PUBLICATIONS

摘要

Polymer-derived ceramics (PDCs) are promising candidates for fabricating three-dimensional (3D) micro/nanodevices. However, their advancement has been constrained by a persistent challenge in that precursor simplicity, high-fidelity shaping of complex 3D architectures, and superior mechanical properties in the final ceramic are incompatible. To overcome this, an extremely simple photosensitive preceramic resin comprising only polycarbosilane and a photoinitiator is proposed to fabricate high-precision 3D PDC microstructures with intricate geometries and exceptional mechanical performance. A process involving prebaking and two-photon polymerization forms stable 3D preceramic polymer networks, which after pyrolysis yield defect-free amorphous SiOC ceramics exhibiting high shape fidelity and low linear shrinkage (28% at 1000 °C). The ceramics show temperature-dependent mechanical properties, with micropillar compressive strength reaching 6.41 GPa (1000 °C) and 7.55 GPa (1200 °C). Leveraging these properties, lightweight high-strength mechanical metamaterials with 20% relative density are fabricated, achieving a compressive strength of 0.54 GPa and a failure strain exceeding 10%. Functional microneedle arrays are also produced, highlighting their potential for biomedical applications. This work establishes a reliable and straightforward route from an extremely simple precursor to high-performance PDC micro/nano devices, showcasing promising prospects for applications in advanced microsystems and lightweight metamaterials.

摘要

Four-dimensional (4D) printing enables simple structures to undergo programmed and controlled morphological reconfiguration for fabricating more complex three-dimensional (3D) architectures, which has recently garnered considerable research interest. However, 4D printing of glass, particularly for glass microstructures, faces fundamental challenges due to the limited deformability of glass and the lack of reliable deformation mechanisms. Here, a capillary-force-assisted assembly approach is presented to realize the 4D printing of glass microstructures with programmable morphing capabilities. The precursor microstructures fabricated by two-photon polymerization are reconfigured into complex 3D microassemblies under postprinting capillary force, ultimately yielding transparent glass microstructures upon thermal sintering. Compared with conventional 3D printing approaches, our 4D printing approach enables the fabrication of geometrically sophisticated glass microstructures, particularly development-resistant geometries such as hollow microarchitectures, which are previously unattainable through additive manufacturing techniques. Furthermore, the fabricated glass-based chiroptical metamaterials demonstrate giant chiroptical responses and enhanced environmental stability when compared to conventional polymeric counterparts. Fully enclosed hollow microarchitectures successfully encapsulate a diversity of inorganic particles. This work provides a scalable platform for advanced glass microfabrication and allows for the 4D printing of functional inorganic devices.

摘要

Current glass additive manufacturing relies on high-temperature processing to achieve optical transparency accompanied by significant structural shrinkage. These factors significantly restrict the micro-optical applications of three-dimensional (3D) glass microstructures in microsystems. Here, a low-temperature, low-shrinkage 3D printing strategy for transparent nanoporous glass microstructures is presented using a molecular cross-linker-free resin containing methacrylic acid-functionalized nanoparticles (MAA-NPs). The MAA-NPs serve dual roles as photopolymerizable units and silica precursors, enabling the creation of 3D microarchitectures with a 78 wt % solid loading through two-photon polymerization. In stark contrast to conventional particle-loaded composites, uniform nanoparticle dispersion eliminates wavelength-scale pores in the microstructure after sintering at 650 °C, achieving 97% visible-light transmittance. Most importantly, the combination of MAA cross-linking, which enables small interparticle spacing, and low-temperature sintering results in nanoporous glass 3D microarchitectures with low linear shrinkage (∼5%), thereby enabling high-fidelity fabrication of complex micro-optics. Crucially, our strategy enables direct in situ integration of glass microlenses on optical fibers at low temperatures, achieving high alignment precision without assembly steps. This strategy exhibits potential across multiple domains, including micro-optics, photonics, biomedical devices, and integrated optics.

摘要

Artificial helical microswimmers with shape-morphing capacities and adaptive locomotion have great potential for precision medicine and noninvasive surgery. However, current reconfigurable helical microswimmers are hampered by their low-throughput fabrication and limited adaptive locomotion. Here, a rotary holographic processing strategy (a helical femtosecond laser beam) is proposed to produce stimuli-responsive helical microswimmers (<100 μm) rapidly (<1 s). This method allows for the easy one-step fabrication of various microswimmers with controllable sizes and diverse bioinspired morphologies, including spirulina-, Escherichia-, sperm-, and Trypanosoma-like shapes. Owing to their shape-morphing capability, the helical microswimmers undergo a dynamic transition between tumbling and corkscrewing motions under a constant rotating magnetic field. By exploiting adaptive locomotion, helical microswimmers can navigate complex terrain and achieve targeted drug delivery. Hence, these microswimmers hold considerable promise for diverse precision treatments and biomedical applications.