a microfluidic printing apparatus responsive to an image file for printing a plurality of pixels on a receiver . the apparatus includes a plurality of colorant delivery chambers which contain colorants having mobile ions ; and channels for delivering colorants to each colorant delivery chamber . a structure for colorant delivery is connected to the channels for controlling the amount of colorants delivered to the colorant delivery chambers . electric drivers associated with the microfluidic pumps and the microvalves and which operate the microvalves and the microfluidic pumps for delivering the colorant to the colorant delivery chambers .