Electrospun PVDF/MWCNT/OMMT hybrid nanocomposites: preparation and characterization

Development of Highly Flexible Piezoelectric PVDF-TRFE/Reduced Graphene Oxide Doped Electrospun Nano-Fibers for Self-Powered Pressure Sensor

The demand for self-powered, flexible, and wearable electronic devices has been increasing in recent years for physiological and biomedical applications in real-time detection due to their higher flexibility and stretchability. This work fabricated a highly sensitive, self-powered wearable microdevice with Poly-Vinylidene Fluoride-Tetra Fluoroethylene (PVDF-TrFE) nano-fibers using an electrospinning technique. The dielectric response of the polymer was improved by incorporating the reduced-graphene-oxide (rGO) multi-walled carbon nano-tubes (MWCNTs) through doping. The dielectric behavior and piezoelectric effect were improved through the stretching and orientation of polymeric chains. The outermost layer was attained by chemical vapor deposition (CVD) of conductive polymer poly (3,4-ethylenedioxythiophene) to enhance the electrical conductivity and sensitivity. The hetero-structured nano-composite comprises PVDF-TrFE doped with rGO-MWCNTs over poly (3,4-ethylenedioxythiophene) (PEDOT), forming continuous self-assembly. The piezoelectric pressure sensor is capable of detecting human physiological vital signs. The pressure sensor exhibits a high-pressure sensitivity of 19.09 kPa-1, over a sensing range of 1.0 Pa to 25 kPa, and excellent cycling stability of 10,000 cycles. The study reveals that the piezoelectric pressure sensor has superior sensing performance and is capable of monitoring human vital signs, including heartbeat and wrist pulse, masticatory movement, voice recognition, and eye blinking signals. The research work demonstrates that the device could potentially eliminate metallic sensors and be used for early disease diagnosis in biomedical and personal healthcare applications.

Fabrication of β-Phase-Enriched PVDF Sheets for Self-Powered Piezoelectric Sensing

The fabrication of self-powered pressure sensors based on piezoelectric materials requires flexible piezoelectric generators produced with a continuous, large-scale, and environmentally friendly approach. In this study, continuous poly(vinylidene fluoride) (PVDF) sheets with a higher β-phase content were facilely fabricated by the melt-extrusion-calendering technique and a PVDF-based piezoelectric generator (PEG) was further assembled. Such a PEG exhibits a remarkable piezoelectric output performance. Moreover, it possesses prominent stability even after working for a long time, exhibiting potential applications for real-time monitoring of various human movements (i.e., hopping, running, and walking) and gait. This work not only provides the possibility of continuous and environmentally friendly fabrication of PVDF sheets with remarkable piezoelectric properties but also paves a new promising pathway for powering portable microelectronic applications without any external power supply.