Electrowetting on a polymer microlens array.
This paper reports on the electrowetting behavior of a flexible poly(dimethylsiloxane) (PDMS) microlens array. A Cr and Au double-layered electrode was formed on an array of microlenses with diameters of 10 microm and heights of 13 microm. A deposition of parylene and a coating of Teflon were followed for electrical insulation as well as for enhancement of the hydrophobicity. On the nearly superhydrophobic microlens array surface, the electrowetting of a deionized water droplet was observed over the contact angle range of approximately 140 degrees to approximately 58 degrees by applying 0-200 V, respectively. The electrowetting phenomenon was reversible even in air environment with applied voltages of less than 100 V. The electrowetting on the microlens array surface lost its reversibility after the microlens array surface was completely wetted when the water meniscus touched the bottom of the microlens array. Analysis of meniscus shapes and net force direction follows to elucidate the reversibility. The convex curvature of the microlens caused gradual rather than abrupt impalement of water into the gap among the microlenses.
Im
Maesoon
M
Department of Electrical Engineering, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea.
Kim
Dong-Haan
DH
Lee
Joo-Hyung
JH
Yoon
Jun-Bo
JB
Choi
Yang-Kyu
YK
D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004560:Electricity; D004566:Electrodes; D057927:Hydrophobic and Hydrophilic Interactions; D007909:Lenses; D046228:Microarray Analysis / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D004129:Dimethylpolysiloxanes; D014867:Water; C013830:baysilon