Biological and sensing application of far UV-C light from LED

Effect of the irradiation of ultraviolet-C (UVC) light to a backside of a leaf is investigated by using irradiation modules with 229nm, 239nm and 269nm light emitting diodes (LEDs), respectively. Observed by an optical microscope, a function of the leaf to open a guard cell disappeared when irradiated at the power density over a threshold. The threshold power density becomes smaller exposed at shorter wavelength due to higher absorption coefficient of the guard cell. The guard cell maintained “closing” indicating a self-organizing-regeneration for recovery didn’t occur. This finding becomes one of the instructions when utilizing a far UVC light in human living environment surrounded by several plants in future.