Development of a Sustainable and Biodegradable Sonchus asper Cotton Pappus Based Piezoelectric Nanogenerator for Instrument Vibration and Human Body Motion Sensing with Mechanical Energy Harvesting Applications.

Energy harvesting from natural resources has gained much attention due to the huge increase in the demand for portable electronic devices and the shortage of conventional energy resources in general. In the present work, the fabrication and realistic applications of a piezoelectric nanogenerator (PENG) using polydimethylsiloxane (PDMS) and the abundantly available, environment-friendly natural fiber Sonchus asper (SA) have been discussed. The biocompatible, low-cost SA fibers were flexible enough and showed high piezoelectric properties as active materials in the study. The SA pappus based piezoelectric nanogenerator demonstrated its ability to convert the harvested biomechanical energy into electrical energy from the various mechanical energy sources available in our environment. The SA pappus/PDMS thin film based piezoelectric nanogenerator (SPENG) fabricated in the laboratory showed colossal output performances (open circuit output voltage, V OC ∼81.2 V; short circuit current, I SC ∼1.0 µA) by continuous finger impartation. Uniform output performance was also obtained by the application of uniform force on the devices (e.g., ∼42 V for 5 N force at 10 Hz frequency). The SPENG was capable to charge a 2.2 µF capacitor to 3.2 V within a short time span (16 s) under continuous finger impartation and illuminate 39 commercial high-power blue LEDs that were connected in series. Thus, the fabricated SPENG can be used as a green and portable energy source to power up portable electronic devices. Apart from this, the SPENG may also be used as a self-powered energy supply for pacemakers or different types of health care units if properly improvised.

Portable Self-Powered Piezoelectric Nanogenerator and Self-Charging Photo-Power Pack Using In Situ Formed Multifunctional Calcium Phosphate Nanorod-Doped PVDF Films.

Herein, biocompatible Ca3(PO4)2 nanorod-incorporated poly(vinylidene) difluoride films have been prepared via an in situ process. A good piezoelectricity (d33 ≈ 56.6 pC/N) along with a large dielectric constant of ∼3.48 × 105 at frequency 20 Hz has been achieved. Then, we have designed a biocompatible, highly durable, low-cost piezoelectric nanogenerator (CPNG) which shows the superiority in open-circuit voltage ∼47 V and current ∼1.8 µA generation with power density ∼47.4 mW cm-3 under the gentle touch of a finger. Excellent mechanical to electrical energy conversion efficiency (∼65.5%) of our developed CPNG leads to fast charging of a capacitor of 1 µF in 18 s and glowing of 26 light-emitting diodes (LEDs) under finger impartation. Further, a portable light-charging power pack (LCPP) has been developed using the high dielectric film as the storage function. Under light illumination, our LCPP generates open-circuit output voltage ∼1.29 V with short-circuit current 5.7 mA cm-2. Areal capacitance ∼1779 F m-2 and storage efficiency ∼88% are achieved. The device is able to lighten up 22 LEDs for 10 days after charging once.

Er3+/Fe3+ Stimulated Electroactive, Visible Light Emitting, and High Dielectric Flexible PVDF Film Based Piezoelectric Nanogenerators: A Simple and Superior Self-Powered Energy Harvester with Remarkable Power Density.

The design of an energy-harvesting unit with superior output characteristics, i.e., high power density, is a great technological challenge in the present time. Here, simple, lightweight, flexible, and cost-effective piezoelectric nanogenerators (PENGs) have been fabricated by integrating the aluminum electrodes onto Er3+/Fe3+ stimulated electroactive, visible-light-emitting, and large dielectric PVDF films in which ErCl3·6H2O and Fe(NO3)3·9H2O act as the catalytic agents for electroactive ß polymorph nucleation and the enhancement of dielectric properties. The developed PENGs exhibit excellent energy-harvesting performance with very high power density and very fast charging ability compared with the previously reported PVDF-assisted prototype nanogenerators. The PENGs lead to very large power density (∼160 and ∼55.34 mW cm-3) under periodic finger imparting for Er3+- and Fe3+-stimulated PVDF-film-based energy-harvester units, respectively. The fabricated self-powered PENG is also able to light up 54 commercially available light-emitting diodes.