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[IEEE 2019 Workshop on Recent Advances in Photonics (WRAP) - Guwahati, India (2019.12.13-2019.12.14)] 2019 Workshop on Recent Advances in Photonics (WRAP) - Development of micro dye laser based on micro wire molding technique
摘要： Three dimensional microfluidic dye laser inside PDMS has been fabricated by microwire molding technique. Visible laser emission from micro-laser was achieved in a micro-laser of 1mM R6G dye dissolved in a mixture of ethanol and benzyl alcohol as the active medium. The laser output intensity profile and variation of the output with the pump power was studied and a threshold of 4.5 mW pump power was observed.
关键词： microwire molding technique,Micro dye laser,Microchannel,PDMS
更新于2025-09-19 17:13:59
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[IEEE 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Sydney, Australia (2018.11.10-2018.11.17)] 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC) - Development of Sealed Tube Microchannel Plate Detectors with Cross Strip Readouts
摘要： Cross strip readout anodes provide a novel high spatial resolution image encoding system for microchannel plate sensors. We have developed cross strip readouts with metal & ceramic layers for 50 mm format sealed tubes based on the “Planacon” concept. These have next generation atomic layer deposited microchannel plates for amplification and selected photocathodes covering the UV and optical regimes. These devices will be relevant for the next generation of moderate and large NASA astrophysics instruments that are baselining 50 mm to 200 mm format detectors. The critical elements of the sensors are high QE, high spatial resolution and large event rate limits, with long lifetimes. Our photocathode work includes customization of bialkali semitransparent cathodes with response from 120 nm to 320 nm and a sharp 360 nm cutoff. Opaque alkali halide photocathodes on the atomic layer deposited microchannel plates have shown high quantum efficiencies (50% @ 115 nm) and could be used simultaneously with bialkali photocathodes. The atomic layer deposited microchannel plates have borosilicate substrates which are robust and can be be produced in large formats (20 × 20 cm) with high open area ratios (~73%). These MCPs have very low intrinsic background (<0.06 events/sec/cm2), high gain, and very good lifetime stability. With the cross strip readout and encoding electronics we achieve high spatial resolutions (<20 μm FWHM) over both 50 mm and 100 mm formats at event rates exceeding 5 MHz, providing a powerful baseline for future NASA UV/optical instruments.
关键词： photocathodes,atomic layer deposited microchannel plates,Cross strip readout,UV and optical regimes,microchannel plate sensors,NASA astrophysics instruments
更新于2025-09-16 10:30:52
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Enhanced flow boiling in silicon nanowire-coated manifold microchannels
摘要： An experimental study was carried out to investigate the heat transfer, pressure drop and flow instability characteristics associated with the flow pattern of deionized water during two-phase boiling in a silicon-based manifold microchannel heat sink coated with silicon nanowires (SiNWs) compared to a plain-wall device. The manifold microchannel device featured parallel transverse microchannels etched on a silicon substrate and longitudinal microchannels etched on a glass cover plate. Silicon nanowires were generated on the bottom and the sidewalls of the silicon microchannels. A closed-loop experimental system was constructed to demonstrate thermal and hydraulic performance. Experimental results were presented with mass fluxes ranging from 250 to 1250 kg/m2s and subcooled inlet temperatures from 15 K to 65 K. Results for the SiNWs device showed an approximate 20% improvement in heat flux rejection compared to the plain-wall device under the same wall superheat conditions. A subcooled inlet temperature of 65 K associated with a mass flux of 1250 kg/m2s is shown to be capable of dissipating an effective heat flux of 431.3 W/cm2 with a wall superheat of about 85K. Overall, the SiNW coatings proved positive effects on enhancing the flow boiling heat transfer with slower pressure drop increase, meanwhile the three-dimensional manifold microchannel design is revealed to effectively mitigate flow instability during the entire single and two-phase flow regions. This indicates great potential in utilizing three-dimensional flows by integrating SiNWs surface structures in high heat flux cooling applications.
关键词： silicon nanowire,manifold microchannel,flow boiling,two-phase
更新于2025-09-10 09:29:36
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Energy performance analysis of a novel solar PVT loop heat pipe employing a microchannel heat pipe evaporator and a PCM triple heat exchanger
摘要： This study presents a numerical analysis of the energy efficiency for a novel solar PVT Loop Heat Pipe (PVT-LHP) employing a novel Micro-channel evaporator and a novel PCM heat storage exchanger. It presents a description of the different sub-models in the PVT-LHP system (the PVT model, the microchannel heat collector model and the novel PCM triple heat exchanger model) and the integrated model of the system. The integrated model of the system was solved by ensuring a heat balance at the condenser and the evaporator. A parametric analysis has been performed in order to assess the influence of the environmental parameters (i.e. solar radiation, air temperature, wind velocity), structural parameters (i.e. glazing cover, the number of absorbing microchannel heat pipes, PV cell packing factor), the circulating fluid variables (i.e. cold-water inlet temperature and water mass flow rate) on the energy performance of the system. The novel PVT-LHP has been compared with a conventional Solar PVT-LHP system. It was found that lower solar radiation, lower ambient air temperature, higher wind speed, higher packing factor, lower cold-water inlet temperature and a smaller cover number led to an enhanced electrical efficiency, but a reduced thermal efficiency of the module; whereas a higher cold-water mass flow rate and a greater number of microchannel heat pipes gave rise to both thermal and electrical efficiencies of the module. It was also found that an increase of solar radiation, ambient temperature, cover number, microchannel heat pipe number and packing factor are favourable factors for the overall COP (Coefficient Of Performance) of the system, whereas an increase of wind velocity and cold water mass flow rate are unfavourable. The study indicated the existence of an optimal cover number, number of microchannel heat pipes and mass flowrate. Under the given design conditions, the electrical, thermal and overall efficiency of the PV/LHP module were 12.2 %, 55.6 % and 67.8% respectively and the novel system can achieve 28% higher overall energy efficiency and 2.2 times higher COP compared to a conventional system. The integrated computer model developed in this study can be used to design and optimize the novel PVT-LHP heating system.
关键词： microchannel,power supply,PVT,Loop Heat Pipe,PCM triple heat exchanger,heating
更新于2025-09-10 09:29:36
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Simulation of microchannel plate photomultiplier tube in high magnetic fields
摘要： The microchannel plate photomultiplier tube (MCP-PMT) used in high energy physics experiments usually needs to be able to operate in strong magnetic fields. In this paper, a 3D MCP-PMT model is developed in CST studio suite to study the magnetic field up to 5 T effect on the photoelectrons traveling from the photocathode to the MCP. Results predict that a growing number of photoelectrons strike back to the photocathode with enhancing magnetic field, which not only decreases electron collection efficiency and gain, but also impairs the photocathode lifetime.
关键词： Magnetic field,MCP-PMT,Collection efficiency,Microchannel plate
更新于2025-09-09 09:28:46
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Operation of microchannel plate PMTs with TOFPET multichannel timing electronics
摘要： We describe an experimental programme to evaluate TOFPET multichannel timing electronics using microchannel plate PMTs in single photon counting mode. Time resolution measurements were made using: (i) the on-board electronic stim signal; (ii) a Photek PMT210 high speed single anode MCP photomultiplier detector, and; (iii) imaging with a PMT240MA multi-anode MCP detector using a pixelated multi-layer ceramic readout. Experimental measurements using an electronic stim with the ASIC electronics gave a time resolution of 43 ps rms. Detector timing of the PMT210 detector was evaluated using a 40 ps wide pulsed laser with amplitude walk correction using the time over threshold capability of the TOFPET electronics. Single photon timing resolution of better than 100 ps rms was demonstrated. Furthermore, 256 discrete pixel imaging has been demonstrated by coupling a multi-anode pixelated MCP detector to the TOFPET system.
关键词： MCP,Photomultiplier tube,TOFPET,ASIC,PMT,Microchannel plate,Time of flight,Front-end electronics,FEE
更新于2025-09-09 09:28:46
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Single-Step CMOS Compatible Fabrication of High Aspect Ratio Microchannels Embedded in Silicon
摘要： This paper presents a new method for the CMOS compatible fabrication of microchannels integrated into a silicon substrate. In a single-step DRIE process (Deep Reactive Ion Etching) a network of microchannels with High Aspect Ratio (HAR) up to 10, can be etched in a silicon substrate through a mesh mask. In the same single etching step, multidimensional microchannels with various dimensions (width, length, and depth) can be obtained by tuning the process and design parameters. These fully embedded structures enable further wafer processing and integration of electronic components like sensors and actuators in wafers with microchannels.
关键词： mesh mask,HAR,single-step DRIE (Bosch process),embedded microchannel
更新于2025-09-09 09:28:46
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Heat Transfer Characteristics and Flow Pattern Visualization for Flow Boiling in a Vertical Narrow Microchannel
摘要： For improving the functionality and signal speed of electronic devices, components have been miniaturized and an increasing number of elements have been packaged in the device. As a result there has been a steady rise in the amount of heat necessitated to be dissipated from the electronic device. Recently microchannel heat sinks have been emerged as a kind of high performance cooling scheme to meet the heat dissipation requirement of electronics packaging, In the present study an experimental study of subcooled flow boiling in a high-aspect-ratio, one-sided heating rectangular microchannel with gap depth of 0.52 mm and width of 5 mm was conducted with deionized water as the working fluid. In the experimental operations, the mass flux was varied from 200 to 400 kg/m2s and imposed heat flux from 3 to 20 W/cm2 while the fluid inlet temperature was regulated constantly at 90 ℃. The boiling curves, flow pattern and onset of nucleate boiling of subcooled flow boiling were investigated through instrumental measurements and a high speed camera. It was found that the slope of the boiling curves increased sharply once the superheat needed to initiate the onset of nucleate boiling was attained, and the slope was greater for lower mass fluxes, with lower superheat required for boiling incipience. As for the visualization images, for relatively lower mass fluxes the bubbles generated were larger and not easy to depart from the vertical upward placed narrow microchannel wall, giving elongated bubbly flow and reverse backflow. The thin film evaporation mechanism dominated the entire test section due to the elongated bubbles and transient local dryout as well as rewetting occurred. Meanwhile the initiative superheat and heat flux of onset of nucleate boiling were compared with existing correlations in the literature with good agreement.
关键词： microchannel heat sinks,heat transfer,subcooled flow boiling,electronic cooling,flow pattern visualization
更新于2025-09-09 09:28:46
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Microchannel Plate Efficiency to Detect Low Velocity Dust Impacts
摘要： Recent space experiments suggest that electron and ion energy analyzers using microchannel plates (MCPs) as detectors are also registering direct hits by nanodust particles. To allow the analysis and interpretation of these putative dust events, the detection e?ciency of MCPs has to be characterized. We report on a series of experiments to investigate the detection e?ciency of MCP detectors to direct impacts for both positively and negatively charged micron and submicron sized iron particles. A double-stack MCP detector in a chevron con?guration was mounted as a target in a dust accelerator. A range of particle velocities and masses were used for a comprehensive examination. The MCP detected and produced de?nite signals associated with con?rmed particle impacts of the MCP for both positively and negatively charged dust particles. The detection e?ciency was found to be (6 ± 1)% for positively charged dust and (9 ± 3)% for negatively charged dust particles with a characteristic mass of 6.0 × 1011 μ (10?15 kg) and speed of 100 m/s. The examined particle velocity range accurately replicates Rosseta’s interaction with dust grains emanating from comet 67P/ Churyumov-Gerasimenko’s nucleus. Additionally, the MCP detection e?ciency for low velocity particles shows a possible underestimate of higher speed nanograin signals from Cassini’s electron plasma spectrometer during its ?yby through Enceladus’ active south pole.
关键词： Microchannel plate,Cassini,detection efficiency,dust impacts,Rosetta
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - A Novel Method for Fabricating Graphene Sensors in Channel for Biomedical Applications
摘要： Graphene is a 2D material possessing extraordinary electrical, mechanical and optical properties which paves way for fabricate biomedical applications. A well-known method graphene-based devices is depositing graphene using chemical vapor deposition and transferring it to any substrate using polymer support like PDMS (Polydimethylsiloxane). In this process multiple wetting and drying steps are required which compromises the quality of graphene. Also, PMMA leaves residues that are difficult to remove. Here, we report a novel method to fabricate graphene sensors inside PDMS channels. In this method graphene/copper stack is bonded on a PDMS surface using mechanical pressure and temperature. This PDMS layer is then bonded to another PDMS substrate containing microchannel. Etchant is flown through the microchannel to etch the copper and obtain graphene on PDMS. The graphene obtained on PDMS is characterized using optical images, scanning electron microscopy and Raman spectroscopy. This is an easy, simple to use and scalable method to obtain graphene sensors inside microchannels for biomedical applications.
关键词： Chemical Vapor Deposition,Biomedical Applications,Microchannel,Graphene,PDMS
更新于2025-09-04 15:30:14