Electrowetting on Dielectric (EWOD) Device with Dimple Structures for Highly Accurate Droplet Manipulation

Katsuo Mogi,Shungo Adachi,Tomoya Inoue,Tohru Natsume,Naoki Takada

doi:10.3390/app9122406

Katsuo Mogi, Shungo Adachi + Show 3 more

Open Access

https://doi.org/10.3390/app9122406

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Abstract

Digital microfluidics based on electrowetting on dielectric (EWOD) devices has potential as a fundamental technology for the accurate preparation of dangerous reagents, the high-speed dispensing of rapidly deteriorating reagents, and the fine adjustment of expensive reagents, such as the preparation of for positron emission tomography (PET). To allow single substrate type EWODs to be practically used in an automatic operation system, we developed a dimple structure as a key technique for a highly accurate droplet manipulation method. The three-dimensional shape of the dimple structure is embossed onto a disposable thin sheet. In this study, we confirmed that the dimple structure can suppress unintended droplet motion caused by unidentified factors. In addition, the stability of the droplets on the dimple structures was evaluated using a sliding experiment. On a flat substrate, the success rate of a droplet motion was lower than 70.8%, but on the dimple structure, the droplets were able to be moved along the dimple structures correctly without unintended motion caused by several environmental conditions. These results indicated that the dimple structure increased the controllability of the droplets. Hence, the dimple structure will contribute to the practical application of digital microfluidics based on single substrate type EWODs.

Highlights

Various fields—e.g., medicine, drug discovery [1], industrial chemistry [2,3], and basic chemistry [4]—are supported by basic wet-lab experiments based on handling micro reagents with pipettes
We proposed a dimple structure to realize the accurate digital manipulation of
The success rate of the dropletdigital motionmanipulation was lower than droplets devices

Summary

Introduction

Various fields—e.g., medicine, drug discovery [1], industrial chemistry [2,3], and basic chemistry [4]—are supported by basic wet-lab experiments based on handling micro reagents with pipettes. Statistical analyses of large amounts of data using computer technology have become possible [5,6,7]. With the progress in technology, wet-lab experiment results are becoming proportionally required in large quantities [8,9]. An enormous burden is being placed on researchers who perform wet-lab experiments with simple pipetting operations. Simple operations should be automated to enable the high reproducibility of reagent adjustments, because personal differences in manual dispensing operations can greatly affect the results of the adjustments. There are some groups that promote mechanical automation [10], but most other groups have difficulty installing expensive, large equipment

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