An integrated and automated digital microfluidic device for dairy milk droplet actuation

Digital microfluidics is an emerging lab-on-a-chip technology with strength in reconfigurability, parallelization, robustness, and automation. These traits are of urgent need in on-site dairy testing where current methods are manually intensive and time consuming. This work addresses challenges of device integration and biofouling which must be overcome for the application of digital microfluidics to dairy testing. The challenge of device integration is addressed, as the device developed in this work features a modular and inexpensive printed circuit board design. Users can reconfigure and automate device operation from a versatile computer graphical user interface. The challenge of biofouling is addressed through experimental analyses of milk and water droplet actuation in an air filler medium. Closed versus open digital microfluidic configuration experiments show an open system is advantageous. The reduction and mitigation of biofouling is shown through spectroscopy. Polydimethylsiloxane versus parafilm dielectric layers show a thin-film dielectric is advantageous in open configurations. Droplet velocities versus voltage experiments are performed in both configurations. Droplet velocities versus actuation frequency experiments demonstrate that the results are similar in both configurations and that at high frequencies the actuation force is weakened. The results show promise for development of a digital microfluidic on-site dairy tester.