Size dependent droplet actuation in digital microfluidic systems

Biddut Bhattacharjee; Homayoun Najjaran

doi:10.1117/12.818031

11 May 2009 Size dependent droplet actuation in digital microfluidic systems

Biddut Bhattacharjee, Homayoun Najjaran

Proceedings Volume 7318, Micro- and Nanotechnology Sensors, Systems, and Applications; 73180H (2009) https://doi.org/10.1117/12.818031
Event: SPIE Defense, Security, and Sensing, 2009, Orlando, Florida, United States

Abstract

Digital microfluidic systems (DMFS) manipulate liquid droplets with volumes in submicroliter range in two dimensional arrays of cells. Among possible droplet actuation mechanisms, Electrowetting-on-dielectric (EWOD) actuation has been found to be most feasible and advantageous because of low power consumption, ease of signal generation and basic device fabrication. In EWOD based DMFS, droplets are actuated by applying an electric field and thus increasing the wettability on one side of the droplet. In this paper, we show that the EWOD actuation of a droplet can be modeled as a closed loop system having unity feedback of position. Electrode, dielectric and droplet are modeled as a capacitor with variable area as the droplet, considered as a conductor, moves over the dielectric layer. The EWOD force depends on the rate of change of droplet area over the actuated electrode, which in turn depends on the direction of motion and the position of the droplet between the actuated and previous electrode. Thus, EWOD actuation intrinsically utilizes the droplet position to generate sufficient force to accelerate the droplet. When the droplet approaches the final position, the magnitude of force reduces automatically so the droplet decelerates. In case the droplet has sufficient momentum to exceed the final position, the EWOD force, according to the model, will act on the opposite side of the droplet in order to bring it back to the desired position. The dynamic response has been characterized using the proposed model for different droplet sizes, actuation voltages, dielectric thicknesses and electrode sizes.

Citation Download Citation

Biddut Bhattacharjee and Homayoun Najjaran "Size dependent droplet actuation in digital microfluidic systems", Proc. SPIE 7318, Micro- and Nanotechnology Sensors, Systems, and Applications, 73180H (11 May 2009); https://doi.org/10.1117/12.818031

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available