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