Piezoelectric Nanocomposites Research Articles

3D‐Printing of Highly Piezoelectric Barium Titanate Polymer Nanocomposites with Surface‐Modified Nanoparticles at Low Loadings

AbstractThis work describes the development and characterization of tetragonal barium titanate nanoparticles (BTO NPs) and their surface functionalization with dopamine dodecylamine (DDA), a lipophilic organic ligand. The so‐obtained lipophilic NPs (BTO‐DDA) are then formulated at low loadings (< 5 wt.%) into liquid photocurable resins for vat photopolymerization (VP) and 3D printed into solid objects. The printed composites are mechanically characterized in order to assess the effect of the nanomaterial on the mechanical properties of the 3D printed polymer, revealing no significant variations in the mechanical properties (tensile or flexural) of the nanocomposites compared to the original polymer matrix. In light of these results, the printed nanocomposites are studied in terms of their capacity to generate a separation of charge by the piezoelectric effect, typical of the BTO crystal structure. This study reveals that BTO‐loaded nanocomposites display outstanding piezoelectric coefficients as high as 50 pC/N when BTO‐DDA is formulated at 3.0 wt.%, only slightly less than one‐third of the piezoelectric coefficient previously reported for bulk BTO, while preserving the mechanical properties of the polymer matrix.

Effects of Silica Nanoparticles on the Piezoelectro-Elastic Response of PZT-7A-Polyimide Nanocomposites: Micromechanics Modeling Technique.

By using piezoelectric materials, it is possible to convert clean and renewable energy sources into electrical energy. In this paper, the effect on the piezoelectro-elastic response of piezoelectric-fiber-reinforced nanocomposites by adding silica nanoparticles into the polyimide matrix is investigated by a micromechanical method. First, the Ji and Mori-Tanaka models are used to calculate the properties of the nanoscale silica-filled polymer. The nanoparticle agglomeration and silica-polymer interphase are considered in the micromechanical modeling. Then, considering the filled polymer as the matrix and the piezoelectric fiber as the reinforcement, the Mori-Tanaka model is used to estimate the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites. It was found that adding silica nanoparticles into the polymer improves the elastic and piezoelectric properties of the piezoelectric fibrous nanocomposites. When the fiber volume fraction is 60%, the nanocomposite with the 3% silica-filled polyimide exhibits 39%, 31.8%, and 37% improvements in the transverse Young's modulus ET, transverse shear modulus GTL, and piezoelectric coefficient e31 in comparison with the composite without nanoparticles. Furthermore, the piezoelectro-elastic properties such as ET, GTL, and e31 can be improved as the nanoparticle diameter decreases. However, the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites decrease once the nanoparticles are agglomerated in the polymer matrix. A thick interphase with a high stiffness enhances the nanocomposite's piezoelectro-elastic performance. Also, the influence of volume fractions of the silica nanoparticles and piezoelectric fibers on the nanocomposite properties is studied.

Programming Piezoelectric Phase of Poly(Vinylidene Fluoride) via Hybrid Metal Halide Perovskite for Enhanced Electromechanical Performance

AbstractFluoropolymers and metal halide perovskites (MHPs), as two classes of important piezoelectric materials, suffer from active phases through a facile process and brittleness led poor manufacturability, respectively. Here, TMCM‐CdCl3/PVDF nanocomposites (TMCM = trimethylchloromethyl ammonium, PVDF = polyvinylidene fluoride) are synthesized to overcome the above shortcomings. The abundant hydrogen (H) and chlorine (Cl) sites in TMCM‐CdCl3 can interlock with H and fluorine (F) atoms within PVDF via C─H···Cl and C─H···F interactions. This programming effect augments the dipole alignment and consequently promotes the formation of polar phases within PVDF. The devices made by these nanocomposites exhibit high energy harvesting properties surpassing established MHP/PVDF analogues, and prominent performance in sensing delicate human motions. Moreover, the devices show exceptional capabilities for detecting underwater ultrasound waves. The signal intensity is ≈4 times that of commercial PVDF film devices, and the frequency distortion is only a quarter of that observed in commercial ceramic transducers. This study opens up new possibilities for developing high‐performance piezoelectric nanocomposites and the creation of advanced electromechanical devices.

Homogenized moduli and local multiphysics fields of unidirectional piezoelectric nanocomposites with energetic surfaces

The study extends the locally-exact homogenization theory (LEHT) to determine the effective parameters and localized multiphysics fields of unidirectional piezoelectric nanocomposites with energetic surfaces. The interface is simulated using the generalized Gurtin-Murdoch model for piezoelectric nanocomposites, taking into account the discontinuities between surface stresses and electrical displacement. By characterizing hexagonal and square repeating unit cells (RUC), the interactions across a fiber's or pore's interface in piezoelectric nanocomposites with energetic surfaces have been analyzed. The extended LEHT possesses the advantages of fast convergence, excellent stability, and computational efficiency due to its avoidance of mesh discretization and pointwise satisfaction of interfacial conditions. To verify the validity of the present theory, this paper also derives the Eshelby solution for piezoelectric nanocomposite with energetic surfaces. The reliability and accuracy of the present theory are demonstrated by comparing the present results from the Eshelby solution and the finite element method (FEM) with generally good agreement. On this basis, the influence of microstructural effects, such as phase volume fractions and geometrical arrangement, on the effective and local responses of piezoelectric nanocomposites with energetic surfaces are investigated. The results show that effective piezoelectric/dielectric moduli and electric displacement field for piezoelectric nanocomposites are significantly affected by the size effect, along with several other parameters such as unit cell arrays and fiber/pore volume fractions. Those results highlight the significance of neighboring pore or fiber interactions for piezoelectric nanocomposites, which are often overlooked in traditional micromechanics models and are challenging to be captured using numerical methods.

Long-term performance of basalt fiber reinforced composite under coupled effect of alkalinity and freeze-thaw cycles

Basalt fiber, a kind of natural fiber produced from the melt of basalt stones, has been regarded as a promising material in the manufacture of fiber reinforced composites considering the balance between mechanical properties and environmental costs compared with other non-renewable/petroleum materials. Moreover, the basalt fiber reinforced polmyers (BFRP) are capable to fabricate the energy harvesting devices in marine engineering when piezoelectric nanocomposites and piezoelectric polymer matrix are adopted to collect offshore renewable energy. However, the long-term performance of BFRP in concrete alkaline and seawater environment has not been comprehensively understood yet, and the lack of knowledge on the performance of BFRP reinforcement under coupled alkalinity and freeze-thaw cycles prevents further application of composite structure in the frigid areas. To address above questions, experimental investigations were carried out with respect to the mechanical properties and deterioration mechanism of BFRP under alkaline environment affected by seawater and temperature as well as under coupled alkaline and freeze-thaw cycles. The results showed that the strength retention of BFRP bars in seawater-sea sand concrete and immersed in seawater is higher than that in distilled water. As the erosion time increases and the temperature rises, severe resin damage occurs inside BFRP bars, and the weakening of connections between fibers and matrix becomes critical in the reduction of tensile performance. Moreover, it is found that the long-term performance of BFRP under coupled alkaline and freeze-thaw cycles is affected by deterioration of resin at the surface, while the majority of internal fibers are free from attack by corrosive agents. These findings will provide a scientific basis for the reliable performance evaluation and further development of high performance and durable multifunctional BFRP materials in marine engineering.

Enhanced piezocatalytic degradation of mixed organic dyes using BaTiO3–MoS2 heterostructure nanocomposites: A mechanistic investigation

Piezocatalysis garners significant interest as a potential solution to environmental issues, specifically regarding dye pollutants. Nonetheless, the main obstacle in the piezoelectric efficiency of materials for eliminating organic pollutants from water has been the recombination of charge carriers. Here we report on the fabrication of a piezoelectric nanocomposite of BaTiO3 (BT) Nanoparticles and MoS2 (MS) Nanosheets for the enhanced piezocatalytic degradation of dye pollutants. The sample with 1.0 wt % MoS2 content (BT/MS1) demonstrates greater efficacy compared to both 2.0 wt % MoS2 (BT/MS2) and BaTiO3 (BT) alone in degrading Rhodamine B (Rh B) and Methyl Orange (MO). Specifically, BT/MS1 exhibits 1.84- and 2.8-times enhanced performance for Rh B and MO degradation respectively, in comparison to BT alone. It is demonstrated that the charge transfer system at the interface of BT and MS effectively lowers the recombination of electron-hole (e‒- h+) pairs, generated during piezocatalysis thereby enhancing the degradation. The composite sample was further used for the successful degradation of a mixture of dyes. This study introduces a novel approach to enhance catalysis by hybrid composite in piezoelectric materials.

Utilizing a High-Performance Piezoelectric Nanocomposite as a Self-Activating Component in Piezotronic Artificial Mechanoreceptors.

Challenges such as poor dispersion and insufficient polarization of BaTiO3 (BTO) nanoparticles (NPs) within poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) composites have hindered their piezoelectricity, limiting their uses in pressure sensors, nanogenerators, and artificial sensory synapses. Here, we introduce a high-performance piezoelectric nanocomposite material consisting of P(VDF-TrFE)/modified-BTO (mBTO) NPs for use as a self-activating component in a piezotronic artificial mechanoreceptor. To generate high-performance piezoelectric nanocomposite materials, the surface of BTO is hydroxylated, followed by the covalent attachment of (3-aminopropyl)triethoxysilane to improve the dispersibility of mBTO NPs within the P(VDF-TrFE) matrix. We also aim to enhance the crystallization degree of P(VDF-TrFE), the efficiency characteristics of mBTO, and the poling efficiency, even when incorporating small amounts of mBTO NPs. The piezoelectric potential mechanically induced from the P(VDF-TrFE)/mBTO NPs nanocomposite was three times greater than that from P(VDF-TrFE) and twice as high as that from the P(VDF-TrFE)/BTO NPs nanocomposite. The piezoelectric potential generated by mechanical stimuli on the piezoelectric nanocomposite was utilized to activate the synaptic ionogel-gated field-effect transistor for the development of self-powered piezotronics artificial mechanoreceptors on a polyimide substrate. The device successfully emulated fast-adapting (FA) functions found in biological FA mechanoreceptors. This approach has great potential for applications to future intelligent tactile perception technology.

3D Printing of Anisotropic Piezoresistive Pressure Sensors for Directional Force Perception.

Anisotropic pressure sensors are gaining increasing attention for next-generation wearable electronics and intelligent infrastructure owing to their sensitivity in identifying different directional forces. 3D printing technologies have unparalleled advantages in the design of anisotropic pressure sensors with customized 3D structures for realizing tunable anisotropy. 3D printing has demonstrated few successes in utilizing piezoelectric nanocomposites for anisotropic recognition. However, 3D-printed anisotropic piezoresistive pressure sensors (PPSs) remain unexplored despite their convenience in saving the poling process. This study pioneers the development of an aqueous printable ink containing waterborne polyurethane elastomer. An anisotropic PPS featuring tailorable flexibility in macroscopic 3D structures and microscopic pore morphologies is created by adopting direct ink writing 3D printing technology. Consequently, the desired directional force perception is achieved by programming the printing schemes. Notably, the printed PPS demonstrated excellent deformability, with a relative sensitivity of 1.22 (kPa*wt. %)-1 over a substantial pressure range (2.8 to 8.1kPa), approximately fivefold than that of a state-of-the-art carbon-based PPS. This study underscores the versatility of 3D printing in customizing highly sensitive anisotropic pressure sensors for advanced sensing applications that are difficult to achieve using conventional measures.

Development of Composite-film-based Flexible Energy Harvester using Lead-free BCTZ Piezoelectric Nanomaterials

Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and selfpowered devices owing to their excellent mechanical durability and output performance. In this study, we design a leadfree piezoelectric nanocomposite utilizing (Ba<sub>0.85</sub>Ca<sub>0.15</sub>)(Ti<sub>0.9</sub>Zr<sub>0.1</sub>)O<sub>3</sub> (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solidstate reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 A, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

Physicochemical, electrochemical, and biological characterization of field assisted gold nanocluster-coated barium titanate nanoparticles for biomedical applications.

Fluorescence-based bioimaging is an imperative approach with high clinical relevance in healthcare applications and biomedical research. The field of bioimaging plays an indispensable role in gaining insight into the internal architecture of cells/tissues and comprehending the physiological functions associated with biological systems. With the utility of piezoelectric nanomaterials, the bioelectric interface has been significantly investigated, leading to remarkable clinical relevance. Herein, we have developed barium titanate nanoparticle (BT) coated gold nanoclusters (AuNCs) in the presence and absence of an electromagnetic field (EMF). In this work, the effect of low (0.6 G) and high (2.0 G) EMFs on the structural arrangement of these piezoelectric nanocomposites (ABT) has been extensively studied with the help of X-ray diffraction (XRD), high diffraction resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Furthermore, the two derivatives of ABT i.e. 0.6 ABT and 2.0 ABT have been evaluated for electrochemical behavior for their applicability as a candidate for exploring the bioelectric interface. Additionally, ABT, 0.6 ABT, and 2.0 ABT have been explored for cytocompatibility and bioimaging applications. The proposed piezoelectric nanocomposite, as a multifunctional platform, has enormous proficiency in the field of bioimaging and the capability to be utilized across the bioelectric interface.

Piezocatalytic strategy facilitates diabetic bone regeneration through high-performance anti-oxidative recycling

Anti-oxidative therapy for resistance of oxidative stress-induced damage has attracted substantial attention for bone regeneration under diabetic conditions. However, most anti-oxidants suffer from low efficiency due to their one-off reaction with oxidative products and rapid loss of activity. Herein, the piezoelectric nanocomposite with built-in electric field was fabricated as a cyclic anti-oxidative device for improved reactive oxygen species (ROS) scavenging and pro-osteogenic outcome. Under ultrasound (US) irradiation, the polydopamine (PDA) -functionalized generator with piezocatalytic effect exhibits high-performance recycling of redox catalytic reaction via continuous electron supplementation for cyclic group switch from quinone to phenol. The piezocatalytic method substantially boosts ROS elimination and reverses inflammatory status, contributing to strengthened osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and M2 polarization of macrophages. In vivo results further validated superior bone healing in rats with diabetes mellitus (DM). Our study therefore provides fundamental insights into the potential value of piezocatalytic effect-triggered cyclic anti-oxidative function for optimized osteogenesis under DM condition, and lays a basis for application of piezocatalytic effect in regenerative medicine.

Scale-Dependent MSG Formulations for Vibrational Study of Honeycomb Microplates Covered by Piezoelectric Nanocomposite Patches

This study investigates free vibration analysis of a microplate featuring a honeycomb (HC) core and incorporates two nanocomposite piezoelectric (NP) layers. Carbon nanotubes (CNTs) are hired to enhance the electro-mechanical performance of the piezoelectric patches, which are subjected to an externally applied electric voltage. All layers are tightly bonded together and are supported by an elastic substrate according to the Pasternak model, capable of withstanding both normal and shear loads. To establish the kinematic relations, a trigonometric plate theory is employed. The governing equations of motion are deduced through the application of Hamilton’s principle and variational technique. The modified strain gradient theory, which includes three material length-scale parameters (MLSPs), is used to account for the scale effect. An analytical approach based on Fourier series functions is employed to solve the differential equations of motion. Subsequently, the impact of various factors, such as the geometrical characteristics of the HC core, distribution patterns of CNTs, and other significant parameters, on the normalized frequencies of the model is assessed after validating the accuracy of the results. The outcomes of this research have the potential to facilitate the advancement and production of lightweight and intelligent structures and devices, ultimately enhancing their efficiency.

Nonlinear-optical piezoelectric electrospun nanofibers

This paper presents a nonlinear optical piezoelectric electrospun nanocomposite of polyvinylidene fluoride (PVDF) nanofibers with embedded nanomaterial of poly {1-[p-(3’-carboxy-4’- hydroxyphenylazo) benzenesulfonamido]-1, 2-ethandiyl} (PCBS). PCBS of different weight ratios are added in-situ to the synthesized PVDF nanofibers. The generated nanofibers mats have been proved to possess both properties of piezoelectric response and nonlinear optical conversion due to the presence of both PVDF and PCBS, respectively. Innovatively, embedding PCBS within the PVDF nanofibers increases the piezoelectric response of the nanocomposite, compared to the case of neat PVDF nanofibers, at certain optimum weight concentrations of PCBS. This has been proved by different piezoelectric measurements at different applied forces and vibration frequencies, along with d33 coefficient measurements and supported by FTIR analysis of beta-sheets. Our results support the evidence of the coupling between the polarized diploes of PCBS and PVDF, which can enhance the overall piezoelectric response. Furthermore, the synthesized nanocomposite shows an optical second harmonic generation (SHG) at optimum concentration of added PCBS within the PVDF nanofibers of around 1 wt.%. The synthesized nonlinear optical nanocomposite of PVDF/PCBS can be multi-functionalized sensors/transducer membranes for biomedical and sensing applications.

Nanoindentation response of small-volume piezoelectric structures and multi-layered composites: modeling the effect of surrounding materials

With piezoelectric small-volume composites gaining importance in smart device applications and nanoindentation being recognized as a versatile method for assessing the properties of layer materials, the present study is focused on the indentation response of the small-volume piezoelectric structures multi-layered composites. In particular, the effects of the nature of the substrate and surrounding materials, on the indentation response of piezoelectric nanocomposites, such as nanoislands, nanowires, and multi-layered composites are investigated. By developing three-dimensional finite element modeling, the complex interaction between the fundamental elastic, piezoelectric and dielectric properties of the piezoelectric materials and the elastic, plastic and electrically conducting or insulating properties of the surrounding materials, on the indentation response of the layered composites is analyzed. It is found that: (i) a substrate material that is elastically stiffer enhances the mechanical indentation stiffness and the electric indentation stiffness while plastic deformation in the substrate causes a reduction in the mechanical and electrical indentation stiffness; (ii) the effective piezoelectric and mechanical indentation stiffnesses of piezoelectric multi-layered composites are bounded by the corresponding characteristics of the bulk material counterparts from which the individual layers are constructed; (iii) electrically conducting surrounding materials produce a softening effect while insulating materials enhance the electrical indentation stiffness resulting in more charges being accumulated during the indentation process.

Highly efficient, eco-friendly, flexible piezoelectric nanogenerators based on MA2CuCl4 NPs embedded into a zein matrix

Eco-friendly, piezoelectric MA2CuCl4-zein nanocomposites (NCs) are fabricated using the sol-gel method in which lead-free halide perovskite MA2CuCl4 nanoparticles (NPs) are successfully embedded in a natural polymer zein matrix without chemical decomposition. The MA2CuCl4-zein NCs are utilized as the piezoelectric layer for piezoelectric nanogenerators (PENGs), and PENGs based on the MA2CuCl4-zein NCs are compared with those based on MA2CuCl4 NPs and on zein. The average output voltage of the PENGs based on the MA2CuCl4-zein NCs under vertical pressure is 48.84 V, which is significantly larger than that of the PENGs with MA2CuCl4 NPs alone and with zein alone by factors of 13.49 and 4.62, respectively. The significantly higher output voltage of the PENGs based on the MA2CuCl4-zein NC thin films is attributed to enhanced piezoelectricity and the surface planarization caused by the zein matrix. The output voltages of the rigid PENG and the flexible TENG based on the MA2CuCl4-zein NC thin films remain stable without degradation after 500 taps and after 500 bends, respectively. The flexible PENGs based on MA2CuCl4-zein NC thin films can be operated using various human motions, such as bending with fingers, the palms of hands, and or the arms, and stepping on the PENGs. The utilization of MA2CuCl4-zein NCs provides insight into developing eco-friendly PENGs that utilize lead-free halide perovskites and natural polymers.

Energy harvesting and wireless communication by carbon fiber-reinforced polymer-enhanced piezoelectric nanocomposites

Piezoelectric Internet of Things (IoT) sensors with energy-harvesting capabilities, which can convert mechanical energy into electrical energy, promote battery-less systems. Such sensors can harness the vibration generated by spacecraft and other moving objects, eliminating the need for external power sources or battery replacements, thereby improving the autonomy and reliability of the system. This study investigates the features of a novel piezoelectric vibration energy harvester (PVEH) that comprises a carbon fiber-reinforced polymer (CFRP) electrode. The CFRP electrode provides outstanding electrical conductivity (7190 S/m) and enhances the mechanical characteristics of the energy collector, thereby ensuring a steady electrical energy yield during resonance. The piezoelectric composite consists of potassium sodium niobate (KNN) nanoparticles mixed with epoxy resin. Results show that when the KNN content is about 30 vol%, the piezoelectric properties of d33 and d31 are 15.21 pC/N and − 5.68 pC/N, respectively. Under an applied displacement of 0.05 mm, the CFRP-reinforced PVEH (C-PVEH) provides an impressive output energy volume density of 89.61 μW/cm3, which is capable of lighting LED bulbs with ease. Notably, this technology shows great application potential for powering wireless communication systems, indicating a remarkable advancement in the field of self-powered IoT sensors. This study provides valuable insights into the potential application of this groundbreaking technology.

3D-Printed Flexible PVDF-TrFE Composites with Aligned BCZT Nanowires and Interdigital Electrodes for Piezoelectric Nanogenerator Applications

Piezoelectric nanogenerators based on piezoelectric nanocomposites have attracted much interest in recent decades owing to their excellent piezoelectric properties and application in self-powered systems and wearable sensors. As a promising piezoelectric ceramic filler in composite-based generators, one-dimensional (1D) piezoelectric nanowires were filled into a polymer matrix to enhance its dielectric and piezoelectric properties. In this paper, flexible PVDF-TrFE composite films containing highly aligned Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) nanowires (NWs) have been manufactured via a direct-ink writing method. The effect of BCZT NW content on the dielectric, ferroelectric, and piezoelectric properties was investigated using multiphysics modeling and detailed experiments. An optimum composite composition was discovered, and the piezoelectric composite film with 15 wt % BCZT NWs possessed the highest energy harvesting figure of merit of 5.3 × 10–12 m2/N. Interdigital electrodes were combined with the composite to fabricate a patterned piezoelectric nanogenerator, where the piezoelectric nanogenerator can produce an open-circuit output voltage of 17 V, and the maximum output power density could reach 5.6 μW/cm2. This work provides opportunities for the optimization and fabrication of piezoelectric materials for energy-harvesting and sensing applications.

Carbon Fiber-Reinforced Piezoelectric Nanocomposites: Design, Fabrication and Evaluation for Damage Detection and Energy Harvesting

Carbon fiber-reinforced polymers (CFRPs) can be used in aging infrastructures as a reinforcement because of their excellent mechanical properties, and they can also be used in the support maintenance and repair work of these structures. However, the development of CFRPs as reinforcement while achieving self-powered damage detection is still challenging. Herein, a sodium potassium niobate (KNN) nanoparticle-filled epoxy (KNN–EP) plate was fabricated and combined with advanced CFRP electrodes. The obtained composites exhibited dramatically enhanced mechanical properties. In addition, CFRP contributed to the energy harvesting output (peak-to-peak output voltage Vpp = 7.25 mV), which was over 600 % higher than that of the KNN–EP plate. Thus, this composite could work as a force sensor for damage detection. In the end-notch bending test, the voltage signals generated by CFRP/KNN–EP composite accurately corresponded to the crack growth, which could provide the real-time crack state and prediction of fracture occurrence. Therefore, this work provided a new strategy for structural enhancement and kinetic energy harvesting, which can be used to detect damage behavior in infrastructures.

Preparation and investigation of nanogenerators based on the flexible BTO/P(VDF‐TrFE) composites

AbstractIn this article, a piezoelectric thin film was obtained by mixing polyvinylidene fluoride‐trifluoroethylene (P(VDF‐TrFE)) and barium titanate (BTO) via a solvent vaporization process. All the morphologies, crystal phases, thermal and electrical tests, as well as potential simulations by COMSOL, were studied to analyze sample performances. It has been demonstrated that BTO has a positive effect on increasing the piezoelectric functional phase‐β phase within P(VDF‐TrFE). Furthermore, the optimal ratio of BTO to P(VDF‐TrFE) was determined to be 10 wt%. BTO nanoparticles were evenly distributed in the P(VDF‐TrFE) substrate, forming a more directional structure. Based on the most suitable material composition, piezoelectric, and triboelectric nanogenerators were constructed to harvest mechanical energy from human motions. Moreover, the factors influencing the electrical outputs of nanogenerators were systematically studied, such as the force values and frequencies of excitation, as well as the piezoelectric layer materials. The applications of lighting LEDs highlighted the practical use in everyday life. Finally, the comparison between simulations, theoretical analysis, and experimental results demonstrated the effect of BTO in enhancing the overall material properties. This work expands the application potential of piezoelectric nanocomposites in energy collection and storage by designing and optimizing ceramic‐doped piezoelectric polymer composites.

Balloon Catheter-Integrated Piezoelectric Micropyramid Arrays for Measuring Vascular Stiffness

Atherosclerosis is one of the severe cardiovascular diseases in which blood vessels lose elasticity and the lumen narrows. If atherosclerosis worsens, it commonly leads to acute coronary syndrome (ACS) due to the rupture of vulnerable plaque or aortic aneurysm. As the mechanical properties of vascular tissues vary from their conditions, measuring the vascular stiffness of an inner blood vessel wall may be applied to the accurate diagnosis of atherosclerotic symptoms. Therefore, early mechanical detection of vascular stiffness is highly needed for immediate medical attention for ACS. Even with conventional examination methods such as intravascular ultrasonography and optical coherence tomography, several limitations still remain that make it difficult to directly determine the mechanical properties of the vascular tissue. As piezoelectric materials convert mechanical energy to electricity without an external power source, a piezoelectric nanocomposite could be utilized as a balloon catheter-integrated mechanical sensor on its surface. Here, we present piezoelectric nanocomposite micropyramid balloon catheter (p-MPB) arrays for measuring vascular stiffness. We study the structural characterization and feasibility of p-MPB as endovascular sensors by conducting finite element method analyses. Also, multifaceted piezoelectric voltages are measured by compression/release tests, in vitro vascular phantom tests, and ex vivo porcine heart tests to confirm that the p-MPB sensor properly operates in blood vessels.