit as low as 0.6 Pa was achieved for the HD-μPA-based pressure sensor, showing many potential applications in flexible electronics.

Green flexible electronics based on starch

“…To fabricate FEs, the soft, stretchable, foldable substrates are highly desired. In general protocols, electro-conducting materials including metals, conducting polymers, or carbon-based materials are assembled on the flexible substrates, which involves polymer films such as polyethylene terephthalate (PET) 9 , polyimide (PI) 10,11 , hydrogels 12 , textiles 13 , and elastomers such as polydimethylsiloxane (PDMS) 14,15 . Nevertheless, these substrates are usually nondegradable, which may result in accumulation of electronic waste (e-waste).…”

Piezoelectric sensor based on electrospun poly(vinylidene fluoride)/sulfonated poly(1,4‐phenylene sulfide) blend nonwoven fiber mat

“…In addition, the piezoelectric effect in stretched and poled PVDF film is much higher than in its as‐cast film due to higher β ‐crystalline content 3,4 . β ‐crystalline content in PVDF can be increased in many different ways such as the addition of nanoparticles, 5–10 nanotubes, 11 and metal salts 12,13 …”

“…In addition, the piezoelectric effect in stretched and poled PVDF film is much higher than in its as-cast film due to higher β-crystalline content. 3,4 β-crystalline content in PVDF can be increased in many different ways such as the addition of nanoparticles, [5][6][7][8][9][10] nanotubes, 11 and metal salts. 12,13 Recent advances in electrospinning instrumentation have resulted in rapid improvement of nonwoven fiber mat fabrication with controlled morphology and properties.…”

“…Though, a nanofiber can be formed through a template, self‐assembly, drawing, melt‐blowing, and phase separation techniques, these methods are not favored by the manufacturing industries yet when compared to the electrospinning technique 14 . Since the last two decades, electrospun polymeric nanofibers have been reported for varying applications such as biomedical fields, 15–17 environmental protection as filter, 18 enzyme carriers, 19 sensors, 8–10 energy harvesters, 2 and many others due to the one‐dimensional nature of electrospun nanofiber with larger surface area and high porosity 20…”

“…Though, a nanofiber can be formed through a template, self-assembly, drawing, melt-blowing, and phase separation techniques, these methods are not favored by the manufacturing industries yet when compared to the electrospinning technique. 14 Since the last two decades, electrospun polymeric nanofibers have been reported for varying applications such as biomedical fields, [15][16][17] environmental protection as filter, 18 enzyme carriers, 19 sensors, [8][9][10] energy harvesters, 2 and many others due to the one-dimensional nature of electrospun nanofiber with larger surface area and high porosity. 20 With PVDF getting wider attention in the field of sensors, many researchers started working on electrospun PVDF nanofibers and have reported their suitability for use in healthcare as biomedical sensors, scaffolds, nanogenerators, and piezoelectric sensors.…”