Automatic Disinfectant Sprayer

Innovator: Kanak Shilledar | Living in Nagpur | Currently in 11th Std. | I love to tinker and innovate.

Introduction 

According to Dettol UK, they have said that the COVID-19 is a new strain of coronavirus and is not commercially available for testing. Specific Dettol products have demonstrated effectiveness (>99.9% inactivation) against coronavirus strains from the same family as the 2019 Novel Coronavirus (COVID-19) in third party laboratory testing, when used in accordance with the direction for use. These products are: Dettol Antibacterial Surface Cleanser Spray, Dettol Antibacterial Surface Cleanser Wipes, Dettol All-In-One Disinfectant Spray, and Dettol Disinfectant Liquid. 

The CDC and World Health Organization specifically advices people to wash hands often with soap and water or use an alcohol-based hand sanitizer as a key preventative measure against the spread of Coronavirus COVID-19. A good quality disinfectant will help reduce risk to families. Dettol hand Sanitizers use ethanol (alcohol) as the germ disinfection active ingredient in line with CDC and WHO recommendations. 

According to CDC, disinfectant can be made by diluting 4 teaspoons of bleach with 1 quarts of water.

Materials Required 

  • Arduino 
  • 3D printed enclosure 
  • Atomizer 
  • Bleach Solution 
  • Battery and/or power source 
  • Exhaust Fan (take a pc cooler) 
  • Liquid Level Indicator 
  • LCD Display 

Working 

The disinfectant solution will be made by diluting bleach into water (4 teaspoons in 1 quarts). The whole system is automatic and controlled by a micro-controller (Arduino). It turns on the mist maker every 2 hours for 10 minutes. The duration can be changed using the buttons on the control unit. The ultrasonic mist maker is made up of a piezo disk which is having a resonant frequency of about 1.7 MHz, it vibrates and turns the liquid into mist. These droplets are suspended in the air and settle on the surfaces disinfecting it. Because of bleach we can get the pungent smell of chlorine gas but a fragrance oil can be sprayed after the spraying duration of bleach. We can’t mix the bleach and the oil together as bleach being a strong oxidising agent and it may form other products by reacting with the oil. The piezo disk requires 1.7 MHz AC signal. We can create this by using Full H-Bridge which consists of 4 MOSFETS but to reduce the cost of making the whole circuit we can use the readymade drivers of the piezo disk and control them using Relay modules. If we need the whole system to be portable then we will need to make a Full H-Bridge. The control unit will also contain battery circuit if using it portable. We have also added a liquid level indicator which will stop the atomizer. If the liquid level reaches zero. The indicator gives a variable voltage on the amount of liquid present. The LCD Screen on the Control Unit will give all the necessary details like liquid level present, atomization duration, time interval. The fan helps in forcing out the vapours its speed can also be controlled. 

This system can be scaled up by increasing the number of atomizer modules and can disinfect a large place too. 

Control Logic 

At every interval of time set by the user the atomizer will run for a specific duration. We can change the duration and time interval. The liquid level sensor will not power the atomizer if the liquid level is too low and the LCD will give the indication of low liquid level. All the required information will be displayed on the LCD. 

Cost per Unit 

  • Arduino: Rs. 500 
  • LCD: Rs. 200 
  • Atomizer: Rs. 1000 
  • Exhaust Fan: Rs. 700 
  • Liquid Level Indicator: Rs. 200 
  • Misc.: Rs. 1000 

Therefore, the whole system costs around Rs. 3600 if we add battery to it then the price will increase a bit. 




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