Real-time label-free quantitative monitoring of biomolecules by floating-gate complementary metal-oxide semiconductor sensor

A programmable magnetic cell sorter to seperate different-sized cells was presented. The cell sorter consists of a series of seperating units, comprising ferromagnetic nickel lines and current-carrying gold lines. The magnetized nickel lines and the current of gold lines can generate local field and attract the cells coated with magnetic nanoparticles. By changing the current, we could control the local magnetic field, which enables the device to sort the target cell sizes selectively. We successfully demonstrated this scheme by sorting three different sizes (6, 10, and 15 um in diameter) of magnetic beads under the different current of 21, 37, and 68mA/line to the gold lines in the fabricated microfluidic chip.

Figure 1: The fabricated device.

Specimens obtained from patients contain target cells as well as other cells. For effective drug screening, it is desirable to collect only target cells of a specific size with small variation. A macro magnetic sorter can separate target cells; however, the screened cells are not 100% pure and their sizes vary in a wide range. We have developed a microfluidic magnetic cell sorter which enables to separate cells by size which are coated with magnetic-nanoparticles. The principle of operation is based on the phenomenon that magnetic particles move to the minima of magnetic energy. We designed a programmable magnetic cell sorting scheme combining ferromagnetic layers and current-carrying metal lines to precisely control local magnetic fields.

Figure 2: Experimental sorting results: (A) Overall structure of the sorting device, (B) 15?m beads captured in the third microwell, (C) a 10um bead captured in the second microwell and (D) 6um beads captured in the first microwell.

Experimental Results - Movie

Related Publication
  1. J. Chung, H.-K. Lee, Y.-J. Kim and E. Yoon, "Programmable Magnetic Cell Size Sorter" Proceedings of microTAS 2007, pp. 793-795, Oct., Paris, France, 2007, pp. 793-795, Oct., 2007.