College - Author 1
College of Engineering
Department - Author 1
Biomedical Engineering Department
Degree Name - Author 1
BS in Biomedical Engineering
College - Author 2
College of Engineering
Department - Author 2
Biomedical Engineering Department
Degree - Author 2
BS in Biomedical Engineering
College - Author 3
College of Engineering
Department - Author 3
Biomedical Engineering Department
Degree - Author 3
BS in Biomedical Engineering
Date
3-2020
Primary Advisor
Chris Heylman, College of Engineering, Biomedical Engineering Department
Additional Advisors
Michael Whitt, College of Engineering, Biomedical Engineering Department
Abstract/Summary
At the start of the project, our initial deliverables were to add a low cost camera into virtual otoscope and to add a pediatric attachment to the stethoscope. However, about half way through the first quarter (1.5 months into the project), our deliverables changed to the following: to design a housing unit for the selected otoscope camera and to increase battery life to allow for 12+ battery life. To accomplish our deliverables, we divided up the responsibilities as follows: One person headed the mechanical design, one person headed the electrical design, and one person served as a liaison between the two components as well as a head of communication.
At the beginning of the project, we spent the majority of our time looking into selecting an appropriate camera to serve as the otoscope camera. We focused on specifications including cost, weight, resolution, pixel count, and color. During this time, our sponsor came across a camera that fit her exact requirements. The camera she chose was the AnyKit Camera. We decided to move forward with this selection as we shifted our focus to designing a housing unit around this camera.
Our initial vision for the housing unit was to make it sleek, aesthetic, and easy to hold. Our first housing unit prototype was composed of a small, uniform diameter, and was just short enough to allow for the camera to extend past the front end of the housing. This enabled the speculum tip to fixate onto the housing so that the end of the speculum tip aligned with the end of the camera to allow for an optimal visual feed with no vignetting. However, our vision changed about half way through the project when we learned we needed to incorporate the 2-in-1 stethoscope/otoscope patent requirement into the design of our housing unit. We essentially needed to design the housing unit to allow for a stethoscope to secure onto the back end of the housing unit. To satisfy this requirement, we decided to re-extend the back end diameter to allow for a stethoscope to attach via a press-fit. We measured the dimensions of the stethoscope using a pair of callipers and implemented these dimensions into the CAD model. Additionally, we further defined the tapered grooved that allowed the speculum tip to stay in place to decrease the likelihood that it would fall off during use.
We designed the circuit box to be able to hold a larger battery that would allow the product to be powered for at least 24 hours. We transitioned from a 480 mAh battery to a 8000 mAh battery in order to accomplish this deliverable. Additionally, we redesigned the circuit box itself in Fusion to accommodate the physically larger battery size. These last renditions to the housing unit and circuit box serve as our final prototype.
Our sponsor’s requirements were to design a housing unit compatible with the AnyKit Camera that would securely house and protect it, and to redesign the circuit box in order to accommodate a 12+ hour battery life. The housing unit specifications are as follows: it must be durable, it must be easy to hold, it must secure the AnyKit Camera, it must attach to the stethoscope, and it must not interfere with the image of the ear canal provided by the AnyKit Camera. The circuit box specifications are as follows: it must be able to hold and secure the new, larger battery, and the battery must provide power for at least 12 hours.
We performed an ultimate stress test to get a quantitative description of how much force our prototype could undergo before fracture. While we don’t anticipate our product to ever undergo such a high amount of stress, this test was able to give us an understanding of how strong our prototype structure is. After looking at each of our four trials, the data showed us overall that the ultimate stress of our prototype is about 180 N. Our pass/fail criteria for this test was 75 N, and our data proved that it passed.
We performed a drop test to get an accurate depiction of how the housing unit would be impacted should it be dropped while in use. From our Failure Mode Analysis, we determined that dropping the device would be the most common mode of failure. We dropped one prototype onto hardwood, one onto tile, and one onto linoleum, each 20 times, and recorded the level of damage (see Tables 13, 14, and 15) after each drop. We averaged the ratings for each type of flooring to assess their success. If the average was less than 1, it was deemed successful. We found all of our flooring types to be successful. Seeing as how each of our drop tests on different types of flooring passed our pass/fail criteria, we can say that the data proved our test to be successful.
We performed a tip attachment test to ensure that the tapered groove geometry was precise enough to allow the speculum tip to snap into place without fear of it falling off. The data from our test showed us that the speculum tip, while attached to the otoscope housing unit, can withstand a downward force of up to 10 pounds. Our pass/fail criteria was whether or not the speculum tip could withstand a downward force of 8 pounds and still remain attached to the housing unit. Therefore, the data shows it met our pass/fail criteria.
We performed a battery life test to ensure that the 8000 mAh battery that we selected would provide power for at least 24 hours. The experimental data showed us that the battery life is 21 hours. The pass/fail criteria was whether or not it would sustain power for more or less than 12 hours. The data showed that it did meet our pass/fail criteria.
URL: https://digitalcommons.calpoly.edu/bmedsp/114