1. Cell Culture Stirrer for YSI Design overview: past and present New features Manufacturability improvements

2. Design overview: past and present

3. Design Overview: Past and present: Test tube leakage: the water flowing throughout the system sometimes leaks through the crack between the water bath and the test tubes. Stirrer startup: occasionally magnetic culture stirrers do not start when unit is turned on. Manufacturing costs: the $1,800 price tag necessitates low-cost design modifications. Here are several problems with the current product: Leakage areas

4. Design Overview: Past and present: Test tube leakage: the water flowing throughout the system sometimes leaks through the crack between the water bath and the test tubes. Stirrer startup: occasionally magnetic culture stirrers do not start when unit is turned on. Manufacturing costs: the $1,800 price tag necessitates low-cost design modifications. Here are several problems with the current product: Here are magnets that, when excited by from below, rotate inside the test tubes, and stirring the contents therein.

5. Design Overview: Past and present: Test tube leakage: the water flowing throughout the system sometimes leaks through the crack between the water bath and the test tubes. Stirrer startup: occasionally magnetic culture stirrers do not start when unit is turned on. Manufacturing costs: the $1,800 price tag necessitates low-cost design modifications. Here are several problems with the current product: $1800 USD

6. Thinking Globally: low-cost innovation. Make components easy to manufacture. Reduce the quantity of parts needed. Simplify the assembly process. Attempt to use ‘off the shelf’ components to reduce fabrication costs.

7. Innovations: One-piece test tube One piece upper housing New upper housing clasp design Redesigned base Magnet rotator improvement

8. Innovations 1/5: Test tube One piece test tube: –Fewer parts than previous design Current design: 4 pieces New design: 1 piece –Improved seal design Current design: 1 point of contact New design: 2 points of contact O-ring retaining tab O ring contacts side of upper housing at two points to further prevent leakage. Small tab on test tube keeps o-ring on.

9. Innovations 1/5: Test tube One piece test tube: –Less parts than previous design Current design: 1 piece Previous design: 4 pieces –Improved seal design Current design: 1 point of contact New design: 2 points of contact O-ring retaining tab –Can be molded –Fits current sensor design –Autoclaveable clear plastic (material option) –New threaded collar.

10. Innovations1/5: Test tube These innovations eliminate the first design problem with the current product (water leakage) Additionally, they satisfy the design constraints in terms of manufacturing simplicity and cost effectiveness.

11. Innovations 2/5: Upper housing clasp design One-piece upper housing reduces the number of fabricated parts needed. –Current design: 2 piece upper housing. –New design: 1 piece. Can be made of autoclavable lexan. One downside that the threading will require a secondary operation (after the part is molded)

12. Innovations 3/5: Upper housing clasp design The clasp holds down the upper housing using a socket head cap screw. Clasps extremely inexpensive to manufacture. They may even be available off the shelf.

13. Innovations 4/5: redesigned base Using Pem® hardware, (http://www.pennfast.com) one can fasten screws securely into body with only a negligible increase in cost.http://www.pennfast.com

14. Innovations 4/5: redesigned base Flat rubber strip across bottom is riveted into the base. –This eliminates the need for rubber standoffs, eliminating additional parts. –Using rivets to attach this piece decreases manufacturing cost. –Rubber strips are considerably more cost effective than rubber standoffs.

15. Innovations 4/5: redesigned base Riveted side clasps –These give the body the necessary support so that a bottom plate is not necessary.

16. Innovations 4/5: redesigned base New body design enables better ventilation by convection cooling. Cool air enters through bottom of housing As the motor heats it, the air rises Finally, the hot air exits through the upper vents

17. Innovations 5/5: improved stirring assembly This redesigned stirring assembly will allow each of the samples to be mixed individually. This assembly screws into the under side of the sheet metal base.

18. Innovations 5/5: improved stirring assembly Here is a picture of the stirrer with the shell (base) removed, exposing its inside.

19. Innovations 5/5: improved stirring assembly Here is a view with the base dimmed and the upper housing removed.

20. Overall benefits of new design Simpler assembly. Less custom fabricated parts Increased reliability (the modification of the stirring device should prove more reliable) Faster assembly time More ‘off the shelf’ components

21. Drawbacks of new design Additional expense for stirrer assembly. Although there are fewer custom fabricated parts, the parts that are custom made are more complex than before. Additional overhead required to perfect the new magnet stirrer assembly design.

22. Design questions: Should we use rivets for base or spot welds?

23. Future work: Design: –Get motor specs and a correct 3D model –Determine correct tolerances for PEM hardware –The motor mount assembly can probably be further simplified Documentation –Find manufacturers for all prefab parts. –Check specs to those of parts in assembly

24. Future innovation possibilities Attempt to make test tube more ergonomic for ease of tightening. –In order to do this I would need drafts of the sensor to ascertain whether modification is possible. Use a small electronic device to adjust startup voltage. This way, the magnets would start rotating slowly so that the stirring magnets in the test tube could ‘keep up’ with the rotating magnets at startup.