According to figures of the World Health Organization corresponding to global mortality statistics in 2012, the increasing level of environmental pollution has become a major environmental health risk in big cities worldwide, causing about 7 million deaths annually, nearly one in eight deaths, and twice of those in 2008. Furthermore, according to the statistics of the American Cancer Society, skin cancer accounts for nearly half of all cancers in the United States. Melanoma, the most serious type of skin disease, accounts for more than 9000 of the 12,000-plus skin cancer deaths each year.1 Based on the current situation, early diagnosis of human skin diseases in the skin surface, as a main medical mean, becomes more and more significant. However, the investigation of human skin tissues has received only limited attention, to the point that there are not yet satisfactory modern detection technologies to accurately, noninvasively, and rapidly characterize and diagnose human skin. For example, the most common methods of skin disease detection so far are still palpation and clinical section analysis.2,3 The former is limited by subjective experience, and the latter is a destructive testing not proper for preventive inspection.