Search Results (32)

Additive manufacturing offers a promising route to low-cost, rapidly deployable X-ray focusing optics with geometries that are difficult to realize by conventional machining. Here, we report polymer compound refractive lenses (CRLs) for hard X-ray focusing fabricated by projection micro-stereolithography (PµSL, DLP-based) and by two-photon polymerization (2PP). Two-dimensional bi-parabolic CRL elements were produced in multiple photopolymer resins (HTL, Tough, ST1400 for PμSL; IP-S for 2PP) and evaluated by at-wavelength metrology at the Shanghai Synchrotron Radiation Facility. The single-lens residual phase errors (RMS) less than 0.1 $\mathsf{\lambda }$ were measured for PµSL-fabricated HTL, and Toughlenses, respectively, while 2PP-fabricated IP-S lenses achieved 0.008 $\mathsf{\lambda }$. And the analysis indicates that PµSL lenses are primarily limited by systematic mid-order aberrations, whereas 2PP substantially suppresses coma but shows residual spherical aberration attributable to process calibration and shrinkage. Leveraging the higher fidelity of 2PP, a 65-element parabolic CRL array (radius of curvature of 100 µm) was fabricated and demonstrated hard X-ray focusing at 15 keV with focal spot sizes of 6.4 ± 1 µm (H) and 6.8 ± 1 µm (V), and a flux gain of 220. The measured performance agrees with theoretical expectations when accounting for X-ray source properties, detector resolution and chromatic aberration. These results establish a practical pathway for additively manufactured polymer CRLs with DLP and 2PP techniques as compact, customization focusing optics for synchrotron beamlines. Full article

Two-photon polymerization (2PP) is revolutionizing micro- and nanoscale manufacturing by enabling true 3D fabrication with feature sizes far below the diffraction limit—capabilities that traditional lithography cannot match. By using ultrafast femtosecond laser pulses and nonlinear absorption, 2PP initiates polymerization only at the laser’s focal point, offering unmatched spatial precision. This paper highlights key advancements driving the field forward: the development of new materials engineered for 2PP with improved sensitivity, mechanical strength, and the introduction of high-speed, parallelized fabrication strategies that significantly enhance throughput. These innovations are shifting 2PP from a prototyping tool to a viable method for scalable production. Applications now range from custom biomedical scaffolds to complex photonic and metamaterial structures, demonstrating their growing real-world impact. We also address persistent challenges—including slow writing speeds and limited material options—and explore future directions to overcome these barriers. With continued progress in materials and hardware, 2PP is well positioned to become a cornerstone of next-generation additive manufacturing. Full article

Waveguide bends are critical components for compact routing in integrated photonic circuits, yet their design in air-clad polymer waveguides fabricated by two-photon polymerization direct laser writing (2PP-DLW) is challenging due to multimode behavior. We address this by systematically modeling Bézier-shaped 90° bends and S-bends using a variational FDTD solver, exploring bend span, curvature, and waveguide dimensions. Our results show that smaller waveguides (widths 2–4 µm) and lower Bézier parameters (B = 0–0.2) consistently yield superior performance, enabling sharper bends with minimal loss. For 90° bends, spans as small as 20–30 µm achieve near-unity transmission, while for S-bends, aspect ratios below 1 are feasible, allowing highly compact layouts. Although all configurations transmit energy to the fundamental mode, wider waveguides exhibit stronger higher-order mode excitation and greater sensitivity to fabrication imperfections. Smaller waveguides reduce these effects but approach the resolution limits of 2PP-DLW. Thus, a 2 µm wide waveguide represents an optimal compromise between fabrication feasibility and optical performance. Experimental demonstrations confirm the practicality of these design rules, illustrating trends predicted by simulations. These findings establish clear guidelines for designing low-loss, space-efficient 3D photonic circuits and highlight the critical role of simulation-driven optimization in fully exploiting 2PP-DLW technology, while providing deeper insight for future device architectures. Full article

Advancements in bioinks and three-dimensional (3D) printing and bioprinting have significantly advanced cardiovascular tissue engineering by enabling the fabrication of biomimetic cardiac and vascular constructs. Traditional 3D printing has contributed to the development of acellular scaffolds, vascular grafts, and patient-specific cardiovascular models that support surgical planning and biomedical applications. In contrast, 3D bioprinting has emerged as a transformative biofabrication technology that allows for the spatially controlled deposition of living cells and biomaterials to construct functional tissues in vitro. Bioinks—derived from natural biomaterials such as collagen and decellularized matrix, synthetic polymers such as polyethylene glycol (PEG) and polycaprolactone (PCL), or hybrid combinations—have been engineered to replicate extracellular environments while offering tunable mechanical properties. These formulations ensure biocompatibility, appropriate mechanical strength, and high printing fidelity, thereby maintaining cell viability, structural integrity, and precise architectural resolution in the printed constructs. Advanced bioprinting modalities, including extrusion-based bioprinting (such as the FRESH technique), droplet/inkjet bioprinting, digital light processing (DLP), two-photon polymerization (TPP), and melt electrowriting (MEW), enable the fabrication of complex cardiovascular structures such as vascular patches, ventricle-like heart pumps, and perfusable vascular networks, demonstrating the feasibility of constructing functional cardiac tissues in vitro. This review highlights the respective strengths of these technologies—for example, extrusion’s ability to print high-cell-density bioinks and MEW’s ultrafine fiber resolution—as well as their limitations, including shear-induced cell stress in extrusion and limited throughput in TPP. The integration of optimized bioink formulations with appropriate printing and bioprinting platforms has significantly enhanced the replication of native cardiac and vascular architectures, thereby advancing the functional maturation of engineered cardiovascular constructs. Full article

We experimentally demonstrate high-resolution imaging using micro-objectives fabricated by two-photon polymerization (2PP) lithography, highlighting its potential as a flexible and precise fabrication method. The 2PP manufacturing process offers the ability to develop micro-optics with customized geometries and material properties, including tailored refractive indices. This flexibility introduces new degrees of freedom in optical system design and expands the applicability of micro-optics to advanced imaging tasks where other materials and fabrication methods are insufficient. For our study, bi-convex micro-optics with different geometries with radii of curvature of <15 $\mathsf{\mu }$m and minimized contact areas (<1 $\mathsf{\mu }$${\mathrm{m}}^2$) to ensure easy release from the substrate were fabricated with 2PP and investigated for their optical performance. With these micro-optics, the tracks with a pitch of 320 nm and the pits and lands as small as 130 nm were successfully resolved on a BluRay disc surface, demonstrating for the first time the high-resolution imaging capabilities of bi-convex spherical micro lenses. Full article

This study presents a microfluidic chip platform designed using a multiscale 3D printing strategy for fabricating microfluidic chips with integrated, high-resolution, and customizable membrane structures. By combining two-photon polymerization (2PP) for submicron membrane fabrication with liquid crystal display printing for rapid production of larger components, this approach addresses key challenges in membrane integration, including sealing reliability and the use of transparent materials. Compared to fully 2PP-based fabrication, the multiscale method achieved a 56-fold reduction in production time, reducing total fabrication time to approximately 7.2 h per chip and offering a highly efficient solution for integrating complex structures into fluidic chips. The fabricated chips demonstrated excellent mechanical integrity. Burst pressure testing showed that all samples withstood internal pressures averaging 1.27 ± 0.099 MPa, with some reaching up to 1.4 MPa. Flow testing from ~35 $\mathsf{\mu }$L/min to ~345 $\mathsf{\mu }$L/min confirmed stable operation in 75 $\mathsf{\mu }$m square channels, with no leakage and minimal flow resistance up to ~175 $\mathsf{\mu }$L/min without deviation from the predicted behavior in the 75 $\mathsf{\mu }$m. Membrane-integrated chips exhibited outlet flow asymmetries greater than 10%, indicating active fluid transfer across the membrane and highlighting flow-dependent permeability. Overall, this multiscale 3D printing approach offers a scalable and versatile solution for microfluidic device manufacturing. The method’s ability to integrate precise membrane structures enable advanced functionalities such as diffusion-driven particle sorting and molecular filtration, supporting a wide range of biomedical, environmental, and industrial lab-on-a-chip applications. Full article

Multicomponent oxide systems have many applications in different fields such as optics and medicine. In this work, we developed new hybrid photoresists based on a combination of an organic acrylate resin and an inorganic sol, suitable for 3D printing via two-photon polymerization (2PP). The inorganic sol contained precursors of a binary SiO₂-CaO or a ternary SiO₂-CaO-P₂O₅ system. Complex microstructures were 3D printed using these hybrid photoresists and 2PP. The obtained materials were characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. Our results revealed that the produced microstructures were able to endure sintering at 700 °C without collapsing, leading to scaffolds with 235 and 355 nm resolution and pore size, respectively. According to the TGA analysis, there was no significant mass loss beyond 600 °C. After sintering at 500 °C, the FTIR spectra showed the disappearance of the characteristic bands associated with the organic phase, and the presence of bands characteristic of the binary and ternary oxide systems and carbonate groups. The SEM images showed different morphologies of agglomerated nanoparticles with mean sizes of about 20 and 60 nm for ternary and binary systems, respectively. Our findings open the way towards precise control of bioglass scaffold fabrication with tremendous design flexibility. Full article

We report the realization of metallic 3D microstructures, electroplated in two-photon polymerized molds. These molds are typically 150 × 150 × 30 µm³ in size and the smallest feature size is about 1 µm. After the electroplating process, the mold is removed by means of CF₄/O₂ etching (1 h). The vertical electroplating growth is about two times higher than the horizontal growth, which creates voids. A new design to prevent voids was tested where the pores were arranged at a 35° angle to the chip surface. The remaining structures consisted of a copper base with a palladium finish, or of pure palladium. They were analyzed through SEM and were shown to be a good reproduction of the mold design, resulting in metallic porous structures with a specific surface area of about 6 mm²/mm². Full article

The imaging quality of the Mapping Imaging Spectrometer (IMS) is crucial for spectral identification and detection performance. In IMS, the image mapper significantly influences the imaging quality. Traditional image mappers utilize a single-point diamond machining process. This process leads to inevitable edge eating phenomena that further results in noticeable deficiencies in imaging, impacting spectral detection performance. Therefore, we propose a manufacturing process for the image mapper based on ultra-thin layered glass. This process involves precision polishing of ultra-thin glass with two-dimensional angles, systematically assembling it into an image mapper. The surface roughness after coating is generally superior to 10 nm, with a maximum angle deviation of less than 3′. This results in high mapping quality. Subsequently, a principle verification experimental system was established to conduct imaging tests on real targets. The reconstructed spectrum demonstrates excellent alignment with the results obtained from the Computed Tomography Imaging Spectrometer (CTIS). We thereby validate that this approach effectively resolves the issues associated with edge eating (caused by traditional single-point diamond machining), and leads to improved imaging quality. Also when compared to other techniques (like two-photon polymerization (2PP)), this process demonstrates notable advantages such as simplicity, efficiency, low processing costs, high fault tolerance, and stability, showcasing its potential for practical applications. Full article

Light confinement provided by whispering gallery mode (WGM) microresonators is especially useful for integrated photonic circuits. In particular, the tunability of such devices has gained increased attention for active filtering and lasering applications. Traditional lithographic approaches for fabricating such devices, especially Si-based ones, often restrict the device’s tuning due to the material’s inherent properties. Two-photon polymerization (2PP) has emerged as an alternative fabrication technique of sub-diffraction resolution 3D structures, in which compounds can be incorporated to further expand their applications, such as enabling active devices. Here, we exploited the advantageous characteristics of polymer-based devices and produced, via 2PP, acrylic-based WGM hollow microcylinders incorporated with the azoaromatic chromophore Disperse Red 13 (DR13). Within telecommunication range, we demonstrated the tuning of the microresonator’s modes by external irradiation within the dye’s absorption peak (at 514 nm), actively inducing a blueshift at a rate of 1.2 nm/(Wcm⁻²). Its thermo-optical properties were also investigated through direct heating, and the compatibility of both natural phenomena was also confirmed by finite element simulations. Such results further expand the applicability of polymeric microresonators in optical and photonic devices since optically active filtering was exhibited. Full article

A micro-ring resonator structure was fabricated via the two-photon polymerization technique directly on a single-mode fiber tip and tested for refractive index sensing application. The micro-ring structure was used to excite whispering-gallery modes, and observations of the changes in the resonance spectrum introduced by changes in the refractive index of the environment served as the sensing principle. The proposed structure has the advantages of a very simple design, allowing for measurements in reflection mode, relatively easy and fast fabrication and integration with a single tip of a standard single-mode fiber, which allowed for quick and convenient measurements in the optical setup. The performance of the structure was characterized, and the resonant spectrum giving high potential for refractive index sensing was measured. Future perspectives of the research are addressed. Full article

Recent developments in micro-scale additive manufacturing (AM) have opened new possibilities in state-of-the-art areas, including microelectromechanical systems (MEMS) with intrinsically soft and compliant components. While fabrication with soft materials further complicates micro-scale AM, a soft photocurable polydimethylsiloxane (PDMS) resin, IP-PDMS, has recently entered the market of two-photon polymerization (2PP) AM. To facilitate the development of microdevices with soft components through the application of 2PP technique and IP-PDMS material, this research paper presents a comprehensive material characterization of IP-PDMS. The significance of this study lies in the scarcity of existing research on this material and the thorough investigation of its properties, many of which are reported here for the first time. Particularly, for uncured IP-PDMS resin, this work evaluates a surface tension of 26.7 ± 4.2 mN/m, a contact angle with glass of 11.5 ± 0.6°, spin-coating behavior, a transmittance of more than 90% above 440 nm wavelength, and FTIR with all the properties reported for the first time. For cured IP-PDMS, novel characterizations include a small mechanical creep, a velocity-dependent friction coefficient with glass, a typical dielectric permittivity value of 2.63 ± 0.02, a high dielectric/breakdown strength for 3D-printed elastomers of up to 73.3 ± 13.3 V/µm and typical values for a spin coated elastomer of 85.7 ± 12.4 V/µm, while the measured contact angle with water of 103.7 ± 0.5°, Young’s modulus of 5.96 ± 0.2 MPa, and viscoelastic DMA mechanical characterization are compared with the previously reported values. Friction, permittivity, contact angle with water, and some of the breakdown strength measurements were performed with spin-coated cured IP-PDMS samples. Based on the performed characterization, IP-PDMS shows itself to be a promising material for micro-scale soft MEMS, including microfluidics, storage devices, and micro-scale smart material technologies. Full article

Hearing loss is a highly prevalent multifactorial disorder affecting 20% of the global population. Current treatments using the systemic administration of drugs are therapeutically ineffective due to the anatomy of the cochlea and the existing blood–labyrinth barrier. Local drug delivery systems can ensure therapeutic drug concentrations locally while preventing adverse effects caused by high dosages of systemically administered drugs. Here, we aimed to design, fabricate, and characterize a local drug delivery system for the human cochlea. The design was relevant to the size of the human ear, included two different shapes, and incorporated two different microporous structures acting as reservoirs for drug loading and release. The four cochlear implant designs were printed using the two-photon polymerization (2PP) technique and the IP-Q photoresist. The optimized 2PP process enabled the fabrication of the cochlear implants with great reproducibility and shape fidelity. Rectangular and cylindrical implants featuring cylindrical and tapered tips, respectively, were successfully printed. Their outer dimensions were 0.6 × 0.6 × 2.4 mm³ (L × W × H). They incorporated internal porous networks that were printed with high accuracy, yielding pore sizes of 17.88 ± 0.95 μm and 58.15 ± 1.62 μm for the designed values of 20 μm and 60 μm, respectively. The average surface roughness was 1.67 ± 0.24 μm, and the water contact angle was 72.3 ± 3.0°. A high degree of polymerization (~90%) of the IP-Q was identified after printing, and the printed material was cytocompatible with murine macrophages. The cochlear implants designed and 3D printed in this study, featuring relevant sizes for the human ear and tunable internal microporosity, represent a novel approach for personalized treatment of hearing loss through local drug delivery. Full article

Nitrogen-vacancy (NV) and other color centers in diamond have attracted much attention as non-photobleaching quantum emitters and quantum sensors. Since microfabrication in bulk diamonds is technically difficult, embedding nanodiamonds with color centers into designed structures is a way to integrate these quantum emitters into photonic devices. In this study, we demonstrate a method to incorporate fluorescent nanodiamonds into engineered microstructures using two-photon polymerization (2PP). We studied the optimal concentration of nanodiamonds in the photoresist to achieve structures with at least one fluorescent NV center and good structural and optical quality. Fluorescence and Raman spectroscopy measurements were used to confirm the presence and location of the nanodiamonds, while absorbance measurements assessed scattering losses at higher concentrations. Our results show the feasibility of fabricating microstructures embedded within fluorescent nanodiamonds via 2PP for photonics and quantum technology applications. Full article