Final Project Design Tasks

Now that we are in the last week of classes, we need to buckle down and figure out how to demonstrate our final design. The major change/addition we will have for the final presentation is the microneedle array. We have decided that the best way to demonstrate the needles would be through 3D printing or laser cutting a design where the needles are bigger (not necessarily on the micro-scale) just to get our point across. After all, we just need to demonstrate that our application device will shoot the needles into something (such as cooked chicken, styrofoam, or playdoh - something that would mimic the skin). This task will be hashed out in group meetings between this and next week, before our presentation on Friday, May 9th. Our allergy test device design has come a long way from the beginning of the semester and we can't wait to show everyone how it will physically work (even if it is scaled up to get the proof of concept across).

The future

With our design review due so soon and the graduation approaching, I can't help reflect on the information Jason presented on this week.

He gave us important information on how and where to look for jobs and how to network in the biotech area around us. As a senior graduating in May the word "future" and "job" seem scarier everyday. It felt nice to have help from someone going through the same thing. While the worry of finding a job is constant right now, knowing that not having a job by the summer isn't bad, makes me feel better.

In design review news:

I am in charge of describing the Pugh chart and how we chose our ideas.

Projector out of card box?

Yeah, no joke. I just learned that you can make a projector out of card box and a lens.

In this prototyping session, we were given some lenses, tapes, clips , crayons and a card box to make a projector. While the first idea that came to my mind was, "What?",  Google told me that it's possible.

We covered all the gaps on the edges of the box, and proceeded to cut a hole that was about the shape of a given lens. The lens was then fitted into the hole. Once the phone was placed inside the box and the phone was set to have the most brightless, Voila! we couldn't see a thing.

The trick was to turn off the light. Once we did that, blurry image started to show up. Then, we adjusted the position of the phone, and also added a funnel using tape so that the air can be scattered through the lens. Overall, the projector came out pretty successful (I think).

Feedback from Design Review 3

With the approaching deadlines of senior design projects and interviews, I have had a very busy work schedule the past two weeks. Therefore, I will combine last week's blog post with this week's post below:

Last Week (week of April 7th):
After our presentation for design review 3, we were able to get good feedback on our prototype design. Most of the comments stated how our device seemed to be close to the final product, with great works like mechanisms. One recurring comment involved how the coating of the microneedles would work and how we can possibly color code the matrix, so the allergen locations can be seen. After all, what is the point of the test if the doctor doesn't know which allergen caused any reaction? These two issues will be address in design review four and in our final report and presentation.

This week:
On Friday, we are meeting as a group to discuss the final stages of our project and how to address the remaining issues from design review 3. We will finalize our design and make sure every aspect of our design has solved all of the problems we set out to improve upon at the beginning of the semester. We will also make sure we are concise with all the aspects of the presentation, since so much has to be fit in to a 10 minute presentation.

Close to Final Prototype Pictures

We have introduced two new improvements to our prototype for Design Review 3:

1) In the previous design reviews, our allergy stamp adopts a pressing mechanism. The doctor would place the allergy stamp onto the skin surface and then press down to apply the allergens. One of our classmate, Ian, had expressed a concern that the skin surface might bend in when the micro needles went down too slowly. We decided to adopt the pull and shoot mechanism, where the doctor would pull the micro needles and release to shoot them into the skin. The damping ratio as well as the spring constant must calibrated so that the spring would not bounce up and down on the skin.

2) Since the unused position of the inner plunger is in the downward position, so we also introduced a bottom cover so that the stamp can stay clean when not used.


Pictures for prototype:

How to Read Our Allergy Test

A common question we have gotten over the past three design reviews was some variation of "How do you read the test results?". Normally, allergy tests produce small bumps on the arm called wheals and each allergen has a control bump (if there is a reaction or not) that is about 2-3mm in diameter. A positive reaction would then have a wheal size of up to 5 mm in diameter on average. The wheals can easily be seen by the eye and these sizes are measured using calipers. In our device, however, the needles are much smaller and we are scaling down the dosage of the allergens. Through research, we have found out that this change would only scale down the size of the reaction. For example, instead of a 2-3 mm control size, it might be 0.2-0.3mm (if scaled down by a factor of 10, for example). Then the reaction size might only be about 0.5 mm, which is very small. We proposed using the same caliper measuring method, but adding in a magnifying glass, so the wheals can be seen better. Many people were also skeptical about this method if we were to have a large amount of allergens in our matrix (between 10 and 40, for example).

However, after discussing with Professor Wong about this issue, she explained that the main purpose of our device is to reduce the pain of having an allergy test. Although it is important to have to read the results, we should focus on the device and how the microneedles reduce pain, not necessarily on the reading of the results. If our only design goal was to reduce the pain of having an allergy test, then all we would have to do is show that we could get the microneedles to administer a test with less pain. Therefore, we could include only 2 allergens (2 microneedle clusters on the array) just to make our point. She also mentioned how the reading of the test could also be considered a project of its own and we should just prove the pain-free administration of the test.

Therefore, I think that it is best if we just focus on making the physical/mechanical aspects of the device work and then state that by magnifying the test area, the results can be read. I also think we should address the matrix size/allergen location confusion by creating a "legend" with the microneedle arrays. I think we should have something similar to what is on a box of chocolates to say which type of chocolate is where: just a map that can be used to match the allergens to their location. In order to do this, I think we need to make the matrix not a square so the legend can still be helpful for any orientation of the array.

These are just some of the ideas I had for this one comment we seem to keep getting after design reviews and we can consider them for the final product and presentation.

Questions and Feedback from the Presentation

We got good responses about our device after the presentation.

One of the questions is how do we ensure that all the needles are coated with the allergens. Earlier in our brainstorming sessions we were considering adding a colored dye to the allergens solvent to see the allergens on the needles. However, if the patient is allergic to dyes, all the tests would be positives and there would not be a conclusive result. We could use a fluorescent dyes when we are testing and manufacturing the needles to show that the needles are coated and determine the percentage of the needles that end up being coated.

Another concern of the project is how to determine if the patient is allergic to the allergen or not and how to view the result. The device we are designing is mostly focused on the fast administering of the allergen and not really how to read the results. For now we are considering having the doctor observe the reaction through a magnifying glass and deciding if the patient is allergic or not. However, we don't know if reducing the dosage will make the diagnosing the allergy a yes or no reaction (if there is a reaction there is an allergy vs there is no reaction therefore there isn't an allergy).

For the moment, we are waiting for the results from the survey.