A flow-through microfluidic chip for continuous dielectrophoretic separation of viable and non-viable human T-cells

Dielectrophoresis: Measurement technologies and auxiliary sensing applications

Dielectrophoresis (DEP), which arises from the interaction between dielectric particles and an aqueous solution in a nonuniform electric field, contributes to the manipulation of nano and microparticles in many fields, including colloid physics, analytical chemistry, molecular biology, clinical medicine, and pharmaceutics. The measurement of the DEP force could provide a more complete solution for verifying current classical DEP theories. This review reports various imaging, fluidic, optical, and mechanical approaches for measuring the DEP forces at different amplitudes and frequencies. The integration of DEP technology into sensors enables fast response, high sensitivity, precise discrimination, and label-free detection of proteins, bacteria, colloidal particles, and cells. Therefore, this review provides an in-depth overview of DEP-based fabrication and measurements. Depending on the measurement requirements, DEP manipulation can be classified into assistance and integration approaches to improve sensor performance. To this end, an overview is dedicated to developing the concept of trapping-on-sensing, improving its structure and performance, and realizing fully DEP-assisted lab-on-a-chip systems.

Proposal and performance evaluation of a new parallel plate continuous cell separation device using dielectrophoresis

Along with the rapid development of cellular biological research in recent years, there has been an urgent need for a high-speed, high-precision method of separating target cells from a highly heterogeneous cell population. Among the various cell separation technologies proposed so far, dielectrophoresis (DEP)-based approaches have shown particular promise because they are noninvasive to cells. We have developed a new DEP-based device to separate large numbers of live and dead cells of the human mammary cell line MCF10A. In this study, we validated the separation performance of this device. The results showed the successful separation of a higher percentage of cells than in previous studies, with a separation efficiency higher than 90%. In the past, there have been no confirmed cases in which a separation rate of over 90% and high-speed processing of a large number of cells were simultaneously achieved. It was shown that the proposed device can process large numbers of cells at high speed and with high accuracy.

Study on Microfluidic Chip Flow Rate Uniformity for Cell Activity Detection

During the cell viability detection process inside a microfluidic chip, the more uniform the distribution of medium flow rates, the higher the accuracy of detection results. In order to achieve this goal, a multichannel microfluidic chip with uniform distribution of medium flow rates has been successfully designed. The multichannel microfluidic chip is designed with cell injection channels, vascular network-shaped medium injection channels, buffer zones, and a culture chamber. The medium flow rates inside culture chambers of the multichannel microfluidic chip and the common single-channel microfluidic chip are compared by COMSOL Multiphysics software and particle velocimetry experiment. The simulation and experimental results show that the medium flow rate distribution inside the culture chamber of the multichannel microfluidic chip is more uniform and changes more smoothly. When the medium perfusion flow rate is 0.5 μL/min, the maximum flow rate difference inside the culture chamber of the single-channel microfluidic chip is more than 13 times that of the multichannel microfluidic chip. Therefore, the multichannel microfluidic chip can ensure a uniform supply of medium inside the culture chamber, which is beneficial to improve the accuracy of cell viability detection.

Microfluidic Chips: Emerging Technologies for Adoptive Cell Immunotherapy

Adoptive cell therapy (ACT) is a personalized therapy that has shown great success in treating hematologic malignancies in clinic, and has also demonstrated potential applications for solid tumors. The process of ACT involves multiple steps, including the separation of desired cells from patient tissues, cell engineering by virus vector systems, and infusion back into patients after strict tests to guarantee the quality and safety of the products. ACT is an innovative medicine in development; however, the multi-step method is time-consuming and costly, and the preparation of the targeted adoptive cells remains a challenge. Microfluidic chips are a novel platform with the advantages of manipulating fluid in micro/nano scales, and have been developed for various biological research applications as well as ACT. The use of microfluidics to isolate, screen, and incubate cells in vitro has the advantages of high throughput, low cell damage, and fast amplification rates, which can greatly simplify ACT preparation steps and reduce costs. Moreover, the customizable microfluidic chips fit the personalized demands of ACT. In this mini-review, we describe the advantages and applications of microfluidic chips for cell sorting, cell screening, and cell culture in ACT compared to other existing methods. Finally, we discuss the challenges and potential outcomes of future microfluidics-related work in ACT.

Foundation of the Manipulation Technology for Tiny Objects Based on the Control of the Heterogeneity of Electric Fields

Effective sorting and extraction of tiny plastic objects is becoming increasingly important for manufacturing high-quality recycled plastics. Herein, we designed a manipulation device for tiny objects that can drive multiple target objects individually. This type of device has a potential to sort tiny pieces of a wide variety of materials, not strongly depending on their physical properties, by combining different detection meanings. In this study, two types of devices were tested as the basic components of the proposed device. One of them had a single object-holding point and the other had two of them. These holding points consisted of strip-shaped electrodes facing each other. The high voltage applied to the facing electrodes created forces heading toward the object-holding points caused by the heterogeneity of the electric field in the devices. The forces created in these devices were determined from the motion analysis of a glass sphere, which is a model for target objects, and a numerical simulation. The results indicate that dielectrophoretic forces are dominant at locations that are sufficiently remote from the holding point, and the Coulombic force caused by dielectric barrier discharge is dominant near the high-voltage electrodes with the holding point. Moreover, the transfer of a glass sphere from one holding point to an adjacent point was successfully demonstrated.