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Biomimetic artificial muscles (BMAMs) aim to imitate the movement and capabilities of natural muscles, drawing inspiration from their structure and function. This research utilized multiwalled carbon nanotubes to increase the conductivity of the electrode membrane and replaced traditional electroactive polymers with sodium alginate to improve the output performance of BMAMs. To further strengthen the output force of the electrode membrane, nanoscale ZnO was chosen as the doping material. Various composite electrode membranes were created during the experiments, each containing varying amounts of ZnO nanoparticles. The membranes' surface morphology was extensively examined with scanning electron microscopy, and the composite electrode membranes were fully assessed on an electrochemical workstation. Electrochemical testing showed that adding nanoscale ZnO particles greatly boosted the specific capacitance of the electrode membrane, which was directly linked to the performance of BMAMs. Impedance spectroscopy test results indicated a minimal impact of nanoscale ZnO particle doping on the internal resistance of the electrode membrane. Highlights: Sodium alginate replaces electroactive polymers, easing environmental impact.Nano ZnO doping boosts electrode membrane's capacitance for stronger muscles.ZnO doping shows minimal effect on electrode membrane's resistance. [ABSTRACT FROM AUTHOR]

Solid-state electromechanical smart material actuators are versatile as they permit diverse shapes and designs and can exhibit different actuation modes. An important advantage of these actuators compared to conventional ones is that they can be easily miniaturized to a sub-millimeter scale. In recent years, there has been a great surge in novel liquid pumps operated by these smart material actuators. These devices create opportunities for applications in fields ranging from aerospace and robotics to the biomedical and drug delivery industries. Although these have mainly been prototypes, a few products have already entered the market. To assist in the further development of this research track, we provide a taxonomy of the electromechanical smart material actuators available, and subsequently focus on the ones that have been utilized for operating pumps. The latter includes unidirectional shape memory alloy-, piezoelectric ceramic-, ferroelectric polymer-, dielectric elastomer-, ionic polymer metal composite- and conducting polymer-based actuators. Their properties are reviewed in the context of engineering pumps and summarized in comprehensive tables. Given the diverse requirements of pumps, these varied smart materials and their actuators offer exciting possibilities for designing and constructing devices for a wide array of applications. [ABSTRACT FROM AUTHOR]

Electroactive polymers (EAPs) deform when subject to an electric field, which is generated by two or more electrodes. To ensure proper function of the EAP, these electrodes are connected to a source and they are therefore required to be continuous such that no isolated islands exist. Increasing an EAP's performance using topology optimization while ensuring electrode connectivity is the goal of this work. A topology optimization formulation is introduced where electrode connectivity is ensured using the virtual temperature method. Numerical experiments demonstrate that this is an efficient method to guarantee connectivity. [ABSTRACT FROM AUTHOR]

Multi-scale organization of molecular and living components is one of the most critical parameters that regulate charge transport in electroactive systems-whether abiotic, biotic, or hybrid interfaces. In this article, an overview of the current state-of-the-art for controlling molecular order, nanoscale assembly, microstructure domains, and macroscale architectures of electroactive organic interfaces used for biomedical applications is provided. Discussed herein are the leading strategies and challenges to date for engineering the multi-scale organization of electroactive organic materials, including biomolecule-based materials, synthetic conjugated molecules, polymers, and their biohybrid analogs. Importantly, this review provides a unique discussion on how the dependence of conduction phenomena on structural organization is observed for electroactive organic materials, as well as for their living counterparts in electrogenic tissues and biotic-abiotic interfaces. Expansion of fabrication capabilities that enable higher resolution and throughput for the engineering of ordered, patterned, and architecture electroactive systems will significantly impact the future of bioelectronic technologies for medical devices, bioinspired harvesting platforms, and in vitro models of electroactive tissues. In summary, this article presents how ordering at multiple scales is important for modulating transport in both the electroactive organic, abiotic, and living components of bioelectronic systems.

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Ionic electroactive polymers are considered as electromechanical and mechanoelectrical transducers - actuators and sensors. Transducers with metal (Pt), polymer (PEDOT), and polymer-metal (PEDOT/Pt) hybrid electrodes are prepared. The surface morphology and internal structures of the samples are studied. The measurements of practically important actuation characteristics show that the advantages of transducers with earlier types of electrodes are inherited by those with hybrid electrodes: longer continuous operation in air characteristic of polymer electrodes and higher amplitude and force properties characteristic of metal ones. In the study of the transducer with PEDOT/Pt-electrodes in the sensor mode, the most stable response is obtained when Pt is deposited on the PEDOT external surface in two stages. [ABSTRACT FROM AUTHOR]

Non‐conjugated pendant electroactive polymers (NCPEPs) are an emerging class of polymers that offer the potential of combining the desirable optoelectronic properties of conjugated polymers with the superior synthetic methodologies and stability of traditional non‐conjugated polymers. Despite an increasing number of studies focused on NCPEPs, particularly on understanding fundamental structure‐property relationships, no attempts have been made to provide an overview on established relationships to date. This review showcases selected reports on NCPEP homopolymers and copolymers that demonstrate how optical, electronic, and physical properties of the polymers are affected by tuning of key structural variables such as the chemical structure of the polymer backbone, molecular weight, tacticity, spacer length, the nature of the pendant group, and in the case of copolymers the ratios between different comonomers and between individual polymer blocks. Correlation of structural features with improved π‐stacking and enhanced charge carrier mobility serve as the primary figures of merit in evaluating impact on NCPEP properties. While this review is not intended to serve as a comprehensive summary of all reports on tuning of structural parameters in NCPEPs, it highlights relevant established structure‐property relationships that can serve as a guideline for more targeted design of novel NCPEPs in the future. [ABSTRACT FROM AUTHOR]

This paper aims to enhance the capacitance of electroactive polymer (EAP)-based strain sensors. The enhancement in capacitance was achieved by using a free-standing stretchable polymer film while introducing conducting polymer to fabricate a hybrid dielectric film with controlled conductivity. In this work, styrene-ethylene-butylene-styrene (SEBS) rubber was used as the base material, and dodecyl benzene sulfonate anion (DBSA)-doped polyaniline (PANI) was used as filler to fabricate a hybrid composite conducting film. The maleic anhydride group of the SEBS Rubber and DBSA, the anion of the polyaniline dopant, make a very stable dispersion in Toluene and form a free-standing stretchable film by solution casting. DBSA-doped polyaniline increased the conductivity and dielectric constant of the dielectric film, resulting in a significant enhancement in the capacitance of the EAP-based strain sensor. The sensor presented in this article exhibits capacitance values ranging from 24.7 to 100 µF for strain levels ranging from 0 to 100%, and sensitivity was measured 3 at 100% strain level. [ABSTRACT FROM AUTHOR]

Flexible capacitive sensors based on silicone rubber have gained importance in both academic and industrial fields due to their advantages, including low power consumption and high stability to temperature, and humidity. However, pristine silicone rubber has a low dielectric constant (ε′), requiring the use of dielectric additives such as TiO2, BaTiO3, or Sb2O3‐doped SnO2 rutile‐modified particles (ATO) to enhance electrical properties, but they also increase Young's modulus (E). To overcome this problem, liquid silicone rubbers (LSR) are commonly used in academic research due to their low E, but they often compromise mechanical integrity. In contrast, high‐consistency silicone rubbers (HCR), the industry commodity, maintain mechanical integrity even at high filler loadings but are limited in their use in dielectrics due to high E values. This paper explores the potential of vinyl‐terminated HCR for developing dielectric composites with high electromechanical response, with an improved ε′ and a reduced E while retaining mechanical and processability properties. The resulting dielectric HCR formulations exhibit optimal properties for developing flexible capacitive sensors using well‐established industrial products and processes. [ABSTRACT FROM AUTHOR]

Nature has always been a source of inspiration for the development of novel materials and devices. In particular, polymer actuators that mimic the movements and functions of natural organisms have been of great interest due to their potential applications in various fields, such as biomedical engineering, soft robotics, and energy harvesting. During recent years, the development and actuation performance of electrospun fibrous meshes with the advantages of high permeability, surface area, and easy functional modification, has received extensive attention from researchers. This review covers the recent progress in the state-of-the-art electrospun actuators based on commonly used polymers such as stimuli-sensitive hydrogels, shape-memory polymers (SMPs), and electroactive polymers. The design strategies inspired by nature such as hierarchical systems, layered structures, and responsive interfaces to enhance the performance and functionality of these actuators, including the role of biomimicry to create devices that mimic the behavior of natural organisms, are discussed. Finally, the challenges and future directions in the field, with a focus on the development of more efficient and versatile electrospun polymer actuators which can be used in a wide range of applications, are addressed. The insights gained from this review can contribute to the development of advanced and multifunctional actuators with improved performance and expanded application possibilities. [ABSTRACT FROM AUTHOR]

Solid-state electromechanical smart material actuators are versatile as they permit diverse shapes and designs and can exhibit different actuation modes. An important advantage of these actuators compared to conventional ones is that they can be easily miniaturized to a sub-millimeter scale. In recent years, there has been a great surge in novel liquid pumps operated by these smart material actuators. These devices create opportunities for applications in fields ranging from aerospace and robotics to the biomedical and drug delivery industries. Although these have mainly been prototypes, a few products have already entered the market. To assist in the further development of this research track, we provide a taxonomy of the electromechanical smart material actuators available, and subsequently focus on the ones that have been utilized for operating pumps. The latter includes unidirectional shape memory alloy-, piezoelectric ceramic-, ferroelectric polymer-, dielectric elastomer-, ionic polymer metal composite- and conducting polymer-based actuators. Their properties are reviewed in the context of engineering pumps and summarized in comprehensive tables. Given the diverse requirements of pumps, these varied smart materials and their actuators offer exciting possibilities for designing and constructing devices for a wide array of applications.

Smart textiles combine the features of conventional textiles with promising properties of smart materials such as electromechanically active polymers, resulting in textile actuators. Textile actuators comprise of individual yarn actuators, so understanding their electro‐chemo‐mechanical behavior is of great importance. Herein, this study investigates the effect of inherent structural and mechanical properties of commercial yarns, that form the core of the yarn actuators, on the linear actuation of the conducting‐polymer‐based yarn actuators. Commercial yarns were coated with poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) to make them conductive. Then polypyrrole (PPy) that provides the electromechanical actuation is electropolymerized on the yarn surface under controlled conditions. The linear actuation of the yarn actuators is investigated in aqueous electrolyte under isotonic and isometric conditions. The yarn actuators generated an isotonic strain up to 0.99% and isometric force of 95 mN. The isometric strain achieved in this work is more than tenfold and threefold greater than the previously reported yarn actuators. The isometric actuation force shows an increase of nearly 11‐fold over our previous results. Finally, a qualitative mechanical model is introduced to describe the actuation behavior of yarn actuators. The strain and force created by the yarn actuators make them promising candidates for wearable actuator technologies. [ABSTRACT FROM AUTHOR]

This study presents, for the first time, a comprehensive investigation of the influence of pre- and post-fabrication parameters for the electroactive properties of electrospun chitosan/PVA-based micro- and nanofibers. Chitosan/PVA fibers were fabricated using electrospinning, characterized, and tested as electroactive materials. Solutions with different acetic acid contents (50, 60, 70, and 80 v/v%) were used, and the rheological properties of the solutions were analyzed. Characterization techniques, such as rheology, conductivity, optical microscopy, a thermogravimetric analysis, differential scanning calorimetry, a tensile test, and FT-IR spectroscopy, were utilized. Fiber mats from the various solutions were thermally treated, and their electroactive behavior was examined under a constant electric potential (10 V) at different pHs (2–13). The results showed that fibers electrospun from 80% acetic acid had a lower electroactive response and dissolved quickly. However, thermal treatment improved the stability and electroactive response of all fiber samples, particularly the ones spun with 80% acetic acid, which exhibited a significant increase in speed displacement from 0 cm−1 (non-thermally treated) to 1.372 cm−1 (thermally treated) at a pH of 3. This study sheds light on the influence of pre- and post-fabrication parameters on the electroactive properties of chitosan/PVA fibers, offering valuable insights for the development of electroactive materials in various applications. [ABSTRACT FROM AUTHOR]

Recent work on non‐conjugated pendant electroactive polymers (NCPEPs) has demonstrated significant impacts of structural parameters such as backbone stereoregularity and the spacer connecting the pendant to the backbone on properties, most notably on charge carrier mobilities. Tuning of the pendant group however has not been reported for stereoregular NCPEPs. Here we present a family of novel isotactic poly((carbazolyl‐alkyl‐triazolyl)methyl methacrylates) (PCzATMMAs) for which the effects of increasing the pendant group from carbazole to 3,6‐bis(4‐(2‐ethylhexyl)thiophen‐2‐yl)‐carbazole were investigated. Based on unsuccessful post‐polymerization functionalization with this extended group via previously reported transesterification and thiol‐ene methodologies, we report functionalization via copper‐catalyzed azide‐alkyne cycloaddition which was demonstrated to be highly effective. The effect of spacer length was also investigated for comparison with previously established effects with alkyl spacers. Within the family of PCzATMMAs, hole mobilities were found to increase with longer spacer length and with thermal annealing. The incorporation of an extended pendant with alkyl solubilizing chains was found to result in a lower hole mobility than the equivalent polymer with an unfunctionalized pendant group. Importantly, the copper catalyzed azide‐alkyne cycloaddition proved to be an effective method of post‐polymerization functionalization for stereoregular NCPEPs when extending beyond a simple carbazole pendant. [ABSTRACT FROM AUTHOR]

The process of bone tissue repair and regeneration must occur in a suitable electrical microenvironment, which is one of the most important microenvironments. Electroactive materials appropriately simulate the bioelectric nature of bone and provide the electrical microenvironment required for bone repair, which accelerates bone repair and regeneration. The concept of electrical stimulation-induced osteogenesis promotes the development of electroactive materials as orthopedic implants. This article reviews the general bioelectric phenomena in organisms and the electrical response of natural bone, and briefly explains the promotion of bone regeneration by the electrical microenvironment. Electroactive materials in the field of bone tissue engineering are divided into two categories, such as piezoelectric polymers and conductive polymers, and the material properties, research progress, and applications of each will be described in detail. This article analyzes the limitations of piezoelectric and conductive materials for constructing an electrical microenvironment, reveals the potential of these two materials for overcoming the application limitations of a single type of electroactive material, and discusses the principles. The future challenges and developmental prospects of electroactive materials are discussed. This review comprehensively emphasizes the important characteristics of electroactive biomaterials and points out the direction of development for composite applications of different electroactive materials. [ABSTRACT FROM AUTHOR]

Visible‐light‐driven semiconductor photoelectrodes are promising new devices for on‐demand photocathodic generation of hydrogen peroxide. Herein, the fabrication of organic polymeric photocathodes employing poly(4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole) (pThBTD), and comparatively seven other related derivatives is reported. The monomer dithienobenzodithiazole can be directly polymerized on an electrode via two methods: electropolymerization or iodine‐vapor‐assisted polymerization. Both give polymers with wide visible light absorption and suitable stability for photoelectrodes. These methods yield different active layer morphologies, with electropolymerization yielding photocathodes with better performance. Critical issues affecting oxygen reduction photocurrents are evaluated, namely thickness, wettability, and pH. Photocathodic oxygen reduction currents, as well as photovoltages, are among the highest reported for an organic photoelectrocatalyst, and pThBTD films can stably produce H2O2 with high faradaic yield over at least 8 h. This study shows that single‐component organic semiconductor devices can be highly competitive versus more complex heterostructures and that such low‐bandgap organic polymers can afford remarkable stability. [ABSTRACT FROM AUTHOR]

Minimally Invasive Surgery (MIS) consists of the insertion of a flexible endoscope into the patient body through natural orifices. Over the past few decades, the growing interest in microelectromechanical systems (MEMS) has paved the way for ubiquitous miniaturized integrated sensors and actuators in medical endoscopy. Nowadays, recent advances in materials have opened a promising way to fulfill the surgical requirements and size constraint for the development of smart continuum structures. Among smart materials, electroactive polymers (EAPs) exhibit exceptionally large, fast, repeatable, and reversible motions while perfectly meeting the requirements of micro-integration. However the high applied voltage required for the actuation is not compatible with in vivo medical application. To overcome these issues, a multilayered concept has been proposed. In this work a relaxor ferroelectric electrostrictive polymer is studied for its large electromechanical strain. A wide range of parameters involved in the active material has led us to the development of a finite element model on Abaqus to guide the experimental development. Then, to control this smart endoscopic robot a kinematic and a dynamic models have been built. To test and validate these models a Co-simulation procedure has been developed. This procedure coupled Abaqus and Matlab-Simulink allowing testing proposed control algorithms. [ABSTRACT FROM AUTHOR]

This research paper provides a comprehensive review of the current state-of-the-art and prospects of smart materials for sensing and actuation applications. Smart materials, with their unique ability to respond to external stimuli, have been the subject of extensive research and development in recent years. The paper begins by discussing the various types of smart materials, including piezoelectric materials, shape memory alloys, and electroactive polymers, and their properties and applications in sensing and actuation. the paper covers the advancements in the design and fabrication of smart materials and devices, including the use of nanotechnology and 3D printing. The potential for integration with emerging technologies, such as artificial intelligence and the internet of things, is also explore. The paper provides a comprehensive and in-depth analysis of the state-of-the-art and prospects of smart materials for sensing and actuation applications. The research presented has significant implications for the development of nextgeneration smart materials and devices, with the potential to revolutionize various industries and improve our quality of life.

Abstract Visible‐light‐driven semiconductor photoelectrodes are promising new devices for on‐demand photocathodic generation of hydrogen peroxide. Herein, the fabrication of organic polymeric photocathodes employing poly(4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole) (pThBTD), and comparatively seven other related derivatives is reported. The monomer dithienobenzodithiazole can be directly polymerized on an electrode via two methods: electropolymerization or iodine‐vapor‐assisted polymerization. Both give polymers with wide visible light absorption and suitable stability for photoelectrodes. These methods yield different active layer morphologies, with electropolymerization yielding photocathodes with better performance. Critical issues affecting oxygen reduction photocurrents are evaluated, namely thickness, wettability, and pH. Photocathodic oxygen reduction currents, as well as photovoltages, are among the highest reported for an organic photoelectrocatalyst, and pThBTD films can stably produce H2O2 with high faradaic yield over at least 8 h. This study shows that single‐component organic semiconductor devices can be highly competitive versus more complex heterostructures and that such low‐bandgap organic polymers can afford remarkable stability.

After muscle loss or injury, skeletal muscle tissue has the ability to regenerate and return its function. However, large volume defects in skeletal muscle tissue pose a challenge to regenerate due to the absence of regenerative elements such as biophysical and biochemical cues, making the development of new treatments necessary. One potential solution is to utilize electroactive polymers that can change size or shape in response to an external electric field. Poly(ethylene glycol) diacrylate (PEGDA) is one such polymer, which holds great potential as a scaffold for muscle tissue regeneration due to its mechanical properties. In addition, the versatile chemistry of this polymer allows for the conjugation of new functional groups to enhance its electroactive properties and biocompatibility. Herein, we have developed an electroactive copolymer of PEGDA and acrylic acid (AA) in combination with collagen methacrylate (CMA) to promote cell adhesion and proliferation. The electroactive properties of the CMA + PEGDA:AA constructs were investigated through actuation studies. Furthermore, the biological properties of the hydrogel were investigated in a 14-day in vitro study to evaluate myosin light chain (MLC) expression and metabolic activity of C2C12 mouse myoblast cells. The addition of CMA improved some aspects of material bioactivity, such as MLC expression in C2C12 mouse myoblast cells. However, the incorporation of CMA in the PEGDA:AA hydrogels reduced the sample movement when placed under an electric field, possibly due to steric hindrance from the CMA. Further research is needed to optimize the use of CMA in combination with PEGDA:AA as a potential scaffold for skeletal muscle tissue engineering. [ABSTRACT FROM AUTHOR]

Dielectrophoresis is the electro‐mechanical phenomenon where a force is generated on a dielectric material when exposed to a non‐uniform electric field. It has potential to be exploited in smart materials for robotic manipulation and locomotion, but to date it has been sparsely studied in this area. Herein, a new type of dielectrophoretic actuator exploiting a novel electroactive polymer is described, termed as dielectrophoretic elastomer (DPE), which undergoes electric field‐driven actuation through dielectrophoresis. Unique deflection and morphing behavior of the elastomer induced by controlling the dielectrophoretic phenomenon, such as out‐of‐plane deformation and independence of electric field polarity, are illustrated. The dielectric and mechanical properties of the DPE are studied to gain insight into the influence of materials composition on deformation. Actuation performance using different electrode parameters is experimentally investigated with supplementary analysis through finite element simulation, revealing the relationship between electric field inhomogeneity and deflection. The applications of DPE actuators in a range of robotic devices is demonstrated, including a pump, an adjustable optical lens, and a walking robot. This diverse range of applications illustrates the wide potential of these new soft‐and‐smart electric field‐driven materials for use in soft robotics and soft compliant devices. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) gels have recently been found to exhibit mechanoelectrical transduction or sensing capabilities under compressive loading applications. This phenomenon is not wholly understood but has been characterized as an adsorption-like phenomena under varying amounts and types of plasticizers. A different polymer lattice structure has also been tested, thermoplastic polyurethane, which showed similar sensing characteristics. This study examines mechanical and electrical properties of these gel sensors and proposes a mathematical framework of the underlying mechanisms of mechanoelectrical transduction. COMSOL Multiphysics is used to show solid mechanics characteristics, electrostatic properties, and transport of interstitial plasticizer under compressive loading applications. The solid mechanics takes a continuum mechanics approach and includes a highly compressive Storakers material model for compressive loading applications. The electrostatics and transport properties include charge conservation and a Langmuir adsorption migration model with variable diffusion properties based on plasticizer properties. Results show both plasticizer concentration gradient as well as expected voltage response under varying amounts and types of plasticizers. Experimental work is also completed to show agreeance with the modeling results. [ABSTRACT FROM AUTHOR]

Abstract Multi‐scale organization of molecular and living components is one of the most critical parameters that regulate charge transport in electroactive systems—whether abiotic, biotic, or hybrid interfaces. In this article, an overview of the current state‐of‐the‐art for controlling molecular order, nanoscale assembly, microstructure domains, and macroscale architectures of electroactive organic interfaces used for biomedical applications is provided. Discussed herein are the leading strategies and challenges to date for engineering the multi‐scale organization of electroactive organic materials, including biomolecule‐based materials, synthetic conjugated molecules, polymers, and their biohybrid analogs. Importantly, this review provides a unique discussion on how the dependence of conduction phenomena on structural organization is observed for electroactive organic materials, as well as for their living counterparts in electrogenic tissues and biotic‐abiotic interfaces. Expansion of fabrication capabilities that enable higher resolution and throughput for the engineering of ordered, patterned, and architecture electroactive systems will significantly impact the future of bioelectronic technologies for medical devices, bioinspired harvesting platforms, and in vitro models of electroactive tissues. In summary, this article presents how ordering at multiple scales is important for modulating transport in both the electroactive organic, abiotic, and living components of bioelectronic systems.

This paper aims to enhance the capacitance of electroactive polymer (EAP)-based strain sensors. The enhancement in capacitance was achieved by using a free-standing stretchable polymer film while introducing conducting polymer to fabricate a hybrid dielectric film with controlled conductivity. In this work, styrene-ethylene-butylene-styrene (SEBS) rubber was used as the base material, and dodecyl benzene sulfonate anion (DBSA)-doped polyaniline (PANI) was used as filler to fabricate a hybrid composite conducting film. The maleic anhydride group of the SEBS Rubber and DBSA, the anion of the polyaniline dopant, make a very stable dispersion in Toluene and form a free-standing stretchable film by solution casting. DBSA-doped polyaniline increased the conductivity and dielectric constant of the dielectric film, resulting in a significant enhancement in the capacitance of the EAP-based strain sensor. The sensor presented in this article exhibits capacitance values ranging from 24.7 to 100 µF for strain levels ranging from 0 to 100%, and sensitivity was measured 3 at 100% strain level.

Nature has always been a source of inspiration for the development of novel materials and devices. In particular, polymer actuators that mimic the movements and functions of natural organisms have been of great interest due to their potential applications in various fields, such as biomedical engineering, soft robotics, and energy harvesting. During recent years, the development and actuation performance of electrospun fibrous meshes with the advantages of high permeability, surface area, and easy functional modification, has received extensive attention from researchers. This review covers the recent progress in the state-of-the-art electrospun actuators based on commonly used polymers such as stimuli-sensitive hydrogels, shape-memory polymers (SMPs), and electroactive polymers. The design strategies inspired by nature such as hierarchical systems, layered structures, and responsive interfaces to enhance the performance and functionality of these actuators, including the role of biomimicry to create devices that mimic the behavior of natural organisms, are discussed. Finally, the challenges and future directions in the field, with a focus on the development of more efficient and versatile electrospun polymer actuators which can be used in a wide range of applications, are addressed. The insights gained from this review can contribute to the development of advanced and multifunctional actuators with improved performance and expanded application possibilities.

In this study, the electrical properties of DE materials were systematically tested, and the effects of different effective voltages, electrode types and stretching states on permittivity, dielectric loss, conductivity, capacitance and electrical efficiency were discussed. The frequency dependence of the electric dipole in the material is revealed from the microscopic point of view. Finally, based on the structure and volume incompressibility of the DE, the actuation coefficient of the DE is proposed to characterize its deformation effect. The results show that the permittivity of the DE is very sensitive at high frequency, especially for DE materials with carbon electrode and gold-carbon electrode. At the same effective voltage and gold electrode, the permittivity decreases with the increase of equal biaxial stretching. For the same stretching area, the permittivity of equal biaxial stretching is larger than that of unequal biaxial stretching. The DE with carbon electrode has the largest dielectric loss and is easy to be destroyed in engineering application, which needs further optimization. The dielectric loss decreases with the increase of equal biaxial stretching, which is mainly due to the decrease of orientation deviation between main chain and side chain in DE material. The electric efficiency at low frequency is generally higher than that at high frequency, and the highest electric efficiency can reach 99.64%. With the increase of frequency, the actuation deformation coefficient decreases rapidly. This work will further promote the development of DE materials used in soft robot, and provide a theoretical reference for the design of actuators and sensors.

Melt electrowriting, a high‐resolution additive manufacturing technique, is used in this study to process a magnetic polymer‐based blend for the first time. Carbonyl iron (CI) particles homogenously distribute into poly(vinylidene fluoride) (PVDF) melts to result in well‐defined, highly porous structures or scaffolds comprised of fibers ranging from 30 to 50 µm in diameter. This study observes that CI particle incorporation is possible up to 30 wt% without nozzle clogging, albeit that the highest concentration results in heterogeneous fiber morphologies. In contrast, the direct writing of homogeneous PVDF fibers with up to 15 wt% CI is possible. The fibers can be readily displaced using magnets at concentrations of 1 wt% and above. Combined with good viability of L929 CC1 cells using Live/Dead imaging on scaffolds for all CI concentrations indicates that these formulations have potential for the usage in stimuli‐responsive applications such as 4D printing. [ABSTRACT FROM AUTHOR]

Electroactive polymers (EAPs) have been investigated as materials for use in a range of biomedical applications, ranging from cell culture, electrical stimulation of cultured cells as well as controlled delivery of growth factors and drugs. Despite their excellent drug delivery ability, EAPs are susceptible to biofouling thus they often require surface functionalisation with antifouling coatings to limit unwanted non-specific protein adsorption. Here we demonstrate the surface modification of para toluene sulfonate (pTS) doped polypyrrole with the glycoprotein lubricin (LUB) to produce a self-assembled coating that both prevents surface biofouling while also serving as a high-capacity reservoir for cationic drugs which can then be released passively via diffusion or actively via an applied electrical potential. We carried out our investigation in two parts where we initially assessed the antifouling and cationic drug delivery ability of LUB tethered on a gold surface using quartz crystal microbalance with dissipation monitoring (QCM) to monitor molecular interactions occurring on a gold sensor surface. After confirming the ability of tethered LUB nano brush layers on a gold surface, we introduced an electrochemically grown EAP layer to act as the immobilisation surface for LUB before subsequently introducing the cationic drug doxorubicin hydrochloride (DOX). The release of cationic drug was then investigated under passive and electrochemically stimulated conditions. High-performance liquid chromatography (HPLC) was then carried out to quantify the amount of DOX released. It was shown that the amount of DOX released from nano brush layers of LUB tethered on gold and EAP surfaces could be increased by up to 30% per minute by applying a positive electrochemically stimulating pulse at 0.8 V for one minute. Using bovine serum albumin (BSA), we show that DOX loaded LUB tethered on para toluene sulfonic acid (pTS) doped polypyrrole retained antifouling ability of up to 75% when compared to unloaded tethered LUB. This work demonstrates the unique, novel ability of tethered LUB to actively participate in the delivery of cationic therapeutics on different substrate surfaces. This study could lead to the development of versatile multifunctional biomaterials for use in wide range of biomedical applications, such as dual drug delivery and lubricating coatings, dual drug delivery and antifouling coatings, cellular recording and stimulation. [Display omitted] • Lubricin self-assembly on gold and EAP substrates has minimal impact on charge transfer. • Lubricin self-assembly on gold and EAP substrates has minimal impact on charge transfer. Demonstrated that tethered LUB provides a high loading potential for cationic drugs. • Self-assembled coating that prevents surface biofouling while also serving as a high-capacity reservoir for cationic drugs. [ABSTRACT FROM AUTHOR]

Electroactive polymers (EAP) can alter and change their shape when subjected to an electric field, they have been investigated for a variety of purposes including smart drug delivery and artificial muscles. However, approaches to design electroactive hydrogel structures can be hindered by low polymeric conductivity, which then requires high electrical input to induce movement and results in low cellular viability. Our purpose in this study, was to reduce the input voltage required for movement by layering electroactive PEGDA:Acrylic acid (PEGDA:AA) with poly(ethylene glycol) diacrylate (PEGDA) modified with a conductive nanocomposite of colloidal poly(3,4 ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and graphene oxide (GO). In this study PEDOT:PSS/GO was a flexible electrode that stimulated the PEGDA:AA. The multilayered hydrogel was evaluated for angular movement, electrical properties, and biocompatibility with C2C12 myoblast cells. The data showed that increasing the PEDOT:PSS/GO in the hydrogel decreased the conductivity, potentially due to the presence of GO. The addition of PEDOT:PSS/GO increased scaffold movement compared with PEGDA:AA alone when stimulated at 1 V. Fewer scaffolds displayed significantly more movement with increased voltage, but the 10% PEDOT:PSS/GO group experienced more movement at each tested voltage. C2C12 cells on the 10% PEDOT:PSS/GO were more metabolically active than cells on scaffolds with increased concentrations of PEDOT:PSS/GO. This work is an initial step in creating biocompatible scaffolds capable of actuation for tissue engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • First-ever hybrid piezoelectric P(VDF-TrFE))/Propolis materials. • Propolis increases material surface area and boost bacterial inhibition. • Superior antibacterial activity, with major log 10 reduction of 8.4 in S. aureus. • Low-frequency piezo stimulation boosts hybrid materials antimicrobial effects. • Hybrid materials show promise for medical and public high-traffic applications. The increasing prevalence of antibiotic-resistant illnesses worldwide calls for the development of novel antibacterial strategies, including the ones based on antibacterials materials. This work reports on the combined antibacterial effects of piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) and propolis, a natural antimicrobial agent, on various material structures (2D films and 3D structures) to increase the surface contact area. It is shown that the addition of propolis has a substantial impact on the surface texture and mechanical properties of the materials. In particular, 3D structures exhibit improved distribution of propolis and enhanced mechanical stability in comparison to 2D films. The antibacterial experiments conducted on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) demonstrate a significant increase in the reduction of bacteria, in particular when larger concentrations of propolis are applied and when mechanical stimulation is used at specified frequencies, taking therefore advantage of the surface charge variation associated to the piezoelectric response. It is particularly significant the antibacterial effect on the resistant S.aureus bacteria, emphasising the huge potential of this novel hybrid material in biomedical applications. Thus, it is demonstrated that piezoelectric polymers in combination with natural antibacterial agents, represents a suitable approach to address microbial resistance, with important applications in areas including wound dressings, implant coatings, and high traffic surfaces, among others. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrocatalytic behavior of hybrid electrodes modified with heterocyclic polyazines. • Novel electrodes based on polyphenothiazine nanocomposites for electrochromic devices. • Hybrid electrodes based on nanocomposites of unsubstituted polyazines as mediator catalysts. • Redox active electrode coatings of polyazine nanocomposites with carbon nanomaterials. This work aims to study electrode materials based on unsubstituted polyazines and composites which will allow further advancing both in the molecular design of redox polymers, composites and materials and evaluating their potential applicability. The polymers were prepared by two-phase chemical oxidative polymerization. Polymer-carbon nanocomposites (NC) based on unsubstituted polyphenoxazine were prepared for the first time. The physicochemical and electrochemical properties were compared for NCs based on polyphenothiazine (PPTA), polyphenoxazine (PPOA) and carbon nanomaterials (CNM). The used CNMs comprise reduced graphene oxide (RGO), single-walled and multi-walled carbon nanotubes (SWCNT and MWCNT). The NC structure and morphology were studied by means of FT IR spectroscopy, XRD, FE-SEM and TEM. The limited solubility of some monomers prevents their electrochemical deposition on electrodes. Therefore, to study the electrochemical, spectroelectrochemical behavior and electrochemical impedance of novel redox active electrode coatings, suspensions of synthesized polymers or their NCs were applied onto electrodes and dried. The effect of NC composition on the conductivity and redox activity thereof was discovered. In general, composites have a higher conductivity than individual polymers. Despite differences in electrical conductivity, all samples exhibited electrocatalytic behavior demonstrated for example of Fe(II)/Fe(III) cyanide redox transition on a planar electrode in a K 3 [Fe(CN) 6 ] solution in 1 M H 2 SO 4. The electronic absorption spectra were recorded in-situ in an electrochemical cell by varying the working electrode potential and showed an electrochromic effect for PPTA and CNM/PPTA. The proposed common equivalent electric circuit allowed explaining the different electrochemical properties of polymers and CNM composites thereof. [ABSTRACT FROM AUTHOR]

This study presents, for the first time, a comprehensive investigation of the influence of pre- and post-fabrication parameters for the electroactive properties of electrospun chitosan/PVA-based micro- and nanofibers. Chitosan/PVA fibers were fabricated using electrospinning, characterized, and tested as electroactive materials. Solutions with different acetic acid contents (50, 60, 70, and 80 v/v%) were used, and the rheological properties of the solutions were analyzed. Characterization techniques, such as rheology, conductivity, optical microscopy, a thermogravimetric analysis, differential scanning calorimetry, a tensile test, and FT-IR spectroscopy, were utilized. Fiber mats from the various solutions were thermally treated, and their electroactive behavior was examined under a constant electric potential (10 V) at different pHs (2–13). The results showed that fibers electrospun from 80% acetic acid had a lower electroactive response and dissolved quickly. However, thermal treatment improved the stability and electroactive response of all fiber samples, particularly the ones spun with 80% acetic acid, which exhibited a significant increase in speed displacement from 0 cm−1 (non-thermally treated) to 1.372 cm−1 (thermally treated) at a pH of 3. This study sheds light on the influence of pre- and post-fabrication parameters on the electroactive properties of chitosan/PVA fibers, offering valuable insights for the development of electroactive materials in various applications.

In nature, hydrostatic, endo‐ and exo‐skeletons are widely observed, and provide essential rigidity and anchoring points for the application of muscular forces. The efficient interface between a hard skeleton and soft muscle in biology is made possible by a complex hierarchy of structures and composite materials, extending from the nano‐ to the meso‐scale. In contrast, artificial constructs that aim to bridge this hard‐soft interface are prone to failure due to local discontinuities and concentrations in stress and strain which lead to material ruptures, delamination, and tearing. In this article, the concept of a stiffness‐graded electroactive material is proposed which emulates the soft‐rigid interface in the nature biological systems and provides both electromechanical activity and the smooth stiffness gradient needed to bridge these two extreme states. This is achieved by programming the diffusion of a rigid filler material (polyvinyl chloride) in a liquid plasticizer (diisodecyl adipate). It is shown that the resulting stiffness gradient can match that of biological tissues such as smooth and skeletal muscles, and that the distal rigid region can be drilled and bonded and significant loads can be safely applied. Additionally, the resulting composite shows electroactive capability through graded anodophilic actuation characteristics. This protocol can be extended to numerous morphologies such as vertical or radial gradients depending on the deployment of two precursor ingredients. Finally, example applications including surface morphing and motion generation are demonstrated. The embodied stiffness gradient and electroactivity make this concept suitable for the development of bio‐integrating and wearable artificial muscles systems and more effective soft robots. [ABSTRACT FROM AUTHOR]

Microgrippers that incorporate soft actuators are appropriate for micromanipulation or microsurgery owing to their ability to grasp objects without causing damage. However, developing a microgripper with a large gripping range that can produce a large force with high speed remains challenging in soft actuation mechanisms. Herein, we introduce a compliant microgripper driven by a soft dielectric elastomer actuator (DEA) called a spiral flexure cone DEA (SFCDEA). The submillimeter-scale SFCDEA exhibited a controllable linear displacement over a high bandwidth and the capability of lifting 100.9 g, which was 670 times higher than its mass. Subsequently, we developed a compliant microgripper based on the SFCDEA using smart composite microstructure technology to fabricate three-dimensional gripper linkages. We demonstrated that the microgripper was able to grasp various millimeter-scale objects with different shapes, sizes, and weights without a complex feedback control owing to its compliance. We proved the versatility of our gripper in robotic manipulation by demonstrating adaptive grasping and releasing of small objects using vibrations owing to its high bandwidth.

The peculiarities of electrochemical polymerization of diphenylamine-2-carboxylic acid (DPAC) in alkaline electrolyte on anodized graphite foil (AGF) are studied with using of electrosynthesis (ES) modifiers (EM), namely, nanosheets of reduced graphene oxide (NSGO) and manganese dioxide. The physicochemical properties of the thus obtained electroactive polymer coatings (PDPAC) as well as their electrochemical characteristics in 1 М H2SO4 solution in the potential interval from –1 to +1.5 V are studied. The results of electrochemical, electron-microscopic, and X-ray diffraction investigations make it possible presuppose the presence of specific features in the electropolymerization of diphenylamine-2-carboxylic acid on AGF. The calculated values of the electrochemical capacitance and the stability of polymer coatings during their multicycle and charge–discharge tests have shown that the characteristics of these materials are suitable for developing the electrode materials for supercapacitors on their basis. [ABSTRACT FROM AUTHOR]

Grasping and manipulating objects on a microscale hold great promise, especially using mechanical structures made from soft materials that enable, for example, safe operations during microsurgery. Soft robots should be preferred to manipulate micro-objects, but their adoption requires, inter alia, soft transducers that can operate either in air or in solution. Ultimately, they should enable actuation at low voltage, as well as be easy to fabricate. This paper presents the results on our investigations about conducting polymers -based transducers. We demonstrate that this material is suitable to construct sensitive structures and a microgripper is proposed to illustrate the results. Large strains were observed and a grasping force of 0.17 mN was generated. Moreover, compared to previous work, we show that the fabrication process can be downscaled while preserving the behavior of the material in both actuation and sensing modes. The macroscale mechanical models obtained are still valid for microscale actuation and sensing.

The ability of morphing aircraft to adapt their shape in flight hinges on the incredible flexibility of their skins, which have multiple degrees of freedom. This paper presents a compact overview of the latest advancements in polymorphing skins for morphing aircraft, focusing on polymeric skins, electroactive polymers, and shape memory polymers. It examines the critical mechanical properties such as flexibility, durability, and resilience that influence their application in morphing wings. By detailing the synthesis processes, including the use of natural rubber, silicone, acrylic, and fiber-reinforced composites, and exploring various modeling and simulation approaches, the paper highlights the importance of flexible material selection and design principles tailored to morphing aircraft needs. It emphasizes a multidisciplinary strategy integrating polymer material science, mechanical engineering, and aerodynamics to innovate in the morphing aircraft domain. This review aims to serve as an essential resource for researchers and practitioners, paving the way for future developments in aerospace morphing technologies. • Innovative Material Synthesis : Explores synthesis of cutting-edge materials like SMPs, EAPs, and advanced composites for aerospace applications. • Material Property Evaluation : Evaluates key mechanical properties like tensile strength, elasticity, and fatigue resistance for polymorphic skins in morphing wings. • Advanced Modeling Techniques : Reviews modeling and simulation methods to predict the behavior of morphing skins under operational conditions. • Design and Implementation Strategies : Discusses design principles for polymer-based skins, focusing on morphing mechanisms and integration with structural components. • Challenges and Solutions in Morphing Skins : Addresses challenges like wrinkling and buckling in polymeric skins and optimizes actuation parameters for SMP and EAP skins, proposing future research directions. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) gels have recently been found to exhibit mechanoelectrical transduction or sensing capabilities under compressive loading applications. This phenomenon is not wholly understood but has been characterized as an adsorption-like phenomena under varying amounts and types of plasticizers. A different polymer lattice structure has also been tested, thermoplastic polyurethane, which showed similar sensing characteristics. This study examines mechanical and electrical properties of these gel sensors and proposes a mathematical framework of the underlying mechanisms of mechanoelectrical transduction. COMSOL Multiphysics is used to show solid mechanics characteristics, electrostatic properties, and transport of interstitial plasticizer under compressive loading applications. The solid mechanics takes a continuum mechanics approach and includes a highly compressive Storakers material model for compressive loading applications. The electrostatics and transport properties include charge conservation and a Langmuir adsorption migration model with variable diffusion properties based on plasticizer properties. Results show both plasticizer concentration gradient as well as expected voltage response under varying amounts and types of plasticizers. Experimental work is also completed to show agreeance with the modeling results.

Inspired by the sophisticated design of biological systems, interest in soft intelligent actuators has increased significantly in recent years, providing attractive strategies for the design of elaborate soft mechanical systems. For the construction of those soft actuators, carbon nanomaterials were extensively and successfully explored for the properties of highly conductive, electrothermal, and photothermal conversion. This review aims to trace the recent achievements for the material and structural design as well as the general mechanisms of the soft actuators, paying particular attention to the contribution of carbon nanomaterials resulted from their diversified interplaying properties, which realized the flexible and dexterous deformation responding to various environmental stimuli, including light, electricity and humidity. The properties and mechanisms of soft actuators are summarized and the potential for future applications and research are presented. [ABSTRACT FROM AUTHOR]

The search for alternative antimicrobial strategies capable of avoiding resistance mechanisms in bacteria are highly needed due to the alarming emergence of antimicrobial resistance. The application of physical stimuli as a mean of sensitizing bacteria for the action of antimicrobials on otherwise resistant bacteria or by allowing the action of low quantity of antimicrobials may be seen as a breakthrough for such purpose. This work proposes the development of antibacterial nanocomposites using the synergy between the electrically active microenvironments, created by a piezoelectric polymer (poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE)), with green-synthesized silver nanoparticles (AgNPs). The electrical microenvironment is generated via mechanical stimulation of piezoelectric PVDF-TrFE/AgNPs films using a lab-made mechanical bioreactor. The generated material's electrical response further translates to bacterial cells, namely Escherichia coli and Staphylococcus epidermidis which in combination with AgNPs and the specific morphological features of the material induce important antibacterial and antibiofilm activity. Both porous and non-porous PVDF composites have shown antibacterial characteristics when stimulated at a mechanical frequency of 4 Hz being the effect boosted when AgNPs were incorporated in the nanocomposite, reducing in more than 80% the S. epidermidis bacterial growth in planktonic and biofilm form. The electroactive environments sensitize the bacteria allowing the action of a low dose of AgNPs (1.69% (w/w)). Importantly, the material did not compromise the viability of mammalian cells, thus being considered biocompatible. The piezoelectric stimulation of PVDF-based polymeric films may represent a breakthrough in the development of antibacterial coatings for devices used at hospital setting, taking advantage on the use of mechanical stimuli (pressure/touch) to exert antibacterial and antibiofilm activity. The application of physical methods in alternative to the common chemical ones is seen as a breakthrough for avoiding the emergence of antimicrobial resistance. Antimicrobial strategies that take advantage on the capability of bacteria to sense physical stimuli such as mechanical and electrical cues are scarce. Electroactive nanocomposites comprised of poly(vinylidene fluoride-co-trifluoroethylene (PVDF-TrFE) and green-synthesized silver nanoparticles (AgNPs) were developed to obtain material able to inhibit the colonization of microorganisms. By applying a mechanical stimuli to the nanocomposite, which ultimately mimics movements such as walking or touching, an antimicrobial effect is obtained, resulting from the synergy between the electroactive microenvironments created on the surface of the material and the AgNPs. Such environments sensitize the bacteria to low doses of antimicrobials. [Display omitted] [ABSTRACT FROM AUTHOR]

Haptics involves human touch sensing and tactile feedback and plays a crucial role in physical interactions of humans with their environment. There is an ever‐increasing interest in development of haptic technologies, due to their role in various applications such as robotics, virtual and augmented reality, healthcare, and smart electronics. Electrically driven actuation mechanisms for soft materials like dielectric elastomer actuators (DEAs), electrohydraulic soft actuators (ESAs), ionic polymer−metal composites (IPMCs), and liquid crystal elastomers (LCEs) hold the potential for the development of the next generation of haptic feedback devices due to a variety of advantages such as light weight and compact design, untethered activation and control, large actuation strains, and distributed and localized actuation. Herein, a detailed look is taken at the advancement in material designs for these electrically driven soft actuators. A detailed analysis of the different strategies for improving the electromechanical performance of existing material systems is presented. Approaches adopted to synthesize novel material systems are explained. Advancements in compliant electrode materials for the electrically driven soft actuators are also described. The conclusion reflects on the main challenges in the field and provides perspectives on recent advancements expected to have a significant impact. [ABSTRACT FROM AUTHOR]

Ionic polymer-metal composites (IPMCs) are functional smart materials that exhibit both electromechanical and mechanoelectrical transduction properties, and the physical phenomenon underlying the transduction mechanisms have been studied across the literature extensively. Here we use a new modeling framework to conduct the most comprehensive dimensional analysis of IPMC transduction phenomena, characterizing the IPMC actuator displacement, actuator blocking force, short-circuit sensing current, and open-circuit sensing voltage under static and dynamic loading. The information obtained in this analysis is used to construct nonlinear regression models for the transduction response as univariant and multivariant functions. Automatic differentiation techniques are leveraged to linearize the nonlinear regression models in the vicinity of a typical IPMC description and derive the sensitivity of the transduction response with respect to the driving independent variables. Further, the multiphysics model is validated using experimental data collected for the dynamic IPMC actuator and voltage sensor. With data collected from physical samples of IPMC materials in-lab, the regression models developed under the new computational framework are verified. [ABSTRACT FROM AUTHOR]