Provided herein are systems and methods for reducing the number of input/output connections required to connect a microfluidic substrate to an external controller for controlling the substrate. For example, provided herein is a device with three groups of independently controllable components, where the first group includes a first lead and a first heater configured to heat a valve; where the second group includes a second lead and a second heater configured to heat a reaction chamber; where the third group includes a third lead and the first and second heaters; and where the first heater is independently controllable via a combination of the first lead and the third lead, and the second heater is independently controllable via a combination of the second lead and the third lead.