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In recent years, the piezoelectric polymers and composites have become the topic of significant research interest owing to their versatile mechanical, physical, and chemical properties. The combination of piezoelectricity with functional stuffs gives rise to interesting properties and exhibits great potential in nanoscale electromechanical devices...
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High-performance piezoelectric thin films generally contain toxic lead that limits the application scenarios especially on wearable and medical devices. Alternative lead-free piezoelectric materials such as Ba0.85Ca0.15-Zr0.1Ti0.9O3 (BCZT) have been proved...
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... The piezoelectric coefficients of PVDF range from 8 < d 31 < 30 and −24 < d 33 < −140 pC N −1 , respectively [153]. Other polymers with piezoelectric properties include polyamides (odd-nylons, being nylon-11 the most studied) with d 31 < 12 pC N −1 [154]. ...
... Materials processing optimization led to piezoelectric coefficients (pC N −1 ) for PVDF of d 33 [160], competitive with the ones of ceramic materials. For nylon-11 the piezoelectric response is d 31 <12 pC N −1 [154]. Poly(L-lactide) (PLLA), with d 14 = 12 pC N −1 was discovered by Fukada in 1991 [152] and is relevant for medical applications due to [152,157,158]. ...
Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g., combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g., smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and electromagnetic power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyzes the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
... 15,16 Therefore, they are used for various applications such as wearable sensors, actuators, artificial skin, energy harvesting, drug delivery, wound healing, and so on. 8,[17][18][19][20][21][22][23] Polyvinylidene fluoride (PVDF) which is a semicrystalline polymer with a molecular structure [C2H2F2] n is considered the most important piezoelectric polymer thanks to its excellent piezo-, pyro-, and ferroelectric properties, outstanding mechanical properties, low cost, low density, high flexibility, good chemical stability, ability to be generated in different surface morphologies, and so on. 24,25 PVDF can be found in different polymorphs (α, β, γ, δ, and ε). ...
In recreant years, the attention of researchers has been focused on enhancing the electrical outputs of energy harvesting devices. This study reports the generation and characterization of electrospun polyvinylidene fluoride (PVDF) nanofiber webs obtained from different solvents (Acetone (ACE), ACE: N, N-dimethylformamide (DMF) /3:1, ACE: DMF/1:1, ACE: DMF/1:3, and DMF). These electrospun webs will be used as active layers for piezoelectric nanogenerator (PENG). We found that fibers electrospun using DMF have the highest phase content (F(β)), while fibers electrospun using ACE have the lowest one. Furthermore, the results show that PENG based on fiber web electrospun using DMF has the highest electrical outputs, whereas, the lowest electrical outputs were for PENG based on fiber web electrospun using ACE. We believe this work can serve as a good reference for investigating the effect of solvent systems on diameters of fibers, crystalline phases, and piezoelectric properties.
The piezoelectric effect was discovered over a century ago, and it has found wide application since that time. The direct piezoelectric effect is the production of charge upon application of force to a material, and the converse piezoelectric effect is a change in the material dimension(s) upon the application of a potential. To date, piezoelectric effects have been observed only in solid-phase materials. We report here the observation of the direct piezoelectric effect in room-temperature ionic liquids (RTILs). The RTILs 1-butyl-3-methyl imidazolium bis(trifluoromethyl-sulfonyl)imide (BMIM+TFSI-) and 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide (HMIM+TFSI-) produce a potential upon the application of force when confined in a cell, with the magnitude of the potential being directly proportional to the force applied. The effect is one order of magnitude smaller than that seen in quartz. This is the first report to our knowledge of the direct piezoelectric effect in a neat liquid. Its discovery has fundamental implications about the organization and dynamics in ionic liquids and invites theoretical treatment.
Polymer-based flexible energy harvesting systems based on several physical phenomena such as piezo-, pyro-, thermo- and triboelectric effects have become increasingly relevant for self-powered nanogenerator devices to, as an example, replace batteries in remote or inaccessible places or develop self-powered sensors. Tailored properties of the materials combined with advanced manufacturing technologies will increase the intrinsic properties and improve integration into devices of the energy harvesters’ making them even more attractive to provide energy for applications concerning the increased need for sensors for the digitalization of society and economy. The selection and manipulation of the polymer as a host matrix and filler with appropriated properties is critical for maximizing the output power of the flexible devices, together with the printing technique and the device geometry. Printing techniques allows custom design, improved integration, small to large scale and low-cost devices with improve sustainability.
In this review, the main characteristics of the most used printing techniques and polymer-based materials for the different flexible energy harvesting technologies are provided. The most used physical phenomena are the piezo- and triboelectric ones, based on PVDF for piezoelectric systems, and silicone for triboelectric device applications, mostly based on the contact-separation method and printed by 3D technique to generate energy. Thermoelectric devices are mainly developed by inkjet printing and are based on bismuth materials. Pyroelectric printed devices are the least explored, relying mostly on screen printing and electroactive PVDF. Finally, hybrid systems combining two different effects will maximize the energy generated.
This review presents a comprehensive state-of-the-art technology at ECC that summarizes and critically revises research on PZT, self-sensing, and self-healing concrete. Concepts, methods, and applications used in cement-based sensors are reviewed, and missing aspects and suggestions for future studies are presented. Recent studies have shown that additives are added (e.g., lead zirconate titanate, barium zirconate titanate, nanomaterials, and fibers) to improve the piezoelectric capacity of the cementitious composite. Cement-based piezoresistive sensors have significant potential to monitor the behavior of concrete under rheology, mechanical loading, and durability. The achievement of using a structural material for this effect is that it costs less and is more durable than integrated or embedded devices. Similarly, applications of different mineral and bio-additive materials to induce the self-healing of cracks have received great attention. In addition, greening cement materials resulting from the use of high volumes of industrial wastes in self-healing and self-sensing concrete have wide potential applications in SHM. Furthermore, self-sensing and self-healing materials can help provide structural integrity and safety, extend the life of structures, increase traffic safety and efficiency, as well as reduce resource and energy consumption. Despite all these positive developments, there are currently a number of serious research challenges for these materials.
Piezoelectric materials offer an ability to exchange energy between electrical and mechanical systems with fair ease, by using the simple and inverse piezoelectric effect. Piezoelectric transceivers, sensors, microphones, actuators, or active acoustic noise cancellation devices are some of many applications for piezoelectric materials. Due to the natural ability of the material to convert electricity and mechanical strain, solutions based on piezoelectric materials are often compact and allow applications on micro scales. One of the forms of piezoelectric actuation involves the use of piezoelectric stacks. The stack is composed of multiple piezoelectric plates layered by thin dielectric sheets, with electrodes attached along the sides. The main aim of piezoelectric stacks is the increase in maximum displacement by multiplying the number of piezoelectric plates that make up the stack. Stacks are composed of plates with the same material properties and the same dimensions. This study aims to investigate the idea of composing piezoelectric stacks of plates that have separate control circuits inducing different carrier frequencies or plates with differing properties and dimensions, in search for new applications for piezoelectric stacks. The main point of interest is the investigation of the ability to use piezoelectric stacks to generate complex vibration spectrums composed of multiple frequencies, resulting from the use of different piezoelectric plates in the stack or different carrier frequencies that stimulate each plate. To achieve this, a stack composed of two piezoelectric plates, each controlled by its own circuit, will be measured by a laser vibrometer, to check the complexity of the output vibration pattern.
