Human Computer Interaction Engineering
In the summer of 2019, I worked as a research assistant for Stefanie Mueller's lab at CSAIL. I was brought on to help Junyi Zhu build example circuits for the "Curveboard" project. Curveboard was exploring the idea of merging the form and fuction of an object in the context of electronics prototyping. Or more explicitly, can you create a 3D printable object with electronics prototyping ability built into the object, rather than appended to the outside.
To achieve this, software was developed to allow a breadboard hole pattern (0.1" pitch holes in a rectangular grid) to be printed on any surface of a 3D print within nominal curvature constraints. These holes are connected with interior channels, and when these channels are filled with injected conductive silicone, they become conductive paths.
The project was successful and was accepted for publication in The Proceedings of CHI 2020 under the title: "CurveBoards: Integrating Breadboards into Physical Objects to Prototype Function in the Context of Form." This page will be updated with the link when it is publicly available.
For me, this was a chance to test my electrical prototyping skills in an academic environment, and see how I would perform in the hallowed halls of MIT. It also served to get me back in the frame of mind of academic research, where the problems are often less defined but the reliability and usability requirements are also much more relaxed. In both of these regards I was successful. I feel validated in my skill set and was listed as an author in the published research mentioned above.
I built four demonstration projects in my ~100 hours at HCIE, pictured below. Of the four, the first three were used in the final paper.
Heart Rate Monitor
The heart rate monitor was to become a component of the smart bracelet demonstration. It works of off the principle that the amount of light that passes through human tissue changes with the amount of blood in that tissue. Therefore a simple photoresistor, properly filtered and amplified, can be used to extract the heartbeat waveform. I used a green LED to draw the signal out of noise (the more light, the greater the difference in signal with blood flow). The raw waveform is output onto a OLED screen alongside the calculated heart rate number.
I implemented a flexible e-ink display on a MellBell Pico microcontroller as a display option for large bodies of text on a curved surface.
Microphone & Equalizer
I used a piezo microphone to take in ambient noise, which was then processed through the MSGEQ7 IC. The MSGEQ7 takes in raw microphone data and outputs an analog value for seven different frequency bands using fast fourier transform. This values can then be easily translated and output to any screen.
Persistance of Vision Display
A persistance of vision (POV) illusion takes advantage of the eye's natural "frame rate". In other words, light sources that are moving quickly appear as lines to human vision. DotStar LEDs have the benefit of running on the very fast, timing tolerant SPI bus. I used five of these LEDs to create a battery powered POV display that would spell "CHI 2020" when the board was spun at a high enough frequency.