- 标题
- 摘要
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- 实验方案
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Improved electrical performance and transparency of bottom-gate, bottom-contact single-walled carbon nanotube transistors using graphene source/drain electrodes
摘要： We propose a centrifuge-based microfluidic device housed in a standard microtube for generation of monodisperse microdroplets from tens of μl sample volume. Centrifugation drives overpressure of a dispersed phase, thus infuses the dispersed phase into a microchannel. Because of the channel geometry for step emulsification, the infused dispersed phase is pinched off forming droplets. Then, the droplets accumulate on the bottom of the microtube by centrifugal force. We succeeded in generation of monodisperse droplets with a diameter of 130 μm (CV <2%) by operation of centrifuge. Since the device can produce droplets in a microtube without complex experimental setup (e.g. syringe pump), it will be a powerful tool for simple generation of droplets for droplet-based applications.
关键词： centrifuge-based,microfluidic device,monodisperse droplets,step emulsification
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optical Control in a 3D Flow-Focusing Microfluidic Sorting System
摘要： Separation and sorting of particles (cells, beads, and droplets) is critical in a variety of biomedical applications including early disease diagnostics, therapeutics, cell tracking, and clinical research. Currently, standard microfluidic methods use 2D-chips fabricated using PDMS based soft lithography or embossing/etching materials such as Topas or glass. Often hydrodynamic flow focussing is used to spatially confine the sample flow to particular areas on the chip and so facilitate target species detection; however, 2D systems have limitations when it is necessary to make fine, micrometre scale, adjustments to flow profiles and/or the spatial position of the focused sample stream so as to match up with elements of external bulky equipment such as the laser or light paths of a spectrometer or internal fields used in electrical or acoustic actuation. These limitations can be overcome by using a 3D flow focussing method which can dynamically adjust the flow patterns within the sample chip (Figure 1a, left). For complex systems containing multiple sensor and actuation stages that are best made using hybrid construction of plug-and-play subsystems, a critical aspect of the overall functioning of the system is knowing at what points in time individual particles (e.g. cells, beads) are in the vicinity of different functional parts of the device. For high throughput and high particle densities, this becomes more difficult the larger the chip and the faster the flow. To address this, here we used a strategy of integrating several optical sensors into a hybrid device made from 3D printed and conventional soft lithography PDMS parts (Figure 1a, right), and so provide this timing data. Using these, it has then been possible to develop an automated flow- focusing and sorting microfluidic system with the flexibility and stability required for the sorting and refinement of labelled cells and beads (Figure 1b).
关键词： sorting,hybrid device,optical control,microfluidic,3D flow-focusing
更新于2025-09-12 10:27:22
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Wettability analysis of water on metal/semiconductor phases selectively structured with femtosecond laser-induced periodic surface structures
摘要： Femtosecond (fs) laser-induced periodic surface structures (LIPSS) were selectively generated on the surface of an Ag-Si alloy consisting of a metallic and a semiconducting phase. For this purpose, the alloy was irradiated with linearly polarized fs-laser pulses (τ = 300 fs, λ = 1025 nm, frep = 100 kHz) using a laser peak fluence F = 0.30 J/cm2. Due to the different light absorption behavior of the semiconductor (Si) and the metal (Ag) phase that results in different ablation thresholds of the respective phase, pronounced LIPSS with a period of Λ ≈ 950 nm and a modulation depth of h ≈ 220 nm were generated solely on the Si phase. The alloy surface was characterized by scanning electron microscopy, optical microscopy, white light interference microscopy and atomic force microscopy before and after laser irradiation. Chemical analysis was carried out by energy dispersive X-ray spectroscopy, revealing surface oxidation of the Si phase and no laser-induced chemical modification of the Ag phase. The surface wettability of the alloy was evaluated with distilled water and compared to the single constituents of the composites. After fs-laser irradiation, the surface is characterized by a reduced hydrophilic water contact angle. Furthermore, the alloy selectively structured with LIPSS revealed a droplet shape change due to the distinctly different contact angles on the Si (θ = 5°) and the Ag (θ = 74°) phase. This phenomenon was evaluated and discussed by local contact angle analyses using a confocal laser scanning microscope and a Rhodamine B dye. In addition, it was shown that the shape change due to different contact angles of the components allowed a targeted droplet movement on a macroscopic material boundary (Ag/Si) of the alloy. Selectively structured metal/semiconductor surfaces might be of particular interest for microfluidic devices with a directional droplet movement and for fundamental research of wettability.
关键词： Contact angle,Wettability,Microfluidic devices,LIPSS,Ag-Si alloy,Femtosecond laser
更新于2025-09-12 10:27:22
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Online Monitoring of Cell Growth on PDMS-PDMS Reversible Microfluidic Bioreactor Integrated to Optical Fiber Sensor
摘要： A microfluidic bioreactor was fabricated by curing PDMS over 3D-printed molds, and it contains microchannels and perfusion chambers instrumented with optical fibers for the online analysis of the cellular growth. The channels were designed for allowing both the complete mixture of reagents and the possibility of generation of concentration gradients, and the perfusion chambers are isolated from them by polycarbonate membranes, providing a chemical environment with a constant concentration of nutrients for the cells. The optical fibers are laterally inserted in the chambers, and the monitoring of cells concentration is based on the quasi-elastic light scattering: as the total number of cells grows, there is an increase on the dispersion of the reflected intensity data, and the autocorrelation of the values allows the inference of the concentration. The sensor signals obtained during the fermentation of S. cerevisiae were equivalent to the cell counting on the Neubauer chamber using an optical microscope, leading to a value of the maximum specific growth rate μm of 0.50 h-1. This optical monitoring system has proven to be easily manufacturable and capable of performing fast screening and online monitoring of the microbial kinetics.
关键词： microbial kinetics,online monitoring,optical fiber sensor,quasi-elastic light scattering,Microfluidic bioreactor
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Nanoparticle Sorting Technique using Laser Induced Dielectrophoresis with Phase Modulated Interference
摘要： A novel nanoparticle sorting technique using the laser-induced dielectrophoresis (LIDEP) and phase modulated interference has been developed. In this paper, a proposed method of nanoparticle sorting and fabrication of microfluidic device are reported, and the validity of a method is discussed.
关键词： microfluidic,optical phase modulation,separation,nanoparticle,laser-induced dielectrophoresis,sorting
更新于2025-09-12 10:27:22
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Maskless, rapid manufacturing of glass microfluidic devices using a picosecond pulsed laser
摘要： Conventional manufacturing of glass microfluidic devices is a complex, multi-step process that involves a combination of different fabrication techniques, typically photolithography, chemical/dry etching and thermal/anodic bonding. As a result, the process is time-consuming and expensive, in particular when developing microfluidic prototypes or even manufacturing them in low quantity. This report describes a fabrication technique in which a picosecond pulsed laser system is the only tool required to manufacture a microfluidic device from transparent glass substrates. The laser system is used for the generation of microfluidic patterns directly on glass, the drilling of inlet/outlet ports in glass covers, and the bonding of two glass plates together in order to enclose the laser-generated patterns from the top. This method enables the manufacturing of a fully-functional microfluidic device in a few hours, without using any projection masks, dangerous chemicals, and additional expensive tools, e.g., a mask writer or bonding machine. The method allows the fabrication of various types of microfluidic devices, e.g., Hele-Shaw cells and microfluidics comprising complex patterns resembling up-scaled cross-sections of realistic rock samples, suitable for the investigation of CO2 storage, water remediation and hydrocarbon recovery processes. The method also provides a route for embedding small 3D objects inside these devices.
关键词： glass microfluidic devices,laser micromachining,picosecond pulsed laser,maskless manufacturing,laser microwelding,rapid prototyping
更新于2025-09-12 10:27:22
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Highly sensitive quarter-mode spoof localized plasmonic resonator for dual-detection RF microfluidic chemical sensor
摘要： In this paper, benefited from ultrathin corrugated metal-insulator-metal (MIM) ring resonator, for the first time, we proposed a dual-detection microfluidic chemical sensor based on quarter-mode spoof LSP resonator with higher sensitivity among all the dual/multichannel microwave chemical sensors. First, we study full-mode spoof plasmonic resonator and we show that the resonance modes of the quarter-mode structure are exactly one-fourth of the full-mode structure. By placing two asymmetric microfluidic channels in the strongest E-field regions, the capability of detecting two aqueous solutions is feasible. By utilizing 85070E performance probe connected to vector network analyzer (VNA), we determined the relative permittivity and loss tangent of fluids under test. Afterward, the fabricated prototype was tested and our experimental results collaborate well our simulation predictions. Our proposed RF sensor exhibits 87% growth in sensitivity (MHz εr? ) compared with the most sensitive previously existing multichannel microwave chemical sensor. Furthermore, we show that our elaborately designed sensor has the potential to detect chemicals with very close dielectric constant corresponding to 1,4-Dioxin, Cyclohexane, n-Hexane with the relative permittivity of 2.12, 2.012, 1.95 respectively.
关键词： RF sensors,microfluidic chemical sensors.,spoof LSP resonator,corrugated MIM ring resonator
更新于2025-09-12 10:27:22
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Photothermal Microfluidic Sensing Platform Using Near-Infrared Laser-Driven Multiplexed Dual-Mode Visual Quantitative Readout
摘要： The application of different sensing principles in microfluidic devices opens up further possibilities for the development of point-of-care testing (POCT). Herein, the photothermal sensing principle is introduced in microfluidic paper-based analytical devices (μPADs) to develop a photothermal microfluidic sensing platform using near-infrared (NIR) laser-driven multiplexed dual-mode visual quantitative readout. Prussian blue (PB) as the analyte-associated photothermal agent was in-situ synthesized in thermoresponsive poly(N-isopropylacrylamide) hydrogels to serve as the on-chip photothermal sensing element. NIR laser-driven photothermal effect of PB triggered not only on-chip dose-dependent heat generation but also phase transition-induced dye release from the hydrogels, simultaneously enabling both thermal image- and distance-based dual-mode visual quantitative readout of the analyte concentration in a multiplexed manner. Both the on-chip temperature elevation value of the hydrogels and the traveling distance of released dye solutions were proportional to the concentration of PB. Using the detection of silver ions in environmental water as a proof-of-concept study, the photothermal μPAD can detect silver ions at a concentration as low as 0.25 μM with high selectivity and satisfactory accuracy. The photothermal microfluidic sensing platform holds great potential for POCT with promising integratability and broad applicability, owing to the combination of synergistic advantages of the photothermal sensing principle, μPADs and photothermally responsive hydrogels.
关键词： Microfluidic device,Photothermal effect,Visual readout,Point-of-care testing,Thermoresponsive hydrogel
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Lossy Mode Resonance Fiber-Optic Biosensing Allowing Ultra-Low Detection Limit
摘要： Fiber-optic biosensors can offer great advantages over other optical technology platforms thanks to the typical features of optical fibers. Moreover, the opportunity of depositing nm-thick overlays on optical fibers with a high degree of accuracy, repeatability and reproducibility has enabled spreading the application domains of this technology. Recently, the concept of guided mode resonance has been exploited in thin film coated fiber-optic sensors, under the name of lossy mode resonance (LMR). LMR occurs when the real part of the thin film permittivity is positive and greater in magnitude than both its own imaginary part and the permittivity of the material surrounding the thin film. Therefore, metallic oxides and polymers can be used to generate LMRs, instead of the noble metals typically used in SPR devices. Instead of using multi-mode fibers, D-shaped single-mode fibers have been used to excite LMR, which enables tracking the spectral displacement of the 1st LMR, the most sensitive LMR, at wavelengths in the NIR, where the sensitivity is enhanced if compared to the visible region. By coating the D-shaped region of the fiber with a nanometric layer of tin oxide (SnO2) and integrating it into an ad-hoc microfluidic system, an ultra-low detection limit (LOD) biosensing device has been developed. The sensing principle is quite simple: when the target analyte interacts with the fiber-functionalized surface, this induces a change in the optical properties of the overlay (i.e. effective refractive index and thickness); in turn, this causes a change in the spectral position of the LMR that can be accurately and precisely measured through a conventional wavelength interrogation system. The deposition of the tin oxide layer (roughly 160-180 nm), which is performed with a DC sputter machine (ND-SCS200, Nadetech S.L.), has been characterized by FESEM images (UltraPlus Carl Zeiss Inc.). The round inset of the same figure details the functionalization of the sensitive region, which is carried out with the deposition of a nm-thick polymeric layer of poly(methyl-methacrylate) (Eudragit L100) that provides free functionalities necessary for the IgG antibody immobilization. The assay has been completed by spiking increasing concentrations of anti-IgG antigen (from 1 pg mL-1 up to 10 μg mL-1) in a real sample of CRP-free human serum. The real-time tracking of the LMR shift has enabled following all the biochemical steps during the assay implementation and then the calibration curve (n=4) of the proposed biosensor has been obtained, together with the sigmoidal fit with the Hill function, which is a well-accepted mathematical model used to quantify the degree of interaction between ligand binding sites. A LOD of 150 fg mL-1 has been attained. This result has confirmed a big leap in performance thanks to the capability to detect analyte concentrations down to few fM in real samples, enhancing the LOD by three orders of magnitude when compared with other fiber-based configurations and matching a LOD comparable with the most outstanding optical technology platforms.
关键词： Fiber-optic biosensors,lossy mode resonance,microfluidic system,ultra-low detection limit,tin oxide
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Photonic Bandgap Bragg Waveguide-based Terahertz Microfluidic Sensor
摘要： A 3D printed photonic bandgap Bragg waveguide-based resonant fluidic sensor operating in the THz spectral range is theoretical analyzed and experimental studied. The liquid analytes injected into a microfluidic channel inside the reflector region result in anticrossing of the dispersion relation between the core-guided mode and the defect state. By tracking the spectral positions of the induced absorption dips and phase changes on the transmission spectra, the fluidic sensor exhibits a sensitivity of 110 GHz/RIU and a resolution of 0.0045 RIU. The sensor provides a non-contact measurement method for real-time monitoring of the refractive index change of liquid flow in practical applications.
关键词： 3D Printing,Photonic Bandgap,Microfluidic Sensor,Bragg Waveguide,Terahertz
更新于2025-09-11 14:15:04