Abstract: Devices and systems are provided in which one or more electrochemical sensors are integrated within a digital microfluidic device. According to one example embodiment, a two-electrode electrochemical sensor is integrated into a top or bottom plate of a digital microfluidic device, where the counter electrode is provided within a defined spatial region, and where the working electrode is formed such that it is spatially distributed within the spatial region associated with the counter electrode. The working electrode may be provided as one or more elongate segments that are spatially distributed within, and/or surround a perimeter of, the counter electrode. The area of the working electrode may be selected to be smaller than that of the counter electrode in order to improve the performance of the electrochemical sensor.