A wearable device includes a testing portion, the testing portion includes receiving space, a bottom surface defining an opening, an opposite top surface, and a first side surface defining a slot. A white light source is received in the receiving space. A wearable portion of the device is secured to the testing portion and the wearable portion can be placed around a terminal device comprising a camera. The opening faces the camera when the wearable portion is around the terminal device, allowing the camera to capture a standard image of the white light, and capture a wet image of a test paper imbued with user bio-matter when the test paper is inserted into the slot. A biological information of the user, as an indicator of health, is calculated according to a color comparison between the wet image and the standard image.
