Development of High Precision Ultra-Slim UV Sensor by ROHM
No one disputes the harmfulness of Ultraviolet rays to human health but its exact measurement is another matter making ultraviolet sensor market a rapidly growing segment. The currently available UV sensors in the market come as sheet-type or as a silicon photodiodes type. In case of sheet-type, the sensors change their color when hit by UV rays, but they come with a very poor precision rate plus they can not be used repeatedly. In case of the silicon photodiodes, the sensors cannot extract and measure UV rays alone due to the absorption of the silicon itself in the visible light spectrum requiring a visible light filter which results in an increased overall size. One solution would be to detect harmful UV at a specific frequency band using specialized sensor.
Based on this, Rohm has developed a new sensor composed of zinc oxide (ZnO), making it possible to detect UV rays based on their frequency band such as frequency ranges of UV-A (l400–320nm), which are UV rays that darken the skin, and UV-B (320–280nm), which causes blistering and red sores allowing user to obtain detailed information on the existing UV rays and take appropriate actions. Furthermore, the newly developed sensor does not require any optical filter resulting in extremely small sensors. The use of ZnO is as a result of its inherent physical properties which among them being inexpensive, easy to procure and it possess unique characteristics when exposed to light, where it becomes transparent under visible light and opaque under the ultraviolet light rays. Additionally, it provides the ability to control the absorption of wavelength rage based on the specific material composition making it possible to perform sensing at a particular wavelength ranges in a small form factor.
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