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1.
Nanomaterials (Basel) ; 11(5)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33925105

RESUMO

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (αME) of the magnetoelectric effect. Another strategy is the use of 3-component composites through the inclusion of piezoelectric BaTiO3 particles. Developed strategies allow us to increase the αME value from ~5 mV/cm·Oe for the composite of randomly distributed CoFe2O4 nanoparticles in PVDF matrix to ~18.5 mV/cm·Oe for a composite of magnetic particles in PVDF-TrFE matrix with 5%wt of piezoelectric particles. The applicability of such materials as bioactive surface is demonstrated on neural crest stem cell cultures.

2.
Sensors (Basel) ; 20(24)2020 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-33322153

RESUMO

The article is devoted to the theoretical and experimental study of a magnetoelectric (ME) current sensor based on a gradient structure. It is known that the use of gradient structures in magnetostrictive-piezoelectric composites makes it possible to create a self-biased structure by replacing an external magnetic field with an internal one, which significantly reduces the weight, power consumption and dimensions of the device. Current sensors based on a gradient bidomain structure LiNbO3 (LN)/Ni/Metglas with the following layer thicknesses: lithium niobate-500 µm, nickel-10 µm, Metglas-29 µm, operate on a linear section of the working characteristic and do not require the bias magnetic field. The main characteristics of a contactless ME current sensor: its current range measures up to 10 A, it has a sensitivity of 0.9 V/A, its current consumption is not more than 2.5 mA, and its linearity is maintained to an accuracy of 99.8%. Some additional advantages of a bidomain lithium niobate-based current sensor are the increased sensitivity of the device due to the use of the bending mode in the electromechanical resonance region and the absence of a lead component in the device.

3.
Langmuir ; 36(30): 8680-8686, 2020 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-32631066

RESUMO

A mixture of water suspensions of graphene oxide (GO) and polytetrafluoroethylene (PTFE) was used to make the films GO-PTFE (50:50). They became conductive (2.0-2.8 S/cm) while maintaining flexibility after reduction with hydrazine and subsequent annealing at 370 °C. The structure and morphology of the reduced films (rGO-PTFE) are examined in detail by means of a number of techniques such as scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman, and contact angle wetting. The results of the films tested as current collectors in a metal-free supercapacitor with electrodes from microwave exfoliated GO and an acid (1 M H2SO4) electrolyte are presented.

4.
Artigo em Inglês | MEDLINE | ID: mdl-31985416

RESUMO

With the recent thriving of low-power electronic microdevices and sensors, the development of components capable of scavenging environmental energy has become imperative. In this article, we studied bidomain congruent LiNbO3 (LN) single crystals combined with magnetic materials for dual, mechanical, and magnetic energy harvesting applications. A simple magneto-mechano-electric composite cantilever, with a trilayered long-bar bidomain LN/spring-steel/metglas structure and a large tip proof permanent magnet, was fabricated. Its vibration and magnetic energy harvesting capabilities were tested while trying to optimize its resonant characteristics, load impedance, and tip proof mass. The vibration measurements yielded a peak open-circuit voltage of 2.42 kV/g, a short-circuit current of [Formula: see text]/g, and an average power of up to 35.6 mW/g2, corresponding to a power density of 6.9 mW/(cm [Formula: see text]), at a low resonance frequency of 29.22 Hz and with an optimal load of 40 [Formula: see text]. The magnetic response revealed a resonant peak open-circuit voltage of 90.9 V/Oe and an average power of up to [Formula: see text]/Oe2, corresponding to a relatively large magnetoelectric coefficient of 1.82 kV/(cm · Oe) and a power density of [Formula: see text]/(cm [Formula: see text]). We thus developed a system that is, in principle, able to scavenge electrical power simultaneously from low-level ambient mechanical and magnetic sources to feed low-power electronic devices.

5.
Sensors (Basel) ; 19(3)2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30717160

RESUMO

We present a low-frequency sensor for the detection of vibrations, with a sub-nm amplitude, based on a cantilever made of a single-crystalline lithium niobate (LiNbO3) plate, with a bidomain ferroelectric structure. The sensitivity of the sensor-to-sinusoidal vibrational excitations was measured in terms of displacement as well as of acceleration amplitude. We show a linear behavior of the response, with the vibrational displacement amplitude in the entire studied frequency range up to 150 Hz. The sensitivity of the developed sensor varies from minimum values of 20 µV/nm and 7 V/g (where g = 9.81 m/s² is the gravitational acceleration), at a frequency of 23 Hz, to peak values of 92.5 mV/nm and 2443 V/g, at the mechanical resonance of the cantilever at 97.25 Hz. The smallest detectable vibration depended on the excitation frequency and varied from 100 nm, at 7 Hz, to 0.1 nm, at frequencies above 38 Hz. Sensors using bidomain lithium niobate single crystals, as sensitive elements, are promising for the detection of ultra-weak low-frequency vibrations in a wide temperature range and in harsh environments.

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