We present a novel optical sensor platform designed for the detection of medical biomarkers. The sensor operates by utilizing reflection variation resulting from the modification of Fano resonance conditions. By fabricating one- and two-dimensional subwavelength quasi-periodic structures made of polymer and coated with an inorganic layer, we enable the functionality of the sensor, ultimately leading to increased sensitivity and detection threshold. The development of the sensor’s platform involves a multi-step process. The detection mechanism primarily relies on the optical response of the biosensor. The presence of analytes induces a spectral shift of the Fano resonance, which is caused by the modification of the biolayer thickness. This optical sensor platform holds significant potential for the detection of a variety of medical biomarkers, including analytes related to various pathogenes, cancer biomarkers, and others.
In this work we presents effect of ultra high pressure annealing on Si-implanted GaN n-type and p-type epilayers on ammonothermally grown bulk GaN substrates. Samples were blanked implanted with different Si ion fluences from 3x1014 cm-2 to 3x1015 cm-2 and then annealed using UHPA at temperature of 1200, 1300 and 1400°C for 5 minutes at 1 GPa. Ion distribution before and after annealing where investigated using SIMS method showing no Si diffusion in p-type GaN along with Mg diffusion from epilayer and very low Si diffusion in n-type GaN epilayers. X-ray diffraction studies shows that not all defects were recovered after annealing, especially for high ion fluences. Annealing at 1400°C causes changes in implanted GaN morphology. The surface roughness where increased after annealing especially for samples implanted with 3x1015 cm-2Si dose. Our results shows that more work is needed to optimize UHPA parameters for defect recovery in Si-implanted GaN especially for high ion fluences.
Low angle bevelled-mesa structures are crucial for development of high quality GaN p-n high voltage diodes and photodetectors. However, there is lack of details of development of such a process in the literature. Here in this work, we present results of optimization of bevelled mesa fabrication process for vertical GaN p-n diodes using plasma etching through photoresist mask prepared using reflow process. Developed process of formation of low angle bevelled mesa structures was integrated in the vertical GaN p-n diodes on bulk GaN substrates fabrication process. Very low leakage current density below 10-9 A/cm2 and very high Ion/Ioff current ratio over 1013 was obtained. Low values of ideality factor down to 1.5 were obtained as well. These prove applicability of developed process in technology of vertical GaN p-n diodes on bulk gallium nitride substrates.
Fast and non-invasive screening test based on electrochemical detection of structural proteins of SARS-CoV-2 was developed. The measurement being the basis of the test is carried out in a standard three-electrode system, in which the working electrode is covered by bioreceptors immobilized on its surface by durable covalent bonding, ensuring specificity of the detection of desired analyte present in the sample. The carried out measurements allowed for detection of given protein of SARS-CoV-2 in standardized buffered samples and in samples containing virus-like particles. The estimated detection limit of the biosensor does not exceed 10^5 copies of the virus per milliliter.
We present a fibre optic biosensor for SARS-CoV-2 detection based on the lossy-mode-resonance (LMR) [6] effect, generated in a single-mode fibre with a thinned cladding and coated by thin-film dielectric with appropriately selected optical properties and thickness. The detection of selected viral structural proteins in the tested sample is ensured by specific bioreceptors. As a result of the interaction with the SARS-CoV-2 antigen, optical response in the short-wave-IR range is observed, and the detection limit does not exceed 1.3*10^2 copies/ml, when converted to the viral load concentration - sufficiently for virus detection even in the first days after infection.
In this work, new graphene-based screen-printed electrodes are proposed as a new, cheaper alternative to more common electrodes for determination of dopamine. Electrodes were designed, manufactured and tested to look for correlations between different graphene weight percentages used in electrodes and oxidation peaks and sensitivity in dopamine determination. All electrodes were tested using cyclic voltammetry. For a reference, graphite electrodes were tested. With sensitivity of 0.0161 μA/μM and detection limit of 5.549 μM those electrodes showed potential promise in use of graphene for electrode material. In electrodes manufacturing, Laroflex and PMMA based vehicles were mixed in with graphene platelets with diameters ranging over 2 μm and thickness between 8-15 nm. Initial tests with electrodes screen printed with graphene layers of 150 μM showed very low response. 0.0077 μA/μM sensitivity and 11.970 μM detection limit were achieved with Laroflex based electrodes. Further testing with thicker layers gave more impressive results with detection limit going as low as 1.349 μM and 0.1343 μA/μM sensitivity. Such results bring those electrodes to comparable level with other electrodes available.
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