Microfluidics system, device, and methods for performing rapid polymerase chain reaction (PCR) protocols

A method of thermal cycling a droplet comprising:

• (a) providing a device comprising an array of electrodes wherein the array comprises first and second electrodes within a dielectric layer, and wherein:
• (i) the first and second electrodes are separated by a gap, the gap comprising a space between the electrodes, the space being about 50 μM to about 200 μM, and the gap being a portion of the dielectric layer;
• and
• (ii) the gap dielectric layer portion is configured to have a different thermal conductivity relative to the first and second electrodes;
• (b) establishing a first temperature at the first electrode and a second temperature at the second electrode, and a thermal zone between the first electrode and the second electrode, the thermal zone comprising a temperature gradient;
• (c) using one or more droplet operations mediated by the first and second electrodes to cycle a droplet between the first temperature and the second temperature.