UV-transparent Polymer Research Articles

Glass marking by laser transfer implantation (LTI) of plasmonic nanoparticles

Gold nanoparticles in the near surface volume of glass are generated by combining laser-induced forward transfer (LIFT) and laser implantation into one single laser process called laser transfer implantation (LTI). Nanosecond pulses of a KrF excimer laser at 248 nm wavelength are used to transfer and implant the material from a gold- coated, UV-transparent polymer film into soda lime, borofloat, and flint glasses. The process can be applied for marking glass with colored labels consisting of spectrally selectively absorbing plasmonic nanoparticles.

Microfabrication of the UV transparent polymer CYTOP using a conventional pulsed green laser

We report the surface microfabrication of CYTOP, an amorphous UV transparent fluoric polymer, using a conventional pulsed green laser. Fluorine-based polymers have unique characteristics, including high transparency from the deep-UV to the IR wavelengths, chemical stability and low refractive indices, and thus are expected to have a number of industrial applications. However, CYTOP and other fluoric polymers are generally very difficult to microfabricate. Therefore, we have developed a technique for the crack-free surface microfabrication of a CYTOP substrate based on ablation with a pulsed green laser followed by successive wet etching and annealing. In this work, the fundamental surface characteristics of the fabricated area were investigated. Following the surface microfabrication of CYTOP, a three-dimensional biochip was fabricated using a conventional bonding technique to demonstrate that a CYTOP biochip is superior to conventional transparent biochips with regard to the microscopic observation of cell motion.

Demonstration of a High Power, Wideband 220-GHz Traveling Wave Amplifier Fabricated by UV-LIGA

We present the first vacuum electronic traveling wave amplifier to incorporate an interaction circuit fabricated by ultraviolet (UV) photolithography and electroforming, demonstrating over 60 W of output power at 214.5 GHz from a 12.1 kV, 118 mA electron beam. The tube also achieved an instantaneous bandwidth of ${\sim}{\rm 15}~{\rm GHz}$ in $G$ -band in the small signal regime. The all-copper circuit was fabricated in two layers using a UV-transparent polymer monofilament embedded in the photoresist to form the beam tunnel prior to electroforming. Effects arising from fabrication errors and target tolerances are discussed. This microfabrication technique and demonstration paves the way for a new era of vacuum electron devices that could extend into the 1–2 THz range with advances in high-current-density electron guns.

Organic polymer composite random laser operating underwater

In this work, an organic composite polymer random laser (RL) operating underwater has been studied. The RL structure used in the test is a rod-shaped composite, formed by a mixture of an organic green light-emitting polymer and a UV transparent polymer matrix. RL action was sustained by both the multiple scattering and whispering-gallery-mode effect. The demonstration of RL action and the test of its operation lifetime in such an organic composite RL operating in water suggest the feasibility of its promising future applications in areas of underwater optical communications and/or remote optical sensing.

Model stream channel testing of a UV-transparent polymer-based passive sampler for ultra-low-cost water screening applications

Passive samplers are increasingly being considered for analyses of waters for screening applications, to monitor for the presence of unwanted chemical compounds. Passive samplers typically work by accumulating and concentrating chemicals from the surrounding water over time, allowing analyses to identify temporally short concentration surges that might be missed by water grab samples, and potentially reducing analysis and sample handling costs, allowing a greater number of sites to be monitored. The work described here tests a recently-developed passive sampling device which was designed to provide an ultra-low-cost screening method for organic chemicals in waters. The device was originally designed for detection of endocrine disrupting chemicals, but has the advantage that it is capable of simultaneously detecting a wide range of other aqueous organic contaminants as well. The device is based on a UV-transparent polymer which is used both to concentrate dissolved chemicals, and as an optical cell for absorbance detection and full-spectrum deconvolution to identify compounds. This paper describes the results of a test of the device conducted at the US EPA Experimental Stream Facility in Milford, Ohio. The test examined detection of triclosan and 4-nonylphenol in model stream channels using two different deployment methods. Results indicate that deployment method can significantly impact measured results due to differences in mass transfer. Passive samplers deployed in vials with permeable membrane septa showed no detection of either compound, likely due to lack of water motion in the vials. In contrast, passive samplers deployed directly in the flow were able to track concentrations of both compounds, and respond to temporal changes in concentration. The results of the work highlight the importance of using internal spiking standards (performance reference compounds) to avoid false non-detection results in passive sampler applications.

UV waveguides light fabricated in fluoropolymer CYTOP by femtosecond laser direct writing

We have fabricated optical waveguides inside the UV-transparent polymer, CYTOP, by femtosecond laser direct writing for propagating UV light in biochip applications. Femtosecond laser irradiation is estimated to increase the refractive index of CYTOP by 1.7 x 10(-3) due to partial bond breaking in CYTOP. The waveguide in CYTOP has propagation losses of 0.49, 0.77, and 0.91 dB/cm at wavelengths of 632.8, 355, and 266 nm, respectively.

Gamma Ray Scintillators via BaF2:Ce Nanopowders

Nano-scale BaF2:Ce phosphor powders (“nanophosphors”) show great potential for improving the functioning of inorganic scintillators for gamma ray detectors. These particles may offer greater ef ciency and ease of manufacture than most state-of-the-art single crystal scintillators currently in use. Chemical precipitation similar to that of LaF3: Ce synthesis was used to prepare the BaF2:Ce powders, while care was taken to optimize doping levels to prevent internal absorption while maximizing photon production. Select particle samples were then encapsulated in a polymer matrix in an attempt to improve mechanical robustness while maintaining photon yield. Results from photoluminescence excitation and emission measurements of samples of BaF2: Ce powders doped from 1-30mol% suggest that the BaF2:15mol%Ce sample exhibited the greatest photon production, but that a more UV transparent polymer must be found in order to maximize light transmission when the powder is encapsulated in a polymer matrix.

Selective cell culture on UV transparent polymer by F 2 laser surface modification

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F 2 laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F 2 laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

Fluorinated ethylenepropylene copolymer as a potential capillary material in CE

In this work, a new generation UV-transparent polymer, fluorinated ethylenepropylene copolymer (FEP) exhibiting a low degree of crystallinity, extruded in dimensions similar to the most commonly used CE capillaries of approximately 80 mum id and about 360 mum od was investigated for its use as a CE capillary. FEP is transparent down to the low-UV region, and as fluorinated polymers in general are good electrical insulators and exhibit reasonable heat conductivity, it has considerable potential as a material for electrodriven analysis in capillary or microchip formats. The FEP capillary has been characterised with regard to some important aspects for its use as a CE capillary, including its profile of EOF versus pH, as well as procedures for manipulating EOF by coating the inner capillary wall with various semipermanent and dynamic layers. The FEP capillaries were tested and compared with fused-silica capillary for the separation of inorganic and small organic ions using conditions involving direct and indirect detection in the low-UV region. Finally, advantages of the use of the FEP capillary for simultaneous detection of a mixture containing nine inorganic cations and anions using indirect photometric detection with a movable light-emitting diode (LED) detector and a novel electrolyte are demonstrated.

Fabrication of microchip based on UV transparent polymer for DNA electrophoresis by F2 laser ablation

A microchip for DNA electrophoresis made of a new UV transparent polymer material (CYTOP) whose absorption edge is much shorter than 190 nm has been fabricated by F2 laser ablation. F2 laser ablation achieves high-quality microfabrication of CYTOP surface with little deterioration of the optical property and little debris deposition at etched area. The microchip in which the microchannel connected with two reservoirs was embedded was successfully fabricated by bonding the ablated sample to the virgin CYTOP sheet. The fabricated microchip was applied for DNA analysis by electrophoresis and succeeded in separating different base-pares (bp) of DNA from 50 to 766 bp with resolution of 100 bp.

Analysis of ethoxylated polymers by capillary electrophoresis in UV-transparent polymer networks and by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

This report describes the application of capillary electrophoresis (CE) in UV-transparent polymer solutions to the separation of poly(ethylene glycol)s and ethoxylated surfactants. Polymer networks of dextran and polyethylene oxide provide size selectivity in these separations. These ethoxylates were derivatized prior to CE analysis with 1,2,4-benzenetricarboxylic anhydride (BTA) to impart charge and detectability on the neutral polymer. The utilization of a polymer network with low UV absorbtion at 210 nm permits the detection of the ethoxylates with high sensitivity at this wavelength. Migration time was found to be linearly dependent on analyte molecular mass. The results obtained by capillary electrophoresis (CE) are compared with those obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and the off-line coupling of these techniques is described.

Solar UVB dosimetry by amplification of short and long segments in phage lambda DNA.

DNA UVB dosimeters, consisting of minidots of dried bacteriophage DNA placed on a UV-transparent polymer film, were analyzed by polymerase chain reactions (PCR). Ultraviolet-B dosimetry obtained with amplification of phage lambda DNA of segments of 1.08 kilobase pairs (kbp) and 2.24 kbp was compared with that obtained with amplification of a 0.5 kbp segment (H. Yoshida and J. D. Regan, 66, 82-88, Photochem. Photobiol. 1997). The number of lesions in each segment induced by UV radiation is proportional to the size of the amplified segments; thus, the average lesion frequency per unit dose was greatest in the 2.24 kbp and least in the 0.5 kbp segment. The average lesion frequency per unit dose was approximately 3.5 x 10(-2) and approximately 11.9 x 10(-2) m2 kJ-1 for 1.08 kbp and 2.24 kbp, respectively, compared to that for 0.5 kbp of approximately 1.7 x 10(-2) m2 kJ-1 at 50 ng DNA. Dependability of DNA dosimeters, containing 50 ng and 100 ng, was tested by placing the DNA dosimeters for a time period of either 1 or 2 days outdoors on 8-12 January at Melbourne, FL. The daily dose was obtained directly with amplification of the 2.24 kbp segment and the 2 day continuous dose was obtained with amplification of the 1.08 kbp segment. Although the average lesion frequencies were different, both 50 ng and 100 ng DNA dosimeters provided about the same UVB dose, equivalent to the dose applied with a solar UVB simulator. The total UVB dose for 4 days obtained by amplification of the 1.08 and 2.24 kbp segments was 19.4-20.8 kJ m-2, which is within experimental error with the 4 day continuous dose obtained with 0.5 kbp segments. The average daily dose obtained by 0.5 kbp and 1.08 kbp agreed with the average daily dose directly obtained with 2.24 kbp.

UVB DNA dosimeters analyzed by polymerase chain reactions.

Purified bacteriophage lambda DNA was dried on a UV-transparent polymer film and served as a UVB dosimeter for personal and ecological applications. Bacteriophage lambda DNA was chosen because it is commercially available and inexpensive, and its entire sequence is known. Each dosimeter contained two sets of DNA sandwiched between UV-transparent polymer films, one exposed to solar radiation (experimental) and another protected from UV radiation by black paper (control). The DNA dosimeter was then analyzed by a polymerase chain reaction (PCR) that amplifies a 500 base pair specific region of lambda DNA. Photoinduced damage in DNA blocks polymerase from synthesizing a new strand; therefore, the amount of amplified product in UV-exposed DNA was reduced from that found in control DNA. The average lesion frequency per 500 base pair per strand at 16 PCR cycles was approximately 1.22, 1.00, 0.70 and 0.50 for 30 ng, 50 ng, 100 ng and 150 ng of dried DNA, respectively, after a total dose of 60 kJ m(-2) delivered with a solar UVB simulator. Although the average lesion frequency increases linearly with increasing doses for four different amounts of template DNA, the lesion frequency seems to be averaged by the amplified products from the protected lambda DNA molecules below the top few layers. The average daily dose, equivalent to the UV dose applied with the solar UVB simulator was 10.2 +/- 0.4 kJ m(-2) with the 50 ng containing DNA dosimeter in September 1995 in Melbourne, FL. Both 50 ng and 150 ng containing DNA dosimeters produced the same average daily dose within experimental error in January 1996, which was 5.2 +/- 0.3 kJ m(-2) at the same location. The dried lambda DNA dosimeter is compact, robust, safe and transportable, stable over long storage times and provides the total UVB dose integrated over the exposure time.

High-performance capillary electrophoresis of SDS-protein complexes using UV-transparent polymer networks.

This paper demonstrates the use of UV-transparent replaceable polymer networks for the separation of SDS-protein complexes on the basis of molecular weight. First, the use of linear (i.e. non-cross-linked) polyacrylamide is shown to provide molecular separation of SDS-protein complexes. A study reveals such columns to yield significantly greater lifetime than cross-linked gels because of the flexibility of the noncovalently attached polymer chains. However, column lifetime was still found to be limited (approximately 20-40 injections), and detection at 214 nm was problematical because of the absorbance of polyacrylamide. UV-transparent polymer networks of dextran and PEG were substituted for polyacrylamide with successful molecular weight sieving of SDS-protein complexes at 214 nm. Due to their low to moderate viscosities, these networks could be routinely replaced leading to the possibility of hundreds of injections with a single column. Migration time reproducibilities of 0.5% RSD or less were found with replacement of the network. Using dextran, calibration plots of peak area vs concentration of standard protein were linear over the range of 0.5 microgram/mL up to at least 0.25 mg/mL. Furthermore, plasma samples could be directly utilized because of the strong solvating power of SDS. Rapid separation of protein mixtures are demonstrated with these UV-transparent polymer networks.