Microfluidics and Nanofluidics最新文献

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.

We employ a three-dimensional numerical model to analyze the dynamics of single-phase flow in a parallel branched microchannel with varying geometric dimensions of constrictions. The primary objective is to delve into the intricacies of flow within microdevices featuring a branched network and constrictions. The findings illustrate nonlinear variations in velocity, pressure, acceleration, and shear stress along the streamwise direction, underscoring their significant dependence on the converging/diverging angles of the constrictions. To gain deeper insights into the effects of geometric parameters resulting from converging/diverging constrictions in microchannels, a geometric Reynolds number is introduced as the governing parameter for flow transition, further highlighting the novel approach. Our results demonstrate a notable improvement in the magnitude of inertial forces, a feature uncommon in simple microchannels. From the results, it is asserted that microdevices with higher converging–diverging angles combined with lower width ratios are a preferable choice compared to those with lower converging–diverging angles and higher width ratios. Such configurations exhibit lower pumping power, contributing to enhanced energy efficiency. These findings provide fundamental insights that can guide the design of necessary modifications aimed at improving the performance of micropumps or microvalves.

Microfluidic-MEMS (micro-electromechanical system) devices consist of complex subsystems in which the transfer of mass, momentum and energy is critical. This is often achieved by a pressure gradient-driven, low-speed rarefied gas transport in long micro-ducts. Gaseous rarefaction, and geometrical properties of micro-ducts, such as cross-section profile and surface roughness, play a decisive role in the segregation of the flow into inertia-driven and surface-dominated domains. In this work, a parallel stochastic kinetic particle solver that solves the low-variance Boltzmann Bhatnagar-Gross-Krook (BGK) formulation is utilized to study isothermal rarefied gas transport through polar and triangular cross-sections. The effect of geometrical features such as surface proximity to the inertial core and the role of corners, are characterized. A novel parameter to indicate surface influence is introduced, which can be gainfully used in MEMS design and optimization.

Microfluidics has emerged as a highly promising technology for miniaturizing chemical analysis laboratory into a single, small lab-on-a-chip device. In our previous research, we have developed an innovative approach to particle-based microfluidics by screen printing silica gel microparticles onto glass substrate to create a patterned porous material. In this article we demonstrate a multi-step sample analysis – combining conventional and affinity thin-layer chromatography with competitive assay for detection – along with blister reservoirs that can be integrated into the particle-based microfluidic point-of-care test. This integration achieves high analytical performance and makes the test simple to use. Biotin was chosen as the exemplary analyte, because measuring it is crucial in immunoassays, where high circulating biotin concentrations can lead to false results. This research also addresses the challenge of biotin interference in immunoassays by making it possible to produce rapid biotin tests. Need for these tests is particularly critical in emergency situations. Validation of the developed test demonstrated a dynamic range of 0.09 to 0.24 µg ml^− 1 and that artificial urine matrix does not have significant effect on the results. This would make it possible to assess whether the biotin interference occurs in urine sample immunoassays.

The utilization of external magnetic or electric fields, particularly through a Riga setup, markedly enhances flow dynamics by mitigating frictional forces and turbulent fluctuations, thereby facilitating superior flow management. Such improvements are especially beneficial in optimizing the operational efficiency of machinery and turbines. Our research focuses on the behavior of a weakly ionized fluid within a porous, infinitely extended Riga channel (or electromagnetic channel) set in a rotational framework affected by Hall and ion-slip electric fields. This model integrates the cumulative repulsions of an abruptly applied pressure gradient, electromagnetic forces, electromagnetic radiation, and chemical reactions. The physical configuration of the model features a stationary right wall and a left wall subjected to transverse vibrations, establishing a complex flow environment. This scenario is analytically modeled using time-dependent partial differential equations, with the Laplace transform (LT) method applied to achieve a closed-form solution for the flow controlling equations. Through detailed graphical and tabular data, the study explores the impact of various pivotal parameters on the model’s flow traits and quantities. Our results indicate that an upswing in the modified Hartmann number significantly enhances fluid flow within the channel, with the primary flow component showing marked improvement as Hall and ion-slip parameters amplify, and secondary flow component diminishing. Additionally, species concentration lowers with higher Schmidt numbers and chemical reaction rates, while an expanded modified Hartmann number correlate with enhanced shear stresses at the channel wall. Moreover, an elevation in the radiation parameter reduces the rate of heat transfer (RHT) at the vibrating wall, whereas RHT at the stationary wall improves. This study has profound implications across several fields, notably in fusion energy research, spacecraft propulsion systems, satellite operations, aerospace engineering, and advanced manufacturing technologies.