title: Powerful actuation of magnetized microtools by focused magnetic field for particle sorting in a chip.
abstract: This paper describes a novel powerful noncontact actuation of a magnetically driven microtool (MMT), achieved by magnetization of the MMT and focusing of the magnetic field in a microfluidic chip for particle sorting. The following are the highlights of this study: (1) an MMT was successfully fabricated from a mixture of neodymium powder and polydimethylsiloxane; the MMT was magnetized such that it acted as an elastic micromagnet with a magnetic flux density that increased by about 100 times after magnetization, and (2) a pair of sharp magnetic needles was fabricated adjacent to a microchannel in a chip by electroplating, in order to focus the magnetic flux density generated by the electromagnetic coils below the biochip; these needles contribute to miniaturization of an actuation module that would enable the integration of multiple functions in the limited area of a chip. FEM analysis of the magnetic flux density around the MMT showed that the magnetic flux density in the setup with the magnetic needles was around 8 times better than that in the setup without the needles. By magnetization, the drive frequency of the MMT improved by about 10 times--from 18 Hz to 180 Hz. We successfully demonstrated the separation of copolymer beads of a particular size in a chip by image sensing.
authors.affiliation: Japan Science & Technology Agency (JST), PRESTO, Department of Mechanical Science & Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Aichi-ken, Japan. yoko@mech.nagoya-u.ac.jp
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamanishi
authors.forename: Shinya
authors.initials: S
authors.lastname: Sakuma
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Onda
authors.forename: Fumihito
authors.initials: F
authors.lastname: Arai
mesh_terms: D020342:Finite Element Analysis; D007091:Image Processing, Computer-Assisted; D008280:Magnetics; D046208:Microchip Analytical Procedures / Q000379:methods*; D055616:Microtechnology