Magnetic Micro/Nano Structures for Biological Detection and Manipulations. (Invited)

Magnetic micro-/nano-structures were designed and fabricated for bio-detection and bio-manipulation. First, some three dimensional micro-/nano-structures were proposed as biosensors. These three dimensional magnetic sensors can actively attract the magnetically labeled cells to the sensor position and fix the cells to be detected, which is advantageous over traditional two dimensional thin film biosensors. [1] Besides, by the integration of the spintronics and microfluidics, a Wheatstone bridge giant magnetoresistance (GMR) biosensor was also demonstrated for the detection and counting of magnetic cells. [2] Second, manipulating cells in specific positions is a very important issue for cell scaffold applications. In our study, by controlling magnetic domain walls in patterned magnetic thin films or by controlling the aligned direction of electrospun PVA-gelatin nano-fibers [3] with magnetic nanoparticles, the patterning of magnetic cells can be achieved. We also demonstrated that self-assembling of magnetic fluid or microdroplets can be used to form periodic lattice structures which can be employed for cell culture scaffolds. These research results can be applied to tissue engineering. Finally, the microstructured cone arrays made from ferrofluid molding technique as shown in Figure 1 were employed to systematically understand how the inclination of the trichome structures on leaf surface influences the wettability of leaves. By this engineering approach, it can also reveal how the inclination angle is optimized through natural selection. [4].