Droplet Position Sensing in TFT Active-Matrix Digital Microfluidics

This letter presents a droplet position sensing circuit designed for thin film transistor active-matrix digital microfluidics. The presented pixel design facilitates simultaneous implementation of droplet driving and position sensing functions. An ${8}\times {8}$ array was fabricated with standard thin film transistors compatible to mainstream display backplane technology. Measured results indicate a difference in output voltage of approximately 4 V between deionized water and air, demonstrating ample precision for accurate droplet position sensing. The driving and readout capability of the array has also been experimentally verified. The approach presented here is suitable for integration of TFT active-matrix digital microfluidics, offering a solution to enhance the efficiency and precision of droplet manipulation.