UVC Air Disinfecting Face Mask

1,367

8

9

Introduction: UVC Air Disinfecting Face Mask

UVC is a germicidal wavelength of the UV spectrum. With sufficient intensity, UVC can deactivate viruses in air as fast as you can breathe.

The goal of this mask is to provide a way for people to protect themselves from COVID while allowing for expressive social interactions. The design aims to create easy breathing with a fan that keeps fresh air available in the mask, while also regulating airflow speed so a single UVC LED can disinfect air. An aluminum tube internally reflects UVC as air travels through.

I am designing a mask for production, and have made this as one of the prototypes. Since there will not be any UVC masks on the market for months, I thought I would share this as a temporary solution, or just as a quarantine project for DIYers. It uses all standard parts.

Open to any feedback about the design. Stay safe everyone!

Step 1: Materials and Tools

Step 2: Print Enclosure

Find the .STL files for the enclosure at:

https://github.com/jackmqiu/mixellatormask

There is a top shell, bottom shell, and 2 chamber caps. The Solidworks part files are available as well for your own adjustments!

Using standard slicing in Cura makes this about a 4hr print.

Step 3: Cut and Bend Aluminum Tube

I popped the fan in first to check that the print dimensions are correct. Then I cut the aluminum tube.

I cut out a longer length than I needed, about 10", so I could have some leverage while I bent the tube. 6" is enough for air to disinfect as it travels through the tube at 10 liters a minute, the higher end of normal human air intake rate. The U-bend with straight sections entering air intake and exit chambers should be just over 6".

Make sure that the tube can enter both chambers while siting in the enclosure grooves, then mark and cut.

Step 4: Electronics Pt1

  • Solder battery leads onto the B+ and B- pins of the 18650 chip, wires going out the bottom of the chip
  • Glue switch into socket, solder 18650 chip's OUT+ lead to first 2 pins of switch
  • Solder 18650 chip's OUT- lead to IN- lead of voltage converter chip
  • Pop in 18650 chip into it's spot in lower right corner of the enclosure top shell face down. You should be able to see the micro USB port through the opening of the enclosure
  • Place Arduino nano into position at top of enclosure face down as well. Check that the micro usb port is lined up with the groove on the side

Step 5: Electronics Pt2

  • Move voltage converter chip into its spot over the 18650 chip. Solder the 3rd lead of the switch onto the IN+ lead of the voltage converter
  • Hook multimeter to OUT+ and IN+ of voltage converter, and use screwdriver to adjust the voltage output to 12V

Step 6: Electronics Pt3

  • Solder wires to Vin and GND leads of Arduino Nano. Use the GND next to Vin. The wires should reach OUT+ and OUT- of the voltage converter
  • Solder the negative lead of the fan to middle pin of your C1815 NPN transistor
  • Solder emitter pin to GND and base pin to D2 lead of Arduino. You can search for the transistor to see which pin is which
  • Solder GND wire from Arduino that you attached earlier onto OUT- of voltage converter
  • Solder the Vin wire from Arduino and positive lead of fan onto OUT+ of voltage converter

Step 7: Test Fan and Connections Up to This Point

  • Plug Arduino in and upload Arduino sketch from:

https://github.com/jackmqiu/mixellatormask/blob/ma...

  • Unplug Arduino and plug micro usb into 18650 chip. You should see the chip light up red, indication the battery is charging. Toggle the switch and the fan should also turn on. The 18650 chip should provide power while battery is charging

Feel welcome to update the sketch! This setup allows you to change the speed of the fan by updating the PWM output value. According to the datasheet this fan is able to output more air than you need, but with the narrow tube and light filter as resistance, I just have it set to max.

Step 8: Affix Aluminum Tube

  • use black fabric to close off exit end of tube -our goal is to block UV exiting the tube while allowing airflow
  • Add sealant to bottom of tube junctions and press down tube

Step 9: Affix UVC LED and Close Off Intake and Exit Chambers

  • Add solder to anode and cathode of LED
  • Glue onto raised tab on the enclosure
  • Solder wires onto LED
  • Solder 50 Ohm resistor to anode and solder resistor to OUT+ of voltage converter
  • Solder cathode wire to GND of Arduino
  • Optional: power Adafruit UV sensor and test UVC intensity - look at the datasheet to convert voltage reading into radiant intensity. Make sure to wear gloves and cover skin/protect eyes
  • Add sealant and affix both chamber caps

Step 10: Make Mask

  • Form mask shape out of clay - make sure shape fits vacuum machine
  • Allow clay to dry
  • Load some bbs (come with vacuum machine) and your mask mold. Load plastic sheet
  • Turn on heat on vacuum machine, wait until plastic sheet sags 1cm before pulling lever and flipping vacuum switch for a few seconds. Turn off heat immediately and allow mask to cool.
  • Don't step away from Vacuum machine while heating even though it takes a few minutes. The plastic sheet can catch on fire if overheated
  • Cut around edge of mask until you have a comfortable fit, making sure to leave some of the flat section on the edge for straps
  • Cut a hole and pop on a valve
  • Cut 2 slits on each side and weave strap through as pictured

Step 11: Finishing Steps

  • Seal enclosure
  • Use sealant and attach tube
  • Affix enclosure to mask and you're done!

Be the First to Share

    Recommendations

    • First Time Author Contest

      First Time Author Contest
    • Soup & Stew Speed Challenge

      Soup & Stew Speed Challenge
    • Fashion Challenge

      Fashion Challenge

    9 Comments

    0
    wannabemadsci
    wannabemadsci

    1 year ago

    Very neat concept and I think it has merit. Lots of great detail. Thanks for sharing.
    However, I have four concerns:

    1) Deactivating viruses with UVC takes a specific intensity and dwell time. Because of the low intensity of the UVC output of the LED and the speed with which the air will pass through the radiation, I don't think your design will be effective. Also, the FDA has stated, "...currently there is limited published data about the wavelength, dose, and duration of UVC radiation required to inactivate the SARS-CoV-2 virus."

    2) There does not appear to be any reservoir of 'cleaned' air to provide air when breathing in. This would lead to the air traveling substantially faster through the UVC light during inhalation.

    3) Some wavelengths of UV light create ozone which can be irritating or damaging to the lungs.

    4) It appears that the mask has an exhalation valve. This makes it easy for the user to exhale but does nothing to prevent the user from expelling virus laden droplets if they become an asymptomatic carrier. It leaves those around the user unprotected. (The common masks used during the pandemic are to prevent the user from expelling virus droplets, and protect those around them; not to protect the wearer. That's why EVERYONE needs to wear a mask.)

    The concept is commendable but I am not sure of how effective it would be.

    0
    Cdebee
    Cdebee

    Question 1 year ago on Step 7

    I tried to compile your code but each time I get an error. see attached
    Chris DeBanks

    function error.png
    0
    jackmqiu
    jackmqiu

    Answer 1 year ago

    You have "void setup() {" at the top.
    delete that first line and you should be good

    0
    Cdebee
    Cdebee

    Reply 1 year ago

    Thanks not good at coding.
    Will 47 ohm resistor be ok?
    Chris

    0
    jackmqiu
    jackmqiu

    Reply 1 year ago

    Should be fine. Please be careful when handling UVC

    0
    Cdebee
    Cdebee

    Reply 1 year ago

    Talking to my daughter who works all day in ppe she thinks the mask would be very welcome. I understand the dangers of UV c but thank you for the reminder. One last question the air delivery tube can it be any length?
    regards
    chris

    0
    jackmqiu
    jackmqiu

    Reply 1 year ago

    Might be a better question for a fluid dynamics expert if you want to make it a lot longer. There will be more resistance and you might need a more powerful fan. This length used here is 3"

    0
    tercero
    tercero

    1 year ago

    Brilliant. I like the lightweight design, and it addresses what I feel is the primary problem with "masks" in general. They don't really filter. At least your design filters and probably destroys any viruses or bacteria.
    Thanks for presenting this.