Browsing by Subject "Infrared absorption spectroscopy"

Now showing 1 - 4 of 4

Open Access
Bio-insprired optoelectronic digital nose for breath analysis
(2011) Bayındır, Mehmet; Yıldırım, Adem; Yaman, Mecit; Vural, Mert
A novel electronic nose device is presented that can be used in disease diagnostics by exhaled breath analysis. Exhaled breath contains more than a thousand organic compounds that can be analysed to insect various diseases and metabolic activity. The novel device is an electronic nose, based on photonic bandgap fibers that can selectively guide infrared radition inside a hollow core plastic fiber. Instead of a laser line source, a broadband balackbody source is used that exploits the filtering/ guiding properties of the fibers to scan the whole mid-infrared region, making it high selectivity of volatile organic compounds possible. In addition waveguiding inside the fiber enhances the electromagnetic radiation intensity, resulting in improved infrared absorption cross-section. The fiber electronic nose can be integrated and deployed as a portable electronics device to point-of-care institutes.
Open Access
Novel miniaturized sensors for on-site biological and chemical detection
(2016-08) Güner, Hasan
The development of miniaturized analytical systems brought several examples of novel platforms for a variety of applications in medical diagnostics, food safety, biodefense, agricultural and environmental monitoring. Portability, sensitivity, reliability, short turn-around-time, cost-effciency and connectivity are some of the critical assets that successful devices should possess. The advancements in such areas enabled the detection and analysis of biological and chemical agents outside the laboratory settings. In this thesis, we focus on the development of miniaturized sensor designs for on-site biological and chemical detection utilizing surface plasmon resonance sensing and infrared absorption spectroscopy. We proposed an integrated refractometric sensor combining a grating-coupled plasmon resonance surface with a planar photodiode which can find applications in lab-on-a-chip designs with high integration density. In order to address the use of lab-on-a-chip systems in point-of-care testing applications, we have developed a surface plasmon resonance imaging platform integrated with a smartphone. We have fabricated low cost and sensitive grating coupled surface plasmon resonance sensor chips using of-the-shelf optical storage discs. Then we have experimentally shown the capability of multiplexed detection and biomolecular sensing. Finally, we demonstrated infrared absorption spectroscopy on a mobile phone by developing a compact mid-infrared spectrometer that hosts a miniature uncooled thermal camera and a custom-designed silicon transmission diffraction grating.
Open Access
Thermally tunable ultrasensitive infrared absorption spectroscopy platforms based on thin phase-change films
(American Chemical Society, 2016-11) Bakan, G.; Ayas S.; Ozgur E.; Celebi, K.; Dana, A.
The thermal tunability of the optical and electrical properties of phase-change materials has enabled the decades-old rewritable optical data storage and the recently commercialized phase-change memory devices. Recently, phase-change materials, in particular, Ge2Sb2Te5 (GST), have been considered for other thermally configurable photonics applications, such as active plasmonic surfaces. Here, we focus on nonplasmonic field enhancement and demonstrate the use of the phase-change materials in ultrasensitive infrared absorption spectroscopy platforms employing interference-based uniform field enhancement. The studied structures consist of patternless thin GST and metal films, enabling simple and large-area fabrication on rigid and flexible substrates. Crystallization of the as-fabricated amorphous GST layer by annealing tunes (redshifts) the field-enhancement wavelength range. The surfaces are tested with ultrathin chemical and biological probe materials. The measured absorption signals are found to be comparable or superior to the values reported for the ultrasensitive infrared absorption spectroscopy platforms based on plasmonic field-enhancement.
Open Access
Universal infrared absorption spectroscopy using uniform electromagnetic enhancement
(American Chemical Society, 2016) Ayas S.; Bakan, G.; Ozgur E.; Celebi, K.; Dana, A.
Infrared absorption spectroscopy has greatly benefited from the electromagnetic field enhancement offered by plasmonic surfaces. However, because of the localized nature of plasmonic fields, such field enhancements are limited to nanometer-scale volumes. Here, we demonstrate that a relatively small, but spatially uniform field enhancement can yield a superior infrared detection performance compared to the plasmonic field enhancement exhibited by optimized infrared nanoantennas. A specifically designed CaF2/Al thin film surface is shown to enable observation of stronger vibrational signals from the probe material, with wider bandwidth and a deeper spatial extent of the field enhancement as compared to such plasmonic surfaces. It is demonstrated that the surface structure presented here can enable chemically specific and label-free detection of organic monolayers using surface-enhanced infrared spectroscopy, indicating a great potential in highly sensitive yet cost-effective biomolecular sensing applications.