3D printing of polymers can now be considered as a common processing technology for the development of biomaterials. These can be constituted out of polymeric abiotic material alone or can be co-printed with living cells. However, the adaptive and shape-morphing characteristics cannot be developed with the rigid, pre-determined structures obtained by 3D printing. In order to produce functional engineered biomaterials, the dynamic properties/characteristics of the living cells must be attained. 4D printing can be envisaged as a route to achieve these goals. This paper intends to give a brief review of the pioneer 4D printing research that has been developed and to present an insight into future research in this field.

Technological development is leading to an exponential growth in the implementation of sensors and actuators where the concern about environmental problems is also focusing on electronic waste (e-waste), which is composed of hazardous materials, corresponding to a large part of urban waste, and has a strong environmental impact. Therefore, more environmentally friendly electronic components are required, natural polymers being a suitable approach to solve or attenuate those problems. This work reports on a bio-based polymer, carrageenan, embedded with dielectric barium titanate (BTO) nanoparticles to tailor the electrical response. The inclusion of the filler induces slight modifications in the thermal characteristics and on the physicochemical properties of the polymer matrix. On the other hand, the mechanical and dielectric properties improve with the addition of BTO and a high dielectric constant of epsilon ' approximate to 13 000 is obtained for the composite with 20 wt% BTO content. The increase of the dielectric constant is accompanied by a high AC electrical conductivity, leading to a high-epsilon '-high-loss material. The 20 wt% BTO composite is used to produce a force measuring sensor, due to the highest dielectric response. The functional response of the sensing system shows good stability over cycling.

A smart asphalt mixture holds new capabilities different from the original ones or can react to a stimulus. These capabilities can be categorized based on smartness or function: smartness, mechanical, electrical, optical, energy harvesting, electromagnetic wave/radiation shielding/absorbing, and water related. The most important capabilities applied to asphalt mixtures are the photocatalytic, self-cleaning, self-healing, superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage abilities. This research deals with a bibliometric review of the peer-reviewed journal articles published on the Scopus database, with the strings of terms related to these capabilities and asphalt or bitum in their titles, abstracts, and keywords. The review analysis highlighted the increasing number of accumulated publications, confirming the relevance of this research topic in recent years. The capability most often referred to was self-healing. The study showed that China was the most productive country. Research articles were mostly published in the journal Construction and Building Materials. Several techniques and methods are being developed regarding smart asphalt mixtures; for that reason, this research work aims to evaluate the literature under a bibliometric analysis.

Abstract Core/shell structures of carbon-based materials/ metal oxide have been considered as potential candidates for electrochemical devices due to their improved pseudocapacitance/electrical double layer capacitance and high conductivity/ superior surface area. The development of multiple core-shell structures of MWCNT@MnO2@PPy was analyzed as a standard procedure for mass production of supercapacitor electrodes. The relative concentration of carbon nanotubes in the composite was varied to optimize the double layer capacitance contribution in overall response of device. Resulting structures presented capacitance in order of 272.7 Fg-1 and reasonable cycling performance.

In this work, superelastic behavior of single crystals shape memory alloys has been investigated by the electric resistivity (ER) measure technique coupled simultaneously during traction tests. Samples in austenitic phase were submitted to stress induced martensite (SIM) under several conditions such as: different temperatures, different deformation rate, throughout successive martensitic transformations and different crystallographic orientation axes. ER vs. deformation curves presented a linear relation without hysteresis and independence on temperature. In the case on the increasing of deformation rate, these curves show a little hysteresis due to adiabatic transformations. For samples submitted to successive transformations, ER curves showed changes with induced martensite types. In samples of the same alloy with different crystallographic orientations was observed that single variant martensite nucleation presented distinct values, this characterizes martensite electric resistivity anisotropy.

The use of shape memory alloys (SMA) as smart structures and other modern applications require a previous evaluation of its performance under load as well as a training procedure. In general, these requirements lead to the design and assembly of a specific test bench. In this work, an experimental set-up was specially designed to perform the electro-thermomechanical characterization of SMA wires. This apparatus was used to determine the strain-temperature (epsilon - T) and electrical resistance-temperature (R - T) hysteretic characteristics curves of a Ti-Ni shape memory wire (90 mm in length and 150 µm in diameter) under mechanical load. The SMA wire is loaded by means of constant weights and a controlled system for injection of electrical power allows performing the heating-cooling cycles. The obtained hysteretic epsilon - T and R - T characteristics curves for some levels of applied loads are used to determine important shape memory parameters, like martensitic transformation temperatures, temperature hysteresis, temperature slopes and shape memory effect under load. These parameters were in accord with the ones found in literature for the studied SMA wires.

With the evolution of the digital society, the demand for miniaturized multifunctional devices has been increasing, particularly for sensors and actuators. These technological translators allow successful interaction between the physical and digital worlds. In particular, the development of smart materials with magnetoelectric (ME) properties, capable of wirelessly generating electrical signals in response to external magnetic fields, represents a suitable approach for the development of magnetic field sensors and actuators due to their ME coupling, flexibility, robustness and easy fabrication, compatible with additive manufacturing technologies. This work demonstrates the suitability of magnetoelectric (ME) responsive materials based on the magnetic ionic liquid (MIL) 1-butyl-3-methylimidazolium tetrachloroferrate ([Bmim][FeCl4]) and the polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE) for magnetic sensing and actuation device development. The developed sensor works in the AC magnetic field and has frequency-dependent sensitivity. The materials show voltage responses in the mV range, suitable for the development of magnetic field sensors with a highest sensitivity (s) of 76 mV·Oe−1. The high ME response (maximum ME voltage coefficient of 15 V·cm−1·Oe−1) and magnetic bending actuation (2.1 mm) capability are explained by the magnetoionic (MI) interaction and the morphology of the composites.

Sensing Technology (ST) plays a key role in Structural Health-Monitoring (SHM) systems. ST focuses on developing sensors, sensory systems, or smart materials that monitor a wide variety of materials’ properties aiming to create smart structures and smart materials, using Embedded Sensors (ESs), and enabling continuous and permanent measurements of their structural integrity. The integration of ESs is limited to the processing technology used to embed the sensor due to its high-temperature sensitivity and the possibility of damage during its insertion into the structure. In addition, the technological process selection is dependent on the base material’s composition, which comprises either metallic or composite parts. The selection of smart sensors or the technology underlying them is fundamental to the monitoring mode. This paper presents a critical review of the fundaments and applications of sensing technologies for SHM systems employing ESs, focusing on their actual developments and innovation, as well as analysing the challenges that these technologies present, in order to build a path that allows for a connected world through distributed measurement systems.

Ionic thermoelectrics (TEs), in which voltage generation is based on ion migration, are suitable for applications based on their low cost, high flexibility, high ionic conductivity, and wide range of Seebeck coefficients. This work reports on the development of ionic TE materials based on the poly(vinylidene fluoride-trifluoroethylene), Poly(VDF-co-TrFE), as host polymer blended with different contents of the ionic liquid, IL, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI]. The morphology, physico-chemical, thermal, mechanical, and electrical properties of the samples are evaluated together with the TE response. It is demonstrated that the IL acts as a nucleating agent for polymer crystallization. The mechanical properties and ionic conductivity values are dependent on the IL content. A high room temperature ionic conductivity of 0.008 S cm<sup>−1</sup> is obtained for the sample with 60 wt% of [EMIM][TFSI] IL. The TE properties depend on both IL content and device topology-vertical or planar-the largest generated voltage range being obtained for the planar topology and the sample with 10 wt% of IL content, characterized by a Seebeck coefficient of 1.2 mV K<sup>−1</sup>. Based on the obtained maximum power density of 4.9 µW m<sup>−2</sup>, these materials are suitable for a new generation of TE devices.

Composites based on a piezoelectric polymer (PVDF) doped with different silica nanoparticles (SiNPs) content (8, 16 and 32wt%) and functionalization (WF-without, NF-negative and PF-positive) have been investigated. Composite films were prepared by solvent casting and melt crystallization to investigate the effect of the presence of the SiNPs on the physico-chemical characteristics and, in particular, in the nucleation of the electroactive -phase of the polymer. It is shown that the introduction of the SiNPs allows to increase water surface angle up to 34% with respect to -PVDF, as well to increase the elastic modulus. Filler content and type have an important effect on the nucleation of the electroactive beta phase content and the dielectric properties of the composites, the larger values of both being obtained for positively surface charged nanoparticles. It is concluded that, taken into consideration the overall properties of the composites, the SiNPs-PF/PVDF nanocomposites with 8wt% filler content offer a promising approach for applications due to the improvement of the electroactive phase of PVDF.