Project development: Door Handle Streilizer

Welcome back everyone! This will be my last blog and it is focused on the project me and my group mates have been working on for the past semester! In this blog, I will be documenting the entire design process of my group's prototyping of an automatic door handle steriliser. My group consists of Devin, Yuhan, Ji Hinn, and myself. We have been working on this project since Week 5, and we are proud to announce that it is now complete!

The purpose/significance of our product

Door handles are a significant culprit in the spreading of viruses and bacteria. This is because everyone must touch them to open the door, and they rarely get cleaned since they do not look dirty to the naked eye. Also, most door handles are made of stainless steel, which is a perfect material for bacteria to cultivate on. Some examples of viruses that can spread are the coronavirus (COVID-19), norovirus, hand foot and mouth disease, and influenza.

To emphasise, ever since COVID-19 started, the need for sterilisation tools/equipment/media to minimise its spread has increased. One of the commonly touched areas that requires specific sterilisation equipment is door handles. Disinfecting and sterilising are types of decontamination, a process that makes something safe to touch. The purpose is to kill enough germs so the risk of infection, in this case COVID-19, is extremely low.

Hence, producing an automatic door handle steriliser will be a great and convenient way to curb this problem.

Hand sketches of our product from week 5 to 18!

The following hand sketches are all one-point perspective sketches, with the point being located at the top right. (Special thanks to Yuhan for the drawings)

Allocation of roles in the team

Chief Executive Officer (CEO): Devin Tan Wei Jie

Chief Financial Officer (CFO): Ang Yu Han

Chief Operating Officer (COO): Leong Rui Ren, Brice

Chief Security Officer (CSO): Chang Ji Hinn

 

Finalised Bill of Materials (BOM)

Since most of the materials that we needed were mostly readily available at W319 (such as the Arduino kit, 3D printing filaments, hot glue, cardboard), we barely had to purchase anything.

Finalised Gantt Chart

Part 1: Arduino programming / Coding (done by Ji Hinn)

Here is the link to Jihinn’s blog: https://cp5070-2022-2b01-group3-jihinn.blogspot.com/2023/02/blog-entry-6.html

Jihinn’s hero shots:

What an iconic lad.

Part 2: 3D Printing (done by Myself)

Having done 3D printing in the prerequisite module to CPDD I was quite familiar with the fusion 360 software and decided to take up the role of creating and subsequently 3D printing the parts needed for our product.

After deciding on the design of our product, I suggested that our group used 3D printing to print the shell of our product which was agreed upon. To start I had to take measurements of the Arduino uno, breadboard and power bank to estimate how big the diameter of the shell had to be. On the first attempt I had designed a shell with a diameter of 70 mm and a height of 125 mm with 2 holes for the UV light and the ultrasonic sensor.

However after printing it out, when we tried to fit the electronics in it did not fit as I did not account for the wiring as such I had to increase the diameter of the print. This time at a diameter of 120 mm with nothing else changing the electronic did fit this time… kind of

Though now with a different problem. The height of the print could not fit the wire to connect the Arduino uno to the power bank as it was very long and thick making it unable to bend when coiled up. Our solution was to print a hollow cylinder with the same thickness and diameter as the shell with a height of 60 mm to add to the top of the shell to extend its height.

We had also overlooked the mechanism part of the project and did not include it in our original design but was kindly reminded by our lecturer Mr Chua (Thanks!). We decided to use the mechanism as a way to produce an input to our ultrasonic sensor by using a lever.

The lever was to be made out of acrylic and a 3D printed part which was good since before this our plan to show laser cutting was to engrave our group number unto a piece of acrylic and paste it on our product.

Since the lever needed a point to pivot upon, I 3D printed a small hollow rectangle which could fit a nail through which served as out pivot point for the lever. The specifications are 45 mm length, 8 mm breath, 4 mm hole diameter.

Part 3: Laser Cutting (Done by Devin)

Here is the link to Devin’s blog: https://cp5070-2022-2b01-group3-devin.blogspot.com/2023/02/blog-6-project-development.html

Devin’s hero shots:

Part 4: Prototyping (Done by Yuhan)

Here is the link to Yuhan's blog:https://yuhan21.wixsite.com/cp5070-2022-2b01-gro/post/blog-entry-6-project-development

Yuhan’s hero shots:

Part 5: Integration of All Parts and Electronics (Done by everyone)

We met in W3 after our End of Semester Test to put everything together. Firstly, we had to check that the code was working. While waiting for that we worked on our lever. After a while, our coder, Ji Hinn managed to get it done!

We then put everything into the cylinder and realized that the wire is too long so we had to 3D print a 6 cm hollow cylinder to fit the wire in our device to make it compact. We had to use hot glue to glue the extra 6cm hollow cylinder onto our previous 12.5cm cylinder. We also had a 1.8cm cover so our total device height is 20.3cm with a diameter of 10.6cm.

After managing to get all the component into our cylinder, its time to test our lever. We chose a random handle in W3 and stick our device onto the door and the lever below the door handle.

 

Final Product:

Here are some picture that we took during our building process:

Internals of product:

Demonstration of product:

Hero Shot with our product!!

5. Project Design Files as downloadable files

https://drive.google.com/drive/folders/1n1h9Rhs2q37NNfngmhLOyig3nlxStEn8

6. Learning Reflection on the overall Project Development.

Overall, though the journey was a bit rushed and at times the work load seemed too much for me to handle, I enjoyed the challenge that it presented and it allowed me to use my skills which I have learnt from previous modules. There were many challenges we had to overcome within the project and outside of it (eg. exams/tests).

Having to use 3D printing, laser cutting and Arduino programming all in this project allowed for us to think outside the box when trying to come up with unique solutions to our problems. 

Working with my team was a blast and I wish to thank them for all the effort they have put into which made this possible.