The front clip is replaced by a guide to help the device remain stable while not impeding the movement of the hand during the procedure.Â
The back clip must snap onto the syringe plunger easily, but not be difficult to remove.Â
Issues
Back Clip
Revolve 120° x 2: Doesn't snap onto the plunger.
Revolve 150° x 2: Doesn't snap onto the plunger.
Thickness (Th) - 0.10: Difficult to remove from plunger.
Thickness (Th) - 0.20: Difficult to remove from plunger, fragile.
Revolve (Re) - 15°: Doesn't snap onto the plunger.
Revolve (Re) - 30°: Doesn't snap onto the plunger.
Guide
70°: Provides more support than 60°.
75°: Provides more support than 70°.
80°: Provides more support than 75°, does sometimes impede hand during procedure.
80° + 65°: Provides more support than 60°, does impede either right or left hand depending on 80° orientation on device.Â
80° Guide and 220° Clip Used on Final Prototype
80° guide was chosen because physicians preferred some hand impedance during the procedure over potential instability. The wider guide provided significantly more stability than other designs.
220 ° clip was chosen because it snapped on and off the syringe plunger easily but would not accidentally detach during the procedure.Â