Published March 23, 2021 © LGPL

Hand Sanitizer

Keep clean and healthy!

IntermediateFull instructions provided12 hours2,936

Things used in this project

Hardware components

Arduino Nano R3

Ultrasonic Sensor - HC-SR04 (Generic)

SG90 Micro-servo motor

Jumper wires (generic)

Accessory, Screw

Plastic Enclosure, Project Box

Tinned Copper Wire, Solid

Software apps and online services

Arduino IDE

Fritzing

Hand tools and fabrication machines

Hot glue gun (generic)

Story

In this current situation of global pandemic, it is advised by World Health Organization to keep hands washed. Although the main problem is the way we do it, that is by physical touch, which in short doesn’t serve our purpose. So we will learn how to make our own Arduino Based Soap or Hand Sanitizer Dispenser.

Supplies:

Electronics:

Arduino Nano ( or any Arduino ).
Ultrasonic Sensor ( HC-SR04)
Servo Motor ( metal Geared Preferred ).
Jumper Wires ( female to female ).

Tools:

Hot Glue Gun.
Computer or Laptop.

Misc:

Alcohol Based Hand Rub or Sanitizer.( most important)
Self Threading Screw ( 1 pcs).
0.8 mm copper wire ( 0.5 meter ).
plastic container ( which fits everything inside comfortably)
Stationary ( marker and ruler scale ).

Step 1: Select the Sanitizer

Figure 1

First and the most important thing we will need for this build is Alcohol Based Hand Rub or Hand Sanitizer or Hand Wash as suggested by WHO.

It is very important to get right kind of dispenser, since we are just making a dispenser and not printing the entire mechanism, we will need alcohol or hand rub in dispenser or push type bottle.

Step 2: Selection of Components

Figure 2

Sensor:

We will need a Sensor to sense our proximity or presence which will basically act as a trigger or touch less switch for this system. We have two choices here, that is we can use either IR sensor Module, or Ultrasonic sensor Module. We can use IR sensor Module, which is basically a cheap and efficient option, but sometimes inaccurate, or we can use HC-SR04 Ultrasonic sensor, which is quite accurate above 2 cm range, and slightly expensive option, but we will use Ultrasonic Sensor for this Tutorial, for better accuracy.

Motors:

For motion or to process the Output, we might need either a pump, either motor, or some electronic component that will convert electrical signal to mechanical displacement of alcohol based hand rub or sanitizer through the dispenser, best choice would be to use a Servo motor with metal gears for maximum torque. We will avoid using micro pumps, since they are to be inserted into the container, which again creates vulnerable containment spot. So using an external mechanism with help of servo would be a wise choice.

Microcontroller:

For this project build, we will need a Microcontroller to control the Input and Output, to Calculate the distance or sense the Trigger from Sensor and Process the Output in form of Servo Sweep in our Example, for which we can use any arduino, which makes it easy to adjust the parameters, fine tune outputs, so you can use any Arduino, we will use Arduino Nano for our work case.

Step 3: Understand the Mechanics

Figure 3

Let's Understand the Mechanical Arrangement before we start making it. We will need a mechanism which will create a force to push the nozzle down and dispense the liquid, since we are using servo motor, that provides circular motion, it alone can’t create a downwards force, we will need some kind of mechanical arrangement to make it happen, we will use pulley mechanism to fix one end and convert the rotational force to push, we can do that using Copper Wire to create a downwards vector force for transmission, what it basically does is, it convert the circular force of Servo to a downwards acting force vector, to simulate push. but this all sounds complicated, so let’s execute this task bit by bit, following the further steps

Step 4: Connections

Figure 4

Connections for this build is very simple !

Sensor to Arduino:

Trigger to D10

Echo to D11

Vcc to Vcc

Gnd to Gnd

Servo to Arduino:

Signal to D9

Vcc to Vin

Gnd to Gnd

Step 5: Attach Servo to Base

Figure 5

Step 6: Upload the Code

Figure 6

In theory our idea sounds perfect, let’s code this Arduino and test our idea in real world.

The code is very simple to understand, we used the servo library, and defined basic setups and variables, the main code is such that it calculates the distance in centimeters and if the distance is less than 10 cm the servo motor performs a sweep motion to release the liquid.

Once our project seems to be working, it's time to complete the enclosure.

follow the steps to complete it:

measure the Dimensions for Ultrasonic Sensor and holes for Bottle.
make a slot for Copper wire with extra room for Moment.
mark all cutting holes.
use Sharp Blade or Drill to plot the holes.
fix everything with the help of hot glue.

And finally this project comes to life.

Code

Sanitizer

#include <Servo.h>
const int echo = 8;
const int trigger = 7;
const int servo = 9;

int distance;
long duration;
int pos;

Servo myservo;
void setup() 
{

pinMode(trigger,OUTPUT);
pinMode(echo,INPUT);
pinMode(trigger,OUTPUT);
myservo.attach(servo);
myservo.write(0);
Serial.begin(9600);
}
void Sanitizer(){
  Serial.print("Servo is moving");
  for (int i=0;i<4;i++)
  {
   Serial.print("...");
   }
 myservo.write(45);
  delay(100);
 myservo.write(90);
  delay(100);
 myservo.write(135);
  delay(100);
 myservo.write(120); //Adjust how far you want the servo to go.
  delay(1000);
 myservo.write(00);
  delay(3000);
}
void loop() 
{
//Distance calculation
digitalWrite(trigger,LOW);
delay(500);

digitalWrite(trigger,HIGH);
delay(100);
digitalWrite(trigger,LOW);

duration = pulseIn(echo, HIGH);

distance = duration*0.034/2;

Serial.print("Distance: ");
Serial.println(distance);

//Servo job 
//cm
if(distance<1)
{ 
  Sanitizer();
}
}

Credits

Iasonas Christoulakis

9 projects • 31 followers

Biomedical Engineer MedispLab Instructor Former General Manager at IEEE NTUA Student Branch

Hand Sanitizer

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Supplies:

Step 1: Select the Sanitizer

Step 2: Selection of Components

Step 3: Understand the Mechanics

Step 4: Connections

Step 5: Attach Servo to Base

Step 6: Upload the Code

Schematics

Schematics

Code

Sanitizer

Credits

Iasonas Christoulakis

Comments

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Hand Sanitizer

Hand Sanitizer

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Supplies:

Step 1: Select the Sanitizer

Step 2: Selection of Components

Step 3: Understand the Mechanics

Step 4: Connections

Step 5: Attach Servo to Base

Step 6: Upload the Code

Schematics

Schematics

Code

Sanitizer

Credits

Iasonas Christoulakis

Comments

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