THERMOMAGNETIC MICRO-TRACKS-GUIDED MAGNETIC BEAD MANIPULATION: A DEMONSTRATION OF MOVING BEAD ACROSS DIFFERENT TRACKS ENABLED BY NOVEL EMBEDDED ON-CHIP MICRO HEATING WIRES

Abstract

In this paper, we show a demonstration of moving bead across different tracks enabled by novel embedded on-chip micro heating wires for thermomagnetic micro-tracks-guided magnetic bead manipulation. The demonstration includes a magnetic-bead-manipulation chip (which consists of thermomagnetic NiCu micro-disk tracks deposited on top of on-chip platinum micro heating wires fabricated on top of a silicon substrate), a magnetic bead, a thermoelectric generator (TEG), a pulse-generation circuit, and four external electromagnets. Because curie temperature of the track is approximate in room-temperature range, when we apply a pulse current to the heating wires to individually heat the track higher than room temperature, the magnetic property of the track is switched to paramagnetic. Oppositely, when we apply a current to TEG to cool the track lower than room temperature, the track is switched to ferromagnetic. By sequentially/selectively heating or cooling the tracks to switch the tracks to paramagnetic or ferromagnetic, together with applying directional magnetic field, we can achieve moving bead across different NiCu micro-disk tracks. This is an important and significant progress for conventional thermomagnetic micro-tracks-guided magnetic bead manipulation which cannot demonstrate moving bead across different tracks. Therefore, our approach provides a new and complete thermomagnetic micro-tracks-guided magnetic bead manipulation for lab-on-chip micro systems and biomedical MEMS/NEMS.