2nd Iteration of Prototype

20 March 2025

For the second iteration of prototyping, the squeezing component was made with a smaller radius at its widest part. We also referred to the average palm size as stated in our traceability matrix to define the dimensions of our design. Another change we made was changing the bottom of the squeezing part to be less of a pointy tip, and more round. This is because we realized that minimizing the number of sharp corners and prioritizing smooth transitions would enable our device to be as ergonomic as possible. The general shape of the squeezing component was made even more ovular to emphasize the aspect of our first iteration, where the shape of the component guided where the user would be able to/should position their hand.

In terms of the positioning component, a complete overhaul of the first design was carried out. Essentially, instead of having an encased hole within the center of the component where the eyedrop bottle would be able to slit into, we ensured that a slit — accurate to the neck of a 15 mL eyedrop bottle — was designed as shown in the images above. Essentially, the design features a cylindrical shape with a central circular hole and a radial cut-out extending from the outer edge to the inner hole, creating a C-like form. The rationale of this design was to ensure that the user would be able to more easily remove the eyedrop bottle and also be able to unscrew and rescrew the cap of the bottle with no difficulty. Since the positioning component now featured a notch-like design, it was able to better hold onto the neck of the eyedrop bottle than the previous iteration.

Another important design change that was made was the removal of a latch meant to hold together the two components constituting the device. This change was made after we defined the materials that we wanted to mold and cast with. Essentially, the material we wanted to proceed with for the squeezing component was a flexible and elastic silicone such as OOMOO. On the other hand, the positioning component was planned to be 3D printed with PLA filament, or to be molded and casted using polyurethane, and both materials are harder, less flexible materials. This was when we realized that a latch design would not be able to hold a soft, rubbery part and a harder part together.

We therefore did some research and more brainstorming on how the two components would actually fit together. We realized that small neodymium magnets could be incorporated into the two respective components during the molding and casting process. Specifically, mangets can be placed within the mold before pouring the casting material into the cavity. Hence, this was an avenue that we wished to follow, but also realized that it came with its own specific set of problems. Essentially, the magnets would have to be placed towards the top surface of each component, and this meant that the magnets cannot sink when the casting material is poured in.

Despite some considerations that we still had left to address, we thought that this second 3D printed prototype looked promising and therefore decided to move on with the molding and casting process to find out if the squeezing component would actually be able to translate the force applied by the user to act on the eyedrop bottle itself.