A Self-Powered Wearable Pressure Sensor and Pyroelectric Breathing Sensor Based on GO Interfaced PVDF Nanofibers

Abstract

This paper reports a self-powered, flexible, piezo-and pyro-electric hybrid nanogenerator (NG) device that can be fixed on different locations of human skin for detecting static and dynamic pressure variations and can also monitor temperature fluctuations during the respiration process. An efficient and cost-effective fabrication strategy has been developed to create electrospun poly(vinylidene fluoride) (PVDF)/ graphene oxide (GO) nanofibers, which are used to create a highly sensitive wearable pressure sensor and pyroelectric breathing sensor. The sensor can accurately and rapidly detect pressures as low as 10 Pa with a high sensitivity (4.3 V/kPa), a key performance indicator for wearable sensors. Importantly, the sensor exhibits a high sensitivity to bending and stretching by finger, wrist, and elbow. The pressure sensor is also highly sensitive to vocal vibrations when attached to the human throat. The device can generate a maximum output power density of ∼6.2 mW/m 2 when subjected to a compressive stress, which enhances its range of applications. Moreover, it is demonstrated that doping with GO improves the pyroelectric energy harvesting and sensing performance of the device under repeated temperature fluctuations. The PVDF/GO-based nanogenerator has a maximum pyroelectric output power density of ∼1.2 nW/m 2 and can sense temperature changes during respiration, which makes it promising as a pyroelectric breathing sensor. It is demonstrated that processing of the PVDF-GO self-powered multifunctional pressure and pyroelectric breathing sensor can be up-scaled for fabricating compact and high-performance electronic skins for application in health monitoring, motion detection, and portable electronics.

Dielectric and piezoelectric augmentation in self-poled magnetic Fe3O4/poly(vinylidene fluoride) composite nanogenerators

“…The trend of as-calculated internal resistance for the samples are in agreement with the dielectric results. The stability and long-cycle durability of the as-fabricated devices are also satisfactory, compared to contemporary literature [26][27][28][29][30][31][32][33]. These nanogenerators can also be utilized to deliver power to electronic equipments by stabilizing the pulsed outputs by employing full-wave rectifiers & voltage regulators and finally storing the charge in high power-density electrostatic capacitors, high energy-density batteries or in supercapacitors having moderate values of both energy & power densities [59,60].…”

“…Previously many filler-materials having ferroelectric/piezoelectric characteristics and mechanically robust 1D morphologies such as nanorod or aligned fiber structure have been incorporated in different members of the PVDF-family i.e., polymers of vinylidene fluoride (VDF), trifluoroethylene (TrFE), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE) etc to boost up electromechanical response. Among them, binary oxides/ chalcogenides (ZnO, ZnS, CdS), normal & relaxor ferroelectric all-inorganic perovskites (BaTiO 3 , BiFeO 3 , ZnSnO 3 , PbTiO 3 , and solid solutions of similar materials), organic/hybrid perovskites (CH 3 NH 3 PbX 3 ; X=Cl, Br, I), carbon nanotubes (CNT), graphene oxide (GO) & reduced graphene oxide (rGO), Ag-nanoparticles etc have been used vigorously in this regard, which delivered interesting outcomes [24][25][26][27][28][29][30][31][32][33][34][35]. Im and Park recently developed mechanically robust Fe 3 O 4 /PVDF nanofibers to fabricate triboelectric nanogenerators using magnetite as an electret filler [10].…”

Medical Health Big Data Classification Based on KNN Classification Algorithm

“…Fuzzy and ant colony optimization are two new methods to introduce an enhanced feature selection framework [19]- [21]. The related scholars brought the maximum entropy model into the research of text automatic classification system for the first time [22], [23]. Through the simulation experiment, the different entropy model based classifiers were analyzed in different text feature generation methods.…”

Flexible piezoelectric cum‐ electromagnetic ‐absorbing multifunctional nanocomposites based on electrospun poly (vinylidene fluoride) incorporated with synthesized porous core‐shell nanoparticles

“…Upon exposure to external forces, the variation of the dipolar structure will lead to a potential difference in the polymer. This feature of the smart piezoelectric polymers resulted in their extensive applications in medicine, 2,3 biomedical, [4][5][6][7] and sensor industry [8][9][10] as well as for energy harvesting purposes. [11][12][13][14][15] Monitoring the vital signals of human health (eg, heartbeat) and movement, [16][17][18] charging the hearth batteries, 19 and supplying the energy required for wireless sensors 20 as well as electric power generating clothes 21,22 are some applications of these materials.…”