title: Electrically-driven hydrogel actuators in microfluidic channels: fabrication, characterization, and biological application.
abstract: The utility of electro-responsive smart materials has been limited by bubble generation (hydrolysis) during application of electrical fields and by biocompatibility issues. Here we describe the design of a device that overcomes these limitations by combining material properties, new design concepts, and microtechnology. 4-hydroxybutyl acrylate (4-HBA) was used as a backbone hydrogel material, and its actuating behavior, bending force, and elasticity were extensively characterized as a function of size and acrylic acid concentration. To prevent bubble generation, the system was designed such that the hydrogel actuator could be operated at low driving voltages (<1.2 V). A microfluidic channel with an integrated electroactive hydrogel actuator was developed for sorting particles. This device could be operated in cell culture media, and the sorting capabilities were initially assessed by sorting droplets in an oil droplet emulsion. Biocompatibility was subsequently tested by sorting mouse embryoid bodies (mEBs) according to size. The sorted and collected mEBs maintained pluripotency, and selected mEBs successfully differentiated into three germ layers: endoderm, mesoderm, and ectoderm. The electroactive hydrogel device, integrated into a microfluidic system, successfully demonstrated the practical application of smart materials for use in cell biology.
authors.affiliation: Department of Biomedical Engineering, College of Health Science, Korea University, Seoul 136-703, Republic of Korea. dbiomed@korea.ac.kr
authors.forename: Gu Han
authors.initials: GH
authors.lastname: Kwon
authors.forename: Yoon Young
authors.initials: YY
authors.lastname: Choi
authors.forename: Joong Yull
authors.initials: JY
authors.lastname: Park
authors.forename: Dong Hun
authors.initials: DH
authors.lastname: Woo
authors.forename: Kyu Back
authors.initials: KB
authors.lastname: Lee
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000818:Animals; D002454:Cell Differentiation; D002469:Cell Separation; D004548:Elasticity; D004560:Electricity; D053595:Embryonic Stem Cells / Q000166:cytology; D004867:Equipment Design; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D055595:Mechanical Phenomena; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods
chemical_list: D000179:Acrylates; D020100:Hydrogels; C120172:4-hydroxybutyl acrylate