Freescale Semiconductor's MPL115A2 is a tiny thing that will sit quite comfortably on the tip of your finger. It's hard not to marvel at the engineering that went into the creation of something so small, yet so sensitive. The little metal square is minute enough to be plunked into a cell phone, offering up location pinpointing technologies that supplement GPS, gauging positions based on changes in atmospheric pressure. Harvard's Biorobotics team was clearly impressed when it discovered the technology, devising a fascinating implementation that extends beyond the walls of the cell phone. The sensors would go on to form the core of the department's TakkTile open-source boards capable of bringing sensitive touch sensing to robot hands.
The I2C bus / USB-compatible boards incorporate several of the sensors, with the whole thing covered in 6mm of rubber, to help protect them. The rubber lends some durability to the TakkTile -- in fact, if you click on after the break, you can see footage of the team placing a 25 pound dumbbell on the board and banging it with a hammer (which seems to be a fairly popular activity over there). Even with that extra layer, the TakkTile is still quite sensitive -- as evidenced by the five gram weight in the video. In fact, it's even possible to get it to detect a pulse by placing it against your wrist, though the team was unable to recreate that during our visit.
Also compelling is the price -- bought in bulk, the tiny barometers will run you $1 a piece, making the tactile array relatively inexpensive to assemble. Once you buy one, you can also get the most bang for your buck by snapping off the rows for individual use, a possibility given the symmetry of the design. Or you can just make one yourself, as the department has opted to open-source the technology, to help make it even more readily accessible to interested parties.