title: Optoelectrofluidic field separation based on light-intensity gradients.
abstract: Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82-16 mum) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest.
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Lee
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Park
authors.forename: Jin Sung
authors.initials: JS
authors.lastname: Yoon
authors.forename: Kwan Hyoung
authors.initials: KH
authors.lastname: Kang