EWOD using P(VDF-TrFE)

A novel electrowetting on dielectric (EWOD) digital microfluidic device using the high dielectric constant material P(VDF-TrFE) (poly-vinylidene fluoride-trifluoroethylene) as the dielectric layer fabricated by spin-coating process is proposed. The device is featured with the advantages of both IC compatible process and low driving voltage. The contact angle between the liquid droplet and surface of the device changes from 118° to 75° under an applied voltage of 30V. The voltage-polarity-related electrowetting on dielectric phenomenon is observed and applied in our study. A novel single-side coplanar electrodes EWOD device is developed. EWOD at positive and negative voltage is so different that a droplet 3μL is successfully transported reciprocally under 20V based on the polarity change of driving voltage.

I. Introduction

Recently, with the scaling down of MEMS (micro-electro-mechanical-systems) device, interfacial tension as an inherently dominant force on micrometer and nanometer scale has attracted serious attention. Although it has been founded one century ago that the interfacial tension can be controlled by thermal and electrical methods [1], MEMS devices such as microfluidic devices using interfacial tension as driven force only start to emerge in recent years. For the advantage of high energy efficiency, electrical control is preferred in microfluidic systems [2].