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.
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