Sensor Chair

The Sensor Chair was designed in Fall 1994 for a new mini-opera, Media/Medium, that Tod Machover composed for magicians Penn & Teller. The trick starts with a performance by Penn on this new "magical" instrument. In the show, after performing this "sensor solo," Penn explains how it works to the audience, and then explains how such technology would have been very useful 100 years ago to measure such invisible and ineffable things as ghosts and spirits. This leads to a wild exploration, through music and magic, of the fine line between state-of-the-art technology and "magic," and between the performance bravura of entertainment and the cynical fakery of mystics and mediums. A rather large team worked on the project, including Pete Rice and Eran Egozy for software, and Joe Paradiso, Neil Gershenfeld and Ed Hammond for hardware. The person seated in the chair becomes an extension of a transmitting antenna placed in the chair cushion. antenna; and their body acts as a conductor which is capacitively coupled into the transmitter plate. Four receiving antennas are mounted at the vertices of a square, on poles placed in front of the chair. These pickups receive the transmitted signal with a strength that is determined by the capacitance between the performer's body and the sensor antenna. As the seated performer moves his hand forward, the intensities of these signals are thus a function of the distances between the hand and corresponding pickups. The pickup signal strengths are digitized and sent to a Macintosh computer, which estimates the hand position. A pair of pickup antennas are also mounted on the floor of the chair platform, and are used to similarly measure the proximity of left and right feet, providing a set of pedal controllers. Therefore, all movements of the arms and upper body are measured very accurately, and turned into different kinds of music depending on the state of the Hyperlisp software.

[Jpeg of Sensor Chair]