title: Generation of stable complex gradients across two-dimensional surfaces and three-dimensional gels.
abstract: Many chemical and biological processes are dependent on molecular gradients. We describe a new microfluidic approach that can be used to produce spatiotemporal gradients across two-dimensional surfaces and three-dimensional gels under flow-free conditions. Free diffusion between dynamically replenished flow channels acting as a sink and source is utilized to give rise to stable steady-state gradient profiles. The gradient profile is dictated by the engineered design of the device's gradient-generating region. Different designs can yield both linear and non-linear gradients of varying profiles. More complex gradients can be made by juxtaposing different designs within a single gradient-generating region. By fabricating an array of designs along the gradient-generating region, different gradient profiles can be generated simultaneously, allowing for parallel analysis. Additionally, simple methods of localizing gels into microdevices are demonstrated. The device was characterized by experimentally obtained gradient profiles of fluorescent molecules that corroborated closely with a simulated finite element model.
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, 3109 Natural Sciences 2, Irvine, California 92697-2715, USA.
authors.forename: Bobak
authors.initials: B
authors.lastname: Mosadegh
authors.forename: Carlos
authors.initials: C
authors.lastname: Huang
authors.forename: Jeong Won
authors.initials: JW
authors.lastname: Park
authors.forename: Hwa Sung
authors.initials: HS
authors.lastname: Shin
authors.forename: Bong Geun
authors.initials: BG
authors.lastname: Chung
authors.forename: Sun-Kyu
authors.initials: SK
authors.lastname: Hwang
authors.forename: Kun-Hong
authors.initials: KH
authors.lastname: Lee
authors.forename: Hyung Joon
authors.initials: HJ
authors.lastname: Kim
authors.forename: James
authors.initials: J
authors.lastname: Brody
authors.forename: Noo Li
authors.initials: NL
authors.lastname: Jeon
mesh_terms: D001698:Biomedical Engineering; D004867:Equipment Design; D005782:Gels; D046210:Microfluidic Analytical Techniques; D044085:Microfluidics; D008856:Microscopy, Fluorescence; D013499:Surface Properties
chemical_list: D005782:Gels