Numerical simulation of critical particle size in asymmetrical deterministic lateral displacement

Performance optimization of a DLD microfluidic device for separating deformable CTCs

Deterministic lateral displacement (DLD) microfluidic devices work based on the streamlines created by an array of micro-posts. The configuration of pillars alters the isolation efficiency of these devices. The present paper optimizes the performance of a DLD device for isolating deformable circulating tumor cells. The input variables include cell diameter (d), Young's modulus (E s ${E}_s$ ), Reynolds number (Re), and tan θ, where θ is the tilted angle of micro-posts. The output, which is the response of the system, is DLD. The numerical simulation results are employed to optimize the device using the response surface method, leading to the proposition of a correlation to estimate DLD as a function of input variables. It is demonstrated that the maximum and minimum impacts on cell lateral displacement correspond toE s ${E}_s$ and Re, respectively.

High-throughput microalgae sorting based on the deterministic lateral displacement technique

Microalgae are a group of photosynthetic organisms that can grow autotrophically, performing photosynthesis to synthesize abundant organic compounds and release oxygen. They are rich in nutritional components and chemical precursors, presenting wide-ranging application prospects. However, potential contamination by foreign strains or bacteria can compromise their analytical applications. Therefore, the obtaining of pure algal strains is crucial for the subsequent analysis and application of microalgae. This study designed a deterministic lateral displacement (DLD) chip with dual input and dual outlet of equal width for the separation of Haematococcus pluvialis and Chlorella vulgaris. Optimal separation parameters were determined through a series of experiments, resulting in a purity of 99.80 % for Chlorella vulgaris and 94.58 % for Haematococcus pluvialis, with recovery rates maintained above 90 %, demonstrating high efficiency. This study provides a reliable foundation for future research and applications of microalgae, which holds considerable significance for the subsequent analysis and utilization of microalgae.

Design and fabrication of a polydimethylsiloxane device for evaluating the effect of pillar geometry and configuration in the flow separation using deterministic lateral displacement

The advancement of microfluidics and the manufacturing of microdevices has led to a strategic change in the biomedical industry. The flow through narrow channels and the pillars are placed strategically, leading to the phenomenon of particle separation through deterministic lateral displacement (DLD). In such a phenomenon, the shape, size, location and orientation of the obstacles play an important role. For the first time, particle separation is achieved with DLD modules having high row shift angles of 25°, 30° and 35°, reducing the number of pillars. The significance of circular and triangular micropillars executing deterministic lateral displacement, oriented at different angles, has been investigated, and it is found that the triangular pillars oriented at 75° resulted in better separation compared to the other configurations. In this report, the fabrication, location, orientation of the micropillars and the selection of appropriate process parameters are detailed. The structures are fabricated on silicon wafers using the standard photolithography process followed by the deep reactive ion etching process. These dies are further used to fabricate the polydimethylsiloxane-based microfluidic chips. These fabricated devices are characterised by their size, structure and quality using 3D microscopy and scanning electron microscopy. Further, blood plasma separation is carried out using the devices fabricated in this work, and the particles at the inlet and outlets are evaluated using microscopy and a novel image processing technique, replacing the use of a hemocytometer. The path traced by the particles at different flow conditions is numerically evaluated and validated with experiments. The novel device is capable of separating blood cells from plasma with a recovery factor varying from 44% to 100%. PDMS-PDMS bonding experiments using oxygen and argon plasma have been carried out to evaluate the maximum bond strength and flow velocity in the devices. It is observed that the oxygen plasma results in a bond strength of 0.404 N mm-1, thus a high throughput of 135.34 μL s-1 is achieved using the fabricated device.

On-chip dielectrophoretic device for cancer cell manipulation: A numerical and artificial neural network study

Breast cancer, as one of the most frequent types of cancer in women, imposes large financial and human losses annually. MCF-7, a well-known cell line isolated from the breast tissue of cancer patients, is usually used in breast cancer research. Microfluidics is a newly established technique that provides many benefits, such as sample volume reduction, high-resolution operations, and multiple parallel analyses for various cell studies. This numerical study presents a novel microfluidic chip for the separation of MCF-7 cells from other blood cells, considering the effect of dielectrophoretic force. An artificial neural network, a novel tool for pattern recognition and data prediction, is implemented in this research. To prevent hyperthermia in cells, the temperature should not exceed 35 °C. In the first part, the effect of flow rate and applied voltage on the separation time, focusing efficiency, and maximum temperature of the field is investigated. The results denote that the separation time is affected by both the input parameters inversely, whereas the two remaining parameters increase with the input voltage and decrease with the sheath flow rate. A maximum focusing efficiency of 81% is achieved with a purity of 100% for a flow rate of 0.2 μ L / min and a voltage of 3.1 V . In the second part, an artificial neural network model is established to predict the maximum temperature inside the separation microchannel with a relative error of less than 3% for a wide range of input parameters. Therefore, the suggested label-free lab-on-a-chip device separates the target cells with high-throughput and low voltages.

From Conventional to Microfluidic: Progress in Extracellular Vesicle Separation and Individual Characterization

Extracellular vesicles (EVs) are nanoscale membrane vesicles, which contain a wide variety of cargo such as proteins, miRNAs, and lipids. A growing body of evidence suggests that EVs are promising biomarkers for disease diagnosis and therapeutic strategies. Although the excellent clinical value, their use in personalized healthcare practice is not yet feasible due to their highly heterogeneous nature. Taking the difficulty of isolation and the small size of EVs into account, the characterization of EVs at a single-particle level is both imperative and challenging. In a bid to address this critical point, more research has been directed into a microfluidic platform because of its inherent advantages in sensitivity, specificity, and throughput. This review discusses the biogenesis and heterogeneity of EVs and takes a broad view of state-of-the-art advances in microfluidics-based EV research, including not only EV separation, but also the single EV characterization of biophysical detection and biochemical analysis. To highlight the advantages of microfluidic techniques, conventional technologies are included for comparison. The current status of artificial intelligence (AI) for single EV characterization is then presented. Furthermore, the challenges and prospects of microfluidics and its combination with AI applications in single EV characterization are also discussed. In the foreseeable future, recent breakthroughs in microfluidic platforms are expected to pave the way for single EV analysis and improve applications for precision medicine.

Recent advances in non-optical microfluidic platforms for bioparticle detection

The effective analysis of the basic structure and functional information of bioparticles are of great significance for the early diagnosis of diseases. The synergism between microfluidics and particle manipulation/detection technologies offers enhanced system integration capability and test accuracy for the detection of various bioparticles. Most microfluidic detection platforms are based on optical strategies such as fluorescence, absorbance, and image recognition. Although optical microfluidic platforms have proven their capabilities in the practical clinical detection of bioparticles, shortcomings such as expensive components and whole bulky devices have limited their practicality in the development of point-of-care testing (POCT) systems to be used in remote and underdeveloped areas. Therefore, there is an urgent need to develop cost-effective non-optical microfluidic platforms for bioparticle detection that can act as alternatives to optical counterparts. In this review, we first briefly summarise passive and active methods for bioparticle manipulation in microfluidics. Then, we survey the latest progress in non-optical microfluidic strategies based on electrical, magnetic, and acoustic techniques for bioparticle detection. Finally, a perspective is offered, clarifying challenges faced by current non-optical platforms in developing practical POCT devices and clinical applications.

3D numerical simulation of acoustophoretic motion induced by boundary-driven acoustic streaming in standing surface acoustic wave microfluidics

Standing surface acoustic waves (SSAWs) have been widely utilized in microfluidic devices to manipulate various cells and micro/nano-objects. Despite widespread application, a time-/cost-efficient versatile 3D model that predicts particle behavior in such platforms is still lacking. Herein, a fully-coupled 3D numerical simulation of boundary-driven acoustic streaming in the acoustofluidic devices utilizing SSAWs has been conducted based on the limiting velocity finite element method. Through this efficient computational method, the underlying physical interplay from the electromechanical fields of the piezoelectric substrate to different acoustofluidic effects (acoustic radiation force and streaming-induced drag force), fluid–solid interactions, the 3D influence of novel on-chip configuration like tilted-angle SSAW (taSSAW) based devices, required boundary conditions, meshing technique, and demanding computational cost, are discussed. As an experimental validation, a taSSAW platform fabricated on YX 128 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}∘ LiNbO₃ substrate for separating polystyrene beads is simulated, which demonstrates acceptable agreement with reported experimental observations. Subsequently, as an application of the presented 3D model, a novel sheathless taSSAW cell/particle separator is conceptualized and designed. The presented 3D fully-coupled model could be considered a powerful tool in further designing and optimizing SSAW microfluidics due to the more time-/cost-efficient performance than precedented 3D models, the capability to model complex on-chip configurations, and overcome shortcomings and limitations of 2D simulations.