We are all experiencing the impact of COVID19, after hearing stories of our front line health workers are reusing their masks and gowns in brown bags it really hit home.
After COVID19 hitting all the countries very hard, the countries will no longer have more resources to spare when the virus starts to spread in developing nations. If we, the United States can not even guarantee the safety of our healthcare workers by providing the PPE, when the virus reaches the developing nations it will have a much larger impact.
PPE in a brown bag
We want to build an affordable sterilizer that's easy to scale and rebuilt so that people can sterilize their PPEs and use them safely. And easy enough so that any developing nations can build this.
Hydrogen Peroxide SterilizationAccording to Steris Healthcare, "Hydrogen peroxide sterilization, also known as hydrogen peroxide gas sterilization, is a low-temperature sterilization process commonly used to sterilize heat-sensitive devices. A hydrogen peroxide sterilization cycle typically requires less time than alternative forms of sterilization, such as ethylene oxide sterilization. A hydrogen peroxide sterilization process involves H2O2 vapour filling the sterilizer chamber, contacting and sterilizing exposed device surfaces."
Credit: Steris Healthcare
1) Liquid H2O2 gets converted into vapour
2) The vapour fills the chamber, contacting all surfaces and penetrating lumens
3) After sterilization, the vapour is vacuumed from the chamber and converted into water and oxygen
And by that concept, we can build a much cheaper solution using maker components.
Cost-effectiveness
Currently, the H2O2 sterilize machines usually operates at an industrial level and is a standard for hospitals and other health facilities for sterilization and decontamination of PPEs. With the COVID19, all of these sterilization machines are all back-ordered.
While these machines are hard to come by, we want to use basic equipment and build them. To do so we simply need the following
- $1 Hydrogen Peroxide Liquid
- $10 Arduino Zero (equipped with Arm Cortex M0) or anything cheaper
- $10 Seeed Atomizer
- $5 DFRobot LED and Buttons
- $0 Recycled containers
- $0.5 Cottons Ball
With the above bill of material, we will be able to build an H2O2 sterilization device under $35
Bill of Material
Hydrogen Peroxide vs. UV Light sterilizationH2O2 is the standard for sterilization used among hospitals and facilities, the UV light is often good for hard surfaces, to penetrate the normal layered surfaces it would require prolonged use.
Hydrogen Peroxide vs. UV Light sterilization
Also, only UVC is effective for sterilization and decontamination, according to UV Resources, unsafe exposure to UVC would potentially cause skin damage, eye damage and skin cancer. So making any UV sterilization machine would require a carefully designed product.
UVC warning sign
H2O2 is being used for treating wounds, which is much safer for usage. It is also easily accessible anywhere around the world, with local hospitals and clinics already equipped with it.
Not to mention, a certified UVC bulb cost about $80+ and is currently in short supply.
Step 1: Building out Arduino SchematicSo first we will gather our bill of material, which is shown below
We are connected the button to input as D6, LED as D7, Atomizer as D8. And LCD via I2C bridge through DFRobot Arduino Shield on top of the Arduino Zero. This should give us enough materials to display the following demo. The LCD Display is optional.
Schematic
When all is connected, we should have the following
Hygieia in action
Step 2: Code the ArduinoLet's explain the logic a little bit, we are planning to use this for 15 minutes, which is 900 seconds. The LCD is an optional piece which can be removed for Developing Nations to cut cost. We are setting up LED as pin 7, Button as pin 6 and vaporizer as pin 8.
Upon pressing the button we are activating both LED and Vaporizer for 15 minutes. When this is done we go back to the ready state.
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