O2 Polmoni

Our project is a model of the lungs and it has an educative goal witch is why we decided to make a lung that shows the exchange of the gasses through leads of different colors, red for the oxygen and blue for CO2. In the menwhile the other shows the movement that the lungs do when breathing .

Arduino, LED, cables, silicone, resin, hot-glue, baloon, 3D printer, mold, jumper, resistences, stagnant worker.

We brainstormed and decided to make the two lungs so that each represented a different function. One represents the exchange between oxygen and carbon dioxide, the other represents the expansion and contraction it makes during breathing. We decided to make the first one in resin, so that we had a transparent, resistant material that took the shape of the lung. To represent the gases we decided to use two rows of LEDs, of two different colors, red and blue, one representing oxygen and the other carbon dioxide. The other lung we decided to make it from silicone, an elastic and moldable material.

We made the silicone lung starting from the creation of a mold on a blender.

Before trying to make the lung on the model created with blender, we did various tests using smaller models that we already had, trying to use the glass bell and learning how to work with silicone.

The mold is composed of three parts: the two outer halves, hollowed out in the shape of the lung, and the inner lung. We left a thickness between the inner lung and the outer parts to insert the silicone into. We printed the mold with the 3D printer, creating, after the original one, an improved version, in which we increased the thickness of the space for the silicone and increased the diameter of the hole at the top from which the internal lung should be removed.

We covered the model with vaseline to prevent the silicone from sticking to the mold and we did various tests in which we spread the silicone in the mold space, finding the problems solved with the second version of the mold. In particular a problem that always arose was the uneven thickness of the silicone, which concentrated on one side of the mold during drying. The final lung in fact has a thicker side and a thinner side, but the effect is very beautiful because the thinner side swells and deflates very visibly.

We inserted the silicone lung into a transparent cylindrical plastic case, in which we made a hole in the center at the bottom, into which we glued, with silicone, the neck of the lung. At the other end of the case, we inserted a wooden round, also with a hole in the center, so that it fit perfectly into the cylinder, and sealed the wooden round to the case with hot glue. On this side we fixed a pink balloon about the same size as the lung. To secure it, we inserted a tube into the initial part of the balloon, and fitted it and fixed it with hot glue in the hole.

We have therefore created a case in which on one end there is the silicone lung (open, to allow the passage of air) and on the other a balloon (at the opening of which a tube is inserted to allow the entry of air). A pump is connected to the balloon tube that lets air into the balloon. As a result, the silicone lung deflates due to the change in air pressure, and then inflates again when the pink balloon deflates.

We started making the lung out of resin, since making it out of silicone made the color of the LEDs less visible, which represents the gas exchange between the CO₂ and O₂.

We obtained the structure of the resin lung using a 3D mold, covered with food film, on which the two-component epoxy resin was then spread. Using a smaller-scale 3D-printed lung than the first, the concavity of the two halves of the lung was set.

To make the led circuit, we learned how electric current works. At first we used a breadboard to understand how resistors and LEDs work. We then wrote the program on Arduino, to regulate the ignition of LEDs, so as to describe the effect of oxygen and carbon dioxide exchange.

We then built the LED circuit structure.

We started from the Arduino board, from which we connected jumpers to an LED tape. From the tape, we then connected a resistor and one leg of the LED to the tinning; we then connected the other leg of the LED to the other side of the tape, again via tinning. Once the circuit was complete, we loaded the code onto arduino, covered the LED wires with tape, tucked them neatly inside the lungs to better enhance the effect of the LEDs, and closed the resin lung with the LEDs inside with hot glue.

Finally, after creating the two lungs, we created an external structure to show the two neighboring lungs joined by the trachea.

We created a wooden pedestal, consisting of a roundel with a hole in the middle and three legs to keep it standing. On this pedestal we placed the plastic case, with the balloon facing down so that the tube would fit into the hole in the pedestal, to then connect it to the pump.

We then made a support to attach the resin lung to. The support consists of a wooden pole with a base that allows it to stand, and at the upper end another piece of wood that protrudes so that the resin lung can be attached to it.

We then placed the two components side by side so that the two lungs were at the same height. Using plastic tubes, which we colored pink with tempera, we made the trachea and attached it to one of the two components so that the ends were on the lungs.

We finally created the two lungs at the same height and the trachea that joins them, even though the trachea is attached to only one of the two components and not both so that the structure is easier to transport.