標題: Asymmetric electrowetting - moving droplets by a square wave
作者: Fan, Shih-Kang
Yang, Hanping
Wang, Tsu-Te
Hsu, Wensyang
機械工程學系
材料科學與工程學系奈米科技碩博班
Department of Mechanical Engineering
Graduate Program of Nanotechnology , Department of Materials Science and Engineering
公開日期: 2007
摘要: Here droplet oscillation and continuous pumping are demonstrated by asymmetric electrowetting on an open surface with embedded electrodes powered by a square wave electrical signal without control circuits. The polarity effect of electrowetting on an SU-8 and Teflon coated electrode is investigated, and it is found that the theta-V ( contact angle-applied voltage) curve is asymmetric along the V = 0 axis by sessile drop and coplanar electrode experiments. A systematic deviation of measured contact angles from the theoretical ones is observed when the electrode beneath the droplet is negatively biased. In the sessile drop experiment, up to a 10 degrees increment of contact angle is measured on a negatively biased electrode. In addition, a coplanar electrode experiment is designed to examine the contact angles at the same applied potential but opposite polarities on two sides of one droplet at the same time. The design of the coplanar electrodes is then expanded to oscillate and transport droplets on square-wave-powered symmetric ( square) and asymmetric ( polygon) electrodes to demonstrate manipulation capability on an open surface. The frequency of oscillation and the speed of transportation are determined by the frequency of the applied square wave and the pitch of the electrodes. Droplets with different volumes are tested by square waves of varied frequencies and amplitudes. The 1.0 mu l droplet is successfully transported on a device with a loop of 24 electrodes continuously at a speed up to 23.6 mm s(-1) when a 9 Hz square wave is applied.
URI: http://hdl.handle.net/11536/11261
http://dx.doi.org/10.1039/b704084a
ISSN: 1473-0197
DOI: 10.1039/b704084a
期刊: LAB ON A CHIP
Volume: 7
Issue: 10
起始頁: 1330
結束頁: 1335
顯示於類別:期刊論文


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  1. 000249740500023.pdf