Novel continuous particle sorting in microfluidic chip utilizing cascaded squeeze effect

Abstract

This article presents a novel technique for the continuous sorting and collection of microparticles in a microfluidic chip using a cascaded squeeze effect. In the proposed approach, microparticles of different sizes are separated from the sample stream using sheath flows and are then directed to specific side channels for collection. The sheath flows required to separate the particles are generated using a single high voltage supply integrated with a series of variable resistors designed to create electric fields of different intensities at different points of the microchip. Numerical simulations are performed to analyze the electrical potential contours and flow streamlines within the microchannel. Experimental trials show that the microchip is capable of continuously separating microparticles with diameters of 5, 10 and 20 lm, respectively. To further evaluate the performance of the microchip, a sample composed of yeast cells and polystyrene beads is sorted and collected. The results indicate that the microchip achieves a recovery ratio of 87.7% and a yield ratio of 94.1% for the yeast cells and therefore attains a comparable performance to that of a largescale commercial flow cytometer. Importantly, the high performance of the microchip is achieved without the need for a complex control system or for sophisticated actuation mechanisms such as embedded microelectrodes, ultrasonic generators, or micropumps, and so forth.

High-performance microfluidic rectifier based on sudden expansion channel with embedded block structure

“…A detailed discussion of the fabrication process can be found in a previous study by the current group. [48][49][50] Briefly, microchannels with a depth of 36 lm were created using a wet chemical etching process in which patterned glass substrates coated with positive photoresist were immersed in BOE etchant for 40 min. The etched substrates were then sealed with drilled bare glass substrates in a fusion bonding process performed at a temperature of 670 C for 10 min.…”

Sorting of circulating tumor cells (MV3-melanoma) and red blood cells using non-inertial lift

“…The following enlargement of the microchannel expands the flow field in z-direction and the streamlines diverge to fill the broader channel after the expansion. 46 This leads to a scaling of the distances to the lower wall with a factor 276 lm 68 lm % 4 if the cells follow the streamlines and the influence of the lift force can be neglected in this part of the microchannel. The measured z-positions at x 3 confirm this theoretical expectation with z MV3_x3 ¼ (111 6 14) lm and z RBC_x3 ¼ (62 6 10) lm.…”

Enhancement of microfluidic particle separation using cross-flow filters with hydrodynamic focusing

“…6,7 Various particle separation techniques have been developed for a fast, accurate, and label-free approach. [8][9][10][11][12] As an ideal tool for manipulating microscale objects, microfluidics have demonstrated to separate particles and cells, including pinched flow fractionation (PFF), [9][10][11][12] cross-flow filtration, [13][14][15][16][17] microfluidic disk, 18 laminar vortices, 19,20 and centrifugation/inertial focusing. [21][22][23][24][25] They possess the advantage of low-cost fabrication and massive parallelization, making high throughput sample processing possible for downstream analysis.…”