Highly Deformable Microfluidic Liquid Metal Antennas Based on Direct Ink Writing 3D-Printed Microchannels

Three-dimensional (3D) printing is emerging as a promising alternative to soft lithography for fabricating microfluidic structures and devices due to its digital control, automation, and assembly-free capabilities. Current 3D printing technologies face challenges in simultaneously achieving direct printing of multilayered microfluidic structures without sacrificial or support materials, integrating electronic components with microchannels during printing, and ensuring flexibility and stretchability in the resulting devices. This study introduces a novel method using direct ink writing (DIW) 3D printing to fabricate flexible and stretchable microfluidic structures and devices [1,2]. Our approach allows for the direct printing of interconnected, multilayered microchannels using silicone sealant without the need for supporting materials or complex post-processing. During the printing process, electronic components are seamlessly integrated with the microchannels. Infusing liquid metal into the 3D-printed microchannels establishes electrical connections, enabling the creation of functional microfluidic electronics.<br/>To demonstrate the capabilities of this technology, we designed and fabricated liquid metal antenna coils powered by a standard near-field communication (NFC) system operating at 13.56 MHz. These microfluidic devices exhibit significant advancements in deformability compared to traditional metal-based systems. Practical applications of this technology are showcased through two prototypes: a skin-attachable radio-frequency identification (RFID) tag using a commercial skin-adhesive plaster as the substrate, and free-standing flexible wireless light-emitting devices targeted for potential implantable applications. This advanced fabrication method facilitates the automated production of stretchable 3D electrical circuits, particularly beneficial for devices requiring seamless integration with biological tissues and soft robots. This research paves the way for new advancements in flexible and stretchable microfluidic electronics, offering innovative solutions for next-generation soft electronic devices.<br/><br/>References<br/>[1] K. Yamagishi et al., <i>Adv. Mater. </i>33, 2008062 (2021).<br/>[2] K. Yamagishi et al., <i>Adv. Funct. Mater.</i> (2023), doi:10.1002/adfm.202311219.