A method of loading a fluid into an active matrix electrowetting on dielectric AM-EWOD microfluidic device, the microfluidic device comprising: upper and lower spaced apart substrates (16, 10) defining a fluid chamber therebetween; an aperture for receiving fluid into the fluid chamber; and a plurality of independently addressable array element electrodes, each array element electrode defining a respective array element, and each array element defining a respective region of the fluid chamber; the method comprising: loading a filler fluid into the microfluidic device; disposing the dispensing end of a fluid applicator at or near the aperture; dispensing working fluid from the fluid applicator into a loading region adjacent the aperture and external to the fluid chamber; and forcing the working fluid from the loading region into the fluid chamber via the aperture by actuating at least one of the array elements of the microfluidic device to draw the dispensed working fluid into the fluid chamber of the microfluidic device. wherein actuating at least one of the array elements of the microfluidic comprises actuating at least one array element in a second region of the microfluidic device, the second region being between the aperture and a target region of the microfluidic device for the working fluid, wherein the second region of the microfluidic device has, at its nearest point to the aperture, a width less than the width of the aperture and wherein the second region comprises a first part having a width less than the width of the aperture and a second part having a second, greater width, the boundary between the first part and the second part being between the aperture and the flow edge of working fluid; the method further comprising applying a time varying actuation pattern, so that the boundary between the first part and the second part moves away from the aperture as the flow edge of working fluid moves away from the aperture. upper and lower spaced apart substrates (16, 10) defining a fluid chamber therebetween; an aperture for receiving fluid into the fluid chamber; and a plurality of independently addressable array element electrodes, each array element electrode defining a respective array element, and each array element defining a respective region of the fluid chamber; the method comprising: loading a filler fluid into the microfluidic device; disposing the dispensing end of a fluid applicator at or near the aperture; dispensing working fluid from the fluid applicator into a loading region adjacent the aperture and external to the fluid chamber; and forcing the working fluid from the loading region into the fluid chamber via the aperture by actuating at least one of the array elements of the microfluidic device to draw the dispensed working fluid into the fluid chamber of the microfluidic device. wherein actuating at least one of the array elements of the microfluidic comprises actuating at least one array element in a second region of the microfluidic device, the second region being between the aperture and a target region of the microfluidic device for the working fluid, wherein the second region of the microfluidic device has, at its nearest point to the aperture, a width less than the width of the aperture and wherein the second region comprises a first part having a width less than the width of the aperture and a second part having a second, greater width, the boundary between the first part and the second part being between the aperture and the flow edge of working fluid; the method further comprising applying a time varying actuation pattern, so that the boundary between the first part and the second part moves away from the aperture as the flow edge of working fluid moves away from the aperture. loading a filler fluid into the microfluidic device; disposing the dispensing end of a fluid applicator at or near the aperture; dispensing working fluid from the fluid applicator into a loading region adjacent the aperture and external to the fluid chamber; and forcing the working fluid from the loading region into the fluid chamber via the aperture by actuating at least one of the array elements of the microfluidic device to draw the dispensed working fluid into the fluid chamber of the microfluidic device. wherein actuating at least one of the array elements of the microfluidic comprises actuating at least one array element in a second region of the microfluidic device, the second region being between the aperture and a target region of the microfluidic device for the working fluid, wherein the second region of the microfluidic device has, at its nearest point to the aperture, a width less than the width of the aperture and wherein the second region comprises a first part having a width less than the width of the aperture and a second part having a second, greater width, the boundary between the first part and the second part being between the aperture and the flow edge of working fluid; the method further comprising applying a time varying actuation pattern, so that the boundary between the first part and the second part moves away from the aperture as the flow edge of working fluid moves away from the aperture.