Bopscotch was a project that I worked on with two fellow researchers for an arts festival at the Media Lab in the spring of 2013. The installation combined the classic game of hopscotch with some design and technology to create an interactive musical experience. When users jumped on the squares, nearby speakers would play various notes in a musical scale. By jumping forwards and backwards, users could create their own songs in a playful way.
The squares displayed culturally significant designs that were cut out on a vinyl cutter. Underneath each design was a custom built pressure sensor consisting of a double decker construction paper and aluminum foil sandwich (i.e. paper - foil - paper - foil - paper). The sensor was essentially a big (and cheap!) capacitor, with the foil acting as the conductive plates and the paper as the dielectric. One of the pieces of foil in each sensor was hooked up to an Arduino, which used a charge/discharge timing technique to approximate applied pressure. When a user stepped on the pad, the paper compressed slightly, bringing the foil closer together, increasing its capacitance, and thereby increasing the discharge time. The Arduino was connected to a host computer via a serial port, a Processing sketch listened for serial commands, and then the program hit various key strokes when users stepped on the pads. A piano web application ran in the background, which played notes when certain keys were pressed. The user was able to interact with the web app to choose different instruments and styles.