Microfluidics and Nanofluidics最新文献

Contactless dielectrophoresis is an effective method for trapping and manipulating cells in microfluidic devices. However, the efficiency of these devices decreases at higher flow rates. To address the limitation of previous studies, a new pillar shape is introduced and numerically simulated to isolate THP-1 cells and efficiently separate them from red blood cells (RBCs). A comparison is made in two microchannels with the novel pillar shape of two perpendicular ellipses and the circular pillar shape as the reference case. Simulation results demonstrate that the use of two perpendicular ellipticals pillar shape improves the electric characteristics of the device, showing 92.7% higher (nabla {E}_{rms}^{2}) compared to the channel with circular pillars. The working frequency is selected based on the CM factor to isolate THP-1 cells without affecting RBCs. Additionally, the new pillar configuration exhibited 116% higher cell trap efficiency compared to the chip with circular pillars.

This article discusses the significance of Soret and Dufour, non-uniform heat generation, activation energy on radiative 3D flow of trihybrid nanofluid over a sheet with Marangoni convection. The energy equation takes into consideration the impacts of the heat generation, while the concentration equation takes activation energy into account. This trihybrid nanofluid is based on ethylene glycol and contains nanoparticles of titanium dioxide ((Ti{O}_{2})), cobalt ferrite ((CoF{e}_{2}O)), and aluminum oxide ((text{A}{l}_{2}{O}_{3})). For the case of trihybrid nanoparticles, the Yamada–Ota and Xue nanofluid models have been modified. This model is helpful for optimizing heating and cooling systems in fields like energy systems, microelectronics, and aerospace engineering where exact control of thermal properties is essential. By adjusting the characteristics of nanofluids, it also enhances heat transfer rates, which is a critical component in the development of solar collectors and high-efficiency heat exchangers. By using the necessary similarity transformations, non-linear ODEs are obtained from the controlling PDEs. The shooting method (BVP4c) can be utilized to solve this system of highly nonlinear equations numerically. As the surface tension gradient parameter is increased, the velocity distribution, mass transfer, and heat transfer rates all increase but the performance of the thermal and solutal profiles is opposite.

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Microfluidic technology is widely applied in biological detection, primarily utilizing microvalves to control and regulate fluid flow. Increasing attention and research have recently been directed toward magnetic droplet valves, which use magnetic fields to control magnetic droplets in microchannels for sealing purposes. A novel droplet formation technique has been proposed, employing a permanent magnet to attract magnetic fluid through a step emulsification process, thus controllably forming the magnetic droplets required for microvalves. However, the current understanding of the generation mechanism of magnetic fluid step emulsification remains insufficiently deep, with inadequate force analysis during the expansion stage of the magnetic fluid. This shortcoming results in an unclear comprehension of the relationship between the magnetic field and step emulsification formation, impeding the accurate prediction and control of droplet size and formation rate, thereby compromising the performance and reliability of magnetic droplet valves. Therefore, the study initially analyzes the forces acting on the magnetic fluid in a non-uniform magnetic field theoretically and systematically explores the step emulsification mechanism of magnetic fluids through a combination of numerical simulations and experimental validations. The magnetic field inhomogeneity degree directly affects the microdroplet formation process. As the lateral distance between the permanent magnet and the channel outlet increases, the magnetic field inhomogeneity degree decreases, resulting in larger droplet volumes and lower formation rates. Through theoretical analysis and experimental validation, this study provides a significant theoretical foundation and practical guidance for forming magnetic fluid in microfluidic systems.

Inexpensive, autonomous, easy to fabricate and portable self-powered microfluidic pumps are urgently required especially in rapid point-of-care testing (POCT). Here, we propose a “Plug-n-Play” permeable brick-based (PB) micropump for autonomous and continuous liquid flow without any external power sources. The key advantage of this pump is that its operation only requires the user to place the PB pump on the outlet of microfluidic devices. The PB pumps are fabricated by simply slicing permeable bricks into predetermined shapes. The microcosmic morphology investigations unveil that their unique porous structures and uneven surface provide outstanding capillary force. For instance, a typical cuboid PB pump (2 × 2 × 2 cm³) can produce an average flow rate of more than 100 µL min^− 1, a working time of 10 min and a maximum liquid absorption volume of ~ 1200 µL. Also, the flow rate and absorption volume can be programmed by using the PB pumps with different shapes. Moreover, we apply hydrophobic reagents (Glaco) treatment on the PB pumps to achieve the control over the liquid flow rates. Finally, through applying the PB pumps, we can perform blood type detection in POC cases. Based on its advantages of low cost, long service life, and adjustable flow rates, brick pump can be easily integrated into microfluidic systems and has great potential for microfluidic applications, especially in developing regions or in resource-limited settings.

The activation of zebrafish sperm is essential for advancing vertebrate research, including studies in germplasm physiology and cryopreservation. In this study, a magnetic microrobot-based micromixer is developed to maximize zebrafish sperm activation through uniform micromixing and precise hydrodynamic control. Three distinct configurations of the microfluidic channel, labeled Design I, II, and III, are proposed and employed to activate zebrafish sperm cells. These configurations are distinguished by the number of microrobots utilized and their specific placement within the microfluidic channel. The fluid shear rate induced by the microrobot’s rotational motion is quantified to be 0.2 s⁻¹, falling within the lower range conducive to sperm activation. Meanwhile, zebrafish sperm activation percentage is observed to reach 88% within 10 s in an individual experiment. Additionally, the dynamics of sperm motility parameters, including VSL (straight-line velocity), VCL (curvilinear velocity), and LIN (linearity, VSL/VCL), are quantified to verify these results. The LIN value is observed to be 0.91 for Design III at the actuation time period of 10 s, indicating that the activated sperms are highly efficient and progressively motile. This study underscores the efficacy of microrobotic technologies in live cell manipulation, establishing a promising approach for future research.

Buffer exchange is a common process in manufacturing protocols for a wide range of bioprocessing applications, with a variety of technologies available to manipulate biological materials for culture medium exchange, cell washing and buffer removal. Microfluidics is an emerging field for buffer exchange and has shown promising results with both prototype research and commercialised devices which are inexpensive, highly customisable and often have the capacity for scalability to substantially increase throughput. Microfluidic devices are capable of processing biological materials and exchanging solutions without the need for conventional processing techniques like centrifugation, which are time-consuming, unsuitable for large volumes and may be damaging to cells. The use of microfluidic separation devices for cell therapy manufacturing has been under-explored despite some device designs successfully being used for diagnostic enrichment of rare circulating tumour cells from peripheral blood. This mini-review aims to review the current state of microfluidic devices for buffer exchange, provide an insight into the advantages microfluidics offers for buffer exchange and identify future developments key to exploiting the technology for this application.

Cellular mechanical properties influence cellular functions across pathological and physiological systems. The observation of these mechanical properties is limited in part by methods with a low throughput of acquisition or with low accessibility. To overcome these limitations, we have designed, developed, validated, and optimized a microfluidic cellular deformation system (MCDS) capable of mechanotyping suspended cells on a population level at a high throughput rate of ~ 300 cells per second. The MCDS provides researchers with a viable method for efficiently quantifying cellular mechanical properties towards defining prognostic implications of mechanical changes in pathology or screening drugs to modulate cytoskeletal integrity.

Microalgae serve as a valuable biological resource in many industrial applications. Thus, it is essential to obtain a high-efficiency separation technique for microalgae precisely. In this study, a runway-shaped microchannel with ordered semicircular micro-obstacles was introduced to conduct the separation of microalgae with different sizes. The runway-shaped microchannel combined the spiral characteristics with a series of semicircular micro-obstacles to realize the advantage of a sheathless configuration, high-throughput, and low aspect ratio advantages. These micro-obstacles improved the performance of particle focusing, which can promote the microalga separation effectively. These simulated results demonstrated that the runway-shaped channel with ordered semicircular micro-obstacles could form the evident distribution of local Dean vortices to separate particles with different size and density. When the flow rate is considered 4mL/min, the experiment indicated that the microchannel could separate the Chlorella vulgaris and Haematococcus pluvialis in 94.6% and 81.5% purity, respectively. The microchannel with the high throughput and separation efficiency is competent to carry out the task of microalga screening and artificial cultivation.

Sepsis is a major global health concern, necessitating timely and accurate diagnosis for effective patient management. The standard diagnostic methods used to diagnose sepsis often face challenges in sensitivity and rapidity, prompting the exploration of innovative solutions such as microfluidic-based biosensors. Advances in digital microfluidic technology have garnered more interest as a promising approach in biomedical applications due to its unique ability to manipulate discrete fluid droplets on the surface, offering greater flexibility and precision. This paper presents the recent advancements of microfluidic and biosensor technology in sepsis diagnosis over the past ten years (2014–2024), highlighting their potential to revolutionize healthcare. Additionally, the integration of future electrode biosensor materials derived from plant waste is discussed, showcasing their eco-friendly and sustainable attributes in enhancing biosensor performance. Finally, this paper highlights a positive outlook on the future potential of digital microfluidic-based biosensors with green electrode nanomaterials for sepsis diagnosis, making them ideal for point-of-care applications addressing critical challenges in healthcare industries.

In the context of mature oil fields, the management of water production stands out as a formidable challenge. Our prior research endeavors (Saikia et al. J Pet Sci Eng 2020, ACS Omega 2021) have introduced an innovative Pickering emulsified gel system tailored for the precise adjustment of relative permeability in high-temperature reservoirs. To make this system work better, it is required to fully understand how it controls water flow. Traditionally, conformance control studies rely on data from core flooding tests, CT scans, and nuclear magnetic resonance (NMR) techniques, among other methods. However, these traditional approaches often struggle to provide real-time visual data, which limits their accuracy in predicting how conformance mechanisms actually work. In our research study, using two distinct glass micromodels (Micromodel I-water-wet and Micromodel II-oil-wet), we conducted Pickering emulsified gel treatments at 105 °C. Microfluidic analysis revealed that the emulsion enters the pore space as slugs, coalescing during injection. The subsequent gelation of the aqueous phase restricts water flow, while oil preferentially flows through specific channels created by the separated oleic phase. These findings challenge the previously proposed Thin Film mechanism, suggesting instead a Relative Permeability Modified Channel Flow. This research provides a deeper understanding of the Pickering emulsified gel system’s conformance control mechanism, highlighting its potential for managing water production in high-temperature reservoirs.