Wicue dust-free blackboard uses cholesteric liquid crystal, which is a bistable liquid crystal, the arrangement of molecules in the lower layer of liquid crystal changes when the board is under external pressure, and the pressed part reflects natural light, thus showing the highlighted handwriting. No electricity is required for writing, and power is only needed for erasing. It is based on the pressure-sensitive writing principle, so you can also write with objects that have a certain hardness, such as fingers.