Introduction: UV-C Sterilizer

About: Electrical Engineer and a Maker from India. Engineering is fun once you start applying it!

During this pandemic, it has become extremely important to make sure that we take all the necessary steps to keep this coronavirus away from us. Since the vaccines are still under development, the only way to stop the virus is to kill it. The only proven method to kill most of the viruses and germs is by using 'UVC Germicidal Lamp'. Enough exposure to UV-C radiation causes damage to DNA and RNA of the virus so they can't replicate, effectively killing or inactivating a virus. There are several reports claiming the effectiveness of UVC radiation on the new COVID-19. Few big companies have even launched their own UVC sterilizers. So why not make my own!

In this Instructable, I will be showing you how I built a sterilizer using a UVC lamp and a 3D printed enclosure. Using this sterilizer, you can sterilize your mask, mobile, and other small objects. This project is inspired by UVClean by Henry Mayne.

Let's get started!

Step 1: The Plan

Disclaimer: Overexposure to UVC radiation can cause permanent damage to skin and eyes. Take proper care while working with it. This project involves working with AC mains electricity as well which can be lethal. Proceed only if you know what you are doing!

The plan is very simple. Build a box of some kind and put the UVC lamp in it. I designed the enclosure in Fusion 360. It is divided into 3 parts. The uppermost part houses all the electronics and a UVC lamp. One part is the region where the radiation will occur and the last part is the drawer which will hold the objects to be sterilized.

As already stated, it is not a good idea for us to get exposed to UVC radiation frequently. Since the lamp will be in an enclosure made up of plastic which may absorb most of the radiation and prevent it from reaching us, there is a slight chance of radiation leaking through it. I'm not an expert on this so it is better to be safe. I will be using aluminum tape to cover the inside of the enclosure where the light will hit. This will also help in reflecting the light evenly. A magnetic reed switch will be used as an extra step to safety such that the lamp will turn/remain ON only when/till the door is closed.

Everything will be controlled using an Arduino Nano. There will be two modes of operation. First will be Manual Mode wherein you have to manually turn OFF the lamp. The second one will be a Timer Mode wherein the lamp will be turned ON for a set amount of time. A menu will be created and displayed on an OLED display. The menu can be controlled using a rotary controller. Thanks to Henry Mane all the hard work of creating a menu was already done. I figured out how the code works and modified it to suit my need.

Step 2: Things You Will Need

1x Arduino Nano

1x 11W UVC Lamp

1x 11W Electronic Ballast

1x 5V/500mA PCB SMPS

1x Fuse Holder

1x 5V SPDT Relay

1x Rotary Encoder

1x 0.96" OLED (I2C)

1x Piezo Buzzer

1x Reed Switch (NO)

1x Neodymium Magnet

1x prototyping board

2x 2-pin Screw Terminal

1x 2N2222 NPN Transistor

1x 1k Resistor

Step 3: 3D Printing

You don't have to 3D print the enclosure. You can use other ways to make a box. I'm not so good at building mechanical stuff. So, I let my printer do all the hard work. These are pretty big parts and so the overall printing process will take approximately 2 to 3 days to complete. The parts can be printed without any support if printed in correct orientation.

I have designed it in Fusion 360 and all the STL files are attached here.

Step 4: Electronics

I have attached the circuit diagram. The connections are very simple and can be easily soldered onto a prototyping board. But I am currently switching over from EasyEDA to Kicad.and wanted to design my first PCB in it. Also, I have been using JLCPCB for a while now but this time I wanted to try the Make-In-India (MII) service from LionCircuits, an Indian PCB Manufacturer. Click here to download the Gerber file and code.

Placing an order is very easy. Upload your Gerber files and check the DFM Summary to make sure that you have provided all the necessary (and correct) files. Once you are happy, make the payment. You can also use the 'Message' section to get your doubts cleared immediately.

Gather all the components and start soldering! Double-check your connections especially the AC Mains ones for any shorts. It is a good practice to keep the high voltage and low voltage connections separated.

Step 5: Putting Things Together

Stick the clamps on the inside of the lid. The two clamps should be in a straight line or else the tube won't fit.

Cover the inside portion of the enclosure using aluminum tape.

Stick the control panel to the control box using superglue as shown in the picture.

Insert the M3x4mm threaded inserts in the lid using a soldering iron.

Stick the reed switch on the inside of the front side of the lid and a small neodymium magnet on the inside of the drawer such that when the drawer is fully closed the reed switch and magnet lineup thus closing the contacts.

Attach the OLED display and rotary encoder to the front panel as shown. I have broken quite a few OLED displays while screwing them. So this time I printed a holder and attached the OLED to it using pins.

Place the ballast and PCB on top of the lid using some double-sided tape and carefully route the cables to them. I have added a fuse just to be safe. Close all the electronics by placing the cover on top of it and screwing it to the lid using M3 screws.

Stick the handle in place.

Step 6: Enjoy!

That's it! Plug it in into your wall outlet, place the things you want to sanitize in the drawer, and turn it ON the lamp using any two modes.

Thank you for sticking to the end. I hope you all love this project and learned something new today. Let me know if you make one for yourself. Subscribe to my YouTube channel for more such projects.