Abstract
Microfluidic devices employing dielectrophoresis (DEP) have been widely studied and applied in the manipulation and analysis of single cells. However, several pre-processing steps, such as the preparation of purified target samples and buffer exchanges, are necessary to utilize DEP forces for suspended cell samples. In this paper, a sequential cell-processing device, which is composed of pre-processing modules that employ deterministic lateral displacement (DLD) and a single-cell trapping device employing an electroactive microwell array (EMA), is proposed to perform the medium exchange followed by arraying single cells sequentially using DEP. Two original microfluidic devices were efficiently integrated by using the interconnecting substrate containing rubber gaskets that tightly connect the inlet and outlet of each device. Prostate cancer cells (PC3) suspended in phosphate-buffered saline buffer mixed with microbeads were separated and then resuspended into the DEP buffer in the integrated system. Thereafter, purified PC3 cells were trapped in a microwell array by using the positive DEP force. The achieved separation and trapping efficiencies exceeded 94% and 93%, respectively, when using the integrated processing system. This study demonstrates an integrated microfluidic device by processing suspended cell samples, without the requirement of complex preparation steps.
Highlights
Biochemical assays targeting cells suspended in body fluids are clinically used for diagnoses or prognoses
The analysis of cancer cells in blood samples is emerging as an important non-invasive medical method that is known as liquid biopsy
We set the critical diameter for the separation as 10 μm, assuming the purification of cancer cells from other type of particles
Summary
Biochemical assays targeting cells suspended in body fluids are clinically used for diagnoses or prognoses. Various studies regarding the manipulation of mammalian cells have been performed using DEP These studies involve the isolation and separation [1,2,3,4,5,6], sorting [7,8,9], and trapping [10,11,12] of cells inside microfluidic devices. It is always necessary to exchange the existing medium (e.g., culture medium) with the specific buffer to induce strong DEP movements. These processes are performed manually as pre-processing steps, including centrifugation and liquid handling, separate from the main DEP process. It is clear that pre-processing of samples should be integrated with the main analysis step to ensure an efficient analysis of the suspended cell samples
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