Negative Photoresist Materials Research Articles

A Realizable Green Strategy to Negative Polyurethane Photoresists through the Application of a Silicone Resin Photoinitiator

In order to realize the recycling of negative photoresist materials, four thioxanthone silicone resin photoinitiators (TXSRs) were prepared and used in the preparation of a polyurethane acrylate (P...

Studying the impact of depth of focus on 3D profile of negative photoresist material: a simulation approach

For quality patterning of microstructures, it is essential that all process parameters are optimized to ensure well-developed 3D profile of the resist. Advances in direct laser lithography have provided maskless and rapid prototyping methods of manufacturing microstructures. Among all other process parameters, the quality of the patterned structure is critically affected by the depth of focus adjustments of the laser spot. In this study, a simulation approach is adopted and the LAB Module of GenISys lithography simulation software is implemented to determine the optimum depth of focus for negative photoresist material. Modeling and studying straight-line structure at different focusing depths at constant exposure dosages is carried out in this work. At the constant dosage of 45 mJ/cm2, the 15 µm depth of focus yields the best quality for the 3D resist profile.

Manufacturing and Characterization of Femtosecond Laser-Inscribed Bragg Grating in Polymer Waveguide Operation in an IR-A Wavelength Range

Optical sensors, such as fiber Bragg gratings, offer advantages compared to other sensors in many technological fields due to their outstanding characteristics. This sensor technology is currently transferred to polymer waveguides that provide the potential for cost-effective, easy, and flexible manufacturing of planar structures. While sensor production itself, in the majority of cases, is performed by means of phase mask technique, which is limited in terms of its degrees of freedom, other inscription techniques enable the manufacture of more adaptable sensor elements for a wider range of applications. In this article, we demonstrate the point-by-point femtosecond laser direct inscription method for the processing of polymer Bragg gratings into waveguides of the epoxy-based negative photoresist material EpoCore for a wavelength range around 850 nm. By characterizing the obtained grating back-reflection of the produced sensing element, we determined the sensitivity for the state variables temperature, humidity, and strain to be 45 pm/K, 19 pm/%, and 0.26 pm/µε, respectively. Individual and more complex grating structures can be developed from this information, thus opening new fields of utilization.

Maskless Lithography Using Negative Photoresist Material: Impact of UV Laser Intensity on the Cured Line Width

The application of maskless lithography technique on negative photoresist material is investigated in this study. The equipment used in this work is designed and built especially for maskless lithography applications. The UV laser of 405 nm wavelength with 0.85 Numerical Aperture is selected for direct laser writing. All the samples are prepared on a glass substrate. Samples are tested at different UV laser intensities and different stage velocities in order to study the impact on patterned line width. Three cases of spin coated layers of thickness 90 μm, 40 μm, and 28 μm on the substrate are studied. The experimental results show that line width has a generally increasing trend with intensity. However, a decreasing trend was observed for increasing velocity. The overall performance shows that the mr-DWL material is suitable for direct laser writing systems.

ALA-induced fluorescence detection with photoresist-based microfluidic cell sorter for bladder cancer diagnosis

We present a photoresist-based microfluidic fluorescence-activated cell sorter (μFACS) for bladder cancer diagnosis and assess its potential for clinical application. In the developed μFACS system, bladder cancer cells in urine sediment are detected using aminolevulinic acid (ALA)-based fluorescence detection, and then sorted at the Y-junction of the microchannel using an off-chip pinch valve. Once cancer cells are collected, they can be analyzed using polymerase chain reaction (PCR) for detailed gene alteration analysis. Generally, time and cost-effective advantages of negative photoresist material and fabrication technologies have been widely pronounced; however, autofluorescence is a significant drawback when negative photoresist is used as a structural material for μFACS applications. To achieve sensitive fluorescence detection, autofluorescence in the detection area is minimized by thinning the photoresist cover layer of the microchannel and inclining the optical angle of the detection system. Through system calibrations and clinical tests using urine sediments, our experimental results demonstrate a combination of ALA-based photodynamic diagnostic tests using μFACS systems and subsequent PCR analysis is a promising diagnostic approach for bladder cancer.

Emerging trends in precision fabrication of microapertures to support suspended lipid membranes for sensors, sequencing, and beyond

Suspended lipid membranes, also called black lipid membranes (BLMs), are an important model system that approximates the lipid bilayer environment of cell membranes. Increasingly, BLMs are utilized in sensing strategies that harness high sensitivity measurements of ion flux across the membrane, typically facilitated by ion channel proteins. BLMs are suspended across microapertures that connect two otherwise isolated fluidic compartments, and the precision fabrication of such microapertures can contribute to the stability and performance of the resulting BLM. Here, we highlight two emerging trends in the precision fabrication of microapertures for BLM formation: microfabrication in silicon-based thin film substrates, and microfabrication in the negative photoresist material SU-8. Four unique fabrication strategies are outlined, and we project the impact that these microfabrication strategies will have for BLM-integrated bioanalytical technologies.

355nm UV 레이저를 이용한 마이크로 렌즈 어레이 쾌속 제작에 관한 연구

Micro lens array(MLA) is widely used in information technology(IT) industry fields for various applications such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method having the processes of micro etching, electroplating, micro machining and laser local heating. Laser thermal relaxation method is introduced in marking of microdots on the surface of densified glass. In this paper, we have proposed a new direct fabrication process using UV laser local thermal-expansion(UV-LLTE) and investigated the optimal processing conditions of MLA on the surface of negative photo-resist material. We have also studied the 3D shape of the micro lens obtained by UV laser irradiation and the optimal process conditions. And then, we made chrome mold by electroplating. After that, we made MLA using chrome mold by hot embossing processing. Finally, we have measured the opto-physical properties of micro lens and then have also tested the possibility of MLA applications.

Synthesis, Characterization and Photocrosslinking Properties of Poly(1‐(4‐Methacrylamidophenyl)‐1‐(4‐nitrophenyl)prop‐1‐en‐3‐one)

The phenylmethacrylamide monomer, 1‐(4‐methacrylamidophenyl)‐1‐(4‐nitrophenyl)prop‐1‐en‐3‐one (MPNP) containing a photosensitive group was synthesized by reacting 4‐nitrocinnamoylaniline with methacryloyl chloride in the presence of triethylamine at 0–5°C. The functional monomer, MPNP was polymerized in ethyl methyl ketone (EMK) under nitrogen atmosphere at 70°C using benzoyl peroxide (BPO) as the initiator. The synthesized polymer was characterized by UV, IR, 1H‐NMR and 13C‐NMR spectroscopy. The molecular weight data of the polymer as obtained from gel permeation chromatography suggests a higher tendency for chain termination by radical recombination than disproportionation. The thermal studies of the polymer were obtained from thermogravimetric analysis. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The solubility of the polymer was tested in various organic solvents at room temperature. The photosensitivity of the polymer was investigated in various solvents in the presence and absence of triplet photosensitizers. The effect of the different solvents nature and concentration on the rate of photocrosslinking of the polymer were also examined for using the polymer as negative photoresist materials.

Synthesis and characterization of new photoresponsive acrylamide polymers having pendant chalcone moieties

New acrylamide monomers, 4-acrylamidophenyl-2′,3′-benzostyryl ketone (APBSK) and 4-acrylamidophenyl-4′- N, N′-dimethylstyryl ketone (APDSK) having a free-radical polymerizable group and a photocrosslinkable functional group, were synthesized by reacting the corresponding aminochalcones with acryloyl chloride in the presence of triethyl amine. The monomers were polymerized in methyl ethyl ketone at 70 °C using benzoyl peroxide as the initiator. The resulting polymers were characterized by UV, IR, 1H NMR and 13C NMR spectroscopy. The polymers were found to be soluble in several polar aprotic solvents and in chlorinated solvents but insoluble in aliphatic and aromatic hydrocarbons and in alcohols. The molecular weight data of the polymers as obtained from gel permeation chromatography suggests a higher tendency for chain termination by dimerization than disproportionation. The glass transition temperature of the polymers was determined by differential scanning calorimetry. Thermogravimetric analysis of the polymers carried out in air reveals that the polymers possess good thermal and thermo-oxidative stability required of a negative photoresist. The photosensitivity of the polymer was investigated in various solvents in the presence and absence of triplet photosensitizers. The effect of the different solvents and concentration on the rate of photocrosslinking of the polymers were also examined for using the polymers as negative photoresist materials.

Synthesis, characterization and photocrosslinking properties of polyacrylamides having bromo substituted pendant cinnamoyl moieties

New 3- and 4-bromocinnamoyl aniline were synthesized condensing 4-aminoacetophenone and the respective bromobenzaldehydes in the presence of sodium hydroxide. The monomers, 4-(3′-bromocinnamoyl) phenyl acrylamide (4,3′-BCPA) and 4-(4′-bromocinnamoyl) phenyl acrylamide (4,4′-BCPA) were prepared by reacting the respective chalcones and acryloyl chloride in the presence of triethylamine at 0–5 °C. Homopolymers of 4,3′-BCPA and 4,4′-BCPA was carried out in methyl ethyl ketone using benzoyl peroxide (BPO) under nitrogen atmosphere at 70 °C. The prepared polymers were characterized by UV, IR, 1H-NMR and 13C-NMR techniques. The molecular weights ( M w and M n) of the polymers were determined by gel permeation chromatography. The thermogravimetric analysis (TGA) of the polymers in nitrogen atmosphere reveals that they possess very good thermal stability required of a negative type photoresist. The glass transition temperature of poly(4,3′-BCPA) and poly (4,4′-BCPA) were found to be 55 and 64 °C respectively. The solubility of the polymers was tested in various polar and non-polar solvents. Photocrosslinking nature of the polymer samples was carried out in the presence and absence of various triplet photosensitizers in solution phase using chloroform solvent under medium frequency UV light. For using the polymers as negative photoresist materials the rate of photocrosslinking of the polymers was measured under the influence of different solvents, concentrations and position of the substituent.

Studies on photocrosslinkable polymers having bromo-substituted pendant cinnamoyl group

New methacrylate monomers having a pendant photocrosslinkable bromo-substituted cinnamoyl group were synthesized by reacting corresponding hydroxy chalcones with methacryloyl chloride. These monomers were homopolymerized in ethyl methyl ketone solution using benzoyl peroxide as a free radical initiator at 70 °C. The resulting polymers were characterized by UV, Fourier transform infrared, 1H-nuclear magnetic resonance (NMR) and 13C-NMR spectroscopy as well as by size-exclusion chromatography. Thermal properties of the photoreactive polymers were assessed by thermogravimetric analysis and differential scanning calorimetry. The photocrosslinking properties of the polymers were investigated in various solvents in the presence and absence of photosensitizers. The influence of solvent nature and concentration on the rate of photocrosslinking of the newly synthesized polymers were studied for using the latter as negative photoresist materials.

Image diffusion and cross-talk in passive matrix electrochromic displays

A passive matrix electrochromic display (ECD) working in transparent or reflective mode is described. In this paper, we report the main reasons of image diffusion and cross-talk in passive matrix ECD and initial computer simulation results of the 7×7 matrix display. These suggest that the insulation of electrolyte under each pixel and threshold (nonlinearity) of coloration current can in practice completely eliminate the image diffusion and cross-talk. The matrix addressed ECD based on solid polymer electrolyte and two complementary electrodes, (WO 3+0.1TiO 2, TiO 2–0.25CeO 2), in which all pixels were insulated by negative photoresist material was elaborated. An additional protected thin film (0.2Li 2O–0.2CeO 2–0.6SiO 2) deposited on working electrode was used to provide the enhanced threshold effect. The ECD exhibited excellent memory effect and substantially free from image diffusion and cross talk effects.

New photosensitive polymers as negative photoresist materials

New methacrylate photosensitive polymers containing pendent chalcone moieties were prepared by radical polymerization of vinyl–chalcone monomers in anhydrous toluene and tetrahydrofuran. The monomers and the polymers were characterized by UV, FT-IR, 1H-NMR, and 13C-NMR spectra. The average molecular weights of the polymers were determined by gel permeation chromatography. The thermal stability of the polymers was measured by thermogravimetric analysis under a nitrogen atmosphere. The photosensitivity of the polymers was investigated in solution. The effect of solvent, copolymer types, copolymer ratios and concentrations on the rate of photocrosslinking of the polymers were also studied.