The identification of body fluids including blood, saliva, urine, sweat, semen, and vaginal fluid can be a vital evidence that can be used to identify a suspect and reconstructing the criminal case. Since the amount of evidence in the crime site is limited, a multiplex identification system for body fluid using a small amount of sample is prepared. In this research, we proposed a multiplex detection platform for semen and vaginal fluid, which were important for sexual crime using an Ag vertical nanorod metal enhanced fluorescence (Ag-MEF) substrate. The Ag-MEF substrate with a length of 500 nm was fabricated by glancing angle deposition and the Amin functionalization was conducted to improve the binding ability. The effect of incubation time was analyzed and an incubation time of 60 min was selected where the fluorescence signal was saturated. To examine the performance of the developed identification chip, an identification of the semen and virginal fluid was carried out. The developed sensor can selectively identify the semen and virginal fluid without any cross reaction. In addition, the limit of detection for semen was 10 times lower than that of the commercially available RSID-Semen kit.
Fluorescence based detection is a commonly used methodology in biotechnology and medical diagnostics. Metalenhanced fluorescence (MEF) becomes a promising strategy to improve the sensitivity of fluorescence detection, where fluorophores coupling with surface plasmon on metallic structures results fluorescence enhancement. To apply the MEF methodology in real medical diagnostics, especially for protein or DNA microarray detection, a large area (e.g., slide glass, 75 × 25 mm2) with uniform metallic nanostructures is required. In this study, we fabricated a large area MEF substrates using oblique angle deposition (OAD), which is a single step, inexpensive large area fabrication method of nanostructures. To optimize the morphological effect, Ag-nanorods with various lengths were fabricated on the conventional slide glass substrates. Streptavidin-Cy5 dissolved in buffer solution with different concentration (100ng/ml ~ 100μg/ml) were applied to MEF substrates using a pipette, and the fluorescence signals were measured. The enhancement factor increased with the increase in length of Ag-nanorods and maximum enhancement factor ~ 91x was obtained from Ag-nanorods 750nm length compare to bare glass due to higher surface Plasmon effect.
The development of many photonic devices, such as photonic integrated circuit, optical sensors, and photovoltaic devices, demands low-cost and reliable fabrication technologies to fabricate sub-wavelength features. Here, we report a programmable nanoreplica molding process, which is capable of producing photonic devices with a variety of submicrometer patterns. The process utilizes a stretchable plastic mold to generate the desired periodic pattern using a UVcurable polymer on plastic substrates. During the replica molding process, a uniaxial force is applied to the mold and results in changes of the periodic structure, which locates on the surface of the mold. The geometry of the replicated pattern, including the lattice constant and arrangement, is determined by the magnitude and direction of the force. As an example, we present a plasmonic crystal device with surface plasmon resonances carefully tuned by using the uniaxial force. This unique process offers an inexpensive route to generate various periodic nanostructures rapidly.
Replicated polydimethylsiloxane (PDMS) micro/nanostructures are widely used in various research fields due to their inexpensiveness, flexibility, low surface energy, good optical properties, biocompatibility, chemical inertness, high durability, and easy fabrication process. However, the application of PDMS micro/nanostructures is limited when an accurate pattern shape or position is required because of the shrinkage that occurs during the PDMS curing process. In this study, we analyzed the effects of processing parameters in the PDMS replication process on the shrinkage of the final structure. Although the shrinkage can be decreased by decreasing the curing temperature, this reduction also increases the unnecessary curing time. To minimize the inherent shrinkage in the PDMS replica without an accompanying curing time increase, we propose a PDMS replication process on a high modulus substrate (glass and polymer films) with compression pressure, in which the adhesion force between the substrate and the PDMS, and the compression pressure prevent shrinkage during the curing process. Using the proposed method, a PDMS replica with less than 0.1% in-plane and vertical shrinkage was obtained at a curing temperature of 150°C and a curing time of 10 min.
A bilayer wire grid polarizer composed of UV-replicated nanograting and deposited aluminum layer was designed,
fabricated and evaluated for a simpler and less costly reflective polarizer. An electroformed nickel stamp was fabricated
using a lithographed photo resist master pattern having a nanograting with a pitch of 80 nm, a line width of 50 nm, and a
height of grating of 100 nm. A polymer grating was fabricated by the UV replication process and an aluminum layer
with a thickness of 50 nm was deposited by electron-beam evaporation. To examine the performance of the fabricated
bilayer wire-grid polarizer, the transmission spectra of TM- and TE-polarized light, and the extinction ratio spectra were
measured and compared with the simulated values obtained from the rigorous coupled wave analysis. The measured TMtransmittance
and extinction ratio of the fabricated bilayer wire grid polarizer were ~ 40 % and ~ 103 in whole visible
ranges, respectively.
The microlens array is often used for increasing coupling efficiency in vertical cavity surface emitting lasers (VCSELs) to fiber coupling system. Among the various methods to couple VCSEL module with microlenses, a monolithic lithography integration is regarded as better candidate because the process is simple and suitable for mass production. In addition, one can avoid additional assembly process. In the present study, a microlens array with a lens diameter of 40mm and focal length of 150mm was designed to couple a single mode VCSEL array and optical fibers, and tolerance analysis was carried out. A microlens array for VCSEL to fiber coupling was integrated by a UV-transparent mold and a monolithic lithography integration system which utilizes micro UV-molding. Finally, the geometrical properties of the integrated microlens array and the insertion loss of VCSEL to fiber coupling was measured and analyzed.
An experimental method is presented to maximize the replication quality of UV-molded micro-optical components. It is important to maximize the replication quality to obtain the replicated micro-optical components with the desired properties by accurate control of the shape. We suggest a simple technique to avoid micro air bubbles. The effects of the UV-curing dose and the compression pressure on the replication quality of UV-molded structures are examined experimentally. Finally, as a practical application of the process design method, microlens arrays with diameters between 30 and 230 μm were fabricated by the presented method, and the replication quality and the optical properties of the replicated microlens are measured and analyzed.
An experimental method is presented to maximize the replication quality of UV-molded micro-optical components. It is important to maximize the replication quality, because one can obtain the replicated micro-optical components with desired properties by accurate control of the shape. In the present study, a simple technique to avoid micro-air bubbles was first suggested. The effects of the UV-curing dose and the compression pressure on the replication quality of UV-molded structure were examined experimentally. Finally, as a practical application of the process design method, micro-lens arrays with diameters between 8μm and 230μm were fabricated by the present method, and the replication quality and the optical properties of the replicated micro-lens were measured and analyzed.
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