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- D'Humières, Benoit, et al.
(författare)
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The C3PO project : A laser communication system concept for small satellites
- 2017
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9781510606333
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Konferensbidrag (refereegranskat)abstract
- The satellite market is shifting towards smaller (micro and nanosatellites), lowered mass and increased performance platforms. Nanosatellites and picosatellites have been used for a number of new, innovative and unique payloads and missions. This trend requires new concepts for a reduced size, a better performance/weight ratio and a reduction of onboard power consumption. In this context, disruptive technologies, such as laser-optical communication systems, are opening new possibilities. This paper presents the C3PO1 system, "advanced Concept for laser uplink/ downlink CommuniCation with sPace Objects", and the first results of the development of its key technologies. This project targets the design of a communications system that uses a ground-based laser to illuminate a satellite, and a Modulating Retro-Reflector (MRR) to return a beam of light modulated by data to the ground. This enables a downlink, without a laser source on the satellite. This architecture suits well to small satellite applications so as high data rates are potentially provided with very low board mass. C3PO project aims to achieve data rates of 1Gbit/s between LEO satellites and Earth with a communication payload mass of less than 1kilogram. In this paper, results of the initial experiments and demonstration of the key technologies will be shown.
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- Jussi, Johnny, 1989-
(författare)
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Fluorescent quantum dots and graphene-based sensors for forensic applications
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A key emerging concept within the forensic sciences today areportable measurementdevices, where a much more efficient usage of the resources involved with crime-solving is possible if confirmatory measurements can be realised directly at a crimescene with such devices. Today, the majority of the presently used methods duringcriminal investigation at a crime scene involves measurements of a presumptivenature, which is a vital tool as it enables the screening of samples. In this thesis,the overarching goal is the development of tool kits for the analysis of biosampleson-site at a crime scene. This is mainly investigated through two routes: theusage of Quantum Dots (QDs) as a recognition element in sensory applications andfabrication of a graphene-based device for the detection of illicit drugs.The investigations conducted for the studies presented in this thesis focuses onsensory applications with a forensic detection scheme in mind: study I reveals in-trinsic properties of QDs to better understand sensing mechanisms upon bindinginteractions; study II demonstrates the fabrication of a graphene-based device forthe detection of illicit drugs; study III showcases the functionalised and bioconju-gated of QDs for a specific investigation into a biological process; study IV furtherthe investigation into the possible side-effects of QDs on biological specimens.In study I we numerically and experimentally investigate the intrinsic blinkingcharacteristics of CdSe-CdS/ZnS QDs. This includes a thorough examination of theexperimental parameters of the measurement setup: the bin time and excitationpower. Different mechanisms between the off- and on-state probability distributionsare found, wherein the on-state follows the random telegraph signal theory and theoff-state follows the inverse power law distribution.In study II, the detection of illicit drugs (amphetamine and cocaine) is achievedthrough graphene-based sensors processed to contain metal electrodes with superioradhesion and low contact resistance. The construction of a microfluidic system isfurther realised for a detection of molecules based on non-covalent interactions.With this system, a wavelength-dependent photoactivity for amphetamine and arange of its chemical analogs is demonstrated. A molecule dependent interactionwith the graphene surface is shown of the graphene surface either in the form ofp-doping (cocaine) or n-doping (amphetamine).Study III investigates the endocytic pathway of the vascular cell adhesionmolecule 1 (VCAM1) in Human Umbilical Vein Endothelial Cells (HUVECs) in-iiiivABSTRACTduced by Tumor Necrosis Factorα(TNFα) with the usage of 3-Mercaptopropionicacid coated (3MPA)-QDs and 5-Carboxyfluorescein (5FAM) functionalised and la-belled with VCAM1 binding peptides, respectively. Internalisation of the VCAM1molecules into lysosomes is shown with light microscopy through observations ofdifferent pathways of the 5FAM labelled peptides and functionalised QDs.In study IV we investigate the adverse effects of 3MPA-QDs on the humanairway epithelium by an examination of the calcium response in lung cells upon astimulation with QDs. The cellular response to the deposition of QDs is observedwith light microscopy and electrical measurements as a global increase of Ca2+in the epithelial layers and a transient decrease in the electrical response. Theseobservations imply that the influx of calcium caused by the QD deposition is inducedby mechanical stressIn an additional ongoing study, the age determination of dried blood spotsare investigated with the usage of protein markers commonly found in the blood.Human serum (HS) is spiked with a marker of interest to mimic those of normallevels in adult human males. After which the HS is allowed to undergo an ageingprocess in a 96 well plate and further analysed in terms of the enzymatic activitywith commercially available kits. The preliminary test results show that there is ameasurable change of activity dependenton the utilised marker that may act as abasis for the age determination of dried blod spots
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- Karlsson, Mikael, et al.
(författare)
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Chemical Sensors Generated on Wafer-Scale Epitaxial Graphene for Application to Front-Line Drug Detection
- 2019
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 19:10
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Tidskriftsartikel (refereegranskat)abstract
- Generation of large areas of graphene possessing high quality and uniformity will be a critical factor if graphene-based devices/sensors are to be commercialized. In this work, epitaxial graphene on a 2" SiC wafer was used to fabricate sensors for the detection of illicit drugs (amphetamine or cocaine). The main target application is on-site forensic detection where there is a high demand for reliable and cost-efficient tools. The sensors were designed and processed with specially configured metal electrodes on the graphene surface by utilizing a series of anchors where the metal contacts are directly connected on the SiC substrate. This has been shown to improve adhesion of the electrodes and decrease the contact resistance. A microfluidic system was constructed to pump solutions over the defined graphene surface that could then act as a sensor area and react with the target drugs. Several prototypic systems were tested where non-covalent interactions were used to localize the sensing components (antibodies) within the measurement cell. The serendipitous discovery of a wavelength-dependent photoactivity for amphetamine and a range of its chemical analogs, however, limited the general application of these prototypic systems. The experimental results reveal that the drug molecules interact with the graphene in a molecule dependent manner based upon a balance of -stacking interaction of the phenyl ring with graphene (p-doping) and the donation of the amine nitrogens lone pair electrons into the *-system of graphene (n-doping).
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- Petermann, Ingemar, et al.
(författare)
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Characterization of Fiber Bragg Gratings by Use of Optical Coherence-Domain Reflectometry
- 1999
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 17:11, s. 2371-2378
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Tidskriftsartikel (refereegranskat)abstract
- A method based on optical low coherence reflectometry for complete characterization of fiber Bragg gratings (FBG's) is presented. It is shown that the measured signal corresponds to the impulse response of the grating filter, and the measurement therefore. yields all information about the device, Experiments have been carried out with a novel dual-channel interferometer, The results are in excellent agreement with the theory, demonstrating the versatility of the method for characterization of fiber gratings.
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- Petermann, Ingemar, et al.
(författare)
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Fabrication of advanced fiber Bragg gratings by use of sequential writing with a continuous-wave ultraviolet laser source
- 2002
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 41:6, s. 1051-1056
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel scheme based on sequential writing for fabrication of advanced fiber Bragg gratings. As opposed to earlier sequential methods this technique uses a cw UV laser source and allows for very precise control and repetitivity of the formation of the gratings. Furthermore it is possible to use high average irradiances without destroying the fiber, resulting in considerable reduction in fabrication time for complex gratings. The method has been applied to several test gratings, which proved its versatility and quality.
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