- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Microfluidic Long-Term Gradient Generator with Axon Separation Prototyped by 185 nm Diffused Light Photolithography of SU-8 Photoresist
摘要： We have developed a cast micro?uidic chip for concentration gradient generation that contains a thin (~5 μm2 cross-sectional area) microchannel. The diffusion of diffused 185 nm ultraviolet (UV) light from an inexpensive low-pressure mercury lamp exposed a layer of the SU-8 photoresist from the backside and successfully patterned durable 2 μm-high microchannel mold features with smooth bell-shaped sidewalls. The thin channel had appropriate ?ow resistance and simultaneously satis?ed both the rapid introduction of test substance and long-term maintenance of gradients. The average height and width at the half height of the channel, de?ned by a 2 μm-wide line mask pattern, were 2.00 ± 0.19 μm, and 2.14 ± 0.89 μm, respectively. We were able to maintain the concentration gradient of Alexa Fluor 488 ?uorescent dye inside or at the exit of the thin microchannel in an H-shaped micro?uidic con?guration for at least 48 h. We also demonstrated the cultivation of chick embryo dorsal root ganglion neuronal cells for 96 h, and the directional elongation of axons under a nerve growth factor concentration gradient.
关键词： prototyping,axon elongation,micro?uidic gradient generator,SU-8,microchannel
更新于2025-09-23 15:22:29
-
[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Supercritical Carbon Dioxide Solar Thermal Power Generation—Overview of the Technology and Microchannel Receiver Development
摘要： The supercritical carbon dioxide (sCO2) power cycle is being considered for solar thermal central receiver systems in the United States. The cycle lends to increased high-temperature input that is expected of the next-generation concentrating solar thermal power (CSP) systems. Power block efficiencies of about 50% can be achieved for recompression cycles at an input temperature of approximately 720 °C. Additionally, the power block is compact and less complex, raising the possibility of using thermal-storage-coupled CSP sCO2 technologies for modular (*100 MW) peak-load power plants. Three pathways toward providing solar thermal input to the sCO2 cycle have been proposed by various research groups—the molten salt receiver pathway, the solid particle receiver pathway, and the gas-phase receiver pathway. The first two technologies have the advantage of sensible thermal storage within the solid/fluid medium passing through the receiver. In the gas receiver pathway, there is a need for coupling a sensible or latent heat storage technology. Several key technologies are needed to enable the realization of the sCO2 solar thermal technology, key among them being the receiver and thermal storage. In this chapter, some of the key gas-phase receiver technologies are discussed. The group’s past and recent work on the development of microchannel solar thermal receivers for sCO2 is emphasized.
关键词： Solar thermal,Efficiency,Supercritical carbon dioxide,Microchannel,Receiver,Concentrating solar power
更新于2025-09-23 15:21:21
-
Temperature uniformity enhancement of densely packed high concentrator photovoltaic module using four quadrants microchannel heat sink
摘要： The dense solar radiation received by a high concentration photovoltaic module (HCPVM) causes a high cell temperature. In this module, multiple solar cells were electrically connected in both series and parallel. The higher temperature of the solar cell in the series string limits the generated power for the whole string. Therefore, it is crucial to employ a uniform cooling mechanism for higher electrical performance along with a longer lifespan. The uniform cooling is required to attain safe operating temperature and prevent the hot spot formation. Hence, in the current work, a four-compartment microchannel heat sink is proposed for the thermal management of HCPVM under high solar concentration of 1000 suns (1 sun = 1000 W/m2). A three-dimensional (3D) conjugate heat transfer model with exergy analysis is developed and validated. This model was used to investigate the effect of inlet and outlet orientation of four quadrants microchannel heat sink as a cooling method for HCPVM. Eight different orientations of parallel-flow and counter-flow conditions were investigated and compared in terms of temperature non-uniformity, module power, and exergy performance. The results showed that the inlet and outlet orientation was a key role affecting the module temperature non-uniformity. For the counter-flow operated heat sinks, the HCPVM can be operated under a temperature non-uniformity of 3.1 °C at total inlet module mass flowrate of 350 g/min and solar concentration ratio of 1000 suns. In addition, the attained HCPVM electrical, thermal, and overall exergy efficiency were 37.2%, 8.2%, and 45.4% respectively at the same conditions.
关键词： Densely packed module,Solar concentration ratio,Exergy analysis,Microchannel heat sink,Uniform cooling
更新于2025-09-23 15:21:01
-
Enhanced photocatalytic activity under visible light by the synergistic effects of plasmonics and Ti3+-doping at the Ag/TiO2- heterojunction
摘要： A heterojunction of plasmonic Ag particles on Ti3+-doped macro-/meso-porous TiO2 framework consisting of parallel microchannels, denoted as Ag/TiO2-x, has been fabricated by a simple microwave-assisted process employing vitamin C as the reducing agent for forming TiO2-x framework followed by photochemical deposition of Ag particles. Charge transport and recombination processes were detected through transient photocurrent responses. The visible-light photocatalytic hydrogen production rate and the apparent reaction rate constant of RhB photodegradation with 3%-Ag/TiO2-x catalyst are about 5.3 and 14.0 fold higher than those with the pristine macro-/meso-porous TiO2 framework, respectively. A mechanism based on the synergistic effects of Ag plasmonics and Ti3+-doping at the Ag/TiO2-x heterojunction is proposed, which consistently explains the high photocatalytic performance in hydrogen evolution and the improved photocatalytic decomposition of RhB under visible light. This study demonstrates the effective route to synthesize new heterojunction photocatalytic materials with multifunctional properties using low-cost and rapid microwave processes.
关键词： Macroporous/mesoporous TiO2 microchannel,Ag/TiO2-x heterojunction,Ti3+-doped TiO2,Photocatalysis,Surface plasmon resonance
更新于2025-09-23 15:19:57
-
Indoor and outdoor characterization of concentrating photovoltaic attached to multi-layered microchannel heat sink
摘要： Concentrating Photovoltaic technology is a promising option in power generation using the photovoltaics compared to the conventional ?at PV system. This study investigates the performance of a high concentrated photovoltaic single solar cell module attached to a multi-layered microchannel heat sink. The system has been tested the ?rst time experimentally both at indoor and outdoor conditions. The indoor characterization of the system investigated the e?ect of varying the number of the layers of the heat sink and the ?ow rate of the ?uid electrically and thermally. The experiments show that varying the number of the heat sink layers from 1-layer to 3-layers increase the maximum electrical generation by 10% and reduces the cell temperature by 3.15 °C under the same ?uid ?ow rate of 30 ml/min. The outdoor experiments show the maximum output electrical generation of the system of 4.60 W and the short circuit current of 1.96 A. The maximum solar cell temperature was maintained below 61 °C where the extracted heat of the system was 12.85 W which represents of 74.9% of the total generated power.
关键词： Heat sink,Concentrating photovoltaic,Thermal regulation,Multi-layered microchannel
更新于2025-09-23 15:19:57
-
Hexahedral LED Arrays with Row and Column Control Lines Formed by Selective Liquid-Phase Plasticization and Nondisruptive Tucking-Based Origami
摘要： Origami/kirigami of flexible electronics is a promising way to produce 3D electronics because well-developed silicon-based technologies can be used for the planar circuitry layout. However, it is still a challenge to enable general row and column control lines to develop 3D addressable sensory and display systems. This study addresses this issue via selective plasticization of an acrylonitrile butadiene styrene (ABS) film with N,N-dimethylformamide (DMF) through polydimethylsiloxane (PDMS) microfluidic channels. The use of DMF provides plasticization in a controllable manner because of the fast absorption of the DMF in the liquid phase during the plasticization process, a prolonged retention time of DMF in the ABS film at room temperature during the transformation process, and fast desorption at 60–80 °C for the deplasticization process. The use of microfluidic channels allows high-resolution selective plasticization to enable extreme cases of local bending or even folding inward and outward, thereby enabling tucking-based origami with no crack generation. The lamination of membrane-type electronic devices to an ABS film followed by selective plasticization and transformation enables nondisruptive tucking-based origami at the electronics level, such as for the demonstration of a hexahedral light-emitting diode (LED) array with general row and column control lines.
关键词： tucking-based origami,plasticization,microchannel,3D electronics,flexible electronics
更新于2025-09-23 15:19:57
-
Thermal management of high-power LED based on thermoelectric cooler and nanofluid-cooled microchannel heat sink
摘要： Effective thermal management for light-emitting diodes (LEDs) is critical, as temperature significantly affects their lifetime and performance. In this study, a system combining a thermoelectric cooler (TEC) and a microchannel heat sink (MHS) is investigated experimentally for thermal management of high-power LEDs. Nanofluids and water are used as coolant. The LED substrate temperature (Ts) is measured at various TEC powers, nanofluid concentrations, ambient temperatures of LED (Ta), and ambient temperatures of the fluid radiator (Ta,f). The effective thermal resistance (Rs-fa) of the LED substrate to the ambient of the fluid radiator is analyzed. Correlations of Ts and Rs-fa are obtained. Results show that the Ts is lowest when the TEC works at its rated power, and Ts is lower than Ta at Ta ≥ 55 °C. Using nanofluids instead of water as coolant reduces the Ts by up to 18.5 °C and decreases the thermal resistance by as much as 42.4%. The MHS heat transfer capacity is increased by 38.6%. The Ta,f exhibites greater influence on Ts compared to Ta. Results show that favorable performance of the thermal management of the high-power LED is obtained by the proposed nanofluid-cooled TEC-MHS system, particularly at high ambient temperature of LED.
关键词： Thermal management,Nanofluid,LED,Thermoelectric cooler,Thermal resistance,Microchannel heat sink
更新于2025-09-23 15:19:57
-
Characteristics enhancement of one-section and two-stepwise microchannels for cooling high-concentration multi-junction photovoltaic cells
摘要： This paper presents the development of simple, effective, and economic microchannel systems for cooling high-concentration multi-junction photovoltaic (HCMJPV) cells. The developed cooling system uses a short cooling fluid path concept with either one or two microchannel sections per the fluid path. The work is conducted using a 3D numerical model that is based on the finite volume method. The effects of design parameters on the thermal characteristics of one and two-section microchannels and output power of the HCMJPV cells are comprehensively investigated. Cooling systems that attained the largest net output power of HCMJPV cells are identified. Developed cooling systems achieved superior characteristics compared to the existing state of the art system. The two-stepwise microchannel cooling system achieves the best temperature uniformity, whereas the constant-width one-section microchannel cooling system achieves slightly better characteristics than the two-stepwise system. The proposed constant-width one-section cooling system achieves comparable standard deviation and lower surface temperature (35.65 °C), pressure drop (68.41%) and microchannel thermal resistance (49.57%) along with higher generated power (8.27%), net output power (8.44%) and overall heat transfer coefficient (175.8%) than the existed cooling system in literature. The developed cooling system allows the cells to produce an extra 820.5MWh/m2 of cells during their lifetime.
关键词： Hybrid jet impingement-microchannel cooling,Pumping power,High-concentration multi-junction photovoltaic,Stepwise microchannel cooling,High power integrated circuits,Net output power
更新于2025-09-19 17:13:59
-
Experimental study on two-phase boiling in wavy copper microchannels fabricated with ultrafast laser micromachining
摘要： In this study, the sinusoidal wavy (SW) copper microchannels with triangular cross section were fabricated with the ultrafast laser micromachining approach. The flow boiling of de-ionized water in SW microchannel were experimentally studied under mass fluxes of 43.43-217.15 kg/(m2s) and heat fluxes of 0-590 kW/m2. The flow patterns in the SW microchannels were visually observed and the boiling heat transfer characteristics were analyzed based on the obtained data. It shows the SW microchannel has a maximum enhancement of 127.7% in local heat transfer coefficient with an acceptable increase of pressure loss compared to the straight one in present work. In SW microchannel, a low degree of superheat can trigger the onset of nucleate boiling. A slow decreasing tendency of local heat transfer coefficient under a high effective heat flux or a high vapor quality was observed. The heat transfer mechanism of flow boiling in SW microchannel was analyzed based on the experimental visualization. Nucleate boiling and thin film evaporation are the dominant modes under different thermal boundary conditions. The flow boiling instability phenomenon in microchannels can be diminished using the wavy structures.
关键词： Boiling heat transfer,Sinusoidal wavy microchannel,Flow instability,Ultrafast laser micromachining
更新于2025-09-19 17:13:59
-
Analysis and Optimization of a Microchannel Heat Sink with V-Ribs Using Nanofluids for Micro Solar Cells
摘要： It is crucial to control the temperature of solar cells for enhancing e?ciency with the increasing power intensity of multiple photovoltaic systems. In order to improve the heat transfer e?ciency, a microchannel heat sink (MCHS) with V-ribs using a water-based nano?uid as a coolant for micro solar cells was designed. Numerical simulations were carried out to investigate the ?ows and heat transfers in the MCHS when the Reynolds number ranges from 200 to 1000. The numerical results showed that the periodically arranged V-ribs can interrupt the thermal boundary, induce chaotic convection, increase heat transfer area, and subsequently improve the heat transfer performance of a MCHS. In addition, the preferential values of the geometric parameters of V-ribs and the physical parameters of the nano?uid were obtained on the basis of the Nusselt numbers at identical pump power. For MCHS with V-ribs on both the top and bottom wall, preferential values of V-rib are rib width d/W = 1, ?are angle α = 75°, rib height hr/H = 0.3, and ratio of two slant sides b/a = 0.75, respectively. This can provide sound foundations for the design of a MCHS in micro solar cells.
关键词： nano?uid,heat transfer enhancement,micro solar cell,microchannel heat sink,V-ribs
更新于2025-09-19 17:13:59