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Backgrounds of flexible piezoelectric devices for biomedical applications. (a) The past and the predicted global market sizes of piezoelectric devices from 2017 to 2026 [5]. (b) The typical structure of flexible piezoelectric devices. (c) The diverse biomedical applications of flexible piezoelectric devices as wearable electronics (Reproduced with permission [8]. Copyright 2018, Royal Society of Chemistry), including pronunciation monitor [6] (Reproduced with permission [6]. Copyright 2017, American Chemical Society), artificial glove [7] (Reproduced with permission [7]. Copyright 2017, Institute of Physics), electricity generator [8] (Reproduced with permission [8]. Copyright 2018, Royal Society of Chemistry), e-tattoo [9] (Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https ://creativecommons.org/licenses/by/4.0) [9]. Copyright 2019, The Authors, published by Wiley-VCH), movement sensor [10] (Reproduced with permission [10]. Copyright 2015, Elsevier), and energy harvesting shoe insole [11] (Reproduced with permission [11]. Copyright 2020, American Chemical Society); as implantable devices (Reproduced with permission [14]. Copyright 2015, Elsevier), including blood--brain barrier opener [12] (Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https://creativecommons. org/licenses/by/4.0) [12]. Copyright 2020, The Authors, published by United States National Academy of Sciences), bone tissue stimulator [13] (Reproduced with permission [13]. Copyright 2020, Elsevier), aorta electricity generator [14] (Reproduced with permission [14]. Copyright 2015, Elsevier), pacemaker [15] (Reproduced with permission [15]. Copyright 2021, Elsevier), abdomen pressure monitor [16] (Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0) [16]. Copyright 2018, The Authors, published by United States National Academy of Sciences), and neural stimulator [19] (Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0) [19]. Copyright 2020, The Authors, published by Springer Nature).
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Flexible piezoelectrics realise the conversion between mechanical movements and electrical power by conformally attaching onto curvilinear surfaces, which are promising for energy harvesting of biomedical devices due to their sustainable body movements and/or deformations. Developing secondary functions of flexible piezoelectric energy harvesters i...
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... eco-friendly, and maintenance-free energy sources to power biomedical sensors or actuators [2,3]. In addition, biomedical piezoelectrics have the advantages including superior biocompatibility, facile processability, high durability, reliability, and sensitivity [4], therefore serving as a promising solution for biomedical energy harvesting. Fig. 1 (a) shows the past and the predicted global market of piezoelectric devices from 2017 to 2026 [5]. An enormous and steadily expanding market is witnessed, which is predicted to reach 27.5 billion US dollars in 2026. Particularly, lightweight flexible piezoelectric devices can conformally attach to curved human joints and organs, ...
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... which is predicted to reach 27.5 billion US dollars in 2026. Particularly, lightweight flexible piezoelectric devices can conformally attach to curved human joints and organs, serving as biomedical sensors by harvesting mechanical energy. A flexible piezoelectric energy harvester typically contains a flexible piezoelectric thin film, as shown in Fig. 1(b). Two electrodes are attached on the top and bottom surfaces to form a sandwich like structure that is encapsulated by an outer flexible substrate. Fig. 1(c) exemplifies the wearable and implantable biomedical devices based on flexible piezoelectric energy harvesters [6][7][8][9][10][11][12][13][14][15][16][17][18]. These devices are ...
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... joints and organs, serving as biomedical sensors by harvesting mechanical energy. A flexible piezoelectric energy harvester typically contains a flexible piezoelectric thin film, as shown in Fig. 1(b). Two electrodes are attached on the top and bottom surfaces to form a sandwich like structure that is encapsulated by an outer flexible substrate. Fig. 1(c) exemplifies the wearable and implantable biomedical devices based on flexible piezoelectric energy harvesters [6][7][8][9][10][11][12][13][14][15][16][17][18]. These devices are found in diverse applications as energy generators or medical actuators, indicating the huge potential of flexible piezoelectrics in the biomedical ...
Citations
... Triboelectricity can also collect mechanical energy when two dissimilar materials are rubbed together [72,88,89]. Triboelectric materials offer several showing piezoelectric or pyroelectric voltage outputs when stretched or subjected to heat gradients, and therefore being HSNG-compatible with a wide range of human body parts (c) Stretchy flexible piezoelectric helical strap morphology design using stretchable morphologies (d) Schematics and pictures show the 30 mm PVDF sheet coated with 60 nm Al and attached to the respirator as a wearable breathing device that runs a PyNG [199][200][201]. ...
... Collaboration between cardiology, materials science, and medical device engineering experts would be essential in developing and validating such a novel approach for clinical use. Fig. 7 explains that implantable energy harvesters (IEHs) and real- 6. Human body piezoelectric energy Three synergistic processes and architectures that merge flexible piezoelectric and triboelectric energy producers [201][202][203]. ...
... Focusing on Sustainable Development Goals (SDGs), the market value of piezoelectric materials is expected to reach $27.5 billion by 2026 [197][198][199][200] due to their desirable properties, such as high biocompatibility, ease of processing, durability, reliability, and sensitivity. Lightweight and flexible piezoelectric devices can be attached to human joints and organs to harvest mechanical energy for biosensors, contributing to the development of clean and affordable energy [201][202][203][204]. ...
To cater to the extensive body movements and deformations necessitated by biomedical equipment flexible piezoelectrics emerge as a promising solution for energy harvesting. This review research delves into the potential of Flexible Piezoelectric Materials (FPM) as a sustainable solution for clean and affordable energy, aligning with the United Nations' Sustainable Development Goals (SDGs). By systematically examining the secondary functions of stretchability, hybrid energy harvesting, and self-healing, the study aims to comprehensively understand these materials' mechanisms, strategies, and relationships between structural characteristics and properties. The research highlights the significance of designing piezoelectric materials that can conform to the curvilinear shape of the human body, enabling sustainable and efficient mechanical energy capture for various applications, such as biosensors and actuators. The study identifies critical areas for future investigation, including the commercialization of stretchable piezoelectric systems, prevention of unintended interference in hybrid energy harvesters, development of consistent wearability metrics, and enhancement of the elastic piezoelectric material, electrode circuit, and substrate for improved stretchability and comfort. In conclusion, this review research offers valuable insights into developing and implementing FPM as a promising and innovative approach to harnessing clean, affordable energy in line with the SDGs.
... Viscoelastic nanobeams can be utilized for energy harvesting from ambient vibration. Their viscoelastic behavior allows them to efficiently convert mechanical vibration into electrical energy, which can be harnessed for powering small electronic devices or sensors [10][11][12] . ...
The present research focuses on the analysis of wave propagation on a rotating viscoelastic nanobeam supported on the viscoelastic foundation which is subject to thermal gradient effects. A comprehensive and accurate model of a viscoelastic nanobeam is constructed by using a novel nonclassical mechanical model. Based on the general nonlocal theory (GNT), Kelvin-Voigt model, and Timoshenko beam theory, the motion equations for the nanobeam are obtained. Through the GNT, material hardening and softening behaviors are simultaneously taken into account during wave propagation. An analytical solution is utilized to generate the results for torsional (TO), longitudinal (LA), and transverse (TA) types of wave dispersion. Moreover, the effects of nonlocal parameters, Kelvin-Voigt damping, foundation damping, Winkler-Pasternak coefficients, rotating speed, and thermal gradient are illustrated and discussed in detail.
... The use of bioinspired and biomimetic strategies to develop energy storage and harvesting devices could enhance and optimise the performances of these closed-loop systems [100][101][102][103][104][105][106] . The electricity generated by bioinspired energy harvesting devices, such as triboelectric [107] and piezoelectric nanogenerators [108] and solar cells [109] , can be stored in storage units and used to power electronic devices [110] . ...
Recent advances in soft sensor technology have pushed digital healthcare toward life-changing solutions. Data reliability and robustness can be realised by building sensor arrays that collect comprehensive biological parameter data from several points on the underlying organs simultaneously, a principle that is inspired by bioreceptors. The rapid growth of soft lithography and printing, three-dimensional (3D) printing, and weaving/knitting technologies has facilitated the low-cost development of soft sensors in the array format. Advances in data acquisition, processing, and visualisation techniques have helped with the collection of meaningful data using arrays and their presentation to users on personal devices through wireless communication interfaces. Local- or cloud-based data storage helps with the collection of adequate data from sensor arrays over time to facilitate reliable prognoses based on historical data. Emerging energy harvesting technologies have led to the development of techniques to power sensor arrays sustainably. This review presents developmental building blocks in wearable and artificial organ-based soft sensor arrays, including bioreceptor-inspired sensing mechanisms, fabrication methods, digital data-acquisition techniques, methods to present the results to users, power systems, and target diseases/conditions for treatment or monitoring. Finally, we summarise the challenges associated with the development of single and multimodal array sensors for advanced digital healthcare and suggest possible solutions to overcome them.
... It is particularly advantageous to produce flexible and stretchable PEGs to harvest biomechanical energy from a simple action of tiny bio-mechanical human body movements such as bending, folding, twisting, and stretching. [124][125][126] Therefore, there is a need for the development of flexible and stretchable PEGs systems based on piezoelectric hydrogels that can sense pressure and have a wide range of potential applications in the field of electronic skin. ...
The development of next-generation bioelectronics, as well as the powering of consumer and medical devices, require power sources that are soft, flexible, extensible, and even biocompatible. Traditional energy storage devices (typically, batteries and supercapacitors) are rigid, unrecyclable, offer short-lifetime, contain hazardous chemicals and possess poor biocompatibility, hindering their utilization in wearable electronics. Therefore, there is a genuine unmet need for a new generation of innovative energy-harvesting materials that are soft, flexible, bio-compatible, and bio-degradable. Piezoelectric gels or PiezoGels are a smart crystalline form of gels with polar ordered structures that belongs to the broader family of piezoelectric material, which generate electricity in response to mechanical stress or deformation. Given that PiezoGels are structurally similar to hydrogels, they offer several advantages including intrinsic chirality, crystallinity, degree of ordered structures, mechanical flexibility, biocompatibility, and biodegradability, emphasizing their potential applications ranging from power generation to bio-medical applications. Herein, we describe recent examples of new functional PiezoGel materials employed for energy harvesting, sensing, and wound dressing applications. First, this review focuses on the principles of piezoelectric generators (PEGs) and the advantages of using hydrogels as PiezoGels in energy and biomedical applications. Next, we provide a detailed discussion on the preparation, functionalization, and fabrication of PiezoGel-PEGs (P-PEGs) for the applications of energy harvesting, sensing and wound healing/dressing. Finally, this review concludes with a discussion of the current challenges and future directions of P-PEGs.
... While the relationship between piezoelectric performance and in vivo degradation processes is still evolving, recent innovative progresses have laid a solid foundation for future investigations aimed at optimizing the efficiency, controllability, and biosafety of piezoelectric medical applications. Several previous works have made inspiring reviews on biocompatible piezoelectric natural biomaterials [24][25][26][27][28]. These works have primarily focused on elucidating their mechanisms, structures, piezoelectric performance, and potential applications [25][26][27][28]. ...
... Several previous works have made inspiring reviews on biocompatible piezoelectric natural biomaterials [24][25][26][27][28]. These works have primarily focused on elucidating their mechanisms, structures, piezoelectric performance, and potential applications [25][26][27][28]. However, a gap remains in current literatures for the comprehensive and insightful review of biodegradable piezoelectric materials, particularly in terms of their electrical performances and degradability within the context of medical applications. ...
... To date, the power output of biodegradable piezoelectric materials used for energy harvesting remains deficient for a large scale medical equipment, compared with PZT [202] or PVDF [203]. Incorporating piezoelectrics with various energy harvesting systems is a promising strategy to realize enhanced output by harvesting different types of energy sources [28]. Non-degradable piezoelectric systems have been reported to be integrated with pyroelectric [192], thermoelectric [204][205][206][207], photovoltaic [208], triboelectric [23,209], and electromagnetic systems [210]. ...
Piezoelectric devices integrated into physiological systems can be used effectively for biomedical applications such as sensing biological forces, self-powering biomedical devices, stimulating tissue regeneration and healing, and diagnosing medical problems. The limitation of current well-established implantable piezoelectric medical devices is that most of them are non-degradable and require extra removal surgery. Biodegradable piezoelectric implants can avoid the above dilemma by degrading inside the body after fulfilling their service life, and therefore are promising to become the next-generation of biomedical implants. Herein, we firstly systematically review the recent developments in biodegradable piezoelectric materials, including bio-polymers, synthetic polymers, and degradable piezoelectric inorganic materials and their composites. The associated material synthesis methods and device fabrication techniques are summarized. Then, we overview the cutting-edge strategies to realize high-performance biodegradable piezoelectric materials and devices. Subsequently, we discuss the encouraging biomedical applications of biodegradable piezoelectric implants, including biosensing, energy harvesting, tissue engineering, and disease diagnosis and treatment. Finally, future research directions, following the clarification of challenges in mass-market applications are proposed. This article comprehensively reviews biodegradable piezoelectrics from material optimization strategies to device applications, with a focus on the enormous potential of biodegradable transient piezoelectric medical implants.
... Piezoelectric materials have numerous applications in sensors, actuators, transducers, and electronic devices, including microphones, speakers, and ultrasonic transducers. Common examples of piezoelectric materials are quartz, specific ceramics, and certain crystals like tourmaline and topaz [8,9]. Bone plays a crucial role in the body, providing structural support, protecting vital organs, storing minerals and lipids, connecting muscles to the skeleton, and enabling movement. ...
Wireless energy transfer (WET) based on ultrasound‐driven generators with enormous beneficial functions, is technologically in progress by the valuation of ultrasonic metamaterials (UMMs) in science and engineering domains. Indeed, novel metamaterial structures can develop the efficiency of mechanical and physical features of ultrasound energy receivers (US‐ETs), including ultrasound‐driven piezoelectric and triboelectric nanogenerators (US‐PENGs and US‐TENGs) for advantageous applications. This review article first summarizes the fundamentals, classification, and design engineering of UMMs after introducing ultrasound energy for WET technology. In addition to addressing using UMMs, the topical progress of innovative UMMs in US‐ETs is conceptually presented. Moreover, the advanced approaches of metamaterials are reported in the categorized applications of US‐PENGs and US‐TENGs. Finally, some current perspectives and encounters of UMMs in US‐ETs are offered. With this objective in mind, this review explores the potential revolution of reliable integrated energy transfer systems through the transformation of metamaterials into ultrasound‐driven active mediums for generators.
This paper presents a comprehensive exploration of the role of smart materials, specifically triboelectric and piezoelectric materials, in the context of human-integrated healthcare systems. The study begins by elucidating the fundamentals of smart materials in healthcare, providing a detailed definition and characteristics of these materials and underscoring their paramount importance in advancing healthcare technologies. The research approach employed in this study involves a combination of literature review, experimental investigation, and computational modeling to analyze the potential of smart materials in healthcare applications. The subsequent sections delve into the individual contributions of triboelectric and piezoelectric materials in healthcare systems, outlining their unique attributes and potential applications. Eventually, real-world implementation challenges, such as scaling p production, ensuring stability, and establishing ethical deployment protocols, are meticulously examined.
Depletion of fossil fuels and increase in pollution through chemical batteries trigger the development of self‐powered devices based on flexible piezoelectric nanogenerators (PNG). Biocompatible piezoelectric polyvinylidene fluoride (PVDF) nanocomposites merged with piezoelectric fillers like ZnO, KNN, and BaTiO3 reproduce amended piezoelectric current, contributing to the safe application as biosensors and flexible industrial devices. Optimized loading, precise selection, and variating the surface chemistry of piezoelectric filler, along with fabrication schemes comprising different structural configurations of composites, considerably influence its potential for application as an energy harvester. Also, optimized processing condition upgrades dielectric constant and energy storage density, and reduces dielectric loss, thereby plummeting energy dissipation even after prolonged usage. Consequently, this article reviews the principles, properties, fabrication techniques, and market application of PVDF composites. A detailed relationship of significant electrical properties of PVDF composites with its fabrication methods and (piezoelectric parameters of fabricated PVDF composites with reported real‐life wearable, implantable, and industrial‐based portable piezoelectric devices are discussed in detail along with tabulated data for a clear understanding of structure–property relationship. Again, the market strategy for establishing flexible PVDF composite as a PNG has been discussed. A piece of in‐depth knowledge is provided for procuring affordable futuristic large‐scale PVDF‐based nanogenerators exhibiting affordable market worth.
