156B Week 6

Project Status

Silicone Balloon

Current mold worked really well and allows for repeatable functioning prototypes to be made.

After some repetition of the mold making process, a few design choices were tweaked to the final mold design. Mainly, the tube space was strengthened as it kept falling off the top cover.

FEA Analysis - Internal Pressure with (extreme case) 5lb load

Left: Application of the internal pressure of the balloon. In the above, about 2psi was applied (may be inaccurate)

Right: Application of the 5lb load to simulate the weight of the tracheostomy tube. Most likely an extreme case.

With a 5lb load and a 2psi pressure, the ballon shows dramatic deformation. The middle area (which engages the tracheostomy tube) shows a displacement of nearly 10 cm. This definitely not representative of the physical model which only raises by about 1 or 2 cm without a load. We will go back and refine the analysis, changing either the material properties/internal pressure/force applied.

Air Pressure Sensor

Past Week Accomplishments

Poured a few molds and produced a desired final prototype (Udai)
Few design tweak were made and a finalized design is being printed (Ryan)
Internal pressure was measured using a barometer to determine the "popping" pressure (Karie)
- Ranges were to small for our balloon design to determine a more accurate value
Pressure sensors were bought and will be tested further (Karie)
PCB design stated (Philip)

Sponsor Feedback

New prototype looks really good and more balloons should be printed out for testing
FSR data looks encouraging, would like to see the force without any support as well
Will start presenting the device to other nurses to get some feedback on user design and possible steps moving forward

Instructor Feedback

FEA analysis on the ballon should be improved upon
Make sure the mold release being used is food grade and hospital friendly

Current Concerns

Time to complete everything and test it out
- Might have to iterate the housing design with just the breadboard as is vs PCB

Next Steps

Test out new pressure sensor (Karie)
Reiterate molding of final balloon design
Develop and refine FEA analysis (Udai/Ryan)
Work on possible Ideal Gas analysis (Ryan)
Develop PCB schematic and layout (Philip/Ryan)
Incorporate controls code to current Arduino control (Karie/Philip)

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