Human skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-l-lactic acid nanofibers for non-invasive physiological signal monitoring

Flexible and wearable piezoelectric bio e-skin (PBio-e-skin) based on electrospun poly(l-lactic acid) PLLA nanofiber membrane is demonstrated for non-invasive human physiological signal monitoring and detecting dynamic tactile stimuli. The molecular orientations of the CO dipoles by electrospinning technique result in a longitudinal piezoelectric charge co-efficient (d 33 ) value of ∼(3 ± 1) pm V -1 realized by piezoresponse force microscopy, allowing the PBio-e-skin for pressure sensing applications. The robust mechanical strength (Young\u27s modulus ∼50 MPa) of nanofiber membrane ensures PBio-e-skin\u27s superior operational stability over 375000 cycles. Owing to the superior mechanosensitivity of ∼22 V N -1 , PBio-e-skin has the ability to measure subtle movement of muscle in the internal organs such as esophagus, trachea, motion of joints and arterial pressure by recognition of strains on human skin. This flexible and light weight PBio-e-skin precisely detects vital signs and provides important clinical insights without using any external power source. Eventually, the low cost, environmental friendly PBio-e-skin will have a huge impact in a broad range of applications including self-powered wearable health care systems, human-machine interfacing devices, artificial intelligence and prosthetic skin

Relaxation phenomena of acrylic esters and phenols in dilute solution of CCl4 under static and high frequency electric field

Double relaxation times 2 and 1 due to whole molecular rotation and the flexible parts of the binary (jk) polar mixture of p-cresol, p-chlorophenol, 2,4 dichlorophenol and p-bromophenol with methyl methacrylate (MMA) or ethyl methacrylate (EMA) were estimated under 9.37 GHZ electric field dissolved in dilute CCl4 solution at 35°C using high frequency susceptibility data ijk’s for different weight fractions wjk’s. Six systems out of eight exhibit 2, 1; c2, c1 and μ2, μ1, respectively. The estimated 2’s and μ2’s agree well with the measured and reported values indicating the whole rotation of binary polar mixture under high frequency electric field. Solute-solute and solute-solvent molecular formation through H-bonding are ascertained from μav – xj curves for 0.5 mole fraction xj of acrylic ester. The associational aspects are taken into consideration in μtheo from the stand point of inductive, mesomeric and electromeric effects within the polar groups of the molecules. Static μ0’s are calculated and compared with the reported values also

Thermal diffusivity of advanced composite materials of e-glass fiber reinforced plastic in the temperature range 5-120K

273-276Thermal diffusivity of plain-woven fabric composite in a closed cycle cryo-refrigerator (CCR) based setup in the temperature range 5-120K has been studied. The modified temperature wave method (Angstrom) is applied to measure the thermal diffusivity of glass fiber reinforced plastic (GFRP). The set up is a plug in type which can be used anywhere because of its portability and also works without use of any cryogenic fluid. The results show that there exists an inverse relation between the thermal diffusivity of e-glass fiber composite and temperature in very low temperature domain but decreases very slowly after 100K

Improved breakdown strength and electrical energy storage performance of gamma-poly (vinylidene fluoride)/unmodified montmorillonite clay nano-dielectrics

A remarkable improvement in the dielectric breakdown strength (E-b) and discharge energy density (U-e) of flexible polymer nanocomposites is realized by the incorporation of unmodified smectite montmorillonite (MMT) nanoclay into a poly(vinylidene fluoride) (PVDF) matrix. The resulting PVDF/MMT clay nanocomposite (PCN) films stabilize the. phase and increase the path tortuosity via strong intercalation of the PVDF matrix into inorganic layered silicates without sacrificing the quality of surface morphology. The PCN films exhibits superior dielectric properties (up to epsilon(r) similar to 28 and tan delta similar to 0.032 at 1 kHz) than those of pure PVDF. As a result, a large increase in E-b of 873 MV m(-1) and U-e of 24.9 J cm(-3) is achieved. Subsequently, the PCN films possess more than 60% charge-discharge efficiency even at higher electric field and thus provide a scope to develop high energy density flexible and transparent materials for energy storage technologies

The preparation of gamma-poly(vinylidene fluoride)/ZnS nanocomposite for energy storage application

Organic-inorganic nanocomposite film composed of poly(vinylidene fluoride) (PVDF) and zinc sulphide nanoparticles (ZnS-NPs) has been prepared. It is observed that composite film can stabilize the gamma-phase. The PVDF-ZnS composite film exhibits superior dielectric property (epsilon(r) similar to 14 at 1 kHz) than those of pure PVDF. Enhanced saturated polarization (P-sat similar to 0.38 mu C cm(-2)) and remnant polarization values (P-r similar to 0.21 mu C cm(-2)) are obtained in nanocomposite film that indicates to have potential to use as energy storage applications. In addition, ZnS-NPs incorporation also improves dielectric breakdown strength. (C) 2017 Elsevier Ltd. All rights reserved

Improvement in hardness of soda-lime-silica glass

Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-lime-silica glass with loading rate in the range of 0.1-10 N.s(-1). Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate

An Effective Electrical Throughput from PANI Supplement ZnS Nanorods and PDMS-Based Flexible Piezoelectric Nanogenerator for Power up Portable Electronic Devices: An Alternative of MWCNT Filler

We demonstrate the requirement of electrical poling can be avoided in flexible piezoelectric nanogenerators (FPNGs) made of low-temperature hydrothermally grown wurtzite zinc sulfide nanorods (ZnS-NRs) blended with polydimethylsiloxane (PDMS). It has been found that conductive fillers, such as polyaniline (PANI) and multiwall carbon nanotubes (MWCNTs), can subsequently improve the overall performance of FPNG. A large electrical throughput (open circuit voltage ∼35 V with power density ∼2.43 μW/cm³) from PANI supplement added nanogenerator (PZP-FPNG) indicates that it is an effective means to replace the MWCNTs filler. The time constant (τ) estimated from the transient response of the capacitor charging curves signifying that the FPNGs are very much capable to charge the capacitors in very short time span (e.g., 3 V is accomplished in 50 s) and thus expected to be perfectly suitable in portable, wearable and flexible electronics devices. We demonstrate that FPNG can instantly lit up several commercial Light Emitting Diodes (LEDs) (15 red, 25 green, and 55 blue, individually) and power up several portable electronic gadgets, for example, wrist watch, calculator, and LCD screen. Thus, a realization of potential use of PANI in low-temperature-synthesized ZnS-NRs comprising piezoelectric based nanogenerator fabrication is experimentally verified so as to acquire a potential impact in sustainable energy applications. Beside this, wireless piezoelectric signal detection possibility is also worked out where a concept of self-powered smart sensor is introduced