UV Aware Sunglasses
The ozone disappearance and inability to be aware of UV radiation exposure provided a decent reason to design UV aware sunglasses, that will monitor your overall cumulative daily exposure to UV radiation and informs about potential burning risks or rapidly changing UV radiation levels. Current prototype handles present skintype settings, notifying present intensity, rapid intensity changes & daily safe-level exceeds.
During my exchange studies at New Zealand I noticed that UV radiation intensity & skin cancer rates are one of the highest in the world. Southern hemisphere has less ozone, which causes greater amount of UV radiation reaching the surface of the earth. Being exposed to sun is essential and too little UV radiation leads to a lack of Vitamin D, where as too much can lead to a DNA damage, sunburn, and skin cancer. Sunglasses felt most eligible for my purposes and provided good challenging frame for building actual usable product.
Finding a solution for measuring UV intensity wasn't as easy as I though. Normal photodiodes are only sensitive to visible light ranges and industry UV sensors where out of my price range,so I decided to build my own. I chose to build prototype with cheap TSL230R light frequency sensor that I found to be sensitive also for UVA range of wavelengths. I still needed a solution to block everything else than UV light from hitting my sensor. A special Wood’s glass felt to serve my prototyping purpose relatively well. It’s a special glass opaque to almost all visible light wavelengths and quite transparent for wavelengths from 320 to 400 nanometres (UVA) and some infrared with a peak at 365 nanometres. Got mine for my prototyping needs from typical smashed UV light bulb, since they use coating of Wood’s Glass and are available for relatively cheap. Lilypad served as a microprocessor and small batteries where hided inside a paper origami head pin, than can be attached to hairs, hat or sleeve.
TSL230R converts irradiance (the light energy on the surface of the sensor) into frequency, that is directly proportional to the incident light intensity. On Lilypad I measure frequency by counting the number of high pulses per second, partly using code based on a great tutorial by the roaming drone. After computation & error factor considerations, the value is turned into an UV Index value.
When arms are unfolded they will instantly turn on and start measuring. Glasses can be turned off during day and continue use later at the point where they were left. A led inside of arm will inform present UV Index following corresponding UV Index scale. If UV intensity starts rapidly to rise or fall notably, it will be informed with pulsing signals. Implementation includes a one control button build into the arm for setting up skintype level (from 1 to 3) or to enable special override mode to disable any notifications. Same button can also be used to quickly check present UV Index value. Glasses are constantly calculating safe-level of sun exposure based on changing UV radiation conditions & skintype settings. When person exceeds her daily safe-level on a given day, glasses will give continuous warning signal. Daily safe-levels are based on time-to-burn, where e.g. for extra pale skin UV Index of 6 corresponds to a burn time of 24 minutes. Information is only presented in common UV Index format, which gives some interpretation for decision making.
How it works: