Affordable Fabrication of Conductive Electrodes and Dielectric Films for a Paper-based Digital Microfluidic Chip

• Published in: Micromachines (Basel) 2019-02, Vol.10 (2), p.109
• Main Authors: Soum, Veasna, Kim, Yunpyo, Park, Sooyong, Chuong, Mary, Ryu, Soo Ryeon, Lee, Sang Ho, Tanev, Georgi, Madsen, Jan, Kwon, Oh-Sun, Shin, Kwanwoo
• Format: Article
• Language: English
• Subjects: Actuation; ballpoint pen printing; Chemical vapor deposition; Coated electrodes; conductive electrode; Contact angle; Design; dielectric film; Dielectrics; digital microfluidic chip; Electrodes; electrowetting; Low density polyethylenes; Microfluidics; Nanoparticles; plastic wrap; Polymer films; Printing; Silver; Spin coating; Thin films
• ISSN: 2072-666X; 2072-666X
• DOI: 10.3390/mi10020109

In order to fabricate a digital microfluidic (DMF) chip, which requires a patterned array of electrodes coated with a dielectric film, we explored two simple methods: Ballpoint pen printing to generate the electrodes, and wrapping of a dielectric plastic film to coat the electrodes. For precise and programmable printing of the patterned electrodes, we used a digital plotter with a ballpoint pen filled with a silver nanoparticle (AgNP) ink. Instead of using conventional material deposition methods, such as chemical vapor deposition, printing, and spin coating, for fabricating the thin dielectric layer, we used a simple method in which we prepared a thin dielectric layer using pre-made linear, low-density polyethylene (LLDPE) plastic (17-μm thick) by simple wrapping. We then sealed it tightly with thin silicone oil layers so that it could be used as a DMF chip. Such a treated dielectric layer showed good electrowetting performance for a sessile drop without contact angle hysteresis under an applied voltage of less than 170 V. By using this straightforward fabrication method, we quickly and affordably fabricated a paper-based DMF chip and demonstrated the digital electrofluidic actuation and manipulation of drops.