Microfluidic multicolor display by juxtapositional color mixing with a pattern of primary color pixels

This paper describes a microfluidic multicolor display utilizing juxtapositional color mixing of pixels. Our display has a 14 × 14 array of pixels (2.5 mm in pixel diameter, 8.46 ppi) on the display surface where multicolor is expressed by controlling the pattern of the four primary color inks (cyan (C), magenta (M), yellow (Y), and black (= key plate, K)) that fill the pixels. The microfluidic display has a three-layer structure composed of a top layer with pixels for displaying images, a middle layer that serves as a background screen, and a bottom layer with microchannels that connect the pixels. In order to express multicolor by combining CMYK primary colors, we optimized the concentration of the inks used as the primary colors. By designing patterns of pixels filled with CMYK ink, color gradations and multicolor images were displayed on our display. The proposed microfluidic display could be applied to eye-friendly and low-energy-consumption flexible display applications including multi-purpose sign boards used in outdoors, wearing objects, and exterior/interior of vehicles and architects.