A novel approach for droplet position sensing in electrowetting devices

TL;DR

This paper introduces a new droplet position sensing method for electrowetting devices that provides a linear voltage output correlated with droplet position, enhancing monitoring capabilities without disrupting device operation.

Contribution

The paper proposes a novel sensing scheme using additional dielectric and metal layers, enabling direct voltage output proportional to droplet position in EWOD devices.

Findings

The sensing scheme offers linear voltage output correlated with droplet position.

Additional layers do not significantly affect electrostatic actuation forces.

The method is compatible with digital microfluidic operations.

Abstract

A droplet position sensing scheme for monitoring multiple droplets has been proposed, which gives a direct voltage output linearly proportional to droplet position in electrowetting-on-dielectric (EWOD) based devices. An extra dielectric and metal layers are required in the bottom substrate for physical realization of the scheme which provides better isolation between actuation and sensing line. The capacitors formed due to the extra dielectric and metal layers facilitate direct voltage output proportional to droplet position during transport. Energy-based model has been used for analysis purpose. Results show that the additional dielectric and metal layer in the bottom substrate does not significantly change the driving electrostatic force profile. This makes the proposed scheme compatible for digital microfluidic operations.