title: Round-tip dielectrophoresis-based tweezers for single micro-object manipulation.
abstract: In this paper, we present an efficient methodology to manipulate a single micro-object using round-tip positive dielectrophoresis-based tweezers. The tweezers consist of a glass needle with a round-tip and a pair of thin gold-film electrodes. The round-tip, which has a radius of 3µm, is formed by melting a finely pulled glass needle and concentrates the electric field at the tip of the tweezers, which allows the individual manipulation of single micro-objects. The tweezers successfully captured, conveyed, and positioned single cell-sized liposomes with diameters of 5-23µm, which are difficult to manipulate with conventional manipulation methodologies, such as optical tweezers or glass micropipettes, due to the similarities between their optical properties and those of the media, as well as the ease with which they are deformed or broken. We used Stokes' drag theory to experimentally evaluate the positive dielectrophoresis (pDEP) force generated by the tweezers as a function of the liposome size, the content of the surrounding media, and the applied AC voltage and frequency. The results agreed with the theoretically deduced pDEP force. Finally, we demonstrated the separation of labeled single cells from non-labeled cells with the tweezers. This device can be used as an efficient tool for precisely and individually manipulating biological micro-objects that are typically transparent and flexible.
authors.affiliation: Kanagawa Academy of Science and Technology, KSP EAST 303, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan.
authors.forename: Taiga
authors.initials: T
authors.lastname: Kodama
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Osaki
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kawano
authors.forename: Koki
authors.initials: K
authors.lastname: Kamiya
authors.forename: Norihisa
authors.initials: N
authors.lastname: Miki
authors.forename: Shoji
authors.initials: S
authors.lastname: Takeuchi
mesh_terms: D058948:Cell Tracking; D006046:Gold / Q000737:chemistry*; D006801:Humans; D008081:Liposomes / Q000737:chemistry*; D008846:Micromanipulation / Q000295:instrumentation / Q000379:methods; D052898:Optical Tweezers; D059010:Single-Cell Analysis; D013194:Staining and Labeling
chemical_list: D008081:Liposomes; D006046:Gold