Designing & Building a Sharps Container

The practical need for a sharps container for our lab provided our first opportunity to engage with the engineering design process as a team. Our container would serve as a safe receptacle for disposable sharp objects, such as old utility knife blades, that we would generate in the lab. Once the container was full, it would be thrown away into the Wellesley waste stream. Thus, our container needed to be sturdy enough so that the sharps could not puncture through it and harm anyone handling the container or the trash in the future. Our pool of materials was confined to materials we could find in the lab - namely, cardboard, styrofoam, and hot glue.

Before my team began brainstorming, we decided that we wanted our container to be built from less environmentally harmful materials. This criteria immediately ruled out styrofoam. We instead chose cardboard as our material of choice. Cardboard is a thick and rigged material, which would give our container a stable structure that can not be easily punctured by the sharps. And, as the college generates a massive amount of cardboard waste, it would be easy to build more sharps containers once our container became full and was thrown out.

During our brainstorming session we came up with several designs, some of which were quite silly. Our main concern in developing a design was ensuring that the box could be handled safely, so we settled on a "double box design." This consisted of a smaller box with a slot to drop the sharps in, with a cover over the slot. This small box would be suspended in an outer box on L-shaped supports attached to the top and bottom of the outer box. This idea of this design was that if a sharp was to puncture through the inner box, it would still be contained in the outer box, and would not injure the person moving the box. While a new inner box would have to be made after the first one filled up, the outer box would be reusable.

Quick birds-eye sketch of our sharps container

We estimated that the sharps box didn't need to be particularly large, as we did not expect our class of 18 people to dispose of that many sharps during the semester, and the sharps are quite small. Assuming that every member of the class threw out 3 utility knife sharps, an inner box with dimensions of 4 x 4 x 3.25 in would still have plenty of space inside.

Constructing the sharps container was quite simple, but our design changed significantly as we worked. We began by constructing the small box. We first cut out six cardboard squares, which we planned to glue together. We even traced the the corners where the cardboard supports would go, and cut out the supports.

After doing all of this, we realized that tracing out the unfolded box design onto cardboard and then cutting it out as one piece would be faster, easier, and make a more structurally sound box, so we started over. We then folded the cardboard at the lines that we had drawn, and glued the seams.

 

After our small box was constructed, we realized that it was quite sturdy and we decided that constructing a second outer box was unnecessary. We felt confident that the sharps would not puncture through the cardboard, however, we did worry about the safety hazard in the unlikely event that our box got wet.

Our last step was to cut a slit in the top of the box, and then create a cover for it so that the sharps would not escape from the box. We created a cover by cutting out a small square of cardboard and attaching pieces of velcro to the cover and to each side of the slot.

Lastly, to make our sharps box easily distinguishable from the rest of the items in our lab, we painted the box with bright colors!