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The trend toward ever‐increased speeds for microelectronics is challenged by the emergence of heat‐wall, leading to the faltering of Moore's Law. A potential solution may be integrating microfluidic channels into silicon (Si), to deliver controlled amounts of cooling fluid and regulate hot spots. Such meandering microfluidic channels within other transparent materials already played significant roles, including in biomedical and sensor applications; however, analogous channel architectures do not exist in Si. Here, a novel method is proposed to fabricate buried microchannel arrays monolithically integrated into Si, without altering the wafer surface. A two‐step, laser‐assisted subtractive removal method is exploited, enabling fully‐buried multi‐level architectures, with control on the channel port geometry, depth, curvature, and aspect ratio. The selective removal rate is 750 µm per h per channel, and the channel inner‐wall roughness is 230 nm. The method preserves top wafer surface roughness of 2 nm, with significant potential for 3D integrated systems. [ABSTRACT FROM AUTHOR]

The repair of orthopedic and maxillofacial defects in modern medicine currently relies heavily on the use of autograft, allograft, void fillers, or other structural material composites. This study examines the in vitro osteo regenerative potential of polycaprolactone (PCL) tissue scaffolding, fabricated via a three-dimensional (3D) additive manufacturing technology, i.e., a pneumatic micro extrusion (PME) process. The objectives of this study were: (i) To examine the innate osteoinductive and osteoconductive potential of 3D-printed PCL tissue scaffolding and (ii) To perform a direct in vitro comparison of 3D-printed PCL scaffolding with allograft Allowash® cancellous bone cubes with regards to cell-scaffold interactions and biocompatibility with three primary human bone marrow (hBM) stem cell lines. This study specifically examined cell survival, cell integration, intra-scaffold cell proliferation, and differentiation of progenitor cells to investigate the potential of 3D-printed PCL scaffolds as an alternative to allograft bone material for the repair of orthopedic injuries. We found that mechanically robust PCL bone scaffolds can be fabricated via the PME process and the resulting material did not elicit detectable cytotoxicity. When the widely used osteogenic model SAOS-2 was cultured in PCL extract medium, no detectable effect was observed on cell viability or proliferation with multiple test groups showing viability ranges of 92.2% to 100% relative to a control group with a standard deviation of ±10%. In addition, we found that the honeycomb infill pattern of the 3D-printed PCL scaffold allowed for superior mesenchymal stem-cell integration, proliferation, and biomass increase. When healthy and active primary hBM cell lines, having documented in vitro growth rates with doubling times of 23.9, 24.67, and 30.94 h, were cultured directly into 3D-printed PCL scaffolds, impressive biomass increase values were observed. It was found that the PCL scaffolding material allowed for biomass increase values of 17.17%, 17.14%, and 18.18%, compared to values of 4.29% for allograph material cultured under identical parameters. It was also found that the honeycomb scaffold infill pattern was superior to the cubic and rectangular matrix structures, and provided a superior microenvironment for osteogenic and hematopoietic progenitor cell activity and auto-differentiation of primary hBM stem cells. Histological and immunohistochemical studies performed in this work confirmed the regenerative potential of PCL matrices in the orthopedic setting by displaying the integration, self-organization, and auto-differentiation of hBM progenitor cells within the matrix. Differentiation products including mineralization, self-organizing "proto-osteon" structures, and in vitro erythropoiesis were observed in conjunction with the documented expression of expected bone marrow differentiative markers including CD-99 (>70%), CD-71 (>60%), and CD-61 (>5%). All of the studies were conducted without the addition of any exogenous chemical or hormonal stimulation and exclusively utilized the abiotic and inert material polycaprolactone; setting this work apart from the vast majority of contemporary investigations into synthetic bone scaffold fabrication In summary, this study demonstrates the unique clinical potential of 3D-printed PCL scaffolds for stem cell expansion and incorporation into advanced microstructures created via PME manufacturing to generate a physiologically inert temporary bony defect graft with significant autograft features for enhanced end-stage healing. [ABSTRACT FROM AUTHOR]

Recently, flexible devices using intrinsically conductive polymers, particularly poly(3,4-ethylenedioxythiophene) (PEDOT), have been extensively investigated. However, most flexible wiring fabrication methods using PEDOT are limited to two-dimensional (2D) fabrication. In this study, we fabricated three-dimensional (3D) wiring using the highly precise 3D printing method of stereolithography. Although several PEDOT fabrication methods using 3D printing systems have been studied, few have simultaneously achieved both high conductivity and precise accuracy. In this study, we review the post-fabrication process, particularly the doping agent. Consequently, we successfully fabricated wiring with a conductivity of 16 S cm−1. Furthermore, flexible wiring was demonstrated by modeling the fabricated wiring on a polyimide film with surface treatment and creating a three-dimensional fabrication object. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a computer-controlled multidirectional UV-LED lithography system for 3-D microfabrication. The presented UV-LED system has adopted adjustable or programmable high-intensity UV-LEDs as a light source enabling for photopatterning both thin and thick SU-8 photoresist process. The prototype of the proposed system comprises 5-by-5 surface-mounted type LEDs with customized collimation lens, a tilt-rotational sample holder for introducing multidirectional light exposure, and a computer-control asset for synchronized controls of the light source and the sample holder. An adjustable light intensity provides an ease of lithography both for a few micron feature size patterning and a millimeter thick photopatterning by providing optimal light exposure condition by considering diffraction, and absorption of the UV light. Together with the tilt-rotational sample holder, the multidirectional UV-LED lithography can fabricate various 3-D microstructures in a wide range of the photoresist film thickness. The 3-D fabrications include an array of micro triangle slabs, 1-mm tall pillar array, the different scale same 3-D geometry structures on the same substrate.

Serial crystallography has enabled the study of complex biological questions through the determination of biomolecular structures at room temperature using low X-ray doses. Furthermore, it has enabled the study of protein dynamics by the capture of atomically resolved and time-resolved molecular movies. However, the study of many biologically relevant targets is still severely hindered by high sample consumption and lengthy data-collection times. By combining serial synchrotron crystallography (SSX) with 3D printing, a new experimental platform has been created that tackles these challenges. An affordable 3D-printed, X-ray-compatible microfluidic device (3D-MiXD) is reported that allows data to be collected from protein microcrystals in a 3D flow with very high hit and indexing rates, while keeping the sample consumption low. The miniaturized 3D-MiXD can be rapidly installed into virtually any synchrotron beamline with only minimal adjustments. This efficient collection scheme in combination with its mixing geometry paves the way for recording molecular movies at synchrotrons by mixing-triggered millisecond time-resolved SSX.

Precisely controlled manipulation of nonadherent single cells is often a pre-requisite for their detailed investigation. Optical trapping provides a versatile means for positioning cells with submicrometer precision or measuring forces with femto-Newton resolution. A variant of the technique, called indirect optical trapping, enables single-cell manipulation with no photodamage and superior spatial control and stability by relying on optically trapped microtools biochemically bound to the cell. High-resolution 3D lithography enables to prepare such cell manipulators with any predefined shape, greatly extending the number of achievable manipulation tasks. Here, it is presented for the first time a novel family of cell manipulators that are deformable by optical tweezers and rely on their elasticity to hold cells. This provides a more straightforward approach to indirect optical trapping by avoiding biochemical functionalization for cell attachment, and consequently by enabling the manipulated cells to be released at any time. Using the photoresist Ormocomp, the deformations achievable with optical forces in the tens of pN range and present three modes of single-cell manipulation as examples to showcase the possible applications such soft microrobotic tools can offer are characterized. The applications describe here include cell collection, 3D cell imaging, and spatially and temporally controlled cell-cell interaction., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Determination of electronic structures during chemical reactions remains challenging in studies which involve reactions in the millisecond timescale, toxic chemicals, and/or anaerobic conditions. In this study, a three‐dimensionally (3D) microfabricated microfluidic mixer platform that is compatible with time‐resolved X‐ray absorption and emission spectroscopy (XAS and XES, respectively) is presented. This platform, to initiate reactions and study their progression, mixes a high flow rate (0.50–1.5 ml min−1) sheath stream with a low‐flow‐rate (5–90 µl min−1) sample stream within a monolithic fused silica chip. The chip geometry enables hydrodynamic focusing of the sample stream in 3D and sample widths as small as 5 µm. The chip is also connected to a polyimide capillary downstream to enable sample stream deceleration, expansion, and X‐ray detection. In this capillary, sample widths of 50 µm are demonstrated. Further, convection–diffusion‐reaction models of the mixer are presented. The models are experimentally validated using confocal epifluorescence microscopy and XAS/XES measurements of a ferricyanide and ascorbic acid reaction. The models additionally enable prediction of the residence time and residence time uncertainty of reactive species as well as mixing times. Residence times (from initiation of mixing to the point of X‐ray detection) during sample stream expansion as small as 2.1 ± 0.3 ms are also demonstrated. Importantly, an exploration of the mixer operational space reveals a theoretical minimum mixing time of 0.91 ms. The proposed platform is applicable to the determination of the electronic structure of conventionally inaccessible reaction intermediates. [ABSTRACT FROM AUTHOR]

A figure in the article by Huyke et al. [(2021), J. Synchrotron Rad. 28, 1100–1113] is corrected.

Three-dimensional (3D) microfabrication techniques play a crucial role across various research fields. These techniques enable the creation of functional 3D structures on the microscale, unlocking possibilities for diverse applications. However, conventional fabrication methods have limits in producing complex 3D structures, which require numerous fabrication steps that increase the costs. Graphene is an atomically thin material known for its deformability and impermeability to small gases and molecules, including reactive gases like XeF 2 . These features make graphene a potential candidate as an etch mask for 3D microfabrication. Here, we report the fabrication of various 3D microstructures using graphene etch masks directly grown and patterned on a Si substrate. The patterned graphene deforms and wraps the etched structures, allowing for the fabrication of complicated 3D microstructures, such as mushroom-like and step-like microstructures. As a practical demonstration of the graphene etch mask, we fabricate an omniphobic surface of reentrant 3D structures on a Si substrate. Our work provides a method for fabricating complex 3D microstructures using a graphene etch mask, contributing to advancements in etching and fabrication processes.

This paper presents a computer-controlled multidirectional UV-LED lithography system for 3-D microfabrication. The presented UV-LED system has adopted adjustable or programmable high-intensity UV-LEDs as a light source enabling for photopatterning both thin and thick SU-8 photoresist process. The prototype of the proposed system comprises 5-by-5 surface-mounted type LEDs with customized collimation lens, a tilt-rotational sample holder for introducing multidirectional light exposure, and a computer-control asset for synchronized controls of the light source and the sample holder. An adjustable light intensity provides an ease of lithography both for a few micron feature size patterning and a millimeter thick photopatterning by providing optimal light exposure condition by considering diffraction, and absorption of the UV light. Together with the tilt-rotational sample holder, the multidirectional UV-LED lithography can fabricate various 3-D microstructures in a wide range of the photoresist film thickness. The 3-D fabrications include an array of micro triangle slabs, 1-mm tall pillar array, the different scale same 3-D geometry structures on the same substrate. [ABSTRACT FROM AUTHOR]

In this study, we propose a solidified ionic liquid with a 3D microstructure to increase its surface area for the performance enhancement of a vibration energy harvester (VEH). By soft lithography in MEMS technologies, the use of a mold is proposed to perform the solidification, polarization, and microstructure transfer of the solidified ionic liquid simultaneously. We fabricated six samples with different surface shapes and sizes to compare the power generation performance characteristics of VEHs using a solidified ionic liquid. According to a vibration test, the performance of the VEH with nanometer roughness was improved at a 10 Hz frequency. Also, the output power of the VEH with a micro-folded hollow conical structure was improved at a 50 Hz frequency. [ABSTRACT FROM AUTHOR]

Highlights • A new type of maskless lithography system based on DMD has been developed. • The proposed maskless lithography system can fabricate not only 2D but also 3D structures. • A new method for 3D structure fabrication has been proposed. Abstract A new type of maskless lithography system based on digital mirror device (DMD) is proposed, constructed, and experimentally demonstrated. It includes a pin-hole array sandwiched by two microlens arrays on each side, known as double-sided microlens/spatial-filter array (D-MSFA), and aligned with a DMD. Ultraviolet (UV) light reflected by DMD is first collected by the first microlens array, filtered through the pin-hole array, and then re-focused by the second microlens array into a UV spot array. Along with an obliquely scanning method, this D-MSFA/DMD-based maskless lithography system can perform not only 2D but also 3D UV patterning. Experimental testing successfully generates complicated patterns with a minimum line-width of 3.36 μm. Direct 3D patterning and 3D microfabrication are also experimentally demonstrated on a photoresist layer. Excellent profile accuracy and surface structure qualities are observed with great potentials for future 2D and 3D microfabrication in a maskless manner. [ABSTRACT FROM AUTHOR]

A remarkable number of vitreoretinal surgeries are performed each year despite their difficulty. As a result, a high demand exists for a mock-up simulator of retinal vessels to simulate these surgeries. Thus, we propose an artificial retinal vessel model for simulating microcannulation surgery. Using laser lithography, polydimethylsiloxane molding, and hydraulic transfer techniques, we fabricated microchannels approximately ≃10 μm on a 24-mm-diameter curved surface structure that mimics the human eye. In the fabrication, the channel size and wall thickness were controlled to mimic a touch of retinal vessels, which gives important information for microcannulation. We succeeded in fabrication of the proposed model and liquid circulates within the microchannels of this model without leaking. Furthermore, we demonstrated a simulation of microcannulation and measurement of applied force to the model during the simulation using a force sensor placed at the bottom of the model. The results of such experiments are useful to quantitatively evaluate medical techniques. [ABSTRACT FROM AUTHOR]

Porous fiber structures are of great concern to many fields of life-science engineering, but require a complex assembly processes that have geometric constraints. For this reason, tremendous efforts were expended in recent years to develop micro-/nano fabrication techniques. We report on the 3D structuring of a 3.5 mm long branched hollow fiber with 150 μm outer diameter and predefined circular pores (diameter: 30 μm). The investigated process is based on two-photon polymerization (2PP) of the UV curing resin OrmoComp ® . The incident light of a femtosecond pulsed laser at 790 nm wavelength is used to generate the structure. Utilizing the non-linear behavior of two-photon absorption due to a tightly focused, high-intensity laser beam allows the local fabrication of three-dimensional structures in the photoresist. Voxels fabricated by 2PP are studied by controlling average laser power and exposure time. The appropriate average pulse energy and writing speed are determined to apply the optimal exposure parameters concerning the geometric accuracy and overall quality of the structure. The 2PP direct laser writing process is employed to generate the hollow fiber at an average laser power of 105 mW, and a writing speed of 5.0 mm/s. Water flowing through the fiber provides evidence that the core is hollow. [ABSTRACT FROM AUTHOR]

We report a multiple patterning approach utilizing digital-micromirror-device (DMD)-based grayscale lithography, providing a solution to improve fabrication accuracy for entire target three-dimensional structure. Because DMD-based lithography system consists a projection lens system, better resolution can be obtained around focal position comparing to the outer region of depth of focus. Thus, for thick-film resist micro structuring, exposing with multiple focal positions with separate grayscale masks leads to improvement of fabrication accuracy. In order to find the best combination of the multiple focal positions and their grayscale masks, the computational optimization is combined to the multiple patterning approach. Through a several experiments, effectiveness of the proposed approach was successfully demonstrated. [ABSTRACT FROM AUTHOR]

Microstereolithography (MSL) is technology of fabrication of three-dimensional (3D) components by using layer-by-layer photopolymerization. Typical design goals of MSL system are: small features, high resolution, high speed of fabrication, and large overall size of component. This paper focuses on design and development of such a system to meet these optomechatronic requirements. We first analyze various optical scanning schemes used for MSL systems along with the proposed scheme via optical simulations and experiments. Next, selection criteria for various subsystems are laid down and appropriate design decisions for the proposed system are made. Further, mechanical design of the scanning mechanism is carried out to meet requirements of high speed and resolution. Finally, system integration and investigation in process parameters is carried out and fabrication of large microcomponent with high resolution is demonstrated. The proposed system would be useful for fabrication of multiple/large microcomponents with high production rate in various applications. [ABSTRACT FROM AUTHOR]

In this paper, an overview of literature supported by original experimental results on direct laser polymerization of three-dimensional micro-/nano-structuring of various photopolymers is presented. Alternative technologies, principles of threshold based direct laser writing in polymers employing ultrafast lasers, issues of optimization of the laser structuring parameters for increasing fabrication resolution and production throughput are presented and discussed. Examples of woodpile templates and nanogratings are shown as well as an opto-fluidic sensor design for usage in lab-on-chip type devices is demonstrated and its performance is characterized. Additionally, a possibility to produce a three-dimensional electric circuit is introduced. [ABSTRACT FROM AUTHOR]

Abstract: Microlens arrays are becoming increasingly important because of their widespread applications in optical, electronic, and energy fields. Currently, microlens array fabrication processes are mainly developed on planar substrates. For nonplanar substrates, existing fabrication methods suffer from various disadvantages. This is largely due to the inherent technical complexity associated with 3D microstructure fabrication processes. In this study, an innovative 3D fabrication method for microlens arrays on curved surfaces is introduced. To fabricate the microlens array, a polymethylmethacrylate microlens array on a curved surface was used as projection optics. A thick layer of positive photoresist SPR 220 was spin coated on a curved, titanium-coated aluminum substrate. A pre-selected pattern was projected onto the photoresist by using a home built exposure system. The development process resulted in micro cylinders on the curved substrate. A thermal reflow process was then performed on the cylinder array to form the microlens array. Experiments were conducted to evaluate the factors that affect the shapes of the microlenses. These factors include film thickness variation, exposure and development variation, slope of the substrate, height to width ratio and heating time in thermal reflow process. Finally microlenses were tested using a Twyman–Green interferometer. Results showed that the required shape of the microlenses achieved by controlling the process parameters. [Copyright &y& Elsevier]

We present in this paper the implementation of an innovative three dimensional (3D) microfabrication technology coupled with numerical simulation to enhance the mass transport in 3D cell culture. The core of this microfabrication technology is a high-resolution projection micro stereolithography (PμSL) using a spatial light modulator as a dynamic mask which enables a parallel fabrication of highly complex 3D microstructures. In this work, a set of poly (ethylene glycol) microfabricated bioreactors are demonstrated with PμSL technology. We observed both experimentally and numerically the regulation of metabolism and the growth of yeast cells by controlling the density of micro-capillaries. Further development of these 3D microfabricated bioreactors is expected to provide artificially constructed tissues for clinical applications. [ABSTRACT FROM AUTHOR]

We have developed a new 3D X-ray lithography system for LIGA processing using synchrotron radiation at the New SUBARU facility of the University of Hyogo. The X-ray lithography system can utilize two different energy regions; one is a high-energy region from 3 keV to 10 keV, and the other is a low-energy region from 0.1 to 2 keV. Each energy region can be selected in accordance with the size and shape of the desired microstructures. It is demonstrated that a large-area high-luminance 7-inch optical waveguide for the liquid crystal backlight unit was successfully fabricated with this X-ray lithography method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 52–59, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20680 [ABSTRACT FROM AUTHOR]

Efficient two-photon absorbing chromophore based on dithienothiophene has been synthesized and its two-photon absorption cross section (σ2) was evaluated by two-photon induced fluorescence excitation spectroscopy. The chromophore obtained shows a sizable two-photon absorption cross section value of 618 GM at 700 nm. By using one- and two-photon spectroscopic experiment, two-photon absorption properties of the chromophore with the electronic transition dipole moment and one- and two-photon transition energies were evaluated. Besides, we have demonstrated the successful application of this compound in fabrication of 2D and 3D microobjects by using two-photon microfabrication technique. [ABSTRACT FROM AUTHOR]

Abstract: In recent years considerable efforts have been put forth in two-photon initiated polymerization (TPP)-based two- and three-dimensional (2D and 3D) nano/microfabrication for the development of novel nano/microdevices. In less than two decades of research, TPP has been employed in the fabrication of a great number of diverse micro-objects through the use of a wide variety of effective two-photon absorbing chromophores. In TPP, when a near-infrared ultrashort-pulsed laser is closely focused into a volume of photocurable resins, real 3D microstructures can be fabricated using a layer-by-layer accumulating technique making it a promising technique for 3D nano/microfabrication. More recently, a spatial resolution of sub-100nm scale was achieved with TPP by employing a radical quenching mechanism. There also have been many studies that aimed at improving the fabrication efficiency and precision of TPP. Focus of ongoing research is the development of efficient two-photon absorbing chromophores. In this article, we discuss recent efforts in developing two-photon absorbing chromophores with focus on their structure property relationship and some recent outstanding attempts at improving the fabrication efficiency of 3D nano/microfabrications based on TPP. [Copyright &y& Elsevier]

Abstract: Precise fabrication of three-dimensional (3D) microstructures having nano-details has become realized using two-photon induced photopolymerization (TPP) since several years ago; and now, this technology is recognized as a promising process for the creation of 3D neo-conceptive nano- and microscale devices. However, there are still important issues to be settled for the practical use of TPP. One of them is the 3D pattern collapse due to the surface tension of rinse materials in a development process, which impedes the progress of 3D precise microfabrication via TPP. To solve this issue effectively, finite element analyses of 3D pattern collapse using an imperfection model were conducted. Overall of this work, we showed the mechanism of 3D pattern collapse and the way how to reduce pattern deformation effectively during a developing process using experimental and analytical approaches. [Copyright &y& Elsevier]

Abstract: 3D integration of microcomponents in a single glass chip by femtosecond laser direct writing followed by post annealing and successive wet etching is described for application to biochemical analysis. Integration of microfluidics and microoptics realized some functional microdevices like a μ-fluidic dye laser and a biosensor. As one of practical applications, we demonstrate inspection of living microorganisms using the microchip with 3D microfluidic structures fabricated by the present technique. [Copyright &y& Elsevier]

Abstract: We propose a novel approach to material processing: one that implements laser photoexcitation in a direct-write scheme to establish initial excitation states in a protean material that enables the regulation of a particular phase transformation pathway. The effect of regulating the phase transformation process is the controlled alteration of a specific material property. As a test of the concept, we have investigated a class of photostructurable glass ceramics (PSGCs) of the lithium aluminosilicate family. By controlling the incident laser irradiance (i.e., the material exposure), we can affect the material solubility, optical transmission, and material hardness following the phase transformation process. To further enhance the fidelity of the laser photo-induced reaction process, we have developed a scheme that permits the controlled delivery of laser photons during complex motion patterning maneuvers. [Copyright &y& Elsevier]

Abstract: Three-dimensional hollow microstructures acting as microfluidic and microoptical components were directly formed inside a photoetchable glass, Foturan, using femtosecond (fs) laser direct writing followed by post-annealing and successive chemical etching. Benefiting from a multiphoton process and a focus-shaping technique, a resolution as high as 10μm was achieved in both the transverse and longitudinal directions. Microreactors containing microchannels, microcells, and microvalves were fabricated by this technique, and functions like sample mixing and fluid switching were demonstrated. Also, microoptics, such as micromirrors and microbeam splitters, were fabricated by this technique. The microfluidic and microoptical components were also integrated into the same chip for creating microfluidic dye lasers. A dual-color microfluidic laser array which can simultaneously emit light with wavelengths centered at 568 and 618nm was also fabricated and its lasing properties examined. [Copyright &y& Elsevier]

Two-photon absorbing phenylenevinylene derivative having silyloxy moieties in electron donor units (EHSEA) was prepared. The two-photon absorption (TPA) cross-section value of this chromophore was found to be 1.93×10-48cm4sec/photon at 740 nm by using TPA-induced fluorescence method with 80 fs pulse laser. The nonlinear measurement with ns scale pulses has indicated that EHSEA exhibits an efficient optical power limiting activity. We have obtained micropatterns with high resolution by TPA-induced polymerization using EHSEA as a photosensitizer. [ABSTRACT FROM AUTHOR]

This paper presents a novel microfabrication technology of three-dimensional (3D) microstructures with inclined/rotated UV lithography using negative thick photoresist, SU-8. In exposure process, a photomask and a SU-8 coated substrate are fixed together, and tilted or tilted and rotated to a UV source. The reflected UV at the interface between the resist and the substrate is also exploited as well as the incident UV. With the 3D microfabrication technology, various 3D microstructures are easily fabricated such as oblique cylinders, embedded channels, bridges, V-grooves, truncated cones, and so on. The angles between fabricated structures and normal lines are 19.5°, when the incident angle of UV in air is 32°. Thus, the refractive index of SU-8 and the maximum refractive angle at the interface between SU-8 and air are expected about 1.6 and 39°, respectively. [Copyright &y& Elsevier]

We present a novel method for 3D microfabrication with LIGA process that utilizes a deep X-ray mask in which a microactuator is integrated. The integrated microactuator oscillates the X-ray absorber, which is formed on the shuttle mass of the microactuator, during the X-ray exposures to modify the absorbed dose profile in X-ray resist, typically PMMA. The 3D PMMA microstructures according to the modulated dose contour are revealed after GG development. An X-ray mask with integrated comb drive actuator is fabricated using deep reactive ion etching, absorber electroplating, and bulk micromachining with silicon-on-insulator wafer. Silicon shuttle mass (1 mm×1 mm, 20 μm thick) as a mask blank is supported by four 1 mm long suspension beams and is driven by the comb electrodes. A 10 μm thick, 50 μm line and spaced gold absorber pattern is electroplated on the shuttle mass before the release step. The fundamental frequency and amplitude are around 3.6 kHz and 20 μm, respectively, for a dc bias of 100 V and an ac bias of 20 VP–P (peak–peak). Fabricated PMMA microstructure shows 15.4 μm deep, S-shaped cross-section in the case of 1.6 kJ cm−3 surface dose and GG development at 35 °C for 40 min. [Copyright &y& Elsevier]

• Optimal laser parameters after etching were found for high quality optical devices. • A smoothness of 21.8 nm for 1 mm2 area in silica was achieved. • 1.25 m/s scan rate for a system operating with a 2 MHz repetition rate was proved. • Complex writing involving surfaces at different orientations was simplified. We present an optimization study on laser parameters for 3D micromachining of fused silica to achieve critical goals for practical applications including high surface quality, high volume production, and complex surfaces by ultrafast laser direct writing assisted chemical etching. We conducted experiments on laser pulse width of 300 fs and 1 ps, pulse energy ranging from 0.1 µJ to 1.6 µJ, three different polarizations (circular, parallel and perpendicular) and number of overlapped pulses from 3 to 10,000 at 1030 nm with up to 2 MHz repetition rate to investigate their effect on nanogratings and one dimensional (1D) channel and two dimensional (2D) planar surface selective etching on 1 mm thick fused silica. In one configuration, we achieved 21.8 nm RMS surface roughness with 80 µm Gaussian filtering and in another configuration, we estimated the maximum writing speed to be 1.25 m/s for given 2 MHz repetition rate with less than 400 nm filtered root mean square (RMS) surface roughness at a 1 mm2 area which covers the thickness of the glass. [ABSTRACT FROM AUTHOR]

Serial crystallography has enabled the study of complex biological questions through the determination of biomolecular structures at room temperature using low X-ray doses. Furthermore, it has enabled the study of protein dynamics by the capture of atomically resolved and time-resolved molecular movies. However, the study of many biologically relevant targets is still severely hindered by high sample consumption and lengthy data-collection times. By combining serial synchrotron crystallography (SSX) with 3D printing, a new experimental platform has been created that tackles these challenges. An affordable 3D-printed, X-ray-compatible microfluidic device (3D-MiXD) is reported that allows data to be collected from protein microcrystals in a 3D flow with very high hit and indexing rates, while keeping the sample consumption low. The miniaturized 3D-MiXD can be rapidly installed into virtually any synchrotron beamline with only minimal adjustments. This efficient collection scheme in combination with its mixing geometry paves the way for recording molecular movies at synchrotrons by mixing-triggered millisecond time-resolved SSX., (© Diana C. F. Monteiro et al. 2020.)

3D printing technology is widely employed in various scientific disciplines as well as industrial applications such as hearing aid manufacturing. While technological advances and increasing resolution are making 3D printing accessible for microfabrication purposes, one question remains: how can small and delicate components like microgears, lattices, or micromedical devices be released from the build surface of the 3D printer without manual intervention? Herein, a method for 3D printing on top of water‐soluble sacrificial substrates made from polyvinyl alcohol (PVA) is presented. Prefabricated sacrificial PVA substrates can be mounted onto a customized holder and serve as a build surface during the 3D printing operation. The substrates do not only facilitate a mild release of 3D printed objects after dissolution of the sacrificial material, they also potentially allow for a convenient manipulation and further array‐based processing of predetermined patterns of printed structures subsequent to the 3D printing procedure. This, in turn, may enable a full integration into automated production lines. The fabrication of PVA substrates is thoroughly characterized and the 3D printing of various exemplary structures on sacrificial substrates is demonstrated. Finally, the release of 3D printed objects from PVA substrates is shown. [ABSTRACT FROM AUTHOR]

Flexible electronic materials combined with micro-3D fabrication present new opportunities for wearable biosensors and medical devices. This Research Article introduces a novel carbon-nanotube-coated force sensor, successfully combining the advantages of flexible conductive nanomaterials and the versatility of two photon polymerization technologies for creating functional 3D microstructures. The device employs carbon-nanotube-coated microsprings with varying configurations and geometries for  real-time force sensing. To demonstrate its practical value, the device has first been embodied as a patch sensor for transcutaneous monitoring of human arterial pulses, followed by the development of a multiple-point force-sensitive catheter for real-time noninvasive intraluminal intervention. The results illustrate the potential of leveraging advanced nanomaterials and micro-3D-printing for developing new medical devices.

Two-photon stereolithography is used for rapid prototyping of submicrometre molecularly imprinted polymer-based 3D structures. The structures are evaluated as chemical sensing elements and their specific recognition properties for target molecules are confirmed. The 3D design capability is exploited and highlighted through the fabrication of an all-organic molecularly imprinted polymeric microelectromechanical sensor., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)