Abstract
This research is utilizing the stray field induced by magnetized magnetic thin film pattern to attract magnetically labeled cells. According to fabrication of 2-D and 3-D structures, the experimental studies can be divided into four sections which are cell patterning, cell capture, cell sensing and cell transporter. In the first section study of 2-D planar cell patterning, a method of utilizing the stray field induced by north and south poles on the tips of the diamond-shaped and cross-shaped thin films to attract magnetically labeled cells forming a linear cell patterning. In second section study of 3-D cell capture and cultivation, we designed a 3-D cell culture model based on magnetic roll-up structures in ring geometry, which was used to efficiently create spherical Jurkat cell cluster. Specially-designed fishbone magnetic thin films deposited on the roll-up structures provided the magnetic field gradient required for attracting magnetically labeled cells onto the roll-up structures. The time evolution of cell capture on the roll-up structure was observed. In addition, the proliferation rate and viability of the fabricated cell clusters as a function of cultivation time were investigated. A 3-D roll-up structure made of SiO2 layer and fishbone-like magnetic thin film was proposed as a biosensor in the third part of study. The magnetoresistance (MR) measurement results of the sensor suggest that the presence of the stray field, which was induced by the magnetic nanoparticles, significantly increased the switching field. It is worth noting that the MR ratio variation of the 3-D sensor structure was much higher than the 2-D sensor structure, therefore yielding higher sensitivity for the bio detection. The 3-D magnetic biosensor designed here can provide important information for biochip research and applications. In the fourth section, a magnetic capsule was designed for wireless transport of a single cell or multiple cells to a designated position. A rotating magnetic field was applied to magnetize the magnetic thin film array track and the magnetic capsule simultaneously that made the capsule move along the track. We have successfully moved a magnetic capsule carrying a single cell or cell cluster in 1-D and 2-D moving patterns. This technique can provide important information for future applications of positioning, transporting, sorting, capturing and sensing for cells and biomolecules on biochips.