Automatic Hand Disinfectant Using UV Light

In this project, I will show how to create a simple Ultra violet hand sanitizer using LM358 op-amp. The main motive is that, unlike regular hand sanitizers, it does not require any contact to turn on and it never runs out! And since microorganisms are vulnerable to UV light, a few seconds of exposure can help to sanitize your hand properly!

NB: Be careful while handling the UV light, it can be dangerous upon long exposure, and avoid looking directly into the light!

Items needed:

1 x LM358 op amp LINK

1 x micro usb breakout board LINK

1 x IR led LINK

1 x Photodiode LINK

1 x 100 ohm resistor LINK

1 x 10k ohm resistor LINK

1 x 10k ohm preset pot LINK

1 x BC547 npn transistor LINK

1 x UV led LINK

LM358: This is an operational amplifier that is used as a comparator in this project. It compares the resistance value from the photodiode and from the preset potentiometer and turns the output high/low at the pin 1.

USB breakout board: This is used to supply 5V to the circuit using a power bank to make it portable.

IR led: It transmits light that is invisible to the naked eye. The light then bounces back from our hand and is detected by the photodiode.

Photodiode: It detects infra red led and sends the corresponding value to pin 2 of op-amp.

10k preset pot: It is used to adjust the sensitivity of hand detection

BC547: It acts as a switch turning on the UV light when a positive base voltage is applied from pin 1 of op-amp.

UV led: it contains 3 UV led that I salvaged from UV screen protector for my phone.

The whole circuit is built on a Vero board. The IR led, photodiode and the UV led are connected using wires from this circuit board.

I used a simple container box for this project. Wrapped the whole box using A4 paper to make it look appealing.

Watch the video to see how the project works.