Progress Report, Week 2: February 14th
Fortunately, this week wasn’t as defeating as the previous, even though we did run into some speed bumps.
A high point to the week involved receiving our microbeads for the particle indicator. Already behind in creating our prototype, we began preliminary testing with the beads on Monday, after class; however, neither of our membranes have arrived. Therefore, we tentatively used Kimberly Clark nitrile gloves as our 2nd membrane material because they have a high elasticity and are readily available in medical settings. Last week, we sought to find a more quantitative method of evaluating the nitril gloves, but we ran into difficulties finding the shear modulus or poisson's ratio to obtain the deflection of the membrane. As a result, this week we tried a more practical method by stretching the nitrile gloves over various transparent containers and placing the microbeads inside. This "membrane" was placed directly onto the skin at the inner elbow. Unfortunately, testing revealed no movement. We attempted to problem solve by using other, more eleastic gloves but the problem persisted. Other methods of solving this issue included different degrees of tension on the glove; however, this also didn't work and furthermore revealed to us additional issues of deformation over time and uniform tension in manufacturing our device.
On Monday, we also attempted to obtain more data to solidify numbers for the force of the pulse on the inside of the elbow, but we ran into more issues. The time delay within the code does not accurately reflect the time between data acquisition. As a result, we cannot accurately represent the force as a function of time. Reflection upon this issue leads us to believe that there is a significant amount of time required to run the code in between delays. We are looking at the Arduino programming to perhaps insert time stamps to determine if this is true. If so, we can still find the average force of the pulse, but will not be able to plot the function with respect to time.
In seeking a solution to our poisson ratio problem, we found the professor, Dr. Rafailovich, who owns the rheometer. She will be contacted next week in order to see if we can use the machine to determine if nitrile gloves have the material properties we desire.
We additionally began to add on materials from last semester's class into the digication e-portfolio. All the old progress reports have been uploaded and other documents will follow shortly.
Additionally, we completed the lecture assignment on intellectual property during the week.
Lastly, on Friday, February 18th, we met with the instructor to give him an update. We discussed our progress thus far on the project and were presented with a few alternatives to our microbead issues. These include using reflective surfaces, such as defraction grades, and other concepts of interest sparked by light-sensitive stickers and wrapping paper. We intend to do more preliminary testing on these various concepts and may implement them in the future if they prove to be sensitive, cost-effective, and practical to manufacture.