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Dynamic actuation of DNA-assembled plasmonic nanostructures in microfluidic cell-sized compartments
摘要： Molecular motor proteins form the basis of cellular dynamics. Recently, notable efforts have led to the creation of their DNA-based mimics, which can carry out complex nanoscale motion. However, such functional analogues have not yet been integrated or operated inside synthetic cells towards the goal of realizing artificial biological systems entirely from the bottom-up. In this Letter, we encapsulate and actuate DNA-assembled dynamic nanostructures inside cell-sized microfluidic compartments. These encapsulated DNA nanostructures not only exhibit structural reconfigurability owing to their pH-sensitive molecular switches upon external stimuli, but also possess optical feedback enabled by the integrated plasmonic probes. In particular, we demonstrate the power of microfluidic compartmentalization for achieving on-chip plasmonic enantiomer separation and substrate filtration. Our work exemplifies that the two unique tools, droplet-based microfluidics and DNA technology, offering high precision on the microscale and nanoscale, respectively, can be brought together to greatly enrich the complexity and diversity of functional synthetic systems.
关键词： plasmonic enantiomer selection,droplet-based microfluidics,DNA origami,plasmonic nanostructures,pH switch
更新于2025-09-23 15:19:57
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Nanobody Detection of Standard Fluorescent Proteins Enables Multi-Target DNA-PAINT with High Resolution and Minimal Displacement Errors
摘要： DNA point accumulation for imaging in nanoscale topography (PAINT) is a rapidly developing fluorescence super-resolution technique, which allows for reaching spatial resolutions below 10 nm. It also enables the imaging of multiple targets in the same sample. However, using DNA-PAINT to observe cellular structures at such resolution remains challenging. Antibodies, which are commonly used for this purpose, lead to a displacement between the target protein and the reporting fluorophore of 20–25 nm, thus limiting the resolving power. Here, we used nanobodies to minimize this linkage error to ~4 nm. We demonstrate multiplexed imaging by using three nanobodies, each able to bind to a different family of fluorescent proteins. We couple the nanobodies with single DNA strands via a straight forward and stoichiometric chemical conjugation. Additionally, we built a versatile computer-controlled microfluidic setup to enable multiplexed DNA-PAINT in an efficient manner. As a proof of principle, we labeled and imaged proteins on mitochondria, the Golgi apparatus, and chromatin. We obtained super-resolved images of the three targets with 20 nm resolution, and within only 35 minutes acquisition time.
关键词： DNA-PAINT,microfluidics,super-resolution microscopy,fluorescent proteins,molecular localization,multi-color imaging,multiplexing,single domain antibodies (sdAb),linkage error,nanobodies
更新于2025-09-19 17:15:36
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High-throughput label-free molecular fingerprinting flow cytometry
摘要： Flow cytometry is an indispensable tool in biology for counting and analyzing single cells in large heterogeneous populations. However, it predominantly relies on fluorescent labeling to differentiate cells and, hence, comes with several fundamental drawbacks. Here, we present a high-throughput Raman flow cytometer on a microfluidic chip that chemically probes single live cells in a label-free manner. It is based on a rapid-scan Fourier-transform coherent anti-Stokes Raman scattering spectrometer as an optical interrogator, enabling us to obtain the broadband molecular vibrational spectrum of every single cell in the fingerprint region (400 to 1600 cm?1) with a record-high throughput of ~2000 events/s. As a practical application of the method not feasible with conventional flow cytometry, we demonstrate high-throughput label-free single-cell analysis of the astaxanthin productivity and photosynthetic dynamics of Haematococcus lacustris.
关键词： high-throughput,astaxanthin,label-free,single-cell analysis,microfluidics,flow cytometry,Raman spectroscopy,Haematococcus lacustris,coherent anti-Stokes Raman scattering
更新于2025-09-19 17:15:36
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[Lecture Notes in Electrical Engineering] Sensors Volume 539 (Proceedings of the Fourth National Conference on Sensors, February 21-23, 2018, Catania, Italy) || Portable Optoelectronic System for Monitoring Enzymatic Chemiluminescent Reaction
摘要： This work presents a portable lab-on-chip system, based on thin film electronic devices and an all-glass microfluidic network, for the real-time monitoring of enzymatic chemiluminescent reactions. The microfluidic network is patterned, through wet etching, in a 1.1 mm-thick glass substrate that is subsequently bonded to a 0.5 mm-thick glass substrate. The electronic devices are amorphous silicon p-i-n photosensors, deposited on the outer side of the thinner glass substrate. The photosensors, the microfluidic network and the electronic boards reading out the photodiodes' current are enclosed in a small metallic box (10 × 8 × 15 cm3) in order to ensure shielding from electromagnetic interferences. Preliminary tests have been performed immobilizing horseradish peroxidase on the inner wall of the microchannel as model enzyme for detecting hydrogen peroxide. Limits of detection and quantification equal to 18 and 60 μM, respectively, have been found. These values are comparable to the best performances reported in literature for chemiluminescent-based optofluidic sensors.
关键词： Amorphous silicon,Photosensors,Enzymatic reactions,Anodic bonding,Horseradish peroxidase,Microfluidics
更新于2025-09-19 17:15:36
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Optically-Controlled Closable Microvalves for Polymeric Centrifugal Microfluidic Devices
摘要： Microvalving is a pivotal component in many microfluidic lab-on-a-chip platforms and micro-total analysis systems (μTAS). Effective valving is essential for the integration of multiple unit operations, such as, liquid transport, mixing, aliquoting, metering, washing, and fractionation. The ideal microfluidic system integrates numerous, sequential unit operations, provides precise spaciotemporal reagent release and flow control, and is amenable to rapid, low-cost fabrication and prototyping. Centrifugal microfluidics is an attractive approach that minimizes the need for supporting peripheral hardware. However, many of the microfluidic valving methods described in the literature suffer from operational limitations and fail when high rotational frequencies or pressure heads are required early in the analytical process. Current approaches to valve closure add unnecessary complexity to the microfluidic architecture, require the incorporation of additional materials such as wax, and entail extra fabrication steps or processes. Herein we report the characterization and optimization of a laser-actuated, closable valve method for polymeric microfluidic devices that ameliorates these shortcomings. Under typical operational conditions (rcf ≤ 605 *g) a success rate >99% was observed, i.e. successful valve closures remained leak free through 605 *g. Implementation of the laser-actuated closable valving system is demonstrated on an automated, centrifugally driven dynamic solid phase extraction (dSPE) device. Compatibility of this laser-actuated valve closure approach with commercially available polymerase chain reaction (PCR) assays is established by the generation of full 18-plex STR profiles from DNA purified via on-disc dSPE. This novel approach promises to simplify microscale valving, improve functionality by increasing the number of integrated unit operations, and allow for the automation of progressively complex biochemical assays.
关键词： PCR,laser-actuated valve,microvalving,dynamic solid phase extraction,polymeric microfluidic devices,centrifugal microfluidics
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Simulation of Lateral Near- and Far-Field Profiles of Gain-Guided High-Power Semiconductor Lasers
摘要： The conversion of electrical to mechanical power on a sub-centimeter scale is a key technology in many microsystems and energy harvesting devices. In this paper, we present a type of a capacitive energy conversion device that uses capillary pressure and electrowetting to reversibly convert electrical power to hydraulic power. These microhydraulic actuators use a high surface-to-volume ratio to deliver high power at a relatively low voltage with an energy conversion efficiency of over 65%. The capillary pressure generated grows linearly with shrinking capillary diameter, as does the frequency of actuation. We present the pressure, frequency, and power scaling properties of these actuators and demonstrate that power density scales up as the inverse capillary diameter squared, leading to high-efficiency actuators with a strength density exceeding biological muscle. Two potential applications for microhydraulics are also demonstrated: soft-microrobotics and energy harvesting.
关键词： electrowetting,Microhydraulics,porous materials,energy conversion,electrocapillary,microsystems,soft robotics,energy harvesting,microrobotics,actuator,microfluidics,PDMS
更新于2025-09-19 17:13:59
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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) - Femtosecond Laser Induced Surface Micro-Structure Building by Material Ejection and Ablation on Cu and Al
摘要： Theoretical and experimental approaches verifying the fluidic operation of a partially shielded digital microfluidics device are presented in this paper. This paper is motivated by recent demand from the synthetic biology community for electrowetting on dielectric (EWD) enabled in-droplet electroporation, but is generalizable to a range of EWD applications that require shielding structures to be patterned on the EWD. An electrode patterned in an additional metal layer on the insulator that supports EWD actuation reduces the effective strength of the EW force due to dielectric shielding at the droplet contact line. A numerical model was developed to predict the impact of the partially shielding electrode on threshold voltage, EW force, fluid velocity, and droplet transport time. Compared with a batch of devices lacking the extra electrode, the presence of the added metal layer resulted in a 29% increase in threshold voltage, an 82% increase in transport time, and a 44% decrease in average transport velocity. Each trend agrees with the simulation results obtained from the fluid transport model. These results support the development of design rules for microfluidic devices that require partially shielding metal layers to integrate with EWD device architectures.
关键词： gene transfer,Fluidics,model,transport,electroporation,electrowetting on dielectric,electrotransfer,digital microfluidics,mechanics,finite element model,device
更新于2025-09-19 17:13:59
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Excellent quality microchannels for rapid microdevice prototyping: direct CO2 laser writing with efficient chemical postprocessing
摘要： Rapid, simple microchannel prototyping is critical for the development of modern microfluidic devices and platforms. Laser cutting (ablation) using a commercially available continuous wave (CW) CO2 laser followed by thermal bonding is one of the most common approaches for prototyping in thermoplastics such as polymethyl methacrylate (PMMA). However, this technique suffers from poorly controlled channel quality, inconsistent results from solvent-based post-processing, and inconsistency of thermal bonding. We have overcome these challenges through a systematic study of channel ablation in PMMA using a CW CO2 laser. A new solvent treatment approach results in clearly improved microchannel quality and processing consistency, with negligible residual solvent. Thermal bonding of the processed material showed fourfold increase in bonding strength with full retention of PMMA’s favourable optical clarity. As proof of concept, a high-quality three-layered microfluidic prototype is fabricated with this new method and its performance demonstrated.
关键词： CO2 laser,Microfluidics,Nanofluidics,Thermal bonding,Solvent treatment,PMMA
更新于2025-09-19 17:13:59
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High-Efficiency Small Sample Microparticle Fractionation on a Femtosecond Laser-Machined Microfluidic Disc
摘要： The fabrication and testing of microfluidic spinning compact discs with embedded trapezoidal microchambers for the purpose of inertial microparticle focusing is reported in this article. Microparticle focusing channels require small features that cannot be easily fabricated in acrylic sheets and are complicated to realize in glass by traditional lithography techniques; therefore, the fabrication of microfluidic discs with femtosecond laser ablation is reported for the first time in this paper. It could be demonstrated that high‐efficiency inertial focusing of 5 and 10 μm particles is achieved in a channel with trapezoidal microchambers regardless of the direction of disc rotation, which correlates to the dominance of inertial forces over Coriolis forces. To achieve the highest throughput possible, the suspension concentration was increased from 0.001% (w/v) to 0.005% (w/v). The focusing efficiency was 98.7% for the 10 μm particles and 93.75% for the 5 μm particles.
关键词： femtosecond laser,microfluidics,microparticle separation,microfluidic disc
更新于2025-09-19 17:13:59
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Femtosecond Laser-inscribed Non-volatile Integrated Optical Switch in Fused Silica based on Microfluidics-controlled Total Internal Reflection
摘要： We demonstrate a non-volatile optical power switch, fabricated by femtosecond laser inscription in a fused silica substrate, with switching operation based on microfluidics-controlled total internal reflection. The switch consists of crossed waveguides and a rectangular, high aspect ratio microfluidic channel, located at the waveguide crossing. The switching between total internal reflection and transmission at the channel wall is determined by the refractive index of the medium inside the channel. Femtosecond laser inscription allows for co-integration of low-loss optical waveguides and channels with smooth sidewalls and thus the fabrication of low insertion loss switches that are broadband and show low polarization dependent losses. The measured total internal reflection loss of the fabricated switch is about 1.5 dB at the wavelength 1550 nm. The loss due to transmission through the channel filled with refractive index matching liquid is about 0.5 dB. Detailed finite time domain and beam propagation method difference simulations of the switch’s performance indicate that the losses can be further reduced by optimizing its geometry, together with further adjusting the inscription parameters.
关键词： Fused silica,Non-volatile,Single mode waveguides,Total internal reflection,Microfluidics,Femtosecond laser inscription,integrated optical switch
更新于2025-09-19 17:13:59