High-Throughput Cell Trapping in the Dentate Spiral Microfluidic Channel

Cell trapping is a very useful technique in a variety of cell-based assays and cellular research fields. It requires a high-throughput, high-efficiency operation to isolate cells of interest and immobilize the captured cells at specific positions. In this study, a dentate spiral microfluidic structure is proposed for cell trapping. The structure consists of a main spiral channel connecting an inlet and an out and a large number of dentate traps on the side of the channel. The density of the traps is high. When a cell comes across an empty trap, the cell suddenly makes a turn and enters the trap. Once the trap captures enough cells, the trap becomes closed and the following cells pass by the trap. The microfluidic structure is optimized based on the investigation of the influence over the flow. In the demonstration, 4T1 mouse breast cancer cells injected into the chip can be efficiently captured and isolated in the different traps. The cell trapping operates at a very high flow rate (40 μL/s) and a high trapping efficiency (>90%) can be achieved. The proposed high-throughput cell-trapping technique can be adopted in the many applications, including rapid microfluidic cell-based assays and isolation of rare circulating tumor cells from a large volume of blood sample.

Dynamic phase control with printing and fluidic materials' interaction by inkjet printing an RF sensor directly on a stereolithographic 3D printed microfluidic structure

RF electronics is inkjet-printed directly onto a 3D printed microfluidic structure using surface modification for the high conductivity, high resolution, and enhanced the interaction between a RF part and a fluid material.

Microfluidic Acoustic Metamaterial SAW Based Sensor

Introduction. Microacoustic sensors based on surface acoustic wave (SAW) devices allow the sensor integration into a wafer based microfluidic analytical platforms such as lab-on-a-chip. Currently exist various approaches of application of SAW devices for liquid properties analysis. But this sensors probe only a thin interfacial liquid layer. The motivation to develop the new SAW-based sensor is to overcome this limitation. The new sensor introduced here uses acoustic measurements, including surface acoustic waves (SAW) and acoustic methamaterial sensor approaches. The new sensor can become the starting point of a new class of microsensor. It measures volumetric properties of liquid analytes in a cavity, not interfacial properties to some artificial sensor surface as the majority of classical chemical and biochemical sensors.Objective. The purpose of the work is to find solutions to overcome SAW-based liquid sensors limitations and the developing of a new sensor that uses acoustic measurements and includes a SAW device and acoustic metamaterial.Materials and methods. A theoretical analysis of sensor structure was carried out on the basis of numerical simulation using COMSOL Multiphysics software. Lithium niobate (LiNbO3) 127.86° Y-cut with wave propagation in the X direction was chosen as a substrate material. Microfluidic structure was designed as a set of rectangular shape channels. A method for measuring volumetric properties of liquids, based on SAW based fluid sensor concept, comprising the steps of: (a) providing sensor structure with the key elements: a SAW resonator, a high-Q set of liquid-filled cavities and intermediate layer with artificial elastic properties between them; (b) measuring of resonance frequency shift, associated with the resonance in liquid-filled cavity, in the response of weakly coupled resonators of SAW resonator loaded by periodic microfluidic structure; (c) determination of volumetric properties of the fluid on the basis of a certain relationship between the speed of sound in liquid, the resonant frequency of the set of liquid-filled cavities, and the geometry design of the cavity.Results. The new sensor approach is introduced. The eigenmodes of the sensor structure with a liquid analyte are carried out. The characteristic of sensor structure is determined. The key elements of introduced microfluidic sensor are a SAW structure, an acoustic metamaterial with a periodic set of microfluidic channels. The SAW device acts as electromechanical transducer. It excites surface waves propagating in the X direction lengthwise the periodic structure and detects the acoustic load generated by the microfluidic structure resonator. The origin of the sensor signal is a small frequency change caused by small variations of acoustic properties of the analyte within the set of microfluidic channels.Conclusion. The principle of the new microacoustic sensor, which can become the basis for creating a new class of microfluidic sensors, is shown.

Microfluidic chip combined with magnetic-activated cell sorting technology for tumor antigen-independent sorting of circulating hepatocellular carcinoma cells

Purpose We aimed to generate a capture platform that integrates a deterministic lateral displacement (DLD) microfluidic structure with magnetic-activated cell sorting (MACS) technology for miniaturized, efficient, tumor antigen-independent circulating tumor cell (CTC) separation. Methods The microfluidic structure was based on the theory of DLD and was designed to remove most red blood cells and platelets. Whole Blood CD45 MicroBeads and a MACS separator were then used to remove bead-labeled white blood cells. We established HepG2 human liver cancer cells overexpressing green fluorescent protein by lentiviral transfection to simulate CTCs in blood, and these cells were then used to determine the CTC isolation efficiency of the device. The performance and clinical value of our platform were evaluated by comparison with the Abnova CytoQuest™ CR system in the separating of blood samples from 12 hepatocellular carcinoma patients undergoing liver transplantation in a clinical follow-up experiment. The isolated cells were stained and analyzed by confocal laser scanning microscopy. Results Using our integrated platform at the optimal flow rates for the specimen (60 µl/min) and buffer (100 µl/min per chip), we achieved an CTC yield of 85.1% ± 3.2%. In our follow-up of metastatic patients, CTCs that underwent epithelial–mesenchymal transition were found. These CTCs were missed by the CytoQuest™ CR bulk sorting approach, whereas our platform displayed increased sensitivity to EpCAMlow CTCs. Conclusions Our platform, which integrates microfluidic and MACS technology, is an attractive method for high-efficiency CTC isolation regardless of surface epitopes.

Universally applicable three-dimensional hydrodynamic focusing in a single-layer channel for single cell analysis

A microfluidic cytometer which integrated 3D hydrodynamic focusing and integrated optical systems on a single-layer microfluidic structure was demonstrated.

Characterization of MEMS Materials Using Laser Micromachine

Laser micromachining technique was used in this work to produce two different microfluidic structure on three MEMS materials namely silicon, SU-8 photoresist and polydimethylsiloxane (PDMS). The operational parameters of the machine ablation effects on the materials, which are the laser energy, laser pulse rate and the laser size were also investigated. We found that this technique is capable to produce typical MEMS structure similar as being produced using conventional photolithography process.