Diagram: Surface Acoustic Wave (SAW)

Surface Acoustic Wave (SAW)

Sensor Materials

Glass, piezoelectric transducers

Principle of Operation

  • Piezoelectric transmitters on the sensor generate acoustic waves on the surface of the glass substrate on alternating X-axis and Y-axis patterns.
  • The acoustic waves are reflected by a pattern of edge ridges directing the energy to piezoelectric receivers.
  • A touch to the surface of the sensor causes attenuation to a portion of the wave corresponding to touch position.
  • Touch location is based on the time delay from the transmitted pulse to the center of the attenuation area of the wave.

Advantages

  • Touch activated by bare finger, some gloves, or soft conductive stylus
  • Transmission typically >90%

Disadvantages

  • Moving liquids or solid contaminants may cause false touches or non-touch areas until completely removed
  • Dirt and water seal can be difficult
  • Typically wide border
  • Limited to 1 or 2 resolvable points (depending on manufacturer)