Automatic detecting and counting magnetic beads-labeled target cells from a suspension in a microfluidic chip.

A novel microfluidic method of continually detecting and counting beads-labeled cells from a cell mixture without fluorescence labeling was presented in this paper. The detection system is composed of a microfluidic chip (with a permanent magnet inserted along the channel), a signal amplification circuit, and a LabView® based data acquisition device. The microfluidic chip can be functionally divided into separation zone and detection zone. By flowing the pre-labeled sample solution, the target cells will be sequentially separated at the separation zone by the permanent magnet and detected and counted at the detection zone by a microfluidic resistive pulse sensor. Experiments of positive separation and detection of T-lymphocytes and negative separation and detection of cancer cells from the whole blood samples were carried out to demonstrate the effectiveness of this method. The methodology of utilizing size difference between magnetic beads and cell-magnetic beads complex for beads-labeled cell detection is simple, automatic, and particularly suitable for beads-based immunoassay without using fluorescence labeling.