Carmen Rial Tubio

Water contamination by antibiotics and other emerging contaminants is ubiquitous across all water matrices worldwide, and underlines the need for sustainable, easy‐to‐deploy materials that operate efficiently in real aquatic environments. A straightforward implementation is essential for bridging laboratory developments to diverse practical water‐treatment scenarios. In this work, floating poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) grids incorporating TiO ₂ were fabricated via direct ink writing (DIW) 3D printing combined with salt leaching, thereby enabling precise control over geometry and porosity while overcoming the structural limitations of conventional techniques. The resulting grids exhibited interconnected porosity, strong mechanical stability, remarkable reusability, and effective photocatalytic performance, achieving 60% degradation of ciprofloxacin in 540 min under UV‐A radiation and complete degradation in about 120 min under natural sunlight. Distinctively, the materials maintained their photocatalytic activity across multiple reuse cycles, demonstrating robustness and operational durability. These results highlight the potential of this 3D‐printed floating system to provide a scalable, customisable and practical solution for water remediation using just sunlight.

This work presents the development and characterization of 3D‐printed mechanically driven giant magnetoresistance (GMR) sensors using self‐compliant spring structures and piezoresistive materials. Fused deposition modeling 3D printing has been employed to fabricate sensors from conductive and magnetic polylactic acid composite materials, enabling low‐cost and highly customizable designs. Three sensor topologies were fabricated to optimize magnetoresistive and piezoresistive responses. Electromechanical and magnetic characterizations showed that the self‐compliant spring arm width influences the device mechanical stiffness, piezoresistive response, and magnetoresistive sensitivity. Sensitivities up to 0.34%/mm for piezoresistive sensors with a 3‐mm arm under direct mechanical deformation and 0.77%/mT for the magnetoresistive sensors with a 1‐mm arm were obtained, with a response 10 times higher in sensitivity than other printed spin‐dependent GMR devices in the literature. The applicability was demonstrated in pressure sensing and noncontact magnetic position detection, integrated in a Bluetooth low energy application. The sensors showcased reliable performance under dynamic conditions at a frequency range of 0.1, 0.25, and 0.5 Hz, highlighting their potential in automotive, robotics, and consumer electronics. This work establishes self‐compliant structural design as an effective tool for fabricating mechanically driven GMR‐like sensors using low‐cost, additive manufacturing techniques, allowing further integration of geometry‐driven devices into increasingly interconnected IoT networks.

Strong efforts are being carrying out to implement efficient and accurate structural health monitoring (SHM) strategies for large surfaces. The criticality of high demanding structures, such as vessels, pipelines, or aircrafts, requires costly integrity inspections to ensure their performance and security. This study presents a novel SHM approach using magnetic particles for precise damage detection and coating stratigraphy assessment. The methodology is demonstrated on an industrially produced sheet molding compound (SMC) laminate composite, incorporating an epoxy coating layer doped with 20 wt% NdFeB particles. The coating achieves a coercive field (Hc) of 7000 Oe and a saturation magnetization (Ms) of 136.8 emu g ⁻¹ . Uniform dispersion of magnetic particles is confirmed, while surface characterization indicates minimal impact on roughness and wettability. Mechanical testing shows a negligible effect on flexural modulus but a reduction in bending strength due to constrained molecular mobility. Magnetic flux mapping enables fast and accurate damage detection and coating depth assessment. Perpendicular magnetization enhances damage detection and sensitivity, while longer acquisition times (3 s) and higher magnetization fields (1.1 T) improve resolution and facilitate thickness evaluation. These findings highlight the potential of these coatings for SHM, offering precise damage detection and insights into coating uniformity, ultimately supporting advanced monitoring solutions for critical structures.

The IoT and Industry 4.0 have increased demand for smart, wireless, customized, and sustainable sensors in industrial environments. Linear Variable Differential Transformers (LVDTs) are crucial for precision displacement sensing due to their high resolution and durability, but face challenges like complex assembly and high manufacturing costs. In this work, a fully printed LVDT position/force sensor is presented, fabricated using fused filament fabrication (FFF) and 5‐axis piezo‐jet printing, enabling the integration of complex geometries and conductive coil patterns directly onto curved surfaces. Two core configurations are evaluated: a commercial MnZn core and a magnetic poly(lactic acid) (PLA) composite core printed via FFF. Electromagnetic and magnetic characterizations revealed that the MnZn core provided superior sensitivity of 1054.3 ± 11.32 µV·mm ⁻¹ with respect to the printed core, which exhibited a lower sensitivity of 3.86 ± 0.07 µV·mm ⁻¹ . The sensors' wireless are integrated with a custom signal conditioning circuit based on the AD598 and an ESP32 microcontroller, allowing real‐time data transmission via Bluetooth Low Energy (BLE). The sensor is implemented in a pressure sensing application, showcasing a linear response with a sensitivity of 3.18 ± 0.22 mV·N ⁻¹ , offering a highly versatile, scalable, and low‐cost solution for next‐generation industrial sensing in IoT‐enabled environments.

Sandwich‐structured poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDF‐HFP) matrix nanocomposites with solid and interconnected porous central layers are prepared by hot pressing to investigate the structural design's role on their dielectric properties, energy storage, and energy harvesting performances. Solid monolayered nanocomposites reinforced with 4 wt% hexagonal boron nitride (hBN) nanoparticles (NPs) and solid and porous monolayered nanocomposites incorporated with 25 wt% silane‐modified BaTiO ₃ NPs (BT‐VTS) are located in outer and central layers, respectively, to achieve the BN‐BT‐BN configuration. Despite the low energy storage performances (discharged energy densities) of sandwich structures, the charge‐blocking hBN/PVDF‐HFP nanocomposites at the outer layers of the solid sandwiches enhance the breakdown strength of solid monolayered BT‐VTS/PVDF‐HFP nanocomposites ( E _b : 271 MV m ⁻¹ ) by 23%. On the other hand, piezoelectric output voltages of the porous monolayer and sandwich structures (1.7 and 1.1 V) are 6 and 3 times those of their solid counterparts, respectively, under finger bending at 1 Hz. This indicates a significant impact of structural design on the energy harvesting performance, which is considerably improved by a 3D pore network. Therefore, porous sandwich‐structured 4% hBN/25% BT‐VTS/PVDF‐HFP nanocomposites with an enhanced power density of 22.11 μW cm ⁻³ have the capability to be used as flexible piezoelectric nanogenerators in self‐powered wearable devices.

Epoxy resin composites produced by additive manufacturing have been developed for their use as adhesive materials with sensing functionalities as multifunctional piezoresistive and thermoresistive materials. The processing of the composites involves acetone as a solvent to tune the viscosity and achieve a homogeneous dispersion of the carbon nanotubes, resulting in a solution with suitable characteristics for application by additive manufacturing. Doctor blade and screen printing films have been prepared with a low electrical resistivity of approximately 100 Ω/sq. for composites with 10 wt% of carbon nanotubes. The largest piezoresistive sensitivity, determined by a Gauge Factor of approximately 15 under 5 mm bending, has been obtained, with suitable stability over cycling solicitation. Furthermore, the thermoresistive response exhibited a sensitivity of 0.05% °C⁻¹. Self‐sensing bonded structures have been obtained with excellent adhesive forces (approximately 20 MPa in glass fiber joints) in shear lap tests. In addition, the bonded structure demonstrated a linear response to loading–unloading up to 5 mm of bending in the cantilever mode, with cycle stability. Overall, a scalable methodology to obtain high‐performance self‐sensing adhesive materials processable by additive manufacturing is presented, which shows excellent bonding characteristics, together with mechanical and thermal sensing properties.Highlights: Epoxy resin composites have been processed by doctor blade and screen printing. Piezo‐ and thermoresistive responses of GF ≈ 15 and S ≈ −0.05% °C⁻¹ were achieved. Developed adhesive structures with integrated self‐sensing capabilities. Proof‐of‐concepts were developed demonstrating the applicability of the samples.

The generation of sustainable electrical energy from wasted environmental mechanical stimuli is a necessary step for supplying low-power devices in this digitalization era. Sustainable polymers are an attractive class of materials for energy harvesting applications due to their abundance, low ecological impact, and simple and low-cost processing for polymer-based devices. Thus, solvent-processed hydroxypropyl cellulose (HPC), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly-l-lactic acid, and silk fibroin were evaluated as active materials in triboelectric nanogenerators with the aim of replacing non-sustainable synthetic materials. Harvesting devices incorporating sustainable polymers demonstrate superior performance compared to some established materials in the triboelectric series. Notably, HPC and PHBV outperform aluminum, emerging as novel, flexible, and solvent processable sustainable materials that can be included in the triboelectric series as positive tribomaterials. Furthermore, when combined with piezoelectric polyvinylidene fluoride (PVDF), these polymers exhibit enhanced performance as hybrid piezoelectric–triboelectric nanogenerators. The output voltage of the HPC–PVDF pair reaches voltages up to 100 V. This combination demonstrates the feasibility of using sustainable materials to achieve improved energy-harvesting capabilities while supporting eco-friendly devices with a variety of designs based on solvent based processability, compatible with additive manufacturing.

Although an increasing number of studies are being devoted to the field of corrosion, with topics from protection to sensing strategies, there is still a lack of research based on environmentally eco-friendly materials, which is essential in the transition to sustainable technologies. Herein, environmentally friendly composites, based on photoluminescent salts dispersed in vegetable oil-based resins, are prepared and investigated as corrosion sensing coatings. Two salts NaA, where A- is a lanthanide complex anion (with Ln = Nd³⁺, and Yb³⁺), are incorporated into the resins as active functional fillers and different coatings are prepared on carbon steel substrates to assess their functional properties. The influence exerted by a corrosive saline solution on the morphology, structural, and photoluminescent properties of the coatings is evaluated, and their suitability for the practical detection of the early corrosion of coated carbon steel is demonstrated. The photoluminescence of the composite coatings depends on the corrosion time, with the effect being more important for the coatings doped with Nd³⁺. The present work shows that the composites obtained are suitable candidates for corrosion sensing coating applications, offering improved sustainability.

Poly(vinylidene fluoride‐co‐hexafluoropropylene), (PVDF‐HFP), matrix nanocomposites have been prepared by solution casting, reinforced with BaTiO₃ nanoparticles (BT NPs) and surface modified BT NPs (BT‐VTS NPs) with a silane coupling agent (VTS) by 0, 5, 15, and 25 wt.%. The effects of filler content and surface modification of nanofillers on the microstructure development, phase evolution, crystallization behavior, and dielectric properties of the nanocomposites are investigated. Furthermore, the energy storage performance of BT‐VTS‐reinforced nanocomposites is evaluated. The surface modification of BT NPs presents some advantages: it prevents aggregation, restricts interface polarization, and keeps dielectric loss of the nanocomposites low as the relative permittivities rise with filler content. 25% BT‐VTS‐reinforced nanocomposites with a β‐phase fraction of 45% and a crystallinity of 14% provide a higher relative permittivity (22. at 1 kHz) than that of the neat PVDF‐HFP thin films (11). Moreover, they present a low loss tangent (0.043) as the neat thin films (0.042). 25% BT‐VTS/PVDF‐HFP nanocomposites demonstrate a discharged energy density of 4.8 J cm⁻³ at 220 MV m⁻¹ with a charge–discharge efficiency of 26%. Consequently, the energy density of the neat PVDF‐HFP thin films (3.4 J cm⁻³ at 238 MV m⁻¹) is improved by 40% after the addition of 25% BT‐VTS NPs.