Published February 5, 2021 © GPL3+

Automatic Door Handle/Knob Sanitizer for COVID-19🚫🦠🚪😷

A self-sanitizing door handle that works by spraying the handle area with the sanitizing liquid whenever the door handle has been used.

BeginnerFull instructions provided621

Automatic Door Handle/Knob Sanitizer for COVID-19🚫🦠🚪😷

Things used in this project

Hardware components

IR Sensor

Servo Motor

Arduino UNO

Jumper wires and Breadboard

4 AA Battery Holder

AA Batteries

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Box

Small Plastic Spray Bottle

Rubbing Alcohol/ Sanitizer

Story

An Automatic Door Handle Sanitizer for COVID-19

WHY?

In the current world, the COVID-19 pandemic is the defining global crisis of our time. Since its emergence in late 2019, the virus has spread all across the world and the need for extra precaution and hygiene safety measures is crucial to stop the spreading of this infectious disease. One of the small ways to ensure hygiene safety is by creating an automatic door handle sanitizer device. It sprays the sanitizing liquid onto the door handle after it has been used each time which prevents the spreading of germs thus, creating a safer environment.

Door handles are considered of the top five dirtiest objects! And they are often neglected. This device is aimed to be used in public places. Where humans gather and door handles are frequently used and they are not cleaned or sanitized as they should be. Such places need to ensure environmental safety and good hygiene practice. Therefore, it is more archivable using an automatic system rather than manually. Since this device works automatically it is cost, time, and work efficient.

How will the project work

Project flow-chart

This project is quite simple mainly designed based on the components I already had at hand: A microcontroller, servo motor, sensor, and batteries.

To implement the design requirements I chose to use the IR sensor to detect the hand movement and trigger the sanitizer release. For the spray operation, I chose a simple mechanism to determine the correct torque to be used with a servo-motor for sufficiency and low cost. An Arduino Uno used as the microcontroller for the device. A 4 x AA battery pack complemented the power requirements of the design.

Connections

Circuit Diagram

Spray Operation

Designing the spray operation mechanism I have tested the system with different prototypes to have the servo push on the spray bottle. You might have to design a different mechanism depending on the servo motor type or how much force is required for the used spray bottle to spray.

Assemble

So After determining the correct spray operation to be used all that is left is to put together the final project in a box and using detachable adhesive place it on top of the door and then test it.

1 / 3

Future Enhancements

To cut down on cost and time I made the project based on components and tools that were already available for me. However, future enhancements can be made:

Make the device design smaller: by replacing the Arduino Uno with a Smaller size microcontroller. Ex: Arduino Nano.
Soldering the components.
3D printing for the spray mechanism: Easy to replace the spray bottle, provide more efficiency, and is customizable.

How is it used :D

So when the IR sensor light turns green it indicates that the door handle is held once the user released the door handle the sensor light goes back to red the and then the servo motor moves to spray the sanitizer liquid to disinfect the handle. The process iterate to ensure that the door handle is clean after it has been touch/used each time.

Automatic Door Handle Sanitizer Code

#include <Servo.h>

Servo myservo; 
int pos;
int Signal = 8;
int LastState = LOW; 
int SensorState;

void setup() 
{
  pinMode(Signal, INPUT);         //Sensor set as digital input
  myservo.attach(9);              //Server set as output
}

void loop()
{

  
  SensorState = digitalRead(Signal); 
  delay(1); 

   if (SensorState != LastState) //if it changed and it's high
  {
    if (SensorState == HIGH) 
    {
      Spray();                  //Sanitize the door handle
    }
  }
LastState = SensorStat;
//save current sensor input value for next comparison 

}

void Spray()                    //spray operation function 
{   
   delay(200);
   for ( ;pos >= 40; pos -= 1) 
   { 
    myservo.write(pos);             
    delay(15);                        
   } 
   
    for ( ;pos <= 80; pos += 1) 
  { 
    myservo.write(pos);             
    delay(5);                        
  }
}
//end program