The present invention provides modified droplet actuator systems, software, and software-executed methods for use in droplet actuator operation and droplet actuator systems that are configured and programmed to execute such software. An aspect of the software components of the invention is an interface description file for each hardware component of a microfluidics system that allows hardware components to be changed without modifying the program for performing droplet operations protocols. Another aspect of the software components of the invention is the establishment of electrode-to-electrode relationships and other aspects of droplet actuator configurations, which may be used when programming droplet operations protocols. Another aspect of the software components of the invention is a physical design library of predefined electrode elements that may be used by a droplet actuator designer when constructing a layout of electrodes. Another aspect of the software components of the invention is a droplet actuator description file that contains the physical and electrical description of the droplet actuator. Another aspect of the software components of the invention is a router component for determining routes of droplet operations in a droplet actuator. Another aspect of the software components of the invention is the use of tri-state vectors for programming sequences in a droplet actuator. Still other aspects are provided.