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Showing papers on "Lithography published in 2018"


Journal ArticleDOI
TL;DR: A lithography-based process to produce 3D nanoporous nickel nanolattices with octet geometries and a resolution of 100 nm is developed, demonstrating an efficient pathway to 3D-print micro-architected and nano- architected metals with sub-micron resolution.
Abstract: Most existing methods for additive manufacturing (AM) of metals are inherently limited to ~20–50 μm resolution, which makes them untenable for generating complex 3D-printed metallic structures with smaller features We developed a lithography-based process to create complex 3D nano-architected metals with ~100 nm resolution We first synthesize hybrid organic–inorganic materials that contain Ni clusters to produce a metal-rich photoresist, then use two-photon lithography to sculpt 3D polymer scaffolds, and pyrolyze them to volatilize the organics, which produces a >90 wt% Ni-containing architecture We demonstrate nanolattices with octet geometries, 2 μm unit cells and 300–400-nm diameter beams made of 20-nm grained nanocrystalline, nanoporous Ni Nanomechanical experiments reveal their specific strength to be 21–72 MPa g^(−1) cm^3, which is comparable to lattice architectures fabricated using existing metal AM processes This work demonstrates an efficient pathway to 3D-print micro-architected and nano-architected metals with sub-micron resolution

347 citations


Journal ArticleDOI
TL;DR: A new bio-resin based on methacrylated poly(vinyl alcohol), PVA-MA, gelatin-methacryloyl (Gel-MA) and a transition metal-based visible light photoinitiator is developed, which provides important cues for the further development of lithography-based bioprinting of complex, free-form living tissue analogues.
Abstract: Lithography-based three-dimensional (3D) printing technologies allow high spatial resolution that exceeds that of typical extrusion-based bioprinting approaches, allowing to better mimic the complex architecture of biological tissues. Additionally, lithographic printing via digital light processing (DLP) enables fabrication of free-form lattice and patterned structures which cannot be easily produced with other 3D printing approaches. While significant progress has been dedicated to the development of cell-laden bioinks for extrusion-based bioprinting, less attention has been directed towards the development of cyto-compatible bio-resins and their application in lithography-based biofabrication, limiting the advancement of this promising technology. In this study, we developed a new bio-resin based on methacrylated poly(vinyl alcohol) (PVA-MA), gelatin-methacryloyl (Gel-MA) and a transition metal-based visible light photoinitiator. The utilization of a visible light photo-initiating system displaying high molar absorptivity allowed the bioprinting of constructs with high resolution features, in the range of 25-50 μm. Biofunctionalization of the resin with 1 wt% Gel-MA allowed long term survival (>90%) of encapsulated cells up to 21 d, and enabled attachment and spreading of endothelial cells seeded on the printed hydrogels. Cell-laden hydrogel constructs of high resolution with complex and ordered architecture were successfully bioprinted, where the encapsulated cells remained viable, homogenously distributed and functional. Bone and cartilage tissue synthesis was confirmed by encapsulated stem cells, underlining the potential of these DLP-bioprinted hydrogels for tissue engineering and biofabrication. Overall, the PVA-MA/Gel-MA bio-resin is a promising material for biofabrication and provides important cues for the further development of lithography-based bioprinting of complex, free-form living tissue analogues.

203 citations


Journal ArticleDOI
TL;DR: In this article, a simple lignin-based laser lithography technique is developed and used to fabricate on-chip microsupercapacitors (MSCs) using 3D graphene electrodes.
Abstract: DOI: 10.1002/aenm.201801840 inspired by the fabrication technology used in the semiconductor industry. The electrode materials of MSCs can be prepared by various, well-developed techniques, such as inkjet printing,[5–8] screen printing,[9,10] electrophoretic deposition,[11] electrodeposition,[12,13] and laser scribing.[14,15] Compared with other techniques, laser scribing technology is a simple direct-write method that does not require photolithography masks or tedious multistep fabrication processes.[16–23] In previous studies, graphene films were prepared from hydrated graphene oxide (GO) through laser scribing technology,[14,24] where GO could be reduced to rGO through the laser scribing process. However, the preparation of GO is complicated and time consuming. A more simple and direct approach is laser-scribing polyimide, which was developed by Tour and co-workers who fabricated laser-scribed graphene (LSG) electrodes from commercial Kapton polyimide film.[15] Different from thermal carbonization method, the laser scribing carbonization of polyimide provides LSG with highly porous graphene structure and high conductivity. Since then, LSG has been used in microsupercapacitor,[25–30] electrocatalytic hydrogen generation,[31,32] electrochemical oxygen evolution,[33] sensors,[34–36] and antimicrobial applications.[37,38] Recently, Tour and co-workers have done some excellent work that extended the laser scribing technology to wood and several polymers to make porous graphene films.[37,39] Polysulfone-class polymers have been transformed into graphene by one-step laser scribing, and various natural products, textile fabrics, and even bread have been transformed into graphene by multiple-laser-scribing technology.[40] As one of the three ingredients of natural biomass (lignin, cellulose, and hemicellulose), lignin is the most abundant renewable natural aromatic polymer existing in the world. Lignin is a kind of phenylpropane-based complex reticular aromatic poly mer and cannot be utilized by traditional chemical-engineering routes. Most existing lignins are extracted by sulfite pulping in the paper industry as a by-product pollutant in “black liquor.” As a result, lignin is usually considered to be useless and even as an environmental contaminant. Thus, the transformation of In this work, a simple lignin-based laser lithography technique is developed and used to fabricate on-chip microsupercapacitors (MSCs) using 3D graphene electrodes. Specifically, lignin films are transformed directly into 3D laser-scribed graphene (LSG) electrodes by a simple one-step CO2 laser irradiation. This step is followed by a water lift-off process to remove unexposed lignin, resulting in 3D graphene with the designed electrode patterns. The resulting LSG electrodes are hierarchically porous, electrically conductive (conductivity is up to 66.2 S cm−1), and have a high specific surface area (338.3 m2 g−1). These characteristics mean that such electrodes can be used directly as MSC electrodes without the need for binders and current collectors. The MSCs fabricated using lignin laser lithography exhibit good electrochemical performances, namely, high areal capacitance (25.1 mF cm−2), high volumetric energy density (≈1 mWh cm−3), and high volumetric power density (≈2 W cm−3). The versatility of lignin laser lithography opens up the opportunity in applications such as on-chip microsupercapacitors, sensors, and flexible electronics at large-scale production.

135 citations


Journal ArticleDOI
TL;DR: A novel methodology for printing 3D objects with spatially resolved mechanical and chemical properties and the power of this approach is showcased through the one-step fabrication of bioinspired soft joints and mechanically reinforced "brick-and-mortar" structures.
Abstract: A novel methodology for printing 3D objects with spatially resolved mechanical and chemical properties is reported. Photochromic molecules are used to control polymerization through coherent bleaching fronts, providing large depths of cure and rapid build rates without the need for moving parts. The coupling of these photoswitches with resin mixtures containing orthogonal photo-crosslinking systems allows simultaneous and selective curing of multiple networks, providing access to 3D objects with chemically and mechanically distinct domains. The power of this approach is showcased through the one-step fabrication of bioinspired soft joints and mechanically reinforced "brick-and-mortar" structures.

123 citations


Journal ArticleDOI
TL;DR: This review presents several commonly used top-down nanofabrication techniques that have the potential to fabricate nanoparticles, including photolithography, interference lithography, electron beam lithographic, mold-based lithography (nanoimprint lithography and soft lithography), nanostencil lithographers, and nanosphere lithography.

115 citations


Journal ArticleDOI
TL;DR: A DNA-assisted lithography (DALI) method that combines the structural versatility of DNA origami with conventional lithography techniques to create discrete, well-defined, and entirely metallic nanostructures with designed plasmonic properties is reported.
Abstract: Programmable self-assembly of nucleic acids enables the fabrication of custom, precise objects with nanoscale dimensions. These structures can be further harnessed as templates to build novel materials such as metallic nanostructures, which are widely used and explored because of their unique optical properties and their potency to serve as components of novel metamaterials. However, approaches to transfer the spatial information of DNA constructions to metal nanostructures remain a challenge. We report a DNA-assisted lithography (DALI) method that combines the structural versatility of DNA origami with conventional lithography techniques to create discrete, well-defined, and entirely metallic nanostructures with designed plasmonic properties. DALI is a parallel, high-throughput fabrication method compatible with transparent substrates, thus providing an additional advantage for optical measurements, and yields structures with a feature size of ~10 nm. We demonstrate its feasibility by producing metal nanostructures with a chiral plasmonic response and bowtie-shaped nanoantennas for surface-enhanced Raman spectroscopy. We envisage that DALI can be generalized to large substrates, which would subsequently enable scale-up production of diverse metallic nanostructures with tailored plasmonic features.

111 citations


Journal ArticleDOI
TL;DR: A comprehensive review about the current research activities on colloidal lithography, a highly efficient technology for fabricating large-area patterned functional nanostructures is presented in this paper.

109 citations


Journal ArticleDOI
27 Dec 2018-ACS Nano
TL;DR: The orthogonal EBL technique is used to fabricate a 2D layered single-crystal featuring nanoscale patterned electrodes and superior photodetection ability with responsivity of 5.4 mA/W and detectivity of 1.07 × 1013 cm Hz1/2/W to fully enable the high-resolution, high-throughput fabrication of complex perovskite-based electronics in the near future.
Abstract: 3D organic–inorganic hybrid halide perovskites have attracted great interest due to their impressive optoelectronic properties. Recently, the emergence of 2D layered hybrid perovskites, with their excellent and tunable optoelectronic behavior, has encouraged researchers to develop the next generation of optoelectronics based on these 2D materials. However, device fabrication methods of scalable patterning on both types of hybrid perovskites are still lacking as these materials are readily damaged by the organic solvents in standard lithographic processes. We conceived the orthogonal processing and patterning method: Chlorobenzene and hexane, which are orthogonal to hybrid perovskites, are utilized in modified electron beam lithography (EBL) processes to fabricate perovskite-based devices without compromising their electronic or optical characteristics. As a proof-of-concept, we used the orthogonal EBL technique to fabricate a 2D layered single-crystal (C6H5C2H4NH3)2PbI4 photodetector featuring nanoscale p...

101 citations


Journal ArticleDOI
TL;DR: The efficient harvesting of electromagnetic (EM) waves by subwavelength nanostructures can result in perfect light absorption in the narrow or broad frequency range as discussed by the authors, and these metamaterial-based perfec...
Abstract: The efficient harvesting of electromagnetic (EM) waves by subwavelength nanostructures can result in perfect light absorption in the narrow or broad frequency range. These metamaterial-based perfec...

90 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate a new approach to construct 3D magnetic nanostructures of complex geometries using a combination of two-photon lithography and electrochemical deposition.
Abstract: Ferromagnetic materials have been utilized as recording media in data storage devices for many decades. The confinement of a material to a two-dimensional plane is a significant bottleneck in achieving ultra-high recording densities, and this has led to the proposition of three-dimensional (3D) racetrack memories that utilize domain wall propagation along the nanowires. However, the fabrication of 3D magnetic nanostructures of complex geometries is highly challenging and is not easily achieved with standard lithography techniques. Here, we demonstrate a new approach to construct 3D magnetic nanostructures of complex geometries using a combination of two-photon lithography and electrochemical deposition. The magnetic properties are found to be intimately related to the 3D geometry of the structure, and magnetic imaging experiments provide evidence of domain wall pinning at the 3D nanostructured junction.

88 citations


Journal ArticleDOI
23 Apr 2018
TL;DR: A number of challenging issues are waiting ahead, and further technological progresses are required to make the techniques significant and reliable to meet the current demand.
Abstract: Continuous rapid shrinking of feature size made the authorities to seek alternative patterning methods as the conventional photolithography comes with its intrinsic resolution limit. In this regard, some promising techniques have been proposed as next-generation lithography (NGL) that has the potentials to achieve both high-volume production and very high resolution. This article reviews the promising NGL techniques and introduces the challenges and a perspective on future directions of the NGL techniques. Extreme ultraviolet lithography (EUVL) is considered as the main candidate for sub-10-nm manufacturing, and it could potentially meet the current requirements of the industry. Remarkable progress in EUVL has been made and the tools will be available for commercial operation soon. Maskless lithography techniques are used for patterning in R&D, mask/mold fabrication and low-volume chip design. Directed self-assembly has already been realized in laboratory and further effort will be needed to make it as NGL solution. Nanoimprint lithography has emerged attractively due to its simple process steps, high throughput, high resolution and low cost and become one of the commercial platforms for nanofabrication. However, a number of challenging issues are waiting ahead, and further technological progresses are required to make the techniques significant and reliable to meet the current demand. Finally, a comparative study is presented among these techniques.

Journal ArticleDOI
24 Jan 2018
TL;DR: In this article, the authors demonstrate the nanofabrication of flexible plasmonic sensors comprising of gold nanocones achieved by nanoimprint lithography on polycarbonate (PC) sheets.
Abstract: We demonstrate the nanofabrication of flexible plasmonic sensors comprising of gold nanocones achieved by nanoimprint lithography on polycarbonate (PC) sheets. Thermal imprinting was performed consistently over a large area (roughly the size of a 6 in. wafer) with a batch process; this can be extended to a continuous process using UV roll-to-roll nanoimprinting. This provides a process to scale up the fabrication of continuous imprinted rolls of PC sheets at an optimal rate of 3–5 m/min. The geometry of the peaks and the valleys of the nanocones in the as-imprinted PC is defined by the nickel mold used during imprinting; however, the gaps between the nanocones are tailored by varying the thickness of the gold deposited onto the substrate. Two different thicknesses of gold were deposited to study the effect of geometry on plasmonic sensing. The resulting PC sheet with gold coating enables highly sensitive detection of analytes by Surface Enhanced Raman Spectroscopy (SERS) by virtue of plasmonic hotspots ge...

Journal ArticleDOI
TL;DR: In this paper, the influence of printing temperature on the properties of a printed dimethacrylate resin was investigated and the resulting tensile properties were tested, dynamic mechanical analysis was carried out and the double-bond conversion was analyzed.
Abstract: Vat photopolymerization is used for printing very precise and accurate parts from photopolymer resins. Conventional 3D-printers based on vat photopolymerization are curing resins with low viscosity at or slightly above room temperature. The newly developed Hot Lithography provides vat photopolymerization where the resin is heated and cured at elevated temperatures. This study presents the influence of printing temperature (23 °C and 70 °C) on the properties of a printed dimethacrylate resin. The working curve was measured for 23 °C, 50 °C and 70 °C. Specimens were printed in XYZ and ZXY orientation. The resulting tensile properties were tested, dynamic mechanical analysis was carried out and the double-bond conversion was analyzed. It was found that the critical energy E0 was significantly reduced by a higher printing temperature. Therefore, the exposure time was reduced from 50 s to 30 s to reach similar curing depth. Higher printing temperature provided higher double-bond conversion, tensile strength and modulus of the green parts. However, printing temperature did not affect the properties after post-curing in XYZ orientation. Post-cured tensile specimens in ZXY orientation had higher tensile strength when printed at 23 °C, because higher over-polymerization led to a smoother surface of the specimens. Overall, higher printing temperatures lowered the viscosity of the resin, reduced the printing time and provided better mechanical properties of green parts while post-cured properties were mostly not affected.

Journal ArticleDOI
TL;DR: The sensing capabilities of these nanopores are demonstrated by translocating dsDNA through pores fabricated using this method, and find signal-to-noise characteristics on par with transmission-electron-microscope-drilled nanopores.
Abstract: We report a simple and scalable technique for the fabrication of nanopore arrays on freestanding SiN and graphene membranes based on electron-beam lithography and reactive ion etching. By controlling the dose of the single-shot electron-beam exposure, circular nanopores of any size down to 16 nm in diameter can be fabricated in both materials at high accuracy and precision. We demonstrate the sensing capabilities of these nanopores by translocating dsDNA through pores fabricated using this method, and find signal-to-noise characteristics on par with transmission-electron-microscope-drilled nanopores. This versatile lithography-based approach allows for the high-throughput manufacturing of nanopores and can in principle be used on any substrate, in particular membranes made out of transferable two-dimensional materials.

Journal ArticleDOI
TL;DR: In this paper, a combination writing method was implemented to fabricate arrays of regular grooves with a well-defined wavelength of 30 nm, which was twice the feed value utilized, and checkerboard, diamond-shaped, and hexagonal nanodots were also fabricated.

Journal ArticleDOI
TL;DR: A novel high-efficiency, low-reflection, and fabrication-tolerant perfectly vertical grating coupler (PVGC) with a minimum feature size >200 nm to allow for fabrication using 193 nm deep-ultraviolet lithography.
Abstract: We propose a novel high-efficiency, low-reflection, and fabrication-tolerant perfectly vertical grating coupler (PVGC) with a minimum feature size >200 nm to allow for fabrication using 193 nm deep-ultraviolet lithography. The structural parameters of PVGC were optimized by a genetic optimization algorithm. Simulations predicted the coupling efficiency to be −2.0 dB (63.0%) and the back reflections to be less than −20 dB in the wavelength range of 1532–1576 nm. The design was fabricated in a multi-project wafer run for silicon photonics, and a coupling efficiency of −2.7 dB (53.7%) with a 1 dB bandwidth of 33 nm is experimentally demonstrated. The measured back reflection is less than −16 dB over the C-band. The PVGC occupies a compact footprint of 30 μm×24 μm and can be interfaced with the multi-core fibers for future space-division-multiplexing networks.

Journal ArticleDOI
TL;DR: A 3D nanofabrication method based on electron-beam lithography using ice resists (iEBL) and fabricate3D nanostructures by stacking layered structures and those with dose-modulated exposure, respectively is proposed and shows great potential in the fabrication of complicated 2D nanodevices.
Abstract: Three-dimensional (3D) nanofabrication techniques are of paramount importance in nanoscience and nanotechnology because they are prerequisites to realizing complex, compact, and functional 3D nanodevices. Although several 3D nanofabrication methods have been proposed and developed in recent years, it is still a formidable challenge to achieve a balance among resolution, accuracy, simplicity, and adaptability. Here, we propose a 3D nanofabrication method based on electron-beam lithography using ice resists (iEBL) and fabricate 3D nanostructures by stacking layered structures and those with dose-modulated exposure, respectively. The entire process of 3D nanofabrication is realized in one vacuum system by skipping the spin-coating and developing steps required for commonly used resists. This needs far fewer processing steps and is contamination-free compared with conventional methods. With in situ alignment and correction in the iEBL process, a pattern resolution of 20 nm and an alignment error below 100 nm can be steadily achieved. This 3D nanofabrication technique using ice thus shows great potential in the fabrication of complicated 3D nanodevices.

Journal ArticleDOI
TL;DR: In this article, a new nanolithography technique in which sample rotation is incorporated into zeroth-order waveguide mode interference lithography is proposed, where a 325-nm laser was used to excite the waveguide modes, which were loaded by an asymmetric metal-cladding dielectric waveguide structure.
Abstract: A new nanolithography technique in which sample rotation is incorporated into zeroth-order waveguide mode interference lithography is proposed in this report. A 325-nm laser was used to excite zeroth-order waveguide modes, which were loaded by an asymmetric metal-cladding dielectric waveguide structure. The optical field intensity distribution of zeroth-order waveguide modes interference is numerically simulated using the finite element method. The lithography sample consisted of a glass substrate, Al film, and photoresist film, and the rotation operation on the sample is expressed in coordinate matrix transformation. Various subwavelength structures, such as two-dimensional square lattices, two-dimensional hexagonal closed-packed lattices,and circular gratings, were obtained through double, triple, and continuous exposure. These subwavelength structures with different sizes can be produced by changing the thickness of the photoresist. The subwavelength structures simulated with various shapes and sizes can be applied to the field of nano-optics. The proposed technique provides a flexible and promising approach for interference nanolithography because of its simplicity and low cost.


26 Apr 2018
TL;DR: Thomsa et al. as discussed by the authors showed that the use of a backscattered electron image together with a metal coating where appropriate can yield better measurement results than by using secondary electrons.
Abstract: As optical lithography advances toward the 10 nm mark, much effort is being expended to push electron beam lithography into the deep sub-10-nm regime. A significant issue at this length scale is the ability to accurately measure and compare linewidths. Measurements using secondary electron micrographs have a bias of a few nanometers and are therefore difficult to interpret in the sub-10-nm regime. Transmission electron microscopy can give greater accuracy but requires significant effort. This article shows that the use of a backscattered electron image together with a metal coating where appropriate can yield better measurement results than by using secondary electrons. With the use of a suitable model, linewidths for sub-10-nm hydrogen silsesquioxane lines were extracted with an estimated error of 1 nm. © 2010 American Vacuum Society. DOI: 10.1116/1.3505129 Courtesy of S. Thomsa and D. S. Macintyre, University of Glasgow

Journal ArticleDOI
TL;DR: A novel multi-electrode design in which only one lithography step is necessary is provided, thereby offering a greatly simplified fabrication procedure compared to earlier proposed designs.
Abstract: Electrically tunable lenses offer the possibility to control the focal distance by applying an electric field. Different liquid crystal tunable lenses have been demonstrated. In order to minimize lens aberrations, multi-electrode designs allow us to fine-tune the applied voltages for every possible focal distance. In this Letter, we provide a novel multi-electrode design in which only one lithography step is necessary, thereby offering a greatly simplified fabrication procedure compared to earlier proposed designs. The key factor is the use of a high-permittivity layer, in combination with floating electrodes.

Journal ArticleDOI
TL;DR: Here it is demonstrated how the resolution of conventional stereolithographic machines can be improved by a direct programming of the laser path and can contribute to bridge the gap between the two above technologies, allowing the direct printing of features between 10 and 100 μm, corresponding to a large fraction of microfluidic applications.


Journal ArticleDOI
TL;DR: In this paper, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography.
Abstract: A novel fabrication method for high quality aspheric microlens array (MLA) was developed by combining the dose-modulated DMD-based lithography and surface thermal reflow process. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography. And the dose modulation mainly depends on the distribution of exposure dose of photoresist. Then the pre-shaped aspheric microlens is polished by a following non-contact thermal reflow (NCTR) process. Different from the normal process, the reflow process here is investigated to improve the surface quality while keeping the pre-modeled shape unchanged, and thus will avoid the difficulties in generating the aspheric surface during reflow. Fabrication of a designed aspheric MLA with this method was demonstrated in experiments. Results showed that the obtained aspheric MLA was good in both shape accuracy and surface quality. The presented method may be a promising approach in rapidly fabricating high quality aspheric microlens with complex surface.

Journal ArticleDOI
TL;DR: In this article, a 3D optical printer for tabletop gray-tone 3D printing was used for dynamic projection lithography, and the results show that naturally derived resins are suitable candidates for tabletop grey-tone printing.
Abstract: Recent advances in material engineering have shown that renewable raw materials, such as plant oils or glycerol, can be applied for synthesis of polymers due to ready availability, inherent biodegradability, limited toxicity, and existence of modifiable functional groups and eventually resulting to a potentially lower cost. After additional chemical modifications (epoxidation, acrylation, double bonds metathesis, etc.), they can be applied in such high-tech areas as stereolithography, which allows fabrication of three-dimensional (3-D) objects. “Autodesk’s” 3-D optical printer “Ember” using 405-nm light was implemented for dynamic projection lithography. It enabled straightforward spatio-selective photopolymerization on demand, which allows development of various photosensitive materials. The bio-based resins’ photosensitivity was compared to standard “Autodesk” “PR48” and “Formlabs” “Clear” materials. It turned out that the bioresins need a higher energy dose to be cured (a least 16 J · cm − 2 for a single layer varying from 100 to 130 μm). Despite this, submillimeter range 2.5-D structural features were formed, and their morphology was assessed by optical profilometer and scanning electron microscope. It was revealed that a higher exposition dose (up to 26 J · cm − 2) results in a linear increase in the formed structures height, proving controllability of the undergoing process. Overall, the provided results show that naturally derived resins are suitable candidates for tabletop gray-tone lithography.


Journal ArticleDOI
TL;DR: This work has synthesized iodinated acrylate monomers to formulate high-Z photoresist materials that are capable of forming 3D microstructures with sub-150 nm features and developed a formulation protocol to match the refractive index of the photoresists to the immersion medium of the objective lens so as to enable dip-in laser lithography, a direct laser writing technique for producing millimeter-tall structures.
Abstract: Two-photon lithography (TPL) is a high-resolution additive manufacturing (AM) technique capable of producing arbitrarily complex three-dimensional (3D) microstructures with features 2–3 orders of magnitude finer than human hair. This process finds numerous applications as a direct route toward the fabrication of novel optical and mechanical metamaterials, miniaturized optics, microfluidics, biological scaffolds, and various other intricate 3D parts. As TPL matures, metrology and inspection become a crucial step in the manufacturing process to ensure that the geometric form of the end product meets design specifications. X-ray-based computed tomography (CT) is a nondestructive technique that can provide this inspection capability for the evaluation of complex internal 3D structure. However, polymeric photoresists commonly used for TPL, as well as other forms of stereolithography, poorly attenuate X-rays due to the low atomic number (Z) of their constituent elements and therefore appear relatively transpare...

Journal ArticleDOI
TL;DR: In this paper, conventional photolithography and two-photon polymerization are combined for the first time to form a simple hybrid approach in fabricating master molds for soft lithography.
Abstract: Over the past decades, soft lithography has greatly facilitated the development of microfluidics due to its simplicity and cost-effectiveness. Besides, numerous fabrication techniques such as multi-layer photolithography, stereolithography and other methods have been developed to fabricate moulds with complex 3D structures nowadays. But these methods are usually not beneficial for microfluidic applications either because of low resolution or sophisticated fabrication procedures. Besides, high-resolution methods such as two-photon lithography, electron-beam lithography, and focused ion beam are often restricted by fabrication speed and total fabricated volume. Nonetheless, the region of interest in typical microfluidic devices is usually very small while the rest of the structure does not require complex 3D fabrication methods. Herein, conventional photolithography and two-photon polymerization are combined for the first time to form a simple hybrid approach in fabricating master moulds for soft lithography. It not only benefits from convenience of photolithography, but also gives rise to complex 3D structures with high resolution based on two-photon polymerization. In this paper, various tests have been conducted to further study its performance, and a passive micromixer has been created as a demonstration for microfluidic applications.

Journal ArticleDOI
TL;DR: An on-chip ultra-broadband PMA with almost 100% absorption spanned from UV-visible to NIR wavelength ranges is realized and would release the manufacturing barrier for previously reported PMAs and therefore open an avenue to the development of effectively energy harvesting, energy recycling, and heat liberation applications.
Abstract: The on-chip perfect meta-absorber (PMA) is an important optical and thermal energy component in photovoltaics, thermal emitters, and energy harvesting applications. However, most reported PMAs rely on the complicated lithography techniques, which imposed a serious cost barrier on the development of practical applications, especially in the visible to near-infrared (NIR) wavelength range and at very large scales. Importantly, it is hard to realize PMA in the UV wavelength range by using current lithography techniques. In this article, we develop an ultra-broadband PMA by using natural lithography (NL) technique. The morphology of proposed PMA is randomly distributed pod-like nanostructures composed of a nanocomposite (Au/SiO2) covered a gold layer. It can be formed easily on Si substrate to function as an ultra-broadband, omnidirectional, and polarization-independent PMA by controlling the conditions of sputtering deposition and thermal annealing treatment. We experimentally realized an on-chip ultra-broadband PMA with almost 100% absorption spanned from UV-visible to NIR wavelength ranges. This cost-effective and high-efficiency approach would release the manufacturing barrier for previously reported PMAs and therefore open an avenue to the development of effectively energy harvesting, energy recycling, and heat liberation applications.

Journal ArticleDOI
TL;DR: This work incorporates a composite high- k gate dielectric and an aligned conducting polymer gate electrode in the SCALE process to enable a smaller areal footprint than prior designs that yields low-voltage SWCNT TFTs with average p-type carrier mobilities of 4 cm2/V·s and ON/OFF current ratios of 104.5%.
Abstract: We present a self-aligned process for printing thin-film transistors (TFTs) on plastic with single-walled carbon nanotube (SWCNT) networks as the channel material. The SCALE (self-aligned capillarity-assisted lithography for electronics) process combines imprint lithography with inkjet printing. Specifically, inks are jetted into imprinted reservoirs, where they then flow into narrow device cavities due to capillarity. Here, we incorporate a composite high-k gate dielectric and an aligned conducting polymer gate electrode in the SCALE process to enable a smaller areal footprint than prior designs that yields low-voltage SWCNT TFTs with average p-type carrier mobilities of 4 cm2/V·s and ON/OFF current ratios of 104. Our work demonstrates the promising potential of the SCALE process to fabricate SWCNT-based TFTs with favorable I–V characteristics on plastic substrates.