Nowadays, additive manufacturing technologies have impacted different engineering sectors. Three- and four-dimensional printing techniques are increasingly used in soft and flexible electronics thanks to the possibility of working contemporarily with several materials on various substrates. The materials portfolio is wide, as well as printing processes. Shape memory polymers, together with composites, have gained great success in the electronic field and are becoming increasingly popular for fabricating pH, temperature, humidity, and stress sensors that are integrated into wearable, stretchable, and flexible devices, as well as for the fabrication of communication devices, such as antennas. Here, we report an overview of the state of the art about the application of 4D printing technologies and smart materials in electronics.

Concerning environmental safety and mitigating the risk of water pollution, the electroplating industry, historically reliant on the use of elevated concentrations of heavy metals to achieve high-quality products, faces a crucial challenge in monitoring wastewater enriched with these metals, notorious for their adverse effects on ecosystems and human health. Chromium, in both oxidation states Cr (III) and Cr (VI), emerges as a prominently employed metal, yielding noteworthy outcomes throughout the galvanisation process. This research showcases the prototype of an automatic in situ sensor tailored to industry sustainability efforts to facilitate real-time monitoring and efficient water management. This custom sensor, characterized by sensitivity, reliability, and user-friendliness, utilizes UV-Vis colorimetric principle to detect Cr in both oxidation forms ranging from grams per litre (g/L) to parts per million (ppm). This is made possible by the unique vibrant colours induced by chromium ions, enabling the precise measurement of analyte concentrations. Thanks to 3D printing, this sensor system interacts with customized parts, designed and validated through simulation processes, for filtering out particulate that may interfere with the analysis. The outcome represents a synergistic blend of technology and environmental responsibility, aligning industrial processes with the goal of safeguarding water resources and ecosystems.

MEMS devices are more and more commonly used as sensors, actuators, and microfluidic devices in different fields like electronics, opto-electronics, and biomedical engineering. Traditional fabrication technologies cannot meet the growing demand for device miniaturisation and fabrication time reduction, especially when customised devices are required. That is why additive manufacturing technologies are increasingly applied to MEMS. In this review, attention is focused on the Italian scenario in regard to 3D-printed MEMS, studying the techniques and materials used for their fabrication. To this aim, research has been conducted as follows: first, the commonly applied 3D-printing technologies for MEMS manufacturing have been illustrated, then some examples of 3D-printed MEMS have been reported. After that, the typical materials for these technologies have been presented, and finally, some examples of their application in MEMS fabrication have been described. In conclusion, the application of 3D-printing techniques, instead of traditional processes, is a growing trend in Italy, where some exciting and promising results have already been obtained, due to these new selected technologies and the new materials involved.

Nowadays, Additive Manufacturing for Electronics (AME) is gaining ground in device fabrication for the numerous advantages of these types of manufacturing technologies, such as fast production processes, freeform design, and low-cost prototyping. In this scenario, the proposed research work is focused on evaluating an innovative strategy for a common issue in power electronics, which is related to the generation of hotspots. To face this problem, the 3D printing of ceramic substrates with different high surface areas was studied to improve thermal dissipation. Together with improved thermal management, the upper surface of the devices enabled the deposition of a desired conductive pattern and the bonding of bare die components for device fabrication. Finally, thermal exchange was monitored to verify the efficacy and efficiency of the devices’ dissipation capabilities. The proposed models exhibited a 70% temperature reduction upon transitioning from air to water. Furthermore, the operating temperature remained stable for 10 min, meeting the specific requirements of the intended application.