Stephen E. Swiontek

Optical sensing of analytes in aqueous solutions with a multiple surface-plasmon-polariton-wave platform

The commonly used optical sensor based on surface plasmon-polariton wave phenomenon can sense just one chemical, because only one SPP wave can be guided by the interface of a metal and a dielectric material contained in the sensor. Multiple analytes could be detected and/or the sensing reliability for a single analyte could be enhanced, if multiple SPP-wave modes could be excited on a single metal/dielectric interface. For that to happen, the partnering dielectric material must be periodically non-homogeneous. Using a chiral sculptured thin film (CSTF) as that material in a SPP-wave platform, we show that the angular locations of multiple SPP-wave modes shift when the void regions of the CSTF are infiltrated with a fluid. The sensitivities realized in the proof-of-concept experiments are comparable to state-of-research values.

Quality of development of latent sebaceous fingerprints coated with thin films of different morphologies

A new technique to develop a latent sebaceous fingerprint for visualization requires the macroscopically conformal deposition of a columnar thin film on top of the fingerprint. In order to correlate the thin-film morphology to the quality of development, dense thin films as well as films comprising either upright or tilted nanocolumns were deposited on multiple samples of the same fingerprint from a donor. According to an objective grading scheme, films with upright nanocolumns provided the best development while dense films provided the worst development.

Wideband-rejection filters and reflection-hole filters of chalcogenide glass for circularly polarized IR-A and IR-B radiation

Compact infrared filters—either to reject infrared radiation of a specific circular-polarization state in a wide band or to transmit the same radiation in a narrow band—for the IR-A and IR-B spectral regimes were designed and fabricated by thermal evaporation of chalcogenide glass of nominal composition Ge28Sb12Se60 in a vacuum chamber.

Comparison of Quantifiler® Trio and InnoQuant™ human DNA quantification kits for detection of DNA degradation in developed and aged fingerprints

The development techniques employed to visualize fingerprints collected from crime scenes as well as post-development ageing may result in the degradation of the DNA present in low quantities in such evidence samples. Amplification of the DNA samples with short tandem repeat (STR) amplification kits may result in partial DNA profiles. A comparative study of two commercially available quantification kits, Quantifiler(®) Trio and InnoQuant™, was performed on latent fingerprint samples that were either (i) developed using one of three different techniques and then aged in ambient conditions or (ii) undeveloped and then aged in ambient conditions. The three fingerprint development techniques used were: cyanoacrylate fuming, dusting with black powder, and the columnar-thin-film (CTF) technique. In order to determine the differences between the expected quantities and actual quantities of DNA, manually degraded samples generated by controlled exposure of DNA standards to ultraviolet radiation were also analyzed. A total of 144 fingerprint and 42 manually degraded DNA samples were processed in this study. The results indicate that the InnoQuant™ kit is capable of producing higher degradation ratios compared to the Quantifiler(®) Trio kit. This was an expected result since the degradation ratio is a relative value specific for a kit based on the length and extent of amplification of the two amplicons that vary from one kit to the other. Additionally, samples with lower concentrations of DNA yielded non-linear relationships of degradation ratio with the duration of aging, whereas samples with higher concentrations of DNA yielded quasi-linear relationships. None of the three development techniques produced a noticeably different degradation pattern when compared to undeveloped fingerprints, and therefore do not impede downstream DNA analysis.

Surface plasmonic polaritonic sensor using a dielectric columnar thin film

Abstract. The propagation of a surface plasmon polariton (SPP) wave can be guided by the interface of a metal and a columnar thin film (CTF). Theory predicts that the angle of incidence on the prism/metal interface in the Turbadar–Kretschmann–Raether prism-coupled configuration required to excite the SPP wave shifts upon infiltration of the CTF by a fluid. Otherwise identical CTFs of different thicknesses were partnered with dense thin films of aluminum in optical experiments. The angle of incidence for exciting the SPP wave was found to shift to a higher value each time the CTF was infiltrated by a fluid of refractive index of increasing value. Experimental data indicated that the sensor offers a state-of-research sensitivity, thereby proving that a CTF can be a useful platform for SPP-wave-based optical sensing.

Influence of silver-nanoparticle layer in a chiral sculptured thin film for surface-multiplasmonic sensing of analytes in aqueous solution

Abstract. Multiple surface-plasmon-polariton (SPP) waves at a single free-space wavelength can be guided by the interface of a metal and a chiral sculptured thin film (STF). Multilayers comprising a chiral STF of lanthanum fluoride deposited on an aluminum thin film deposited on a glass substrate were fabricated. In some chips, a 5-nm-thick layer of silver nanoparticles was deposited at one of two selected depths in the chiral STF. The chips were then deployed in a prism-coupled configuration in a custom-built machine for surface multiplasmonic resonance imaging (SMPRI), in order to observe the effects of the silver-nanoparticle layer on the multiple SPP-wave modes. The angular locations of the SPP-wave modes were found to be not greatly dependent on whether the silver-nanoparticle layer was deposited after the first or the second period of a three-periods-thick chiral STF. With aqueous solutions of sucrose as infiltrant fluids, the angular shifts of the SPP-wave modes were determined as the refractive index of the infiltrant fluid increased. The use of a charge-coupled devices camera and upgraded motion-control equipment for SMPRI was found to increase the sensitivity of the chip. The silver-nanoparticle layer was also found to enhance the sensitivity.

Simpler Mass Production of Polymeric Visual Decoys for the Male Emerald Ash Borer (AgriAgrilus planipennis)

Polymeric visual decoys of beetle of an invasive species called the Emerald Ash Borer (EAB), Agrilus planipennis, are highly efficacious in luring and trapping EAB males. Although industrially scalable, the bioreplication process to fabricate these decoys involves several operational steps. In a simpler bioreplication process devised by us, a multi-cavity negative die of nickel is made from an array of several EAB females. This die is used to fabricate multiple decoys simultaneously by casting and thermal curing of poly(dimethyl siloxane). Finally, the decoys are sprayed by first a black paint and then a metallic green paint. The new bioreplication process has considerably fewer operational steps than its predecessor and can be adopted by industry.

Enhancement of Dynamic Sensitivity of Multiple Surface-plasmonic-polaritonic Sensor Using Silver Nanoparticles

Multiple surface plasmon-polariton (SPP) waves excited at the interface of a homogeneous isotropic metal and a chiral sculptured thin film (STF) impregnated with silver nanoparticles were theoretically assessed for the multiple-SPP-waves-based sensing of a fluid uniformly infiltrating the chiral STF. The Bruggemann homogenization formalism was used in two different modalities to determine the three principal relative permittivity scalars of the silver-nanoparticle-impregnated chiral STF infiltrated uniformly by the fluid. The dynamic sensitivity increased when silver nanoparticles were present, provided their volume fraction did not exceed about 1 %.

Generation of DNA profiles from fingerprints developed with columnar thin film technique.

Partial-bloody fingerprints and partial fingerprints with saliva are often encountered at crime scenes, potentially enabling the combination of fingerprint and DNA analyses for absolute identification, provided that the development technique for fingerprint analysis does not inhibit DNA analysis. 36 partial-bloody fingerprints and 30 fingerprints wetted with saliva, all deposited on brass, were first developed using the columnar-thin-film (CTF) technique and then subjected to short tandem repeat (STR) DNA analysis. Equal numbers of samples were subjected to the same DNA analysis without development. Tris (8-hydroxyquinolinato) aluminum, or Alq3, was evaporated to deposit CTFs for development of the prints. DNA was extracted from all 132 samples, quantified, and amplified with AmpFlSTR(®) Identifiler Plus Amplification Kit. Additionally, DNA analyses were conducted on four blood smears on un-fingerprinted brass that had been subjected to CTF deposition and four blood smears on un-fingerprinted brass that had not been subjected to CTF deposition. Complete and concordant autosomal STR profiles of the same quality were obtained from both undeveloped and CTF-developed fingerprints, indicating that CTF development of fingerprints preserves DNA and does not inhibit subsequent DNA analysis. Even when there were no fingerprints, CTF deposition did not lead to inhibition of DNA analysis.

High-resolution topograms of fingerprints using multiwavelength digital holography

Abstract. Fingerprint analysis is a popular identification technique due to the uniqueness of fingerprints and the convenience of recording them. The quality of a latent fingerprint on a surface can depend on various conditions, such as the time of the day, temperature, and the composition of sweat. We first developed latent fingerprints on transparent and blackened glass slides by depositing 1000-nm-thick columnar thin films (CTFs) of chalcogenide glass of nominal composition Ge28Sb12Se60. Then, we used transmission-/reflection-mode multiwavelength digital holography to construct the topograms of CTF-developed fingerprints on transparent/blackened glass slides. The two wavelengths chosen were 514.5 and 457.9 nm, yielding a synthetic wavelength of 4.1624  μm, which is sufficient to resolve pores of depths 1 to 2  μm. Thus, our method can be used to measure the level-3 details that are usually difficult to observe with most other techniques applied to latent fingerprints.