Semi-recently-ish (Hey, this is a blog, not an earth-shattering news item!), a group of students from Purdue University's School of Mechanical Engineering developed the Ghost Pedal, a wireless device that uses sensors attached to the guitar player's foot to create a wah effect—minus the physical pedal.
"Because Ghost Pedal is wireless and does not have a physical pedal, guitar players can activate and use their wah distortion effect anywhere on stage at any time," said Robbie Hoye, part of the the Ghost Pedal team at the university in West Lafayette, Indiana, talking to the Wall Street Journal's Market Watch. "They also have the ability to deactivate the effect whenever they choose."
Once the Ghost Pedal is turned on, the user enters a 10-second mode during which the variable resistor calibrates the ability to flex the foot from the floor. After calibration mode, the guitarist enters freeplay mode.
"During freeplay, the user actively manipulates the wah level by changing their foot's angle from the floor," Hoye said. "The calibration mode adapts itself to modify the resistance sensor to each user and their foot flexibility at the touch of a button. Ghost Pedal and traditional wah pedals use the same motion to activate the wah effect; the guitarist doesn't have to learn a new motion."
For more on this story, give Google a try. For some reason, there's not much out there.