On 14 April, Science published a study on 3D printing of quartz glass using axial lithography in a cover article, marking at least the second time that volumetric 3D printing technology has been published in the journal, following previous research in Nature.
Traditional processing methods have been challenged by developments in the size, geometry, surface roughness and mechanical strength requirements of glass for everything from micro-optics to microfluidic systems for chemical synthesis and bioanalysis. Researchers from the University of California, Berkeley, Lawrence Livermore National Laboratory and the University of Freiburg, Germany, have investigated microscale computational axial lithography 3D printing of quartz glass, often referred to as volumetric 3D printing.
Latest: Volumetric 3D printing is back on the cover of Science
Based on holographic exposure, orthogonal stacking, laminar illumination and post-sintering, the researchers have fabricated three-dimensional microfluidic elements with an inner diameter of 150 μm, complex shaped micro-optics with a surface roughness of just 6 nm, and complex high-strength trusses and lattice structures with a minimum feature size of 50 μm. As a high-speed, layer-free digital photomanufacturing process, axial lithography 3D printing allows the processing of nanocomposites with high solids content and high geometric freedom, thus providing scope for new device manufacturing.
Latest: Volumetric 3D printing on the cover of Science again Axial lithography 3D printing of quartz glass
Computational axial lithography tomography is capable of handling glass nanocomposites by iteratively optimising the azimuthal superposition of light projections through temporal multiplexing of exposures to aggregate 3D structures. No relative motion occurs between the precursor material and the manufactured object during the printing process, thus allowing the easy use of highly viscous and thixotropic nanocomposite precursors. The lamelless manufacturing characteristics of the process allow for smooth surfaces and complex geometries. Because the objects manufactured during the printing process are surrounded by the precursor material, there is no need to sacrifice solid support structures. These properties are ideal for 3D printing micro-optical and microfluidic devices.
Latest: Volumetric 3D printing is back on the cover of Science Microscopic glass structures fabricated using axial lithography 3D printing technology
The highly transparent photocurable microstereolithography nanocomposites used in this study consisted of a liquid monolithic photocurable binder matrix and 35 vol% solid amorphous SiO2 nanoparticles. The binder is polymerised by free radicals and holds the nanoparticle support in place in the printed structure. For printing the resulting quartz glass blanks need to be degreased and sintered. The degreasing process burns off the polymer binder matrix and produces porous SiO2. during the sintering process the nanoparticles are fused together to form a dense transparent glass fraction with 26% isotropic linear shrinkage.
The demand for more compact, lightweight and high quality cameras in consumer electronics and biomedical imaging is driving the development of advanced millimetre scale optical systems. Axial lithography 3D printing of free-form refractive microlenses designed for specific applications eliminates the effects of lamellar patterns found in other 3D printing processes, and the excellent geometric freedom, low surface roughness, and high fracture strength and optical transparency of the fused silica glass manufactured by the Institute will drive the development of relevant devices in this field.
Volumetric 3D printing creates parts rapidly through multiple beams in a transparent resin liquid. Compared to traditional DLP and SLA technologies, multi-beam 3D printing can achieve higher throughputs (>105mm3/h) while printing more viscous materials. Distinct from traditional Z-axis laminated 3D printing, volumetric 3D printing based on tomographic exposure also offers considerable advantages in the manufacture of biological organs. Taken together, none of the research in recent years has been a cutting-edge, groundbreaking development, and it is believed that the technology will create even more possibilities in the future.