Electrofluidic displays based on inkjet printing and phase change filling

Abstract

The patterned fluoropolymer film hydrophobicity and colored oil layer uniformity were critical for electrofluidic displays. Typically, reactive ion etching (RIE) is commonly used to pattern fluoropolymer films due to the chemically inert nature of fluorinated materials. However, the RIE process permanently changed the surface properties of the fluoropolymer film. These affect the function of the electrofluidic displays. The development of inkjet printing technology provides an innovative manufacturing pathway for functional materials, such as fluoropolymers. In this work, for the first time, an amorphous fluoropolymer (AF 1600) was patterned by a piezoelectric inkjet printer as a hydrophobic layer for an electrofluidic display. The pattered fluoropolymer films can be inkjet printed by varying the concentration of the fluoropolymer solution and adjusting printing parameters. Phase change filing was explored in combination with inkjet printing of colored oil, enabling the manufacture of electrofluidic cells in the air for the first time. The fluoropolymer and colored oil properties were systematically investigated to fulfill the inkjet printing requirements. The cost of manufacturing can be significantly reduced for large scale production by employing inkjet printing in combination with phase change filling. Furthermore, electrical and optical characterization of the printed electrofluidic cell shows better visual performance, dielectric stability, and fast electrical response and than the traditionally produced devices.