156B Week 7
Overview of Status of Analysis, Design, Fabrication, Tests, etc.
Integrated valve into device and tested
Evaluated valve performance and tuned, pending additional testing
Worked on second draft of report
Implemented solution to replace clamps with latches
Accomplishments from Previous Week
Tested valve in device
Determined clamping requirements for soft tubing and ideal clamp length
Making headway on the report
Circuit schematic completed
Goals for Next Week (list names after each item). Use specific and measurable objectives.
Test the newest valve iteration and have data for presentation (Josh)
If all goes well, print two more
Keep working on report (Basil, Obed, Jeff)
Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
All comments via Zoom (5/13)
Need a name besides "microfluidic device"
Microfluidic Device for Decoupling Shear Stress and Pressure of Pulmonary Arteries?
Given the okay to converse with outside fabrication sources but will likely be too expensive for us to outsource
Suggested alternate cam designs similar to that of an IC engine crankshaft
New snail cam has a fast rise to 3mm deformation and then slow from 3 - 5mm to get a high pressure resolution
Should collaborate with Toni (grad student) to make more intuitive figures
Use the acquired data (P drop and flowrate) to acquire resistance
Resistance can be applied to our desired flowrate (31 mL/s) to obtain predicted pressure drop at this flowrate
Would like the device to be usable by the summer so testing can begin
Need to make sure cover slips are in the proper location, tune by relocating latches
Instructor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
Comments via Zoom (5/8) and report comments via email (5/13)
Check hysteresis with a camera
No hysteresis caused by friction, pusher returns to same location
Stiction
Some stiction and as expected it increased with the addition of the tubing and then flow in the tube
Still not much, worst case was ~5 pwm and stiction only occurs at extremes (0 and 270 degrees)
Suggested talking to Steve Roberts about PCB design
Not a high priority as of now, sponsor says a breadboard is fine for now
Main goal for next sponsor meeting (5/13) would be to present along the lines of "We had a problem, here's how we solved it"
Valve wasn't performing properly, redid clamping tests to see how much deformation was required, designed next valve iteration according to this data
Also intended to reduce the amount of soft tubing in the design to avoid compliance in the system when used with the pulsatile pump
Report
Update figures with direction of flow, add some color
Add photo to exec summary
Add a sentence or two about the ultimate medical outcomes, confer with sponsor
Show how the flow will affect the cells in the device
Some confusion between the original prototype and the device we are building, need to clear this up
Move explanation of cover slips to earlier when they are first mentioned
Confusion about pressure sensors
Cannot directly measure pressure on top of the cells because we would cause disturbances in the flow, need to use pressure sensors before and after the channel to determine the pressure the cells experience
Make the 4 channel design considerations more clear
Should rename the valve of our own design
2D figures of the valves are probably the best solution
Clarifications in the pressure sensor selection process
Wireless control for the future
Comments from Other Students in the Class (indicate date of comments and if via email or in person)
n/a
Risks and Areas of Concern
None at the moment
Resources or Information Required but not Available
None
Schedule
Test and analyze latest valve iteration before next presentation
Clean up plots/add data to our report and make revisions
Finalize valve design and test with all three valves in place
Budget (list amount spent and amount remaining)
Total spent ~$400, ~200 remaining
Progress on Report and Webpage
Updated internal page and other tabs
Received comments on report draft, editing