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Figure A: Final Design Solution
This design considers satisfying the following functional requirements:
Insert a soft catheter into the subcutaneous tissue
Possess a removable stylet
Maintain a fluid path
The soft catheter is inserted by dialing back the top three click to load the torsional spring, then flipping the pawl to release the spring which supplies the force to drive the soft catheter and stylet into the body. After insertion, the top is then dialed back again all the way around to retract the stylet from the cannula. With the stylet retracted, the housing device can be removed from the detachable base, and the fluid path can be attached to an external insulin pump. The detachable base allows for a slim profile to be attached to the body, similar in size to competing products on the market, if not smaller than some. It sticks to the body through an adhesive attached to the bottom of the detachable bottom. This eliminates the bulkiness of the housing device and removes all unnecessary components from the housing device to allow for a fluid path.
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Description of Final Design Solution
Description of Final Design Solution
Figure B: Guided path within device Figure C: Guided path with stylet Figure D: An internal look of the device
Figure E: Internal look at the top portion of the device
As can be seen from figure B, a guided path was implemented into the final design in order to prevent buckling of the stylet within the device. The guided path is not one complete piece, but rather two pieces that come together towards one another when the pawl is released. This creates one unified guided path when the stylet is fully extended into the subcutaneous tissue, preventing kinking of the stylet. In addition, a screw was used to guide the torsional spring instead of the originally used 3d printed post due to its improved durability. Finally, as it can be seen in figure B, a screw was driven through the middle of the device to keep the device aligned along the center.
Most of the parts of the device were 3d printed with the exception of the guided path and modified pushing screw, which were fabricated in the machine shop by hand. The torsional guiding screw had a hole drilled through its center to allow for the second guided path to be driven through it. 5 minute epoxy glue was used to keep the path constrained to the screw. Parts of the 3d printed portions of the device were fabricated after 3d printing to create more precise holes to allow proper room for screws and the guided path. In addition to preventing kinking, the guided path acted as a guide that kept the stylet and teflon cannula retain its helical shape throughout the device and the exit.
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