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[IEEE 2018 XV International Scientific Conference on Optoelectronic and Electronic Sensors (COE) - Warsaw, Poland (2018.6.17-2018.6.20)] 2018 XV International Scientific Conference on Optoelectronic and Electronic Sensors (COE) - Microsystems for Cell Deformability Measurements
摘要： This paper presents a new technical solution in the form of MEMS-type deformation microcytometer and a new methodology for determining the deformability of animal oocytes. As a reference method compression of the oocyte with commercial micromanipulator will be descried and compared with proposed solution. Preliminary results showing the deformation of porcine oocytes will be presented using both methods to validate the work of the microcytometer.
关键词： mechanical properties of cells,microfluidics,compression and indentation of the cell,deformability of oocytes,microcytometry,microsystem
更新于2025-09-23 15:22:29
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Microfluidic dielectrophoretic cell manipulation towards stable cell contact assemblies
摘要： Cell contact formation, which is the process by which cells are brought into close proximity is an important biotechnological process in cell and molecular biology. Such manipulation is achieved by various means, among which dielectrophoresis (DEP) is widely used due to its simplicity. Here, we show the advantages in the judicious choice of the DEP microelectrode configuration in terms of limiting undesirable effects of dielectric heating on the cells, which could lead to their inactivation or death, as well as the possibility for cell clustering, which is particularly advantageous over the linear cell chain arrangement typically achieved to date with DEP. This study comprises of experimental work as well as mathematical modeling using COMSOL. In particular, we establish the parameters in a capillary-based microfluidic system giving rise to these optimum cell–cell contact configurations, together with the possibility for facilitating other cell manipulations such as spinning and rotation, thus providing useful protocols for application into microfluidic bioparticle manipulation systems for diagnostics, therapeutics or for furthering research in cellular bioelectricity and intercellular interactions.
关键词： Cell chain,Rotation,Dielectrophoresis,Cell contact,Microfluidics,Spinning
更新于2025-09-23 15:21:21
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Luminescent nanomaterials for droplet tracking in a microfluidic trapping array
摘要： The use of high-throughput multiplexed screening platforms has attracted significant interest in the field of on-site disease detection and diagnostics for their capability to simultaneously interrogate single-cell responses across different populations. However, many of the current approaches are limited by the spectral overlap between tracking materials (e.g., organic dyes) and commonly used fluorophores/biochemical stains, thus restraining their applications in multiplexed studies. This work demonstrates that the downconversion emission spectra offered by rare earth (RE)-doped β-hexagonal NaYF4 nanoparticles (NPs) can be exploited to address this spectral overlap issue. Compared to organic dyes and other tracking materials where the excitation and emission is separated by tens of nanometers, RE elements have a large gap between excitation and emission which results in their spectral independence from the organic dyes. As a proof of concept, two differently doped NaYF4 NPs (europium: Eu3+, and terbium: Tb3+) were employed on a fluorescent microscopy-based droplet microfluidic trapping array to test their feasibility as spectrally independent droplet trackers. The luminescence tracking properties of Eu3+-doped (red emission) and Tb3+-doped (green emission) NPs were successfully characterized by co-encapsulating with genetically modified cancer cell lines expressing green or red fluorescent proteins (GFP and RFP) in addition to a mixed population of live and dead cells stained with ethidium homodimer. Detailed quantification of the luminescent and fluorescent signals was performed to confirm no overlap between each of the NPs and between NPs and cells. Thus, the spectral independence of Eu3+-doped and Tb3+-doped NPs with each other and with common fluorophores highlights the potential application of this novel technique in multiplexed systems, where many such luminescent NPs (other doped and co-doped NPs) can be used to simultaneously track different input conditions on the same platform.
关键词： Rare earth elements,Single-cell analysis,Nanoparticles,Microfluidics,high-throughput screening
更新于2025-09-23 15:21:21
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Optimized rotation of an optically trapped particle for micro mixing
摘要： The angular momentum transferred by circularly polarized photons is able to rotate an optically trapped microparticle. Here, the optically rotating particle is introduced as an active micromixer to reduce the mixing time in a microfluidic system. To optimize the system for microfluidic application, the effect of several optical parameters such as spherical aberration and the numerical aperture of the objective on the rotation rate of a trapped particle is investigated. The results show that the optimized depth for the rotation of a particle is located close to the coverslip and can be changed by a fine adjustment of the refractive index of the immersion oil. By applying the obtained optimized optical parameters on a trapped particle at the interface of two fluids in a microchannel, the mixing length is reduced by a factor of (cid:2)2.
关键词： microfluidics,numerical aperture,micromixing,angular momentum,optical trapping,spherical aberration
更新于2025-09-23 15:21:21
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Microfluidic approach for controlled ultraviolet treatment of colored and fluorescent dissolved organic matter
摘要： Using microfluidic systems to address the optical properties of Colored and Fluorescent Dissolved Organic Matter (CDOM/FDOM) offers new ways for researching its interactions with the environment, and its response to rapid, as well as extreme, changes of abiotic conditions. Here we present a microfluidic device with an Ultraviolet (UV) component. The manufactured microfluidic device consists of passing a dissolved organic matter sample through a microchannel applying a combination of treatments using different UV wavelengths and exposure times. Here we test the workability of the microdevice by analyzing the effect of UV light on CDOM and FDOM, using as irradiations UVA and UVB to incite photodegradation, over different times. We then compare the absorbance and fluorescence, measured from both treated and non-treated samples. The analysis of the measurements is done by the calculation of the slope ratio, as indicative of molecular weight and dissolved organic carbon, besides the fluorescence humification index (HIX) as an overview of the difference between treated and non-treated of the excitation-emission matrices (EEMs). Our results show the efficiency of the microdevice by demonstrating a direct relation of degradation degree with exposure time. FDOM exposure to UVB shows a possible relation to humic-like fluorophores intensity, shown in HIX and the overview difference. Furthermore, the changes showed in the slope ratio demonstrate photodegradation in all treatments, with UVB exhibiting an increased influence. The combination of microfluidic sample treatment within in situ applications of optical sensors will enhance our capacities in addressing biogeochemical processes in the marine environment, which were not accessible with conventional bulk methods.
关键词： aquatic systems,CDOM,Slopes,FDOM,Microfluidics,EEMS,HIX
更新于2025-09-23 15:21:01
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Sweat monitoring beneath garments using passive, wireless resonant sensors interfaced with laser-ablated microfluidics
摘要： Sweat loss can help determine hydration status of individuals working in harsh conditions, which is especially relevant to those who wear thick personal protective equipment (PPE) such as firefighters. A wireless, passive, conformable sweat sensor sticker is described here that can be worn under and interrogated through thick clothing to simultaneously measure sweat loss volume and conductivity. The sticker consists of a laser-ablated, microfluidic channel and a resonant sensor transducer. The resonant sensor is wirelessly read with a handheld vector network analyzer coupled to two, co-planar, interrogation antennas that measure the transmission loss. A sweat proxy is used to fill the channels and it is determined that the sensor can orthogonally determine the sweat conductivity and volume filled in the channel via peak transmission loss magnitude and frequency respectively. A four-person study is then used to determine level of sensor variance caused by local tissue dielectric heterogeneity and sensor-reader orientation.
关键词： wireless resonant sensors,hydration status,personal protective equipment,sweat monitoring,microfluidics
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Soft Photoactuators in Microfluidics
摘要： Microfluidics, also known as lab‐on‐a‐chip (LOC) and micro‐total‐analysis‐system (μTAS), cover a set of multidisciplinary technologies dealing with the manipulation of small amounts of liquids to perform reactions, analyses, or fundamental investigations in biology, physics, and at the interdisciplinary frontiers. In contrast to the conventional bulky bench‐top instruments and the associated manual methods to handle large amounts of biological and chemical reagents that are pretty time consuming and not so environmentally friendly, a fine control over the motion of continuous fluids or nano/picoliter‐sized discrete droplets in microscale channels is beneficial in miniaturized systems. Therefore, there is a growing interest in downscaling the corresponding processes within LOCs and still retaining cost‐effectiveness and ease of fabrication. The microfluidic systems possess intrinsic features including minimized consumption of reagents, portability, increased automation, reduced time, and cost efficiency, which make them particularly attractive from a wide range of laboratory and industrial perspectives.
关键词： Microfluidics,Lab‐on‐a‐chip,Photoactuators,Soft materials,Micro‐total‐analysis‐system
更新于2025-09-23 15:21:01
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Fluorescence in situ hybridization (FISH): History, limitations and what to expect from micro-scale FISH?
摘要： In this article, we review an important cytogenetic technique - fluorescence in situ hybridization (FISH) - which is used for obtaining spatial genomic and transcriptomic information. FISH is widely utilized in genomic and cell biological research as well as for diagnostic applications in preventive and reproductive medicine, and oncology. It is the gold standard technique for the detection of chromosomal abnormalities. Despite the high specificity of FISH and the possibility of direct quantitative imaging, some of its key limitations prevent its regular use in diagnostics. To promote the extensive use of FISH for these applications, limitations in assay time and probe consumption will need to be addressed. Microfluidic technologies hold great promise in improving exactly these parameters. In the past two decades, microtechnology has matured and enabled a new line of analysis tools for biomedical and chemical sciences. Incidentally, the convergence of microtechnology with microfluidics is starting to have a decisive impact in the field of medical diagnostics. By miniaturizing implementations of diagnostic assays, the special characteristics of fluid flow in small volumes can be leveraged to modify reaction kinetics and thus reagent delivery time of assays. Here we highlight selected important historical views on FISH, review its current implementations, and provide a perspective on the future developments and the micro-scale implementations of FISH.
关键词： Diagnostics,Hybridization kinetics,Microfluidics,Tissue sections,Fluorescence in situ hybridization
更新于2025-09-23 15:21:01
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Immunofunctional Photodegradable Poly(ethylene glycol) Hydrogel Surfaces for the Capture and Release of Rare Cells
摘要： Circulating tumor cells (CTCs) play a central role in cancer metastasis and represent a rich source of data for cancer prognostics and therapeutic guidance. Reliable CTC recovery from whole blood therefore promises a less invasive and more sensitive approach to cancer diagnosis and progression tracking. CTCs, however, are exceedingly rare in whole blood, making their quantitative recovery challenging. Several techniques capable of isolating these rare cells have been introduced and validated, yet most suffer from low CTC purity or viability, both of which are essential to develop a clinically viable CTC isolation platform. To address these limitations, we introduce a patterned, immunofunctional, photodegradable poly(ethylene glycol) (PEG) hydrogel capture surface for the isolation and selective release of rare cell populations. Flat and herringbone capture surfaces were successfully patterned via PDMS micromolding and photopolymerization of photolabile PEG hydrogels. Patterned herringbone surfaces, designed to convectively transport cells to the capture surface, exhibited improved capture density relative to flat surfaces for target cell capture from buffer, buffy coat, and whole blood. Uniquely, captured cells were released for collection by degrading the hydrogel capture surface with either bulk or targeted irradiation with cytocompatible doses of long wavelength UV light. Recovered cells remained viable following capture and release and exhibited similar growth rates as untreated control cells. The implementation of molded photodegradable PEG hydrogels as a CTC capture surface provides a micropatternable, cytocompatible platform that imparts the unique ability to recover pure, viable CTC samples by selectively releasing target cells.
关键词： circulating tumor cell,biomaterials,immunocapture,microfluidics
更新于2025-09-23 15:21:01
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Formation and Characterization of Si Quantum Dots with Ge Core for Electroluminescent Devices
摘要： We report on a distributed circuit model for multi-color light-actuated optoelectrowetting devices. The model takes into consideration the large variation of absorption coefficient (15×) of photoconductors in the visible spectrum and the nonuniform distribution of photogenerated carriers. With the help of this model, we designed opto-electrowetting devices with optimum thickness of photoconductors. This leads to significant improvement in performance compared with prior reports, including 200× lower optical power, 5× lower voltage, and 20× faster droplet moving speed. This enables the use of commercial projectors to create on-demand “virtual” electrodes for large-scale parallel manipulation of droplets. We have achieved simultaneous manipulation of 96-droplet array. Finally, we have demonstrated parallel on chip detection of Herpes Simplex Virus Type 1 within 45 min using a real-time isothermal polymerase chain reaction assay.
关键词： electrowetting,polymerase chain reaction (PCR),optoelectrowetting,light-actuated digital microfluidics,Droplet microfluidics
更新于2025-09-23 15:19:57