Sensor: Pressure

Pressure sensors are found in actions that involve pressing or squeezing like light up shoes, digital drum sets, a safety seat detector,  a do-it-yourself step counter, and other things. Pressure sensors can be found in car tires to alert the driver when the tire pressure is low and more air is needed. Nurses use bed pressure sensors to help them know when to move a patient to prevent body sores. 

Finger-worn pressure sensor to ‘feel’ tumors (by Tokyo University)
Electronic drum kit (Instructables)
Smart shoe with pressure sensors