This week, our team finalized the general design and structure of our device! It’s a relief to have a set plan we are moving with in the future. As I mentioned in my last post, based on expert feedback, we decided to focus on making the base of our mask-disinfecting unit out of a 55 gallon oil drum due to the drum’s high accessibility in Malawi and Tanzania. After we’d decided upon the enclosure for our device, the major decision we had to make was regarding the structure of our frame. We had two main ideas, so to help evaluate our options we created low fidelity prototypes and performed exposure calculations for both.  

Idea A: Triangular-prism frame

• Masks suspended on each long face of a triangular-prism frame
• Two stacked lights attached to the inside of the oil drum in front of each triangular face (leading to 6 bulbs total being attached to the inside wall of the drum), and two lights stacked in the middle of the drum in order to expose the insides of the masks 
• Frame able to be removed, while lights stay in place

Triangular Frame Pros	Triangular Frame Cons
Able to fit a very high number of masks (9 on each face = 27 overall) Higher masks per unit time rate Maximizes space	Stacking bulbs in center may be unstable Large frame harder to remove with one person (bulky and heavy) May not be able to lift frame entirely out with one person Less uniform exposure across all locations of mask frame (based on calculations) Generally more complex to design, build, and operate More bulbs = higher cost

 

Idea B: Single Mask Frame

• Single large mask-hanging frame slides into center of oil drum
• 3 bulbs attached to each side of drum in triangular formation (6 bulbs total) 
• Frame can be removed, bulbs stay in place

Single Frame Pros	Single Frame Cons
High usability – very easy to remove frame (much lighter) Bulbs all stable Very simple Fewer bulbs = lower cost More uniform exposure across all locations on frame	Can fit fewer masks (15) than the triangular prism  BUT still higher masks per unit time than previous prototype More open space (space not maximized)

In the end, after weighing the pros and cons of each idea, we decided to move forward with the single-frame idea! We made this decision because, although the triangular prism could fit more masks, we didn’t think it was worth sacrificing the uniform exposure, ease of use, and simplicity of the single-frame design. 

After we made this decision, we began to finalize our list of materials and place orders for the things we would need to build our final prototype. A major decision was regarding the material to use in the mask frame. Initially, we had been planning to use bamboo, but a conversation with our international clients suggested that bamboo may not be as readily available as we had originally thought. In addition, bamboo often isn’t as uniform as other building materials, which could create issues in standardizing our design. In the end, we decided to use square wooden dowels in order to construct the frame, which we will coat with either chrome paint or carbon black paint to prevent warping from the UV light. After making this decision, we built a higher-fidelity frame with our new wooden dowels and screws (this process involved splitting A LOT of wood in the search for the correct dowel and screw sizes). 

In the next week, our team is going to be busy creating our final device. We have met with two electrical specialists to begin to discuss how we will power our device, and we plan to begin building our circuit. In addition, once our oil drum arrives, we can incorporate our frame and begin doing exposure testing using a UV meter. By the end of the week, we are hoping that our prototype will be nearly functional.

On a different note, because our TAs are often surprising us, we decided it would be fun to surprise them by all wearing red on the same day. We were super excited that everyone pulled through, and the TAs were definitely caught off guard!