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Team DermaTest Phase 5 Functionality Video
Pressure Sensors in Unison
Pressure Sensors in Unison
As seen above, the team was finally able to get the Beta-prototype up and running! While the physical graph in the video is rather hard to see the results are posted here. These tests proved not only was the main pressure sensor capable of accurately relaying pressure over time data but once a full seal was created the secondary ported pressure sensor was able to initiate itself. This was critical for piecing together the final challenges behind our Beta Prototype and all that was left to do was receive our new peristaltic pump!
New Peristaltic Pump
New Peristaltic Pump
Shown above is the team's brand new Peristaltic Pump! This pump is capable of a flow rate of 0.4 to 84 mL/min or an engine rpm of 0 to 150. This pump also has a digital display that can be toggled to show rpm or flow rate and has accuracy within .2mL/min. This will allow for the team to put validity behind testing, and assign specific flow rates to negative pressure cavity measurements. Having these capabilities is critical when attempting to mechanically characterize the skin.
Beta Prototype
Beta Prototype
Even with challenges of COVID-19, the Beta prototype was assembled with key improvements over the alpha prototype. Each of the major improvements outlined are broken down in further detail in the section below. The figure above shows what the Beta prototype system looks like after putting together all the individual components.
What Does Further Testing Look Like?
What Does Further Testing Look Like?
Further prototyping tests for product functionality involves three main components: identifying suitable materials to use for continued testing, determining the settling time of the pump, and collecting data from the aforementioned materials. To determine the functionality of the beta prototype, it is relevant to test the prototype on materials that would provide similar results as skin with known material properties Potential materials for further use in testing are as follows: saran wrap, rubber erasers, rubber bands, swim caps, rubber jar openers, and meat (chicken or beef). The settling time test will help determine at what point after turning on the device does the flow rate of the pump become steady. Steps are as follows:
Utilizing the new peristaltic pump the team will modulate the flow rate and start collecting pressure data for 30 second intervals. From this we will create pressure vs. time graphs. The rest of the procedures are laid out below:
- Determine at what time point the output (pressure) does not deviate from the final pressure value by more than 5% of that value.
- This will be determined to be the settling time of the system, and the time after which the team will be able to collect reliable data.
- Repeat the test two additional times to ensure consistency in the measurements.
- The final functionality test of the device will involve running the device on the aforementioned testing materials. Steps are as follows:
- Turn on the pump to the previously set flow rate. Allow to run until for aforementioned settling time.
- Place probe on the skin. Start timer.
- Collect pressure readings from both sensors for ten seconds.
- At ten seconds, stop data collection and turn off the pump. Turn the manual valve to vent built up pressure.
- Remove probe from material.
- Generate pressure vs time curves. Repeat the test two additional times.
- The results from this test will be used for final analysis of the mechanical properties of the skin discussed in the following section.
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