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

Veasna Soum,Sang Lee,Georgi Tanev,Jan Madsen,Mary Chuong,Oh-Sun Kwon,Soo Ryu,Kwanwoo Shin,Sooyong Park,Yunpyo Kim

doi:10.3390/mi10020109

Veasna Soum, Sang Lee + Show 8 more

Open Access

https://doi.org/10.3390/mi10020109

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Abstract

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.

Highlights

A few decades ago, a digital microfluidic (DMF) chip was introduced as a new type of lab-on-a-chip (LOC) device [1,2,3]
Because of the above factors, we explored a new approach, the hand-wrapping approach, to fabricate a dielectric film for a paper-based DMF chip by using a commercially available plastic film worse, most thin-film deposition methods, such as chemical vapor deposition (CVD) for parylene-C and spin-coating for Teflon, require heavy instruments, including gas- and temperature-control systems on a lab-scale, which is a severe obstacle to the affordable fabrication of DMF chips
Because of the above factors, we explored a new approach, the hand-wrapping approach, to fabricate a dielectric film for a paper-based DMF chip by using a commercially available plastic film made of LLDPE

Summary

Introduction

A few decades ago, a digital microfluidic (DMF) chip was introduced as a new type of lab-on-a-chip (LOC) device [1,2,3]. The actuation principle is based on the so-called electrowetting on dielectric (EWOD) phenomena. EWOD is a very practical way for fluidic manipulation in microfluidic devices. It has been used for creating an electrowetting valve to control the flow of the fluid in a continuous-flow paper-based microfluidic device [4,5]. That type of LOC was a simplified and minimized device, because many scalable components, such as complex pumps, guiding channels and valves, had been removed and replaced with planar structures capable of actuating a DMF drop driven by the EWOD phenomena [9,10,11]

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