Comparative look at strain gauge and piezoelectric sensors

By JAC Chapman, Elexsys

 

Published in:

Electricity+Control, November 2013 (pages 30 - 32)

Enquiries: georgec@elexsys.co.za

 

Download the full article on Comparative look at strain gauge and piezoelectric sensors in PDF format.

 

Numerous sensors are available for measuring the magnitude of mechanical quantities such as force, torque, load and pressure and each of these presents its own set of benefits and drawbacks, arising from the sensor's physical and electrical properties.


Two of the most common forms of physical measurement are piezoelectric-based sensors and strain gauge-based sensors.

Strain gauge-based sensors utilise strain gauges that are individually bonded to the body of the measuring device and arranged so as to make up a Wheatstone bridge circuit. As force is applied to the body of the measuring device, the strain gauges undergo elastic deformation, altering the magnitude of electrical resistance of the gauge and bridge circuit. This deformation and resulting change in resistance generates an electrical output signal that is proportional to the excitation voltage applied to the bridge and to the amount of force applied to the measuring body.

By contrast, piezoelectric sensors make use of the piezoelectric effect to produce a measurement. As asymmetrical, elastic crystals are placed under compressive load, they generate an electrical charge that is directly proportional to the force applied. Examples of piezoelectric materials are quartz, ammonium dihydrogen phosphate (ADP), lithium sulphate, barium titanate, and lead zirconate titanate (PZT).

Both strain gauge and piezoelectric sensors have their place in the measurement of mechanical quantities. As application requirements vary greatly, both technologies offer alternative methods of acquiring measurement. The size and dynamic response limitations of strain gauge sensors are overcome by piezoelectric devices, while strain gauge sensors offer stability and linearity unsurpassed by their piezoelectric equivalents. Both strain gauge and piezoelectric sensors complement each other in their attributes; where the one technology is limited, the other presents a solution.

 

Take note:

  • Numerous sensors are available for measuring the magnitude of mechanical quantities such as force, torque, load and pressure.
  • Two of the most common forms of physical measurement are piezoelectric-based sensors and strain gauge-based sensors.
  • Strain gauge sensors and piezoelectric sensors complement each other; where one technology is limited, the other presents a solution.