Traditional lithography processes use resist materials that require organic solvents during the development step but also often contain components derived from PFASs (per- and polyfluoroalkyl substances), raising concerns about environmental pollution and sustainability. PFASs are difficult to degrade, and their long-term effects on ecosystems and human health are the subject of international concern, making the development of alternative technologies an urgent priority. Lithography is a fundamental technology with applications beyond semiconductor manufacturing, electronics, biomedicine, and microfluidic devices. Addressing its environmental impact remains critical in both academic and industrial contexts. This study introduces a water-developable positive photoresist derived from a polymeric material incorporating plant-derived sugar chains as the resist backbone. The reactivity of the material to ultraviolet irradiation, enabled by a photoacid generator, allows microfabrication through water development. Moreover, successful micrometer-scale patterning demonstrated a superior resolution compared to previous sugar-derived water-developable resists. The dextrin-based resist exhibited the highest performance, achieving a sensitivity of 150 mJ/cm2 and a resolution of 3.6 µm under an environmentally benign, PFAS-free process that enabled development with water. These findings propose a sustainable alternative to conventional petrochemical-derived photoresists, positioning it as a promising candidate for environmentally friendly photolithography processes.

Low-melting bioabsorbable polymers, such as poly(caprolactone-co-lactide) (PCLA), hold significant promise for biomedical applications. However, achieving high-precision micro- and nanotopographical functionalization remains a formidable challenge due to the material's susceptibility to thermal deformation during conventional thermal molding processes. In this study, functional microstructured PCLA coatings were engineered via low-temperature nanoimprint lithography utilizing a TiO2-SiO2 gas-permeable mold. These molds were synthesized via a sol-gel method utilizing titanium dioxide and silicon precursors. The gas-permeable nature of the mold facilitated the efficient evacuation of trapped air and volatiles during the imprinting process, enabling the high-fidelity replication of microstructures (1.3 mu m height, 3 mu m pitch) and nanostructured PCLA coatings featuring linewidths as narrow as 600 nm. The resultant microstructured PCLA coatings demonstrated modulated surface wettability, evidenced by an increase in water contact angles from 70.1 degrees to 91.4 degrees, and exhibited enhanced FD4 elution kinetics. These results confirm morphology-driven functionalities, specifically hydrophobicity and controlled release capabilities. Collectively, these findings underscore the efficacy of this microfabrication approach for polycaprolactone-based materials and highlight its potential to catalyze the development of high-value-added biomaterials for advanced medical and life science applications. This study establishes a foundational framework for the practical deployment of next-generation bioabsorbable materials and is anticipated to drive innovation in precision medical manufacturing.

Transdermal drug delivery minimizes pain and provides a controlled, stable release of drugs, but its effectiveness is limited by the skin’s natural barriers. Microneedles overcome this problem, enabling minimally invasive drug delivery. Microneedle patches (MNPs) with 80 µm-tall needles composed of hyaluronic acid (HA) were developed and evaluated for their formability, structural integrity, dissolution rate, skin penetration ability, and drug transmission capacity. The influence of the molecular weight of HA on these properties was also investigated. MNPs made from low-molecular-weight HA (30 kDa–50 kDa) demonstrated 12.5 times superior drug permeability in ex vivo human skin compared to needleless patches (NLPs). Furthermore, in the same test, low-molecular-weight HA MNPs had 1.7 times higher drug permeability than high-molecular-weight HA MNPs, suggesting superior transdermal administration. The molecular weight of HA significantly influenced its solubility and permeability, highlighting the potential effectiveness of MNPs as drug delivery systems. Puncture tests demonstrated a penetration depth of 50–60 µm, indicating minimal nerve irritation in the dermis and effective drug delivery to the superficial dermal layer. These results present a manufacturing technique for MNPs incorporating model drug compounds and highlight their potential as a novel and minimally invasive drug delivery method for the biomedical applications of soft gels.

Nanoimprint lithography, a technique within microfabrication, continues to progress due to its ability to pattern large areas with high resolution, efficiency, and cost-effectiveness. Among its variants, UV nanoimprint lithography offers rapid curing through UV light and exceeds thermal nanoimprint lithography in terms of the throughput. However, UV nanoimprint lithography often traps air during the imprinting process and molds made from non-gas-permeable materials such as quartz and metal can result in molding defects. In this study, a new TiO2-SiO2 radical-based gas-permeable mold surface material was developed using the sol-gel method to enhance ultraviolet-based nanoimprint lithography for precise processing. Compared to existing material, this surface material exhibited superior performance in terms of both gas permeability and mechanical properties, with oxygen gas permeability 1.2 times higher, carbon dioxide gas permeability 1.3 times higher, and flexural strength 1.1 times higher than those of existing material. Based on these performance enhancements, the microfabrication demonstrated superior transfer accuracy compared to master molds with specifications of (a) pitch: 20 mu m, height: 17.1 mu m, bottom diameter: 7.14 mu m, and (b) pitch: 50 mu m, height: 17.0 mu m, bottom diameter: 7.14 mu m, achieving (a) height 99.9%, bottom diameter 99.0%, and (b) height 99.8%, bottom diameter 94.1%. Additionally, these gas-permeable molds facilitated high-precision fine processing on the surface of lactic acid-glycolic acid copolymers, reaching (a) bottom diameter of 95.3% and (b) 93.7%, respectively. The findings from this study will advance precision processing technology, improve the accuracy of fine processing in machine tools, and enhance production efficiency. This is particularly anticipated to aid the development of advanced production systems in sectors such as medical devices, semiconductor manufacturing, optical components, and microfluidic devices, thereby promoting future industrial growth.

Water-developable photoresist was synthesized by introducing methacrylate groups into hydroxypropyl cellulose (HPC), a cellulose derivative, via substitution of hydroxyl groups. The material enabled micropatterning through ultraviolet (UV) exposure at a wavelength of 365 nm with an exposure dose of 450 mJ/cm2. Line and dot micropatterns were formed on polypropylene substrates applying underlayer, achieving resolutions of 4.5 µm and 5.0 µm, respectively. The photoresist demonstrated superior etching resistance under CF4 plasma compared to another water-soluble photo resist. Unlike conventional photoresists that require hazardous organic solvents, this water-developable photoresist offers an environmentally friendly alternative, reducing health risks and environmental impact in the electronics industry.

Polylactic acid (PLA), a biodegradable material derived from renewable sources, has been challenging to fabricate through injection molding, owing to its narrow crystallization range and poor heat resistance. Conventional injection molding also encounters difficulties with gas venting in the cavity, which impedes microscale processing. This study successfully performed micro-injection molding of standard PLA under typical conditions. Using an amine-containing gas-permeable hybrid molds, PLA microstructures measuring 1.2 mu m in height and 2.7 mu m in base diameter were successfully molded, demonstrating high moldability. This study established the viability of micro-injection molding for PLA and may provide an important foundation for the future development of micro-surface fabricated devices made of PLA in the biomedical field, such as blood coagulation prevention medical devices based on microfabrication

We attempted to perform surface microfabrication of the bioabsorbable material lactic acid–glycolic acid copolymer (LG-80) using a micro-imprint lithography technique with a gas-permeable porous mold at less than 5 °C. As a result, high-resolution surface micromachining with a height of 1.26 μm and a pitch of 2.97 μm was achieved using a convex sapphire mold with a height of 1.3 μm and a pitch of 3 μm. After processing, the LG-80 exhibited high water repellency, and FT-IR analysis of the surface showed no significant change in its chemical structure, confirming that the surface microfabrication was successful, while retaining the properties of the material. This demonstrated new possibilities for surface microfabrication technology for bioabsorbable materials, which are expected to be applied in the medical and life science fields in products such as surgical implants, tissue regeneration materials, and cell culture scaffold materials. In particular, the use of micro-imprint lithography enables low-cost and high-precision processing, which will be a major step toward the practical application of bioabsorbable materials.

In this study, water-developable photoresist materials capable of fine patterning were developed by imparting photosensitive groups to a molecule made from hemicellulose arabinoxylan extracted from corn bran, which were fabricated by UV exposure at 365 nm and 45 J/cm(2). The surface topography of the photoresist pattern developed with water was observed to be approximately 0.46 mu m. The etching resistance was improved in the photoresist material made from hemicellulose arabinoxylan compared with other water-soluble polymers. The development of water-developable photoresist materials derived from hemicellulose is expected to reduce environmental impact. In addition to the electronics field, where photoresist materials have been used in the past, applications in the medical field and biosystems are also expected since the material is derived from biomass.

Microneedles are of great interest in diverse fields, including cosmetics, drug delivery systems, chromatography, and biological sensing for disease diagnosis. Self-dissolving ultrafine microneedles of pure sodium hyaluronate hydrogels were fabricated using a UV-curing TiO2-SiO2 gas-permeable mold polymerized by sol-gel hydrolysis reactions in nanoimprint lithography processes under refrigeration at 5 °C, where thermal decomposition of microneedle components can be avoided. The moldability, strength, and dissolution behavior of sodium hyaluronate hydrogels with different molecular weights were compared to evaluate the suitability of ultrafine microneedles with a bottom diameter of 40 μm and a height of 80 μm. The appropriate molecular weight range and formulation of pure sodium hyaluronate hydrogels were found to control the dissolution behavior of self-dissolving ultrafine microneedles while maintaining the moldability and strength of the microneedles. This fabrication technology of ultrafine microneedles expands their possibilities as a next-generation technique for bioactive gels for controlling the blood levels of drugs and avoiding pain during administration.

In tissue engineering and regenerative medicine, scaffold micropatterning plays an essential role in reproducing the microscopic cellular environment and cell-cell interactions. This study provides a novel molding process for surface microfabricaion of 100% pure fish-derived collagen without the use of photoinitiators, which can be cytotoxic, by low-temperature molding at 5℃ using nanoimprint lithography. TiO2-SiO2 gas-permeable porous mold was used to fabricate collagen micropatterns, which can improve gas entrapment during molding, one of the challenges in nanoimprint lithography. The excellent gas permeability of TiO2-SiO2 gas-permeable porous mold enabled fine patterning with a height of 80 μm and a bottom diameter of 40 μm without molding defects for a collagen solution containing 40 wt% water. FT-IR spectral measurements revealed that low-temperature drying at 5℃ during microfabrication to the collagen surface had almost no effect on the collagen components. This molding process, which does not require chemical modification of collagen and does not cause protein denaturation even at molding temperatures of 5℃, has the potential to be widely used as a next-generation medical application technology in the fields of tissue engineering and regenerative medicine.

In this study, UV-curing gas-permeable mold material was developed that can improve gas entrapment during fabricating, which is a challenge in nanoimprint lithography (NIL). An advanced nanofabrication technology that hybridizes the high-resolution of NIL with the mass productivity of injection molding has enabled nanofabrication of polypropylene with a height of 300 nm and a base diameter of 240 nm. This technology enables nanofabrication of plastics with short cycle times, and is expected to create functional surfaces such as antibacterial through nanofabrication.

Conventional photoresist materials are generally coated and developed using organic solvents, but the water-soluble photoresist material in this study can be coated and developed using water. Patterning of water-soluble photoresist material on PMMA, which was contaminated or damaged by the organic coating solvent and developer in the conventional photoresist material, resulted in the fabrication of 6 µm holes and 3 µm lines. The water-based coating and development process is expected to contribute to biomaterial applications and environmental impact.

In tissue engineering and regenerative medicine, scaffold micropatterning plays an essential role in reproducing the microscopic cellular environment and cell-cell interactions. This study provides a novel molding process for surface micro fabricaion of 100% pure fish derived collagen without the use of photo initiators, which can be cytotoxic, by low temperature molding at 5 degrees C using nanoimprint lithography. TiO2-SiO2 gas-permeable porous mold was used to fabricate collagen micropatterns, which can improve gas entrapment during molding, one of the challenges in nanoimprint lithography. The excellent gas permeability of TiO2-SiO2 gas-permeable porous mold enabled fine patterning with a height of 80 mu m and a bottom diameter of 40 mu m without molding defects for a collagen solution containing 40 wt% water. FT-IR spectral measurements revealed that low-temperature drying at 5 degrees C during microfabrication to the collagen surface had almost no effect on the collagen components. This molding process, which does not require chemical modification of collagen and does not cause protein denaturation even at molding temperatures of 5 degrees C , has the potential to be widely used as a next-generation medical application technology in the fields of tissue engineering and regenerative medicine.

Cationic gas-permeable molds fabricated via sol–gel polymerization undergo cationic polymerization using epoxide, resulting in gas permeability owing to their cross-linked structures. By applying this cationic gas-permeable mold to nano-injection molding, which is used for the mass production of resins, nano-protrusion structures with a height of approximately 300 nm and a pitch of approximately 400 nm were produced. The molding defects caused by gas entrapment in the air and cavities when using conventional gas-impermeable metal molds were improved, and the cationic gas-permeable mold could be continuously fabricated for 3000 shots under non-vacuum conditions. The results of the mechanical evaluations showed improved thermal stability and Martens hardness, which is expected to lead to the advanced production of resin nano-structures. Furthermore, the surface roughness of the nano-protrusion structures fabricated using injection molding improved the water contact angle by approximately 46°, contributing to the development of various hydrophobic materials in the future.

Our research aimed to develop a bioabsorbable material, a mixed compound of polyglycolic acid and polylactic acid, by surface nanopatterning using thermal imprinting technology and utilize it for life science and medical applications. Bioabsorbable materials such as polyglycolic acid and polylactic acid are one of the most difficult materials to surface nanofabricate in terms of melting point and flowability. Therefore, gas generated during processing was allowed to permeate through a porous cyclodextrin-based gas -permeable mold, and surface nanopatterning with a projection height of 1-2 mu m and a pitch of 1.24 mu m was successfully performed. Surface nanopatterning at a thermal imprint firing temperature of 50 degrees C is expected to enhance the surface modification of bioabsorbable materials, which may be used in a wide range of applications.

Photoresist materials are also used in semiconductor manufacturing and have excellent properties for fine processing. In recent years, lithography technology has enabled microscopic processing. Among them, photoresist materials, which are also used in semiconductor manufacturing, are attracting attention for their potential to contribute to the development of biosensors, bioelectronics, and biotechnology in the life science field. However, photoresist materials use organic compounds in the casting solvent and developing solution, which raises concerns about environmental protection and health and safety. Therefore, it has been difficult to apply them to the life science field. In this study, we used amylose and amylopectin sugar chains to create a photoresist material that can be developed in water without using organic compounds. This material is characterized by its ability to be applied and developed with water and processed without the use of organic compounds. The photoresist patterns were fabricated and surface shapes were observed, achieving a fine fabrication of approximately 8 µm.

This study presents the development of photolithography employing biomass-based resist materials derived from polyglucuronic acid. Traditional resist materials require coating and developing procedures involving organic solvents, whereas our approach enables the use of water-based spin-coating and developing processes. The water-soluble biomass resist material, derived from polyglucuronic acid, exhibited exceptional photosensitivity at an exposure wavelength of 365 nm and a dose of approximately 90 mJ/cm2. We successfully patterned the microstructures, creating 3 µm lines and 6 µm holes. This organic solvent-free coating process underscores its applicability in scenarios such as in the microfabrication on plastic substrates with limited organic solvent tolerance and surface-patterning biomaterials containing cells and culture components.

Biomimetic antibacterial nanostructures with a height of approximately 310 nm and a bottom diameter of approximately 240 nm were fabricated by microinjection molding for practical mass production in the fields of biology, electronic engineering, and life science. The gas-permeable hybrid mold fabricated by nanoimprint lithography was used as the mold for microinjection molding to improve the incomplete filling and molding defects caused by gas entrainment in cavities during microinjection molding. One same mold could be used repeatedly without cleaning for 200 injection molding cycles. Antibacterial activity evaluation showed that that the antibacterial activity of the fabricated biomimetic antibacterial nanostructures was 15% greater than that of a flat surface. This work establishes the advanced processing technology of high-resolution nanostructures by microinjection molding with the gas-permeable hybrid mold.

Fluorine materials exhibit excellent properties, such as high water repellency, low adhesion, and chemical resistance, owing to their low surface energy. They also exhibit high thermal and oxidation stability owing to the strength of the C–F bonds. Recently, in the field of life science, further improvement of the low adherence and antifouling properties of biological substances and microorganisms by imparting surface properties to fluorine materials through pattern fabrication technology has attracted considerable attention. However, fluorine materials exhibit high thermal expansion and contraction, making it difficult to apply fabrication methods, such as injection molding and hot embossing. Conventional focused ion beam and laser processing are difficult for further pattern fabrication. Here, an ultraviolet (UV)-curable material with a high fluorine content (44wt%) was created, and the pattern fabrication of 80-nm line structures was performed on the material by UV nanoimprint lithography using the gas-permeable template that can permeate the gas entrained during pressurization. The water contact angle was 127.3°, with 129.7° being the most favorable, achieved by a combination of the water-repellency characteristics of the UV-curable material with high fluorine content and fine line patterning in the nanometer range. We discovered the possibility of creating surface functions on short-chain perfluoroalkyl sulfonate (PFAS) substitutes with a relatively low impact on the environment and human body by establishing a pattern fabrication method for long-chain PFAS, which is more difficult to pattern fabricate, as a preliminary experiment.