For the MOOG HACKATHON 2020, our team would like to make an e-trombone, and I am trying to design an air flow sensor with paper. This is mainly because the current air flow sensor on the market is not sensitive enough to meet the needs of playing musical instruments. The initial idea was to use carbon coated paper to build the sensor.
I first created a CAD model of the trombone and 3D printed the mouthpiece. In order to observe the effect of the airflow on the paper during the blowing, I pasted some small pieces of paper on the end of the mouthpiece and recorded the slow motion video of different blowing.
The performance of paper is completely different under two different ways of blowing. When only blowing air, the paper sheet will be slightly inclined inwardly. When blowing with the lips vibrate, the paper will vibrate according to the frequency of the lips.
Through this experiment, I can conclude that using the carbon coating paper to build the sensor was not feasible. Which means we may have to add the light to make the sensor. The current idea is to keep the current paper and mouthpiece design and add light-related sensors to the blowpipe.
I also tried the Kresling pattern, which allows me to make a scalable feature. My original expectation was that it could retract itself when the blowing stopped, but during testing it was found that it would slowly unfold and only fold again when breathing in. This origami can be used to make a harmonica, which needs both inhale and exhale.