Structural health monitoring (SHM) is a nondestructive process of collecting and analyzing data from structures to evaluate their conditions and predict the remaining lifetime. Multifunctional sensors are increasingly used in smart structures to self-sense and monitor the damages through the measurements of electrical resistivity of composite materials. Polymer-based sensors possess exceptional properties for SHM applications, such as low cost and simple processing, durability, flexibility, and excellent piezoresistive sensitivity. Thermoplastics, thermoplastic elastomers, and elastomer matrices can be combined with conductive nanofillers to develop piezoresistive sensors. Polymer, reinforcement fillers, processing and design have critical influences in the overall properties of the composite sensors. Together with the properties of the functional composites, environmental concerns are being increasingly relevant for applications, involving advances in materials selection and manufacturing technologies. In this scenario, additive manufacturing is playing an increasing role in modern technological solutions. Stretchable multifunctional composites applications include piezoresistive, dielectric elastomers (mainly for actuators), thermoelectric or magnetorheological materials. In the following sections, piezoresistive materials and applications will be mainly addressed based on their increasing implementation into applications.

In automobile, aeronautical, aerospace, sports and energy fields, there has been an increase of the use of carbon fibre reinforced polymers (CFRP) due their considerable advantages, such as, low weight, static and fatigue strength as well as corrosion resistance1. The addition of nanoparticles, in particular carbon allotropes, like graphene nanoplatelets (GNP) or carbon nanotubes (CNT) allow not only enhanced mechanical performance2, but also can alter the electrical conductivity response of the CFRP composite system3. While the carbon fibre is conductive, the epoxy is not conductive, and the aleatory dispersion of the nanoparticles should introduce in the composite system considerable changes in electric conductivity. The present work intends to study the effect of GNP on the mechanical response of composite laminates, and for this purpose CFRP laminates with and without GNP were manufactured and characterized in terms of flexural and viscoelastic behaviour. Furthermore, electric conductivity tests were performed to investigate the influence of the GNP in the electric response. The results obtained, show that the addition of GNP amounts up to 0.75 wt. % to the epoxy matrix improved the flexural results (Figure 1a). Concerning the electromechanical properties, it was possible to conclude that both laminate composites, with and without GNP, presented reproducible piezoresistive response, with a negative relative change in resistance (ΔR/R0) with increasing strain (), which may allow the health monitoring of the structure (Figure 1b).

The nervous system is a complex network composed by cells, tissue, and organs that have the ability of receiving, transmit, regulate, and send information and stimuli, not only within our body but from our surroundings1. This information is produced by a complex system of neurochemical and electrical reactions that produce the perceptions of heat, smell, taste, proprioception, and touch that lead to physical reactions (movement)2. When that transmission of information is lost due to malformations or accident, there are several physiological responses that will either be lost or try to find new pathways to function and make sense out the current situation. Bringing the division of this work into three phases. The first phase, the production of the prosthetic model by 3D printing (Fig. 1a), reducing the time-consuming production of the different parts by changing production characteristics like infill, layer height, surface quality, ironing and type of material used. The second phase, the instrumentalization of the prosthetic (Fig. 1b) focussing on allowing it to function by controlled and regulated force execution, with lowcost servomotors and components, with easy access to replacement. The third phase, the construction of the sensing mimicking, add-on sensory system using piezoresistive sensors attached to the palm side of a glove on specific regions that allowed not only the location and detection of the forces being exerted, but also their quantification (Fig. 1c). The type of instrumentalization planning used on the sensory glove, allow an easier access to the sensors and other components, making it quite to replace or to adapt . Overall, the results produced were very promising, and better than expected, allowing not only the localization and measurement of force, and analog read for each sensor without too much signal interference, but also a better access and cost reduction prototype.

Dielectric barrier discharge (DBD) plasma actuators are simple electrohydrodynamic devices, which are able to provide effective aerodynamic control. One of the main components of these devices is the thin dielectric layer, which allows to separate and prevent the arc between the high-voltage electrodes. Different materials can be used as dielectric layer to reduce the power consumption or boost the flow controlling effect of the actuators. In this context, this report presents a comparative study of two commercial polyimides, Kapton and Cirlex, used as dielectric layer of surface DBD plasma actuators. The electrical, dielectric, mechanical, electromechanical, and thermal properties were obtained to evaluate overall performance. It was verified that Cirlex (8.3 W) consumes less power than Kapton (21.3 W) to generate higher induced flow velocity of ≈3.4 m/s for an input voltage of 11 kVpp and 24 kHz. During one AC cycle at 11 kVpp the charge transferred for Cirlex (70 nC) is lower than for Kapton (100 nC), as well as the dielectric breakdown voltage to ignite the plasma discharge, 1.5 and 2.2 kVpp, respectively. The Cirlex DBD presents a higher voltage operation limit (at least 14 kVpp) and a more regular plasma discharge, which results in a more homogenous thermal profile and temperature distribution during its operation. The Cirlex actuator delivered higher mechanical power (6.2 mW) and achieved higher electromechanical efficiency (0.004%). The polyimide Cirlex proved to be a suitable alternative for Kapton to fabricate DBD plasma actuators for flow control with improved performance.

In this paper a parametric optimization of the dielectric barrier discharge (DBD) plasma actuator is con ducted in order to achieve better ice sensing and deicing performance. For this purpose, different DBD plasma actuators were tested by changing the main geometrical dimension of the DBD plasma actuator and dielectric material. Both the ice sensing and thermal characteristics of the DBD plasma actuator were analyzed and compared. The results reveal that there exists two separate set of optimum parameters that lead to best ice sensing and thermal behavior. For both the sensing and thermal characteristics, the thinnest DBD showed the best performance. Kapton DBD plasma actuator showed the highest surface temperature while PMMA (poly methyl methacrylate) had the best performance for ice sensing. In the end, the deicing performance of a DBD actuator that had in average better thermal and ice sensing performance was tested for deicing an ice layer and a frost layer. The progress of the deicing process and the ice sensing measure on the surface were recorded and analyzed.

Efficient energy storage systems are increasingly needed due to advances in portable electronics and transport vehicles, with lithium-ion batteries standing out among the most suitable energy storage systems for a large variety of applications. In lithium-ion batteries, the porous separator membrane plays a relevant role as it is placed between the electrodes, serves as a charge transfer medium, and affects the cycle behavior. Typically, porous separator membranes are comprised of a synthetic polymeric matrix embedded in the electrolyte solution. The present chapter focus on recent advances in synthetic polymers for porous separation membranes as well as on the techniques for membrane preparation and physicochemical characterization. The main challenges to improve the synthetic polymer performance for battery separator membrane applications are also discussed.

Environmentally resilient antimicrobial coatings are becoming increasingly required for a wide range of applications. For this purpose, nanocomposite thin films of poly(vinylidene fluoride) (PVDF) filled with several types of functionalized nanodiamonds (NDs) were processed by solvent casting. The effects of ND inclusion and functionalization in their morphological, structural, optical, thermal, and electrical properties were evaluated taking into account the type of the nanofiller and a concentration up to 2 wt %. The morphology, structure, and thermal features of the polymer matrix are governed by the processing conditions, and no noticeable changes occurred due to the presence of the ND fillers. The polymer crystallized mainly in the α phase with a crystallinity of ≈60%. In turn, the optical transmittance from 200 to 800 nm and the dielectric constant effectively depended on the ND type and content. The inclusion of the ND particles effectively provided antimicrobial properties to the films, which depended on the ND functionalization. This study thus shows that the incorporation of functionalized NDs into PVDF allows the development of antimicrobial coatings with tailorable optical and dielectric properties, which could be of great importance to face nowadays pandemic crisis scenario.