The assembly of the alignment cells was adapted from previously reported procedure . Prior to the assembly, each corner of the polyimide-coated substrate was deposited with a UV curable glue (Norland UV Sealant 91), which was prreviusly mixed with soda lime glass microspheres (diameter: 100 µm, Cospheric LLC) to define the cell thickness. Two substrate pieces, with their alignment surfaces facing inward, were then joined and exposed to UV light for 1 minute inside an Asiga Flash UV chamber to ensure bonding. The alignment cell was heated to 80°C, at which point the LC mixture was filled in the cell via capillary force. The cell was gradually cooled to room temperature at a controlled rate of 1°C/min. For aligning polymerizable LC ink, the cell was kept in the dark for the during the alignment process.