Design and experimental investigation of a novel spiral microfluidic chip to separate wide size range of micro-particles aimed at cell separation

Efficient separation of large particles and giant cancer cells using an isosceles trapezoidal spiral microchannel

Polyploid giant cancer cells (PGCCs) contribute to the genetic heterogeneity and evolutionary dynamics of tumors. Their size, however, complicates their isolation from mainstream tumor cell populations. Standard techniques like fluorescence-activated cell sorting (FACS) rely on fluorescent labeling, introducing potential challenges in subsequent PGCC analyses. In response, we developed the Isosceles Trapezoidal Spiral Microchannel (ITSμC), a microfluidic device optimizing the Dean drag force (FD) and exploiting uniform vortices for enhanced separation. Numerical simulations highlighted ITSμC's advantage in producing robust FD compared to rectangular and standard trapezoidal channels. Empirical results confirmed its ability to segregate larger polystyrene (PS) particles (avg. diameter: 50 μm) toward the inner wall, while directing smaller ones (avg. diameter: 23 μm) outward. Utilizing ITSμC, we efficiently isolated PGCCs from doxorubicin-resistant triple-negative breast cancer (DOXR-TNBC) and patient-derived cancer (PDC) cells, achieving outstanding purity, yield, and viability rates (all greater than 90%). This precision was accomplished without fluorescent markers, and the versatility of ITSμC suggests its potential in differentiating a wide range of heterogeneous cell populations.

Numerical analysis of pressure drop reduction of bubbly flows through hydrophobic microgrooved channels

Due to the high performance of hydrophobic surfaces in pressure drop reduction, they have been proposed for various applications. However, despite the extensive uses of two-phase flows in many industries, the effect of hydrophobic surfaces on the pressure drop reduction of two-phase flows has not been well understood yet. Thus, in the present study, by implementing the phase-field and finite element methods, the bubbly flows as an example of two-phase flows are considered for examining the effect of hydrophobic microgrooved microchannels on the pressure drop reduction of these regimes in the laminar state. We found out that hydrophobic microgrooved surfaces not only can be efficient in the bubbly flow but also can even cause a maximum pressure drop reduction of up to 70%, which is almost 3.5 times higher than in single-phase flow. We also studied the influence of each parameter, such as bubbles volume or length, Reynolds number, capillary number, and their combination on this phenomenon. The pressure drop reduction grows by increasing the volume of the bubbles but decreases by increasing the flow velocity or the surface tension coefficient. The combination of these parameters demonstrated different results in some circumstances.

High-throughput isolation of cancer cells in spiral microchannel by changing the direction, magnitude and location of the maximum velocity

Circulating tumor cells (CTCs) are scarce cancer cells that rarely spread from primary or metastatic tumors inside the patient's bloodstream. Determining the genetic characteristics of these paranormal cells provides significant data to guide cancer staging and treatment. Cell focusing using microfluidic chips has been implemented as an effective method for enriching CTCs. The distinct equilibrium positions of particles with different diameters across the microchannel width in the simulation showed that it was possible to isolate and concentrate breast cancer cells (BCCs) from WBCs at a moderate Reynolds number. Therefore we demonstrate high throughput isolation of BCCs using a passive, size-based, label-free microfluidic method based on hydrodynamic forces by an unconventional (combination of long loops and U-turn) spiral microfluidic device for isolating both CTCs and WBCs with high efficiency and purity (more than 90%) at a flow rate about 1.7 mL/min, which has a high throughput compared to similar ones. At this golden flow rate, up to 92% of CTCs were separated from the cell suspension. Its rapid processing time, simplicity, and potential ability to collect CTCs from large volumes of patient blood allow the practical use of this method in many applications.

A Hybrid Spiral Microfluidic Platform Coupled with Surface Acoustic Waves for Circulating Tumor Cell Sorting and Separation: A Numerical Study

The separation of circulating tumor cells (CTCs) from blood samples is crucial for the early diagnosis of cancer. During recent years, hybrid microfluidics platforms, consisting of both passive and active components, have been an emerging means for the label-free enrichment of circulating tumor cells due to their advantages such as multi-target cell processing with high efficiency and high sensitivity. In this study, spiral microchannels with different dimensions were coupled with surface acoustic waves (SAWs). Numerical simulations were conducted at different Reynolds numbers to analyze the performance of hybrid devices in the sorting and separation of CTCs from red blood cells (RBCs) and white blood cells (WBCs). Overall, in the first stage, the two-loop spiral microchannel structure allowed for the utilization of inertial forces for passive separation. In the second stage, SAWs were introduced to the device. Thus, five nodal pressure lines corresponding to the lateral position of the five outlets were generated. According to their physical properties, the cells were trapped and lined up on the corresponding nodal lines. The results showed that three different cell types (CTCs, RBCs, and WBCs) were successfully focused and collected from the different outlets of the microchannels by implementing the proposed multi-stage hybrid system.