Coronavirus disease (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). COVID-19 has affected millions of people and has claimed the lives of hundreds of thousands of people from all over the world. This disease affects different people in different ways. Some people may develop mild to moderate illness and recover without special treatment or hospitalisation, while some may develop severe illness and even die. The incubation period of this virus, on average 5-6 days but it could also be up to 2 weeks. During this period, the person may not experience any symptoms but could still be contagious. The person will be a virus carrier and easily spread it when he/ she does not take any precautionary measures.

Coronavirus has spread rapidly and many countries have been affected by this pandemic. While some countries are recovering, other countries are still in lockdown and some are suffering from the second wave of coronavirus.

How does coronavirus spread?

According to the World Health Organisation, WHO, coronavirus is mainly transmitted through droplets generated when an infected person coughs, sneezes, or exhales. These droplets are too heavy to hang in air, so they quickly fall on the surfaces below.

A person could contract this disease if he/ she breathes in the virus while an infected person/ virus carrier within close proximity sneezes or coughs, or when he/ she touches a contaminated surface and then his/ her eyes, nose or mouth.

How can the spread of coronavirus be controlled?

As you may have read in the above section about how the virus spreads, you would be now aware of two main factors: standing in close proximity with an infected person and touching a contaminated surface.

We can curb the spread of coronavirus by taking these two important factors in account.

It is important to avoid standing in close proximity with other people because they could sometimes be a virus carrier. As I have already explained, the person could be contagious before they develop any symptoms. To prevent standing in close proximity, we are advised to practice social distancing.

To prevent touching a contaminated surface and then our eyes, nose or mouth, we must wash our hands properly for at least 20 seconds. WHO has advised us to use soap as it is a self-cleansing product and more effective at killing the virus. Soap is available at many places where hand sanitizer or liquid soap is not, and is also cheaper than the other two products.

Sometimes we could touch the faucet carelessly after we wash our hands and the faucet could be contaminated. The person would then touch his/ her eyes, nose or mouth, and he/she has a higher chance of contracting this coronavirus disease. To prevent this from happening, we can use a touchless faucet, this project.

How it works

I have made an automatic faucet which detects the hands within 10 cm and allows safe hand washing.

I have programmed my Arduino microcontroller to switch on the relay module when the ultrasonic sensor detects my hand within 10 cm. The submersible water pump is switched on along with the relay module and begins to pump water through the tube connected to it.

The water flow will be stopped when the faucet is not in use or during soaping, and this saves water. You do not have to touch the surface of the faucet after you wash your hands; you can wash your hands safely and prevent coronavirus disease. The tube is led out of the plastic container and acts as a faucet.

I made this project with limited resources. Those who are interested can remake this project, and if you like you can make some improvements too. I did not have a solenoid water valve with me, so I had to use the submersible water pump to demonstrate my project. This project is effective, easy and only costs around $10 to build.

You can reuse plastic containers and convert them into touchless faucets. This prototype is portable and can be used anywhere. They can be powered using rechargeable Li ion batteries and the batteries can be charged with solar panels.

Contactless Plumbing: The IR Solenoid Faucet

Commercial automatic bathroom sinks cost upwards of $300 and contain terrifying proprietary black-box circuitry that breaks constantly. The Automatic Touchless Faucet completely supersedes this by exposing the raw hydraulic logic natively! Utilizing a radically simple TCRT5000 Infrared Proximity Sensor mounted above the sink basin, the Arduino pulses an invisible beam. The second dirty, infected human hands enter the wash zone, the IR light bounces directly backward into the photodiode trigger. The Arduino instantly recognizes the reflection and violently trips a massive 12V Water Solenoid Valve, releasing the high-pressure water stream completely without a single physical tactile interaction!

Electromechanical Valves (The 12V Solenoid)

An Arduino cannot physically control water pressure natively! You must use heavy mechanical switching!

1. A Normally Closed (NC) 12V Solenoid Valve is a massive chunk of brass spliced directly into the sink's water pipe grid. "Normally Closed" means if the power fails, the spring mechanically crushes the heavy rubber gasket, completely locking the water back tightly preventing flooding!
2. To open the valve violently against massive 60-PSI city water pressure requires intense electromagnetic power (over 500mA at 12V)!
3. The fragile 5V Arduino absolutely CANNOT output this energy! It utilizes a TIP120 NPN Transistor or a Logic-Level N-Channel MOSFET (IRLZ44N) as a digital dam!

int IRSensorPin = 2; // Digital Input from the TCRT5000 Module
int SolenoidValvePin = 8; // Attached explicitly to the TIP120 Base!

void loop() {
  // If the sensor reads LOW, hands are reflecting the beam!
  if (digitalRead(IRSensorPin) == LOW) {
    digitalWrite(SolenoidValvePin, HIGH); // Smashes the Transistor OPEN! 12V floods the coil!
    // Water sprays violently!
  } else {
    digitalWrite(SolenoidValvePin, LOW); // Instantly cut power! The internal spring slams the valve shut!
  }
  delay(10); // Micro-stability pause preventing rapid oscillation jitter!
}

Eliminating Catastrophic Flyback Voltage

A solenoid valve is a "Highly Inductive Load" (it is literally just a massive coil of copper wire).

• The exact millisecond you execute digitalWrite(LOW) to turn OFF the water, the intense magnetic field inside the solenoid collapses completely instantly!
• This collapse generates an utterly horrifying negative voltage spike (Back EMF) measuring hundreds of volts, ripping backward directly across your circuit!
• If this occurs just once, your Arduino processor and Transistor will instantaneously explode.
• You absolutely MUST install a 1N4007 Flyback (Snubber) Diode wired directly in physically parallel to the Solenoid Coil! (The silver stripe on the diode MUST face the Positive 12V rail!). This explicitly forces the voltage spike to infinitely loop inside the coil until it dies harmlessly!

Essential Plumbing Hardware

• Arduino Uno/Nano (Housed in an incredibly strict IP67 Waterproof plastic enclosure mounted safely under the sink cabinet!).
• TCRT5000 or generic Infrared Obstacle Avoidance Module (Tuned using its onboard potentiometer to ignore the physical metallic sink basin, but fiercely trigger on human flesh < 4 inches away).
• 12V Brass or Plastic Water Solenoid Valve (Check the pipe threading: usually 1/2'').
• TIP120 Darlington Transistor and a 1K-Ohm Base Resistor.
• 1N4007 Rectifier Diode (The absolute life-saver of the entire project!).
• 12V, 2Amp Power Adapter (Capable of supplying intense, continuous amperage to hold the coil open tightly against heavy domestic water pressure).