Low-temperature 3D printing of transparent silica glass microstructures

New light-illuminated silk road: emerging silk fibroin-based optical biomedical sensors

Biomedical silk protein optics has become the subject of intensive research aimed at solving the challenges associated with traditional medical devices in terms of biocompatibility and performance balance. With its significant potential for biomedical applications in the field of drug storage and wound monitoring, it is dedicated to reducing the perturbation of neighbouring tissues. The transparency and biocompatibility of silk proteins make them ideal materials in the field of optical device fabrication, effectively overcoming the challenges posed by conventional materials. In this paper, we explore in detail the complex aspects of the design, synthesis and application related to biomedical silk protein optical devices and comprehensively analyse the potential use of silk protein-centric microstructures (e.g., micropillars, microneedles, and photonic crystals) in the development of optical devices. This review also offers insights into the challenges of applying silk protein optical devices in healthcare and their future trends, aiming to provide a comprehensive overview of the advances, potential impacts and emerging research directions in the field of biomedical silk protein optical devices.

Ultrafast Laser 3D Nanolithography of Fiber-Integrated Silica Microdevices

Fiber-integrated micro/nanostructures play a crucial role in modern industry, mainly owing to their compact size, high sensitivity, and resistance to electromagnetic interference. However, the three-dimensional manufacturing of fiber-tip functional structures beyond organic polymers remains challenging. It is essential to construct fiber-integrated inorganic silica with designed functional nanostructures for microsystem applications. Here, we develop a strategy for the 3D nanolithography of fiber-integrated silica from hybrid organic-inorganic materials by ultrafast laser-induced multiphoton absorption. Without silica nanoparticles and polymer additives, the acrylate-functionalized precursors can be locally cross-linked through a nonlinear effect. Followed by annealing at low temperature, the as-printed micro/nanostructures are transformed to high-quality silica with sub-100 nm resolution. Silica microcantilever probes and microtoroid resonators are directly integrated onto the optical fiber, showing strong thermal stability and quality factors. This work provides a promising strategy for fabricating desired fiber-tip silica micro/nanostructures, which is helpful for the development of integrated functional device applications.

Low-Temperature Deposited Amorphous Poly(aryl ether ketone) Hierarchically Porous Scaffolds with Strontium-Doped Mineralized Coating for Bone Defect Repair

In recent years, the demand for clinical bone grafting has increased. As a new solution for orthopedic implants, polyether ether ketone (PEEK, crystalline PAEK) has excellent comprehensive performance and is practically applied in the clinic. In this research, a noteworthy elevated scheme to enhance the performance of PEEK scaffolds is presented. The amorphous aggregated poly (aryl ether ketone) (PAEK) resin is prepared as the matrix material, which maintains high mechanical strength and can be processed through the solution. So, the tissue engineering scaffolds with multilevel pores can be printed by low-temperature deposited manufacturing (LDM) to improve biologically inert scaffolds with smooth surfaces. Also, the feature of PAEK's solution processing is profitable to uniformly add the functional components for bone repair. Ultimately, A system of orthopedic implantable PAEK material based on intermolecular interactions, surface topology, and surface modification is established. The specific steps include synthesizing PAEK that contain polar carboxyl structures, preparing bioinks and fabricating scaffolds by LDM, preparation of scaffolds with strontium-doped mineralized coatings, evaluation of their osteogenic properties in vitro and in vivo, and investigation on the effect and mechanism of scaffolds in promoting osteogenic differentiation. This work provides an upgraded system of PAEK implantable materials for clinical application.

3D Printing of Glass Micro-Optics with Subwavelength Features on Optical Fiber Tips

Integration of functional materials and structures on the tips of optical fibers has enabled various applications in micro-optics, such as sensing, imaging, and optical trapping. Direct laser writing is a 3D printing technology that holds promise for fabricating advanced micro-optical structures on fiber tips. To date, material selection has been limited to organic polymer-based photoresists because existing methods for 3D direct laser writing of inorganic materials involve high-temperature processing that is not compatible with optical fibers. However, organic polymers do not feature stability and transparency comparable to those of inorganic glasses. Herein, we demonstrate 3D direct laser writing of inorganic glass with a subwavelength resolution on optical fiber tips. We show two distinct printing modes that enable the printing of solid silica glass structures ("Uniform Mode") and self-organized subwavelength gratings ("Nanograting Mode"), respectively. We illustrate the utility of our approach by printing two functional devices: (1) a refractive index sensor that can measure the indices of binary mixtures of acetone and methanol at near-infrared wavelengths and (2) a compact polarization beam splitter for polarization control and beam steering in an all-in-fiber system. By combining the superior material properties of glass with the plug-and-play nature of optical fibers, this approach enables promising applications in fields such as fiber sensing, optical microelectromechanical systems (MEMS), and quantum photonics.

Precise Focal Spot Positioning on an Opaque Substrate Based on the Diffraction Phenomenon in Laser Microfabrication

The precise positioning of the laser focal spot on the substrate is an important issue for laser microfabrication. In this work, a diffraction pattern-based focal spot positioning method (DFSPM) is proposed to achieve the precise positioning of the laser focal spot on opaque substrates. A series of diffraction patterns of laser focus under-positioning, exact positioning and over-positioning were obtained to investigate the cross-section light distribution of the laser focal spot. According to the monotonic tendency of FWHM to exhibit light intensity at the focal spot cross-section away from the focal plane, the FWHM threshold of polynomial fitted curves was used to determine the exact positioning of laser focus. The ascending scanning method was used to obtain the diffraction patterns at various vertical positions and the FWHM threshold of light distribution at the exact position. The polynomial fitted curves verify the FWHM monotonic tendency of light intensity distribution at the focal spot cross-section along the optical axis. Precise positioning can be achieved with a 100 nm adjustment resolution. This work was expected to provide references for laser microfabrication on opaque materials.