The key difference between piezoelectric and piezoresistive is that piezoelectric refers to the presence of electric polarization that results from the application of mechanical stress, whereas piezoresistive refers to the presence of a change in the electrical resistivity of a semiconductor when applying mechanical strain.
Piezoelectricity is the electric charge that accumulates in some solid materials, including crystals, some ceramic types, and biological materials, which includes bones, DNA, and proteins. Piezoresistive effect is the opposite of this phenomenon.
CONTENTS
1. Overview and Key Difference
2. What is Piezoelectric
3. What is Piezoresistive
4. Piezoelectric and Piezoresistive in Tabular Form
5. Summary – Piezoelectric vs Piezoresistive
What is Piezoelectric?
Piezoelectric refers to the presence of electric polarization that results from the application of mechanical stress. This phenomenon is known as piezoelectricity. Piezoelectricity is the electric charge that accumulates in some solid materials including, crystals, some ceramic types, and biological materials that includes bones, DNA, and proteins. This accumulation of electric charges occurs as a response to applied mechanical stress. In other words, the piezoelectricity is electricity which comes from the pressure and latent heat.
Figure 01: A Piezoelectric Balance
Generally, the piezoelectric effect comes from the linear electromechanical interaction between mechanical and electrical phases in the crystalline materials having no inversion symmetry. Moreover, the piezoelectric effect can be identified as a reversible process. In other words, materials that can show the piezoelectric effect can also show the reverse of the piezoelectric effect. The reverse process is the internal generation of a mechanical strain that comes from the applied electrical field.
When considering the history of this effect, it was first discovered by French physicists Jacques and Pierre Curie in 1880. Ever since then, this effect has had many applications, including the production and detection of sound, inkjet printing, generation of high voltage electricity, microbalances, etc.
What is Piezoresistive?
Piezoresistive refers to the presence of a change in the electrical resistivity of a semiconductor when applying mechanical strain. This is the opposite of the piezoelectric effect. It can cause a change only in electrical resistance (not in the electrical potential). The piezoresistive effect was first discovered by Lord Kelvin in 1856 using meta devices under the application of a mechanical load.
In conductors and semiconductors, changes in inter-atomic spacing come from the strain effect of the bandgaps, which makes it easy for the electrons to move to the conduction band. This movement results in a change in the resistivity of materials.
Usually, piezoresistivity in metals occurs due to the change of geometry, which comes from the application of mechanical stress. Even if the piezoresistive effect in some materials is small, it is not negligible. We can simply calculate the piezoresistive effect using the following equation, which is derived from Ohm’s law.
In the above equation, R is the resistance, is the resistivity, l is the conductor length, and A is the cross-section area of the current flow.
What is the Difference Between Piezoelectric and Piezoresistive?
Piezoelectric and piezoresistive are terms that are opposite to each other. The key difference between piezoelectric and piezoresistive is that piezoelectric refers to the presence of electric polarization that results from the application of mechanical stress, whereas piezoresistive refers to the presence of a change in the electrical resistivity of a semiconductor when applying mechanical strain.
The following table summarizes the difference between piezoelectric and piezoresistive.
Summary – Piezoelectric vs Piezoresistive
Piezoelectric and piezoresistive are terms that are opposite to each other. The key difference between piezoelectric and piezoresistive is that piezoelectric means the presence of electric polarization that results from the application of mechanical stress, whereas piezoresistive means the presence of a change in the electrical resistivity of a semiconductor when applying mechanical strain.
Reference:
1. “How Piezoelectricity Works.” Eagle Blog, 2 Feb. 2021.
Image Courtesy:
1. “Piezoelectric balance presented by Pierre Curie to Lord Kelvin, Hunterian Museum, Glasgow” By Stephencdickson – Own work (CC BY-SA 4.0) via Commons Wikimedia