Periodic Reporting for period 1 - 2D-EMI (Development of the next generation of 3D printed EMI shielding solutions based on 2D nanomaterials inks)
Berichtszeitraum: 2022-08-01 bis 2024-01-31
With the fast development of wireless communication, especially the new 5G technology, EMI shielding is becoming a challenge. High-performance EMI shielding materials are urgently needed for controlling electromagnetic radiation pollution which seriously affects the normal operation of sensitive electronic apparatus and systems. Metals are the most used shielding materials but suffer from easy corrosion, high density, and poor processibility. 2D nanomaterials are more promising for EMI-shielding applications due to their outstanding electrical, thermal, and mechanical properties, versatile surface chemistry and their favourable capability to be assembled into macroscopic architectures or serve as conductive fillers for composite fabrication.
3D printing of functional EMI shielding materials with tuneable composition, structure and properties based on 2D nanomaterial inks is proposed in 2D-EMI as a solution, which allows the users to create EMI shielding solutions that precisely fit their real needs. In addition, the printed EMI shielding materials can be sized more economically on demand and work more effectively, providing excellent application flexibility, especially in situations where the space is limited. Printing of EMI shielding materials based on 2D materials requires the formation of highly printable inks and efficient printing and post-printing treatment protocols for accurately generating macroscopic architectures with high structural controllability and shape fidelity. Solution exfoliation and processing of 2D nanomaterials provides low-cost and scalable ink formulation routes enabling the creation of printed electronic devices with digitally designed geometries/structures, for example, by extrusion 3D printing. 2D-EMI built on the PI's expertise in designing printable 2D inks for the 3D printing of functional materials to provide highly efficient and customizable EMI shielding solutions for the electronics industry.
3D printing of functional EMI shielding materials with tuneable composition, structure and properties based on 2D nanomaterial inks is proposed in 2D-EMI as a solution, which allows the users to create EMI shielding solutions that precisely fit their real needs. In addition, the printed EMI shielding materials can be sized more economically on demand and work more effectively, providing excellent application flexibility, especially in situations where the space is limited. Printing of EMI shielding materials based on 2D materials requires the formation of highly printable inks and efficient printing and post-printing treatment protocols for accurately generating macroscopic architectures with high structural controllability and shape fidelity. Solution exfoliation and processing of 2D nanomaterials provides low-cost and scalable ink formulation routes enabling the creation of printed electronic devices with digitally designed geometries/structures, for example, by extrusion 3D printing. 2D-EMI built on the PI's expertise in designing printable 2D inks for the 3D printing of functional materials to provide highly efficient and customizable EMI shielding solutions for the electronics industry.
Various printable inks were synthesised and evaluated for their effectiveness in creating EMI shielding solutions using extrusion 3D printing techniques. A straightforward mechanical mixing technique was used to formulate the primary MXene/PEDOT:PSS inks, with their rheological properties finely adjusted through the manipulation of interfacial interactions and modifications to the ink composition.
- Ink formulation, optimisation and characterisation
Figure 1 shows the formulation, characterisation, rheology investigations carried out for the inks. We successfully obtained inks suitable for 3D printing (Figure 1a). Owing to the synergy of MXene and PEDOT:PSS, the rheology can be easily adjusted by altering the ratio of MXene//PEDOT:PSS, and an excellent printability was achieved at a low solid concentration. More specifically, after optimisation, the obtained ink exhibited appropriate viscosities, moduli and yielding stresses (398-597 Pa) (Figure 1b-e), rendering it highly compatible with extrusion 3D printing techniques. All the inks were stored in a refrigerator at 4 °C before use and have a long shelf life.
- Extrusion 3D printing and post-printing treatments
Figure 2a shows printed devices using different inks. The as-printed object can retain structural integrity without noticeable deformation after freeze-drying but can be further redispersed in water by vigorous vibration, indicating the weak cross-linking structure based on highly reversible physical bonds in the ink system. To ensure shape accuracy of the printed structure, the researcher proposed a ‘freeze-thawing’ post-printing protocol. The typical procedures are as follows: first, the as-printed object was frozen. This step allows the slow formation of ice in the printed object, which can induce closer packing of solid components at the boundaries of ice crystals to form a more stable skeleton structure, as confirmed by SEM image (Figure 2c). Then the frozen object was directly thawed to further facilitate the solidification and enhance the functionality (Figure 2b,c).
- Printed device performance
Having the typical ink formulation, ink printing and post-treatment protocols established, 3D-printed EMI shields were fabricated. The thickness, shapes, structures that affect the shielding performance can be easily controlled using the 3D printing technique. High electrical conductivities ranging from 600-2000 S m-1 were achieved (Figure 3a). The printed EMI shielding demonstrated excellent shielding performance at small thicknesses, achieving shielding efficiencies ranging from 51 to 76 dB (Figure 3b). This indicates that more than 99.99999% of the incident radiation can be successfully shielded. Good mechanical properties and additional features (e.g. sensing, biocompatibility, and performance reliability over wide temperatures) were also achieved by fine-tuning the compositions of the inks (Figure 3c-h).
Publications:
Adv. Funct. Mater. 2023, 33, 2214196;
Mater. Today 2023, 66, 245-272.
- Ink formulation, optimisation and characterisation
Figure 1 shows the formulation, characterisation, rheology investigations carried out for the inks. We successfully obtained inks suitable for 3D printing (Figure 1a). Owing to the synergy of MXene and PEDOT:PSS, the rheology can be easily adjusted by altering the ratio of MXene//PEDOT:PSS, and an excellent printability was achieved at a low solid concentration. More specifically, after optimisation, the obtained ink exhibited appropriate viscosities, moduli and yielding stresses (398-597 Pa) (Figure 1b-e), rendering it highly compatible with extrusion 3D printing techniques. All the inks were stored in a refrigerator at 4 °C before use and have a long shelf life.
- Extrusion 3D printing and post-printing treatments
Figure 2a shows printed devices using different inks. The as-printed object can retain structural integrity without noticeable deformation after freeze-drying but can be further redispersed in water by vigorous vibration, indicating the weak cross-linking structure based on highly reversible physical bonds in the ink system. To ensure shape accuracy of the printed structure, the researcher proposed a ‘freeze-thawing’ post-printing protocol. The typical procedures are as follows: first, the as-printed object was frozen. This step allows the slow formation of ice in the printed object, which can induce closer packing of solid components at the boundaries of ice crystals to form a more stable skeleton structure, as confirmed by SEM image (Figure 2c). Then the frozen object was directly thawed to further facilitate the solidification and enhance the functionality (Figure 2b,c).
- Printed device performance
Having the typical ink formulation, ink printing and post-treatment protocols established, 3D-printed EMI shields were fabricated. The thickness, shapes, structures that affect the shielding performance can be easily controlled using the 3D printing technique. High electrical conductivities ranging from 600-2000 S m-1 were achieved (Figure 3a). The printed EMI shielding demonstrated excellent shielding performance at small thicknesses, achieving shielding efficiencies ranging from 51 to 76 dB (Figure 3b). This indicates that more than 99.99999% of the incident radiation can be successfully shielded. Good mechanical properties and additional features (e.g. sensing, biocompatibility, and performance reliability over wide temperatures) were also achieved by fine-tuning the compositions of the inks (Figure 3c-h).
Publications:
Adv. Funct. Mater. 2023, 33, 2214196;
Mater. Today 2023, 66, 245-272.
The rising ubiquity of portable smart electronics, coupled with the trend towards miniaturization, necessitates that electronic components become smaller, denser, and more compact. Consequently, there is a growing demand for EMI shielding materials that are not only lighter, thinner, and more flexible but also more efficient, and these materials should offer customizable geometry or structure to provide targeted EMI shielding at the component level. Unfortunately, the fabrication of current commercially available EMI shielding solutions still largely relies on traditional manufacturing strategies, such as casting and moulding, which would inevitably limit their applications in situations where space is limited and where fast prototyping or complex design of the shields are needed. In response to these requirements, the researcher formulated specialized inks and established protocols aimed at creating custom EMI shielding solutions using the extrusion 3D printing technique. This approach enables users to create custom EMI shields that are digitally designed to fit component geometries precisely while providing reliable EMI protection. It also facilitates fast prototyping and a reduction in prototyping costs, minimizes material waste, enhances manufacturing flexibility, and provides an accessible method for accurately implementing EMI shielding designs across a wide range of application scenarios. The researcher also developed a novel ‘freeze-thawing’ post-printing protocol that solidifies and functionalizes the printed EMI shields to improve their mechanical properties and EMI shielding performance without compromising the shape fidelity of the printed structure, ensuring highly precise creation of custom EMI shielding solutions. This innovation addresses a longstanding challenge in the field of ink-based extrusion 3D printing by simultaneously achieving high device performance and high printing fidelity. Despite these significant advancements, there remains a need for further research to master the high-fidelity natural drying of printed EMI shields. This is crucial for unleashing the full potential of this technique in commercial applications, as it could streamline the manufacturing process and enhance the usability of printed EMI shields in a wider range of settings.