Skin tone sensor adopts Fitzpatrick taxonomy to divide skin color into six types.

 Structure:

 1. Battery inside, no need charging;

 2. Applicable skin color: I to IV type, the skin type dispaly will show what skin type by indicator;

 3. Unsafe skin color: V type, the skin type display indicator won't light;

 4. Skin tone test for more than 2 times to make sure test results accurately.