Rare Cell Immobilization on MEMS Scale Sensors Using Micro-Electromagnets

Abstract

A novel method is presented for immobilizing rare single cells on MEMS scale sensor sites. The presented method does not require immobilization site to be chemically functionalized. Immobilizing single cells precisely on MEMS sensor sites is a requirement for many single cell analysis methods—reliability of cell analysis directly depends on the reliability of immobilization. The presented method uses magnetic forces to immobilize cells labeled with superparamagnetic beads on MEMS scale sites of interest. It can be coupled with many cell analysis techniques to form MEMS lab-on-a-chip devices due to the simple fabrication setup and principle of operation. The performance of the device was demonstrated with unbound superparamagnetic beads as well as with human breast tumor cells from the cell line MCF-7. Immobilization percentage and area were 95.2% and 1000 $\mu \text{m}^{2}$ , respectively, for superparamagnetic beads. MCF-7 cells labeled with superparamagnetic beads were immobilized at a percentage of 69.2% with the average distance from immobilized cells to micro-electromagnet being $50.8~\mu \text{m}$ . Thus, the presented method is a good candidate for integration with microfluidic sensing and analysis platforms.