Tissue Light Exposure with the DermaSensor Device
In this analysis, the light exposure/dosage derived from a skin measurement with the DermaSensor device is compared with the exposure due to sunlight on a clear day.
It should be noted that the DermaSensor device utilizes incoherent light sources (LEDs); thus, there are no hazards associated with laser light.
Solar exposure:
Maximum solar irradiance at noon, in summer and at mid-latitudes, is ~1,100 W/m2 =  . That is, 1 mJ per square millimetre of skin surface per second.
The wavelength range of sunlight covers ultraviolet to near-infrared wavelengths, including a small portion of mutagenic UVB radiation (280 – 315 nm).
DermaSensor device exposure:
The exposed surface area of the skin during measurement will be ~1 mm2.
Maximum light energy (total for all wavelengths) for measurement on one measured skin site is designed to be less than 1 mJ. Assuming (worst case) that all of this light is absorbed by the skin, this is less than the light dose from 1 second of exposure to sunlight (or less than 10 seconds of exposure in typical indoor room light).
The DermaSensor device will utilize 8-9 discrete wavelengths, one of which is in the UVA range (~350 nm), and none in the UVB. The other wavelengths are in the visible (400 – 700 nm) range and the near-infrared (in the DermaSensor design, 700 – 850 nm).
Given that the DermaSensor device generates an exposure less than that received from 1 second of sunlight, and that only 1 mm2 of skin is exposed with the device (compared with much larger surface areas of skin typically exposed to sunlight), there will be no measurable thermal effect. Additionally, given the absence of UVB light, and the small surface area exposed, the mutagenic potential will be many millions of times smaller than that for 1-second of sunlight exposure.
Since light absorbed by the body and risk is negligible, and the device is essentially noninvasive, the appropriate classification for the DermaSensor device should be Class I.