A droplet actualor having electrodes configured for ejecting droplet operations transporting droplets on a surface, and a sensor arranged in proximity to one or more of the electrodes establishing a detection window on the surface for detection of one or more properties of one or more droplets on the surface, wherein the electrodes establish at least two pathways for transport of droplets into the detection window. Also provided is, A method of detecting a property of a target droplet, including using droplet operations to modulate signals from a droplet set comprising the target droplet, detecting the modulated signals of the droplet set, demodulating the modulated signals to identify the signal produced by one or more individual droplets of the set Related methods and alternative embodiments are also provided.