Enhanced dielectric and hydrophobic properties of PDMS/P(VDF-TrFE) blend films by embedding PS microspheres

Wireless Alerts and Data Monitoring from BNNO-MWCNTs/PDMS Composite Film-Based TENG Integrated Inhaler for Smart Healthcare Application

In recent years, the implementation of energy-harvesting technology in medical equipment has attracted significant interest owing to its potential for self-powered and smart healthcare systems. Herein, the integration of a triboelectric nanogenerator (TENG) is proposed into an inhaler for energy-harvesting and smart inhalation monitoring. For this initially, barium sodium niobium oxide (Ba2NaNb5O15) microparticles (BNNO MPs) are synthesized via a facile solid-state synthesis process. The BNNO MPs with ferroelectricity and high dielectric constant are incorporated into polydimethylsiloxane (PDMS) polymer to make BNNO/PDMS composite films (CFs) for TENG fabrication. The fabricated TENG is operated in a contact-separation mode, and its electrical output performance is compared to establish the optimal BNNO MPs concentration. Furthermore, multi-wall carbon nanotubes (MWCNTs), a conductive filler material, are used to enhance the electrical conductivity of the CFs, thereby improving the electrical output performance of the TENG. The robustness/durability of the proposed BNNO-MWCNTs/PDMS CF-based TENG are investigated. The proposed TENG device is demonstrated to harvest electrical energy from mechanical motions via regular human activities and power portable electronics. The TENG is integrated into the inhaler casing to count the number of sprays remaining in the canister, send the notification to a smartphone via Bluetooth, and harvest energy.

Ultrahigh sensitive and rapid-response self-powered flexible pressure sensor based on sandwiched piezoelectric composites

Flexible sensors and actuators are the basis for realizing the Internet of Everything. This study identifies specific interfacial polarization and filler dispersion challenges in flexible sensors. A novel sandwich-structured flexible sensor with polydimethylsiloxane (PDMS)-filled Nb2CTx as the interlayer and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]-filled barium titanate (BTO) as the upper and lower layers was designed and fabricated. The thickness of the interlayer was optimized to be 6.2 μm, resulting in an ultrahigh sensitivity of 16.05 V/N and ultrashort response time of 626 μs. The interlayer achieved an oriented arrangement of the dipoles in the upper and lower piezoelectric films through interfacial polarization, enhancing the piezoelectric output and sensitivity. The proposed mechanism was confirmed by the dielectric properties, local piezoelectric response, cross-sectional potential simulation, and interfacial electrical calculations. Additionally, the sensor effectively distinguishes various body movements, facial micro-expressions, and throat vibrations during vocalization, and can be applied to ultrahigh-sensitive self-powered flexible piezoelectric pressure sensors.

Enhanced Proliferation and Differentiation of Human Osteoblasts by Remotely Controlled Magnetic-Field-Induced Electric Stimulation Using Flexible Substrates

With the progressive aging of the population, bone fractures are an increasing major health concern. Diverse strategies are being studied to reduce the recovery times using nonaggressive treatments. Electrical stimulation (either endogenous or externally applied electric pulses) has been found to be effective in accelerating bone cell proliferation and differentiation. However, the direct insertion of electrodes into tissues can cause undesirable inflammation or infection reactions. As an alternative, magnetoelectric heterostructures (wherein magnetic fields are applied to induce electric polarization) could be used to achieve electric stimulation without the need for implanted electrodes. Here, we develop a magnetoelectric platform based on flexible kapton/FeGa/P(VDF-TrFE) (flexible substrate/magnetostrictive layer/ferroelectric layer) heterostructures for remote magnetic-field-induced electric field stimulation of human osteoblast cells. We show that the use of flexible supports overcomes the clamping effects that typically occur when analogous magnetoelectric structures are grown onto rigid substrates (which preclude strain transfer from the magnetostrictive to the ferroelectric layers). The study of the diverse proliferation and differentiation markers evidence that in all the stages of bone formation (cell proliferation, extracellular matrix maturation, and mineralization), the electrical stimulation of the cells results in a remarkably better performance. The results pave the way for novel strategies for remote cell stimulation based on flexible platforms not only in bone regeneration but also in many other applications where electrical cell stimulation may be beneficial (e.g., neurological diseases or skin regeneration).

Enhanced Dielectric and Hydrophobic Properties of Poly(vinylidene fluoride-trifluoroethylene)/TiO2 Nanowire Arrays Composite Film Surface Modified by Electrospinning

In this research, we designed a feasible method to prepare composite films with high permittivity and significantly enhanced hydrophobic performance, which showed huge potential in the electrowetting field. TiO2 nanowire arrays were prepared by a one-step hydrothermal process, and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) was spin-coated on the nanowire arrays to form composite, the surface of which was modified by electrospinning. Due to the great orientation of TiO2 nanowires, dipoles and space charges are in ordered arrangement along the electric field, and this strongly reinforced the Maxwell-Wagner-Sillars (MWS) polarization, thus the permittivity of the composite (TiO2 nanowire length/film thickness is 0.769) reaches 53 at 1 kHz, which is nearly 3 times higher than pure P(VDF-TrFE). Meanwhile the composite film possesses low dielectric loss (0.07) and low conductivity (2.69 × 10-9 S/cm), showing good insulation. The contact angle of the composite after electrospinning (about 137°) was greatly enhanced from pure P(VDF-TrFE) spin-coated film (about 89°), which can be attributed to the microrough structure built by P(VDF-TrFE) nanofibers.

Enhancing the mechanical and thermal properties of waterborne polyurethane composites with thermoset epoxy resin microspheres

A facile way to prepare WPU with good mechanical and thermal properties by adding epoxy microspheres.