Example methods, apparatus, systems for diluting samples are disclosed. An example method includes depositing a first fluid droplet on a first electrode of a plurality of electrodes. The first electrode has a first area. The first fluid droplet has a first volume associated with the first area. The example method includes depositing a second fluid droplet on a second electrode of the plurality of electrodes. The second electrode has a second area. The second fluid droplet has a second volume associated with the second area. The second volume is different than the first volume. The example method includes forming a combined droplet by selectively activating at least one of the first electrode or the second electrode to cause one of the first fluid droplet or the second fluid droplet to merge with the other of the first fluid droplet or the second fluid droplet.