SAW devices (including SAW filters) can be built using semiconductor manufacturing processes. They integrate a loudspeaker-like device and a microphone-like device into a piezoelectric layer. Electric signals to the ‘loudspeaker’ generate waves in the material. The waves travel through the material and are detected by the microphone-like device. The difference between the input and output signals can measure mass and other mechanical properties of materials in contact with the SAW device. SAW devices designed as filters are widely used in cellphones and garage door opener remote controls.