Self-Sterilizing Door Handle

Garage Engineer's Prototype




Hello, welcome back to my blog! I will be sharing with you what my group created and our journey. :D

Our team was assigned to create a self-sanitizing door handle. It was truly a challenging task but we were determined especially after researching the statistics for the number of deaths from Covid-19 which was a staggering toll of 6 million. This pandemic/endemic truly inspired us to come up with a successful prototype shown above. Let us see how did we create this!

Planning

Firstly, we did our research about this self-sanitizing door handle which was created by University students.


This was a truly aesthetically pleasing yet a very functional door handle. This door handle is made out of glass to allow UV light to pass through as UV light has its own anti-microbial properties. This door handle also has an photocatalytic coating made of titanium dioxide and a generator that converts kinetic energy into light energy. We were truly intrigued and inspired by this model especially for our first version which I will be showing the sketches done by Daryl.

Version 1

                                  
This looked similar to the model that was shown above, however we added our own twists to it such as adding an automatic spray nozzle and a dryer. However, we have decided to scratch this idea as creating a dryer might be too complex and make our prototype too bulky. This thus brought us to our second idea.

Version 2

                                               
The differences between version 1 and 2 is that the door handle is changed from horizontal to vertical do increase its surface area exposed to the spray and the removal of the dryer. Before moving to our final version, we tested out on this version.

Firstly, Daryl and I found a suitable and simple tutorial on creating a door handle through Fusion 360 and adjusted to our preferred measurements which was assigned to be modelled by Benjamin. Here is our beautiful door handle on Fusion 360!
                           
This is then later exported on Ultimaker Cura to prepare the door handle to be created by the 3D printer shown below.




The areas shaded in blue are the supports for the overhang found on the inlet of the handle. After a 2 hour waiting time, we have gotten this!

                                         

This is our end product after removing the supports.
                                               

Arduino Programming 


With the design of version 2, we have decided to use a servo motor to push down the nozzle of the spray when motion is detected. With the help of Tinkercad, I have managed to retrieve the coding and we adjusted the coding according to our desired movements.

This is the result of the coding. (done by Nikkisha)


However, this was not what we wanted as we want the servo to move 60 degrees and move back to 0 degrees in one movement 4 seconds after a hand is detected, not like the one shown in the video where the hand has to always be detected for four seconds until the motor moves and it would not move back until the hand is away from the infrared sensor. If this was applied onto our prototype, the nozzle would spray disinfectant onto the user's hand instead of the door handle. We found that coding with the IR sensor was quite limited.

The only way that this method would work is that the initial position of the spray nozzle should be pressed down so when a hand gets detected, the servo will release the nozzle and when the hand goes away, it goes back, pushing down the nozzle and spraying onto the door handle four seconds later.

Another problem faced was that the servo motor provided was too weak to push down the nozzle.




 This is the micro servo that was given to us : SG90 
                                                      Torque : 1.8kg/cm



                                             

We had no other choice but to purchase the MG995 which its torque is 10kg/cm.



This servo was definitely much stronger and was able to push down the nozzle, however a new problem has surfaced. The nozzle kept moving out of place and kept turning into undesired directions even though I had filed down a dent for the servo placement and even pasted rubber on it to prevent the servo's 'wing' from moving away. Both methods did manage to keep the servo's 'wing' in place but the nozzle kept turning into random directions.

                                         

We also did not manage to 3D print our circuit box as the printing would take 12 hours even after increasing printing speed and reducing its infill. This is our design on fusion 360.


I assigned Daryl to design the box and gave him the measurements based on the fittings and inlets for wirings, infrared sensor etc.

                                         

After designing the box, I assigned Benjamin to create a cover for the box with a sliding mechanism. In the end, we used a food container to store the wirings and circuits however, we took it as a learning curve and extra experience in Fusion 360. We admired the fact that we started using Fusion 360 in ICPD clueless about anything and now, being able to almost create our own product independently.         
                            
            

Version 3

With all the failures and challenges, we were still committed and have ended up with this final version. Going back to our primary research, I have decided to use the resources that we had and use an LED light to represent a UV light source to replace the spray nozzle.

                                             

I did trial and error with the Arduino coding and came out with this coding.


                    



This is the outcome of the coding.


Similar to the coding problem we faced earlier, we could make it such that the LED will be at high when the sensor is at low and vice versa, it could only be turned on when the sensor is activated as we did not want the hand to be exposed to the UV light might may cause skin damage if being exposed for prolonged periods. Hence I came up with an idea that will have minimal exposure to the skin. Since the only way for the LED to light up is when the sensor detects something, we made it so that the sensor senses the handle and when a user is pushing down the handle, it will be away from the path of the sensor hence switching the LED off. This has led us to our final product.


Door

We measured distance between the box and the handle where the infrared sensor is able to detect it and I added a hole for the inlet of the door handle. We also took note of the kerf so that the handle would fit into the door tight and snug.


                


On CorelDraw, we also added our group's name to engrave onto the door as our signature. Laser cutting this really refreshed ourselves from the laser cutting practical. This is our door after laser cutting, we used recycled acrylic sheet for this.

Final Product

Combining all that we have done, we have our final product !






All in all, creating this product was a fun yet challenging process. It used to seem intimidating until we got our hands on this project where we applied what we have learnt during the previous tutorials and practicals. This has boosted our confidence in excelling for our FYP in the next semester.

General Contributions

Measurements and dimensions (Nikkisha)
Fusion 360 for box (Daryl)
Fusion 360 for door handle (Benjamin)
Arduino Coding (Nikkisha)
Laser cutting of door (Nikkisha and Daryl)
Slides and scripts (Nikkisha and Daryl)
Circuit Assembly (Nikkisha)
Reflection segment for slides (Jia Yu)

Comments

Post a Comment

Popular posts from this blog

CAD Part 1

Image
  FUSION 360 Fusion 360 is an application where you can create 3D sketches and designs which can be made to a real product through 3D printing. It consists of a myriad of features to create very specific shapes and designs. In the making of my name keyring using Fusion 360 Step 1 : In a new sketch, I selected 2-point rectangle and placed it onto the 'canvas' with measurements of 65mm by 25mm. Next, I selected offset of 2mm to the rectangle to create a spacing from the outline. Step 2 : I clicked fillet and applied it on the four corners with a 5mm radius to make them more rounded rather than being sharp. Step 3: I right clicked the line and selected the "Normal/Construction" option. Next, I defined a measurement of mm between the line and the outline. Step 4: I selected 'Point' and placed it in the middle of the line to pinpoint the preferred position of where I would like the whole of the keyring to be. After I have placed my point, I added a 5mm circle on th...
Read more

Hypothesis Testing

Image
  Hypothesis Testing Group members:  Nander (Iron Man) Tzer (Thor) Ashwati (Captain America) Daryl (Hulk) Nikkisha (me, Black Widow) Full factorial data Fractional factorial data Iron Man to use Run 2 from FRACTIONAL factorial and Run 2 from FULL factorial. Thor will use Run 4 from FRACTIONAL factorial and Run 4 from FULL factorial. Captain America will use Run 5 from FRACTIONAL factorial and Run 5 from FULL factorial. Hulk will use Run 4 from FRACTIONAL factorial and Run 4 from FULL factorial. Black Widow (me) will use Run 7 from FRACTIONAL factorial and Run 7 from FULL factorial. The QUESTION The catapult (the ones that were used in the DOE practical) manufacturer needs to determine the consistency of the products they have manufactured. Therefore they want to determine whether CATAPULT A produces the same flying distance of projectile as that of CATAPULT B.   Scope of the test The human factor is assumed to be negligi...
Read more

Home

HOME Ground Rules for Group 1 Everyone to contribute equally Everyone to be present for meetings and discussions Ask for help when in need Must be punctual for all meetings and discussions Everyone has to contribute own ideas when brainstorming Must acknowledge messages in group chats to improve communication Talk it out and solve when there is a problem Roles of Group Members Leader: Nikkisha Facilitator: Daryl Target setter: Benjamin   Self goals To be able to work with other teammates well I've faced difficulty to work well with my teammates especially when it comes to contributing equally. There has been cases where they chose not to contribute at all and it was extremely difficult for me to reach out and communicate especially when we were not physically together. For this semester, I would like to be more bonded with them in order to make them feel more comfortable which will make communication much more easier. I truly believe that good camaraderie plays a huge rol...
Read more