38 results found
Kim J, Yeatman E, Thompson A, 2021, Plasmonic optical fiber for bacteria manipulation—characterization and visualization of accumulation behavior under plasmo-thermal trapping, Biomedical Optics Express, Vol: 12, Pages: 3917-3933, ISSN: 2156-7085
In this article, we demonstrate a plasmo-thermal bacterial accumulation effect usinga miniature plasmonic optical fiber. Combined action of far-field convection and a near-fieldtrapping force (referred to as thermophoresis)—induced by highly localized plasmonicheating—enabled large-area accumulation of Escherichia coli. The estimated thermophoretictrapping force agreed with previous reports, and we applied speckle imaging analysis to mapthe in-plane bacterial velocities over large areas. This is the first time that spatial mapping ofbacterial velocities has been achieved in this setting. Thus, this analysis technique providesopportunities to better understand this phenomenon and to drive it towards in vivo applications.
Kim JA, Wales DJ, Yang GZ, 2020, Optical spectroscopy for in vivo medical diagnosis — A review of the state of the art and future perspectives, Progress in Biomedical Engineering, Vol: 2
When light is incident to a biological tissue surface, combinations of optical processes occur, such as reflection, absorption, elastic and non-elastic scattering, and fluorescence. Analysis of these light interactions with the tissue provides insight into the metabolic and pathological state of the tissue. Furthermore, in vivo diagnosis of diseases using optical spectroscopy enables in situ rapid clinical decisions without invasive biopsies. For in vivo scenarios, incident light can be delivered in a highly localized manner to tissue via optical fibers, which are placed within the working channels of minimally invasive clinical tools, such as endoscopes. There has been extensive development in the accuracy and specificity of these optical spectroscopy techniques since the earliest in vivo examples were published in the academic literature in the early ‘90s, and there are now commercially available systems that have undergone medical and clinical trials. In this review, several types of optical spectroscopy techniques (elastic optical scattering spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and multimodal spectroscopy) for the diagnosis and monitoring of diseases states of tissue in an in vivo setting are introduced and explored. Examples of the latest and most impactful works for each technique are then critically reviewed. Finally, current challenges and unmet clinical needs are discussed, followed by future opportunities, such as point-based spectroscopies for robot-guided surgical interventions.
Kassanos P, Berthelot M, Kim JA, et al., 2020, Smart sensing for surgery from tethered devices to wearables and implantables, IEEE Systems Man and Cybernetics Magazine, Vol: 6, Pages: 39-48, ISSN: 2333-942X
Recent developments in wearable electronics have fueled research into new materials, sensors, and microelectronic technologies for the realization of devices that have increased functionality and performance. This is further enhanced by advances in fabr ication methods and printing techniques, stimulating research on implantables and the advancement of existing medical devices. This article provides an overview of new designs, embodiments, fabrication methods, instrumentation, and informatics as well as the challenges in developing and deploying such devices and clinical applications that can benefit from them. The need for and use of these technologies across the perioperative surgical-care pathway are highlighted, along with a vision for the future and how these tools can be adopted by potential end users and health-care systems.
Kim JA, Wales D, Thompson A, et al., 2020, Fiber-optic SERS probes fabricated using two-photon polymerization for rapid detection of bacteria, Advanced Optical Materials, Vol: 8, Pages: 1-12, ISSN: 2195-1071
This study presents a novel fiber-optic surface-enhanced Raman spectroscopy (SERS) probe (SERS-on-a-tip) fabricated using a simple, two-step protocol based on off-the-shelf components and materials, with a high degree of controllability and repeatability. Two-photon polymerization and subsequent metallization was adopted to fabricate a range of SERS arrays on both planar substrates and end-facets of optical fibers. For the SERS-on-a-tip probes, a limit of detection of 10-7 M (Rhodamine 6G) and analytical enhancement factors of up to 1300 were obtained by optimizing the design, geometry and alignment of the SERS arrays on the tip of the optical fiber. Furthermore, strong repeatability and consistency were achieved for the fabricated SERS arrays, demonstrating that the technique may be suitable for large-scale fabrication procedures in the future. Finally, rapid SERS detection of live Escherichia coli cells was demonstrated using integration times in the milliseconds to seconds range. This result indicates strong potential for in vivo diagnostic use, particularly for detection of infections. Moreover, to the best of our knowledge, this represents the first report of detection of live, unlabeled bacteria using a fiber-optic SERS probe.
Kim JA, Wales DJ, Thompson AJ, et al., 2019, Towards development of fibre-optic surface enhanced Raman spectroscopy probes using 2-photon polymerisation for rapid detection of bacteria, Plasmonics in Biology and Medicine XVI, Publisher: SPIE, ISSN: 0277-786X
In this study, a variety of direct laser written surface-enhanced Raman spectroscopy (SERS) micro-structures, designed for bacteria detection, are presented. Various SERS micro-structures were designed to achieve both a high density of plasmonic hot spots and a strong probability of interaction between the hot spots and the target bacterial cells. Twophoton polymerization was used for initial fabrication of the polymeric skeletons of the SERS micro-structures, which were then coated with a 50 nm-thick gold layer via e-beam evaporation. The micro-structures were fabricated on glass coverslips and were assessed using a confocal Raman microscope. To this end, Rhodamine 6G was used as an analyte under 785 nm laser illumination. The optimal SERS micro-structures showed approximately 7×103 enhancement in Raman signal (analytical enhancement factor, AEF) at a wavenumber of 600 cm-1. Real-time detection of E. coli in solution was demonstrated using the fabricated SERS platform with low laser powers and a short acquisition time (785 nm, 5 mW, 50 ms).
Dugasani SR, Paulson B, Ha T, et al., 2018, Fabrication and optoelectronic characterisation of lanthanide-and metal-ion-doped DNA thin films, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 51, ISSN: 0022-3727
Dugasani SR, Gnapareddy B, Kim JA, et al., 2017, Structural stability and electrical characteristic of DNA lattices doped with lanthanide ions, Current Applied Physics, Vol: 17, Pages: 1409-1414, ISSN: 1567-1739
Shinde M, Qureshi N, Rane S, et al., 2017, Instantaneous Synthesis of Faceted Iron Oxide Nanostructures Using Microwave Solvothermal Assisted Combustion Technique, JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, Vol: 17, Pages: 5024-5030, ISSN: 1533-4880
Kim JA, Park K, Kim C, et al., 2016, Optical contact force monitoring sensor for cardiac ablation catheters, Optik, Vol: 127, Pages: 11823-11827, ISSN: 0030-4026
© 2016 Modern lifestyles can lead to various lifestyle diseases that have become the most threatening health issues to humans. In particular, heart disease is the leading global cause of death. To diagnose heart disease, cardiac catheterization is frequently conducted. The contact force between the tip of the catheter and tissue is very critical because it determines the success or failure of the procedure. In this work, an optical sensor composed of transparent, flexible, and stretchable PDMS layers forming an air cavity was developed and evaluated. The reflectance of the sensor varied with external applied force depending upon the gap between elastomeric layers placed on the catheter tip. The fabricated sensor showed very low minimum resolution (<0.1 gF), which is desired for the application. A wider dynamic range than that of the present sensor (0–0.6 gF), which is inadequate for the practical application, can be achieved by optimizing the thickness of the flexible layers.
Lim YT, Kim T, Kulkarni A, et al., 2016, High-Purity Amino-Functionalized Graphene Quantum Dots Derived from Graphene Hydrogel, Nano, Vol: 11, ISSN: 1793-2920
© 2016 World Scientific Publishing Company. The unique properties of graphene quantum dots (GQDs) make them interesting candidate materials for innovative applications. Herein, we report a facile method to synthesize amino-functionalized graphene quantum dots (AF-GQDs) by a hydrothermal reaction. Graphene oxide (GO) was synthesized by Hummer's method where ultra-small GO sheets were obtained by a prolonged oxidation process followed by sonication using an ultrasonic probe. Subsequently, graphene hydrogel (GH) was also obtained by a hydrothermal synthesis method. Proper care was taken during synthesis to avoid contamination from water soluble impurities, which are present in the precursor, GO solution. Following the treatment of GH in ammonia, ultra-small amino-functionalized graphene fragments (AF-GQDs) were formed, which detached from the GH to eventually disperse evenly in the water without agglomerating. This modified synthesis process enables the formation of high-purity AF-GQDs (99.14%) while avoiding time-consuming synthesis procedures. Our finding shows that AF-GQDs with sizes less than 5nm were well dispersed. A strong photoluminescence (PL) emission at ∼410nm with 10% PL quantum yield was also observed. These AF-GQDs can be used in many bio applications in view of their low cytotoxicity and strong fluorescence that can be applied to cell imaging.
Qin H, Hwang T, Ahn C, et al., 2016, Chemical Amination via Cycloaddition of Graphene for Use in a Glucose Sensor., J Nanosci Nanotechnol, Vol: 16, Pages: 5034-5037, ISSN: 1533-4880
Graphene was chemically aminated via cycloaddition. Aziridine-ring linkages were formed by covalently modifying the C-C double bonds in graphene. The aminated graphene presents an enhanced hydrophilicity, the contact angle with water decreases from 80.5 degrees to 58.5 degrees. And the conductivity of aminated graphene exhibits exponential decay as the reaction time increase. If the reaction time is 90 min, the resistance of aminated graphene was increased from -32 Ω to -2744 Ω. Because the amino group has good biocompatibility, the aminated graphene is designed for use as an enzyme sensor platform, such as glucose sensor based on glucose oxidase. The aminated graphene exhibited a good detection response for glucose. The increase in device current is about 12% in 1.2 mg/mL glucose solution.
Dugasani SR, Hwang T, Kim JA, et al., 2016, Metal electrode dependent field effect transistors made of lanthanide ion-doped DNA crystals, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 49, ISSN: 0022-3727
Kim JA, Kulkarni A, Kim C, et al., 2016, Fiber optic lateral coupling force sensor for biomedical applications, 30th Eurosensors Conference, Publisher: ELSEVIER SCIENCE BV, Pages: 1227-1230, ISSN: 1877-7058
Gnapareddy B, Ahn SJ, Dugasani SR, et al., 2015, Coverage percentage and raman measurement of cross-tile and scaffold cross-tile based DNA nanostructures, COLLOIDS AND SURFACES B-BIOINTERFACES, Vol: 135, Pages: 677-681, ISSN: 0927-7765
Vellampatti S, Mitta SB, Kim JA, et al., 2015, Streptavidin bound DNA open tube and Zn2+-doped DNA open lattice, CURRENT APPLIED PHYSICS, Vol: 15, Pages: 851-856, ISSN: 1567-1739
Dugasani SR, Kim M, Lee I-Y, et al., 2015, Construction and characterization of Cu2+, Ni2+, Zn2+, and Co2+ modified-DNA crystals, NANOTECHNOLOGY, Vol: 26, ISSN: 0957-4484
Choi HM, Kim JA, Cho YJ, et al., 2015, Surface cleaning of graphene by CO<inf>2</inf> cluster, Pages: 68-70, ISSN: 1012-0394
Kim H-U, Dugasani SR, Kulkarni A, et al., 2015, A methanol VOC sensor using divalent metal ion-modified 2D DNA lattices, RSC ADVANCES, Vol: 5, Pages: 67712-67717, ISSN: 2046-2069
Gnapareddy B, Ha T, Dugasani SR, et al., 2015, DNA reusability and optoelectronic characteristics of streptavidin-conjugated DNA crystals on a quartz substrate, RSC ADVANCES, Vol: 5, Pages: 39409-39415
Kulkarni A, Dugasani SR, Kim JA, et al., 2015, Photoelectric properties in metal ion modified DNA nanostructure, 37th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 4359-4362, ISSN: 1557-170X
Kim JA, Kim C, Park K, et al., 2015, Development of an Integrated Optical Contact Force Monitoring Sensor for Cardiac Ablation Catheters, 37th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 4363-4366, ISSN: 1557-170X
San BH, Kim JA, Kulkarni A, et al., 2014, Combining protein-shelled platinum nanoparticles with graphene to build a bionanohybrid capacitor., ACS Nano, Vol: 8, Pages: 12120-12129
The electronic properties of biomolecules and their hybrids with inorganic materials can be utilized for the fabrication of nanoelectronic devices. Here, we report the charge transport behavior of protein-shelled inorganic nanoparticles combined with graphene and demonstrate their possible application as a bionanohybrid capacitor. The conductivity of PepA, a bacterial aminopeptidase used as a protein shell (PS), and the platinum nanoparticles (PtNPs) encapsulated by PepA was measured using a field effect transistor (FET) and a graphene-based FET (GFET). Furthermore, we confirmed that the electronic properties of PepA-PtNPs were controlled by varying the size of the PtNPs. The use of two poly(methyl methacrylate) (PMMA)-coated graphene layers separated by PepA-PtNPs enabled us to build a bionanohybrid capacitor with tunable properties. The combination of bioinorganic nanohybrids with graphene is regarded as the cornerstone for developing flexible and biocompatible bionanoelectronic devices that can be integrated into bioelectric circuits for biomedical purposes.
Choi H, Kim JA, Cho Y, et al., 2014, Conditioning of graphene surface by CO<inf>2</inf>cluster jet, RSC Advances, Vol: 4, Pages: 41922-41926
© the Partner Organisations 2014. The reduction of resistance and surface roughness obtained by CO2cluster jet were up to 81% and 42.3% compared with pristine graphene. The shifts in Raman spectra also implied chemical doping and "mono-layerization". Thus, CO2cluster jet has the potential for planarization, cleaning and flattening of the graphene. This journal is
Gahng S, Ra CH, Cho YJ, et al., 2014, Reduction of metal contact resistance of graphene devices via CO2 cluster cleaning, APPLIED PHYSICS LETTERS, Vol: 104, ISSN: 0003-6951
Qin H, Xu Y, Kim J, et al., 2014, The effect of structure on the photoactivity of a graphene/TiO<inf>2</inf> composite, Materials Science and Engineering B: Solid-State Materials for Advanced Technology, Vol: 184, Pages: 72-79, ISSN: 0921-5107
Graphene/TiO2 composites have been investigated as promising novel photoactive materials. Graphene can slow the recombination of electron-hole pairs and act as a strong electron-collector in the graphene/TiO2 composite system. We designed and prepared four different structures of graphene/TiO2 composite film by chemical vapor deposition (CVD) and aerosol technique. The structure of the graphene/TiO2 composite had a significant effect on the photoactive properties, including the photocurrent and resistance under UV illumination. For the different composite structures, the presence of oxygen and water molecules, as well as the photo-generated electron collection efficiency, were the key factors that affect the photoactive properties. More importantly, the composite structure was a decisive factor for the stability of photocurrent and resistance. The composite of reduced graphene oxide (RGO) and TiO2 with irregularly stacked structure had a higher and stable photoresponse. This study could provide a basis for the structural design of photoelectrical devices based on graphene/TiO2. © 2014 Elsevier B.V. All rights reserved.
Dugasani SR, Kim JA, Kim B, et al., 2014, A 2D DNA Lattice as an Ultrasensitive Detector for Beta Radiations, ACS APPLIED MATERIALS & INTERFACES, Vol: 6, Pages: 2974-2979, ISSN: 1944-8244
Gnapareddy B, Kim JA, Dugasani SR, et al., 2014, Fabrication and characterization of PNA-DNA hybrid nanostructures, RSC ADVANCES, Vol: 4, Pages: 35554-35558, ISSN: 2046-2069
Kim JA, Qin H, Hwang T, et al., 2014, Novel environmental monitoring sensor technologies with fiber optics and various sensing layers
In this study, we have suggested various sensors for aerosol, VOCs (volatile organic compounds), and biomolecules detecting with diverse sensing layers such as, tetraethylorthosilicate (TEOS), thymol blue, polypyrrole, graphene, graphene oxide (GO), reduced graphene oxide (rGO), DNA, and so on. Every sensors have shown very interesting sensing characteristics with good performances. Steadily, we are proceeding various fiber optic sensors with fascinating sensing layers and mechanisms as well.
Hwang T, Kim JA, 2014, Glucose Waveguide Sensor Based on Graphene, 13th IEEE Sensors Conference, Publisher: IEEE, ISSN: 1930-0395
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