Collecting Device for the Wet-Spinning of
Collagen
Team 5 Members:Aashi AlexanderJohn HenenSara MinaGobi Vanniyasingam
BME 496 Final Presentation
Product Description Wet-spinning collagen collector
Elongates and stretches the fiber in the process uniformly
Doesn’t change diameter of fiber after wet spinning Useful for lab technicians in development of collagen
scaffolds
Mechanical method to collect fiber- plate/spool Keep fibers intact with greater than 75% accuracy Drying process of fiber before they are collected Do not change existing device, only add components Secure and stationary mount for the syringe Cost-effective
Customer Needs
Background
Accessory to previous Capstone project (wet-spinning device) Forms collagen fibers used to create scaffold to grow neurons onto
(spinal cord injuries) Current method of collection : manually
Tweezers on Teflon belt can damage tensile strength of collagen More automated system can meet customer needs
Description of How Proposed Design Meets Requirements
Customer Needs Requirements Design Feature Tests
l Mechanical method to collect collagen fibers
Collecting device shall have a slip wheel rotating clockwiseThe fourth gear shall be used to rotate the slip wheel clockwiseThe collecting plate shall be collect the fibersCollecting device shall collect at least 95% of fibersThe collecting plate shall run at 6RPM
Slip Wheel
Collecting plate
Pass
Pass
Pass
Fail
Pass
lKeep fibers intact without distortion to diameter
Collecting device shall have an X-Acto blade #18 scraper The scraper shall be fixed to the wall of the existing structure
Scraper Pass
Pass
lCreating a secure and stationary mount for the syringe
The mount base shall have 4 cm height to reach the bathThe needle head shall be placed in an accessory structure that shall be attached to the mount base The syringe mount shall produce the fibers uniformly with percent error accuracy of more than 75%.
Syringe Mount Pass
Pass
Pass
What we added?
Scraper Mount Gears
Scotch-Yoke
Syringe Mount
Final Design
http://www.youtube.com/watch?v=jPoBmM4We8I
Scraper ClampBelt Scraper
Gears
Scotch-yoke
Collection Plate
Scraper Clamp
Collection Plate
Belt ScraperScraper Clamp
Collection Plate
Gears
Belt ScraperScraper Clamp
Collection Plate
Scotch-yoke
Gears
Belt ScraperScraper Clamp
Collection Plate
Test Plan Execution Test Test Passed Why Test failed?
Syringe Mount Passed
Stand Passed
Scraper Passed
Scarper Mount @ 90o Passed
Gears rotation Passed
Motor 1 (old) Passed
Motor 2 (New) Passed
Scotch-yoke (collection) Passed
Fiber Diameter Passed
Fiber Length Failed 8 in instead of 12 in of fiber
Physical Requirements Testing
Part Measurements
Rotation Angle and Positioning
Stand X
Scraper X X
GearsX X
Rods X X
Syringe
MountX X
Collecting
PlateX X X
Testing-Scraper Eliminated three original materials for scraper against
belt Teflon, silicone rubber, silicone gel
X-Acto blade #18 Advantage- takes fiber off belt Disadvantage- fixed width Results: scrapes fibers off belt successfully in one piece Clamp to keep blade fixed at 90deg. to belt
Testing-Polyethylene Stand Original design did not support device New design supports weight Results: technician finds it easier to
use device and height is good for collection
Eliminated original slip wheel which worked to get fibers off the belt Due to error in calculation of location of
hole into device Advantage: slip wheel with smaller
outer diameter Disadvantage: requires new modeling
of rods and gears
New slip wheel Collects 100% of fibers
Eliminated second scraper Technician must manually pull fiber off
slip wheel and place first piece onto collecting plate
Testing-Slip Wheel
Testing- Gear Meshing Main issues:
Small space to work with ~1.5cm between centers of gears 3-D printing error Due to improper hole placement, new gears had to be made
Original gears did not mesh Changes made to teeth height, width, inner and outer diameter ~20 gears printed (7 min per gear to print)
Better success with different teeth height ratios and rod filing
Testing- Rods for Gears
ROD1 had correct dimensions ROD2 that runs through the slip wheel had to be filed down due
to hole positioning error
Tested by technician for ease of use Fixed on frame wall
of device Successful in keeping
syringe in place at correct angle
Gave better tensile strength results for fibers
Fulfills requirements
Testing- Syringe Mount
Testing- Collecting Plate
Scotch-yoke mechanism to horizontally move plate Manually tested polypropylene as collection for fibers
Successful in attracting fibers Changed position of plate from under device to into device Collected 8in as continuous strand out of 1 foot of collagen
Changes needed to existing device for better collection
Mechanical Requirements
Used tachometer to measure RPM of third and fourth gear which run the rods and slip wheel All rotate at 6RPM
Calculated torque for added parts to see if existing motor could support them Torque was far less than existing motor
Can run 6RPM motor for collection during wet-spinning
Part 6RPM Torque Compatibility
Gears X XRods X XSlip Wheel X XSecond Motor
for Collecting PlateX X
Performance/Reliability Requirements
Control: fixed flow rate = 0.206mL/min
Collecting rate onto plate = 2.5 in/min Most we have collected =
8in Customer need was to
collect 95% of fibers We collected 67%
Problem in testing- all fibers onto slip wheel but when pulling them onto plate, some go back onto conveyor belt
100% collected onto slip wheel
Less than 25%error in fiber diameter
Success with 20% error More uniform fibers
produced
Schedule
Completed mechanical/torque analysis for added parts Modified syringe mount Built product as supplies arrive
Worked on Pro-E to make original gears and rods Made polyethylene stand for device
Schedule
Building Final Model delayed Testing was done on time Collection Device delayed
Estimated to be finished late February (delayed for months) Finished in April
Lessons Learned
Identify roles more efficiently Individual work is very different from group
work Going out of our comfort zone and track is
challenging but important to do Learning experience
The earlier, the better Go to the advisor for a different perspective
when you meet an obstacle
What We Would Do Differently
Ordering parts earlier Learning more about mechanics during the
winter break Learning Pro-e earlier 3D printing gears and yoke earlier Testing the collecting plate in March Managing our time better Following our schedule no matter what
Status of Meeting BudgetInitial Budget Final Budget
Polyethylene ~ $63 (free from John’s lab) Polyethylene ~ $63 (free from John’s lab)
Silicone Gel ~ $30 (made our own in Dr. Pfister’s lab)
Silicone Gel ~ $30 (made our own in Dr. Pfister’s lab)
Silicone Rubber ~$7 Silicone Rubber ~$7
Polish stainless steel ~ $3 Polish stainless steel ~ $3
ABS plastic for syringe mount ~$2/sq.in Second motor ~ $ 14
Static Collector- $5.70 Collector-Polypropylene (free)
X-Acto # 18 ~ $3
Shoulder Screw ~ $ 11
Total Cost ~ $ 20 Total Cost ~$ 38
Next Step:
3 options to better meet customer needs Bring shoulder screw closer to center of moment arm
Reduces distance of plate to travel Make grooves into existing device
Such that slider is aligned under slip wheel Alter device so that more room is available for plate to travel
Limitations from existing device
Roles/Responsibilities
Aashi: scraper materials, mechanical analysis, schedule, testing, drawings
John: mechanics, testing, High Level Requirements
Sara: materials, Pro-E, testing, video recordings
Gobi: scraper positioning, drying method, schedule, testing
All members wrote the Test Plan, are responsible for the collecting device and all design concepts