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Built a 365nm UV-A single wavelength spectrometer for ~$50 that emulates skin application
Anyone interested in seeing the build/how it works?
Basically a $6.50 analog UV sensor lit up by a 365nm peak wavelength LED through 1×1″ UV transparent tape covered with 2 mg/cm2 sunscreen, all hooked up to a 3V DC power source and a multimeter.
Great for quick measurements to check for in vitro improvements, I also had a pro lab do an in vitro test and the results correlate perfectly. Repeatability is also good within a couple %.
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6 Replies
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Yes please! What an excellent idea.
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That’s interesting!
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Ok I will do a simple writeup or instructable this weekend
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I’m going to keep this simple and assume basic electronics knowledge:
UV Sensor: https://www.adafruit.com/product/1918
Breadboard: https://www.adafruit.com/products/64
Fan: Delta 25 mm, 5 V, AFB02505HHB http://www.ebay.com/itm/272241928073?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
365nm UV Flashlight: https://www.amazon.com/gp/product/B01FH2NHWS/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Tube (spraypainted black): https://www.mcmaster.com/mv1478814336/#catalog/8532K21
Enclosure: https://www.mcmaster.com/mv1478814336/#catalog/7593K27
3M Transpore Tape: https://www.amazon.com/gp/product/B005OFM6JE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1Most 2.7 - 3V DC power supplies will work, you could also use two 1.5V batteries in series. Everything shares the same ground. Any multi-meter will do.
Setup with nothing covering the sensor, stabilizes at 198 +/- 2% mV after 5 minutes (temperature of led stabilizes).
The flashlight screws apart and is mounted in the center of the enclosure, breadboard hotglued in place.
Sensor covered by 1×1″ 3M tape, reduces mV reading ~10%.
Smear 10 mg of your formula homogeneously across the center using a small spatula. Do at least two samples per formula to make sure you’re getting repeatable results. In my experience results are usually within 10% of each other; fine for my use. I was able to get from 45 to 15 mV (!) for my 10% ZnO formula.
For reference a SPF50 mineral sunscreen gets around 18 mV. A SPF 27 sunscreen around 40 mV. Keep in mind organic sunscreens usually perform 2-3x better in this type of assay. And it only measures UV-A performance with its 365 nm peak wavelength.
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Thank you very much!
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Hi Zink,
Just looked at this. I am involved with DIY Bio in Barcelona and have passed in on to them in case they want to give it a go. They have built DIY centrifuges, biosafety cabinets and even PCR machines in the past.
One question. Is it possible to but appropriate sensors and LEDs to build a 400nm spec? This would be great for measuring cell optical densities in molecular biology.
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