There are many webpages on how to build a UV cleaning box, but how do you know the device is actually working??
How long should the light be on?
How well do my UV lights work?
Is it really even delivering the needed UVC light?

The answer is obvious => MEASURE IT

This BioBlaster tutorial will show you how to build a lightbox and make a simple device to measure your UVC santitizer's performance in real time, and even notify you when the proper dosage has been delivered.
No more guesswork!
No more crossing your fingers!
It's all pre-configured for you!
Real time UVC level and accumulated dosage tracking and display!
Comes with "done-cooking" notification!
Innovatoin for a safer world!

NOTE: UVC light is low wavelength and high energy. It is dangerous and will damage your skin and eyes. Leave the container closed during the sanitization cycle. Also make sure to wear eye protection to specifically block UVC along with thick gloves/clothing.

Did you know: UVC light is completely blocked by the atmosphere. Broad spectrum suncreen only blocks UVA/UVB.

WARNING: You are working with electricity and UV light. This webpage is provided for educational and informational purposes only. You accept all responsibility and liability for the use of this website.

You will need a container. I am using a 27 gallon plastic bin with a snap on lid 14"H x 20"W x 30"L. The UVC light is mounted lengthwise in the center underside of the lid. You can also mount a bonus second light in the center of the bottom of the box. You can use tape, screws, or clips to secure the light. Add aluminum foil to cover the entire inside increases reflectivity to remove shadows. Add a metal mesh rack to elevate objects and let light pass under the rack.

This is the 13W UVC light I am using from Amazon. Make sure the light you use is specifically a UVC light with wavelength of 200-280nm.

NOW your box should look something like this....

Now the major hardware components for light sensing and display measurements.

Arduino Nano board

Display

GUVA board

VEML board

Other components

• 5V USB power supply with mini USB head
• Soldering iron
• Solder
• Plastic coated wires for soldering display
• Ribbon cable or wires to connect boards together
• Ohm meter to test for shorts
• 2 through hole resistors. R=100Ω - 200Ω
• 0Ω surface mount resistor or just a wire

Hardware assembly
I want to give credit to Akiba for his informational webpage on building a NukeMeter. He also provided GUVA chip UVC calibration using equipment I didn't have. I added to his work and built readout displays and the ability to configure the Arduino program for different types of sanitization. I also added a separate VEML sensor to make sure lights being used did not output UVA/UVB

		Click on images below to enlarge
1. Modify the GUVA board resistors
2. Use pinout connections diagram for soldering of all components.
3. Attach display to Arduino board
4. Connect VEML and GUVA boards to Arduino board
5. Test your connections for opens and shorts.		Use Ohm Meter to verify everything is connected properly
6. Bonus points for printing the 3D case

You can mount your Arduino, power strip, and UVC power supplies like this....  You can thread the wires for GUVA and VEML boards through a drilled hole in the bottom corner of BioBlaster.

Dosage requirements
Bacteria and viruses are more fragile than fungi and algae as the latter 2 have thick leathery outer layers to protect them from the environment. This shows in the time it takes to inactivate. Below is the reference 90% inactivation chart from Osram, and how to calculate 99.9% - 99.99% inactivation also from Osram.

Did you know: The maximum safe UVC dosage for food products is defined by the FDA at 12000 mWs/cm2. You only need ~20mWs/cm2 to wipe out 99.9% of coronovirus. This assumes UVGI reference link value of ≤ 5mJ/cm2 which is ≤ 5mWs/cm2 is the 90% inactivation rate.

Measurement results
Here are the measurement results from my BioBlaster. Several observations can be made:

• Since the box is black, having both lights does not affect the light received by sensor when facing up.
• Lining all sides of the box with aluminum foil greatly increases reflected light
  • Foil removes shadows from objects as long as objects are not touching each other
  • The lights are mounted horizontally. Foil greatly increases light exposure on vertical surfaces
• The intensity is inversely proportional to the square of the distance. Basically intensity drops much faster than distance to the light source.
• The lights can take up to a minute to warm up. Once warmed up, dosage will increase faster. Measurements are made with warm lights.
• The more objects there are in the lighbox, the longer the sanitize cycle.
• Do not block sensor. It already gives the most pessimistic value by sitting in the corner.
• It takes less than 2 minutes to sanitize most objects in this particular setup using a warm bulb with a rack height of 6.5" from the top light.

Light Source	Location	Sensor direction	Intensity (NO Aluminum Foil)	Intensity (WITH Aluminum Foil)
Top light 13W	Centered 6.5" from top	Face up	0.35 mW/cm2	0.51 mW/cm2
Top light 13W	Centered 4" from top	Face up	0.94 mW/cm2	NA
Top & Bottom lights 13W 22W	Centered 6.5" from top	Face up	0.35 mW/cm2	0.66 mW/cm2
Top light 13W	Corner 13" from top center	Vertical facing inward	0.03 mW/cm2	0.13 mW/cm2
Top & Bottom lights 13W 22W	Corner 13" from top center	Vertical facing inward	0.09 mW/cm2	0.37 mW/cm2

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Now you are in the home stretch
Arduino provides basic microprocessor programming language similar to C.
The VEML board screens out defective/counterfeit lights by detecting UVA/UVB.
The GUVA board measure the UVC light.
The Arduino board is programmed to calculate intensity and total dosing. It uses the Osram table to determine when sanitize is complete based on the 99.9% equations.

Here is the Arduino code you can download and use. This has original code from Akiba and additions from me. You will need to download the Wire, SevSeg, and TimerOne libraries as well. All calculations are completed using dosage levels in Ws/m², and the default dosage setting in the Arduino code is 300 Ws/m², which is the 99.9% inactivation dosage, so it would be comparable to 100 Ws/m² in the Osram dosage chart.

How to interpret results
The left digit of the display gives progress tracking of 0-9 and C. 0 is for 0%, 9 is for 90%, and C for complete. The right digit gives the intensity level. 0 for none, L is low, 1-9, and then F for very high. The reading starts at 00 until the light starts to warm up.

A reading of CL means the sanitize cycle is C for complete and L for low level intensity. Right digit of L or 1 is expected at the far corner of the lightbox. Reading might even be 0 while the light is warming up.

For more detailed information, use the Serial Monitor in the Arduino compiler for exact numeric values for UVC while the Arduino is running. Info shown are UVA/UVB detected by VEML, UVC intensity level by GUVA, and total accumulated dosage.

Sometimes units are converted to mW/cm2 as necessary for calculations. Here are the conversion factors for completeness. You will not need to perform calculations which are done for you.

1mJ = 1mWs (1 milli-Watt second)

1Ws/m² = time (seconds) * 1,000 mW / 10,000 cm² = time (seconds) * 0.1 mW /cm²

THAT"S IT!! YOU HAVE COMPLETED THE BIOBLASTER PROJECT. ENJOY!!

Food for thought:

• You can modify the Arduino code to add addtional bonus options like a "done-cooking" buzzer to augement the display.
  
• Add in a voltage controlled power switch to turn off the lights once cycle is complete.
• You can culture, in a petri dish, the surface swabs of items before and after sanitization to compare microbe count.

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