Abstract
Flow cytometry is a front-end basic instrument in biomedical field. The flow cytometry can count and sort cells fast and precisely, and contributes greatly in areas such as immunoassay. In this study, we innovatively use micro Giant Magnetoresistive (GMR) sensor to detect cells. By measuring the magnetoresist variations induced by the magnetic-marked cells, the number of magnetic cells passed through the sensor can be counted. Besides, we also sort the magnetic cells magnetically after the counting. Our magnetoresistive flow cytometry is composed of three parts including microfludic part for hydrodynamic focusing of cell stream, spintronic part for cell detecting, and cell separation and sorting part. The most important part is the cell detecting. In this part, GMR sensors are designed in different shapes to test their sensitivity for magnetic cell detecting. From the experiment results, we found a sensor have smaller shape anisotropy is a better choice to be used to count cells. In addition to counting cells, the sensor also need to distinguish cells which endocyte different numbers of magnetic particles. In the separation and sorting part, the threshold fields for making cells’ flow direction bending adequately are found at different flow velocities. It will be useful for future automation work.