Piezoelectric pressure sensor: charge (PE) vs. voltage (IEPE) output

What is the difference between a piezoelectric sensor with charge (PE) or voltage (IEPE) output?

For piezoelectric pressure sensors, one of the most important selection criteria is the output signal. Piezoelectric pressure sensors are connected to an electronic circuit which converts the charge generated by the sensor into a proportional voltage. If the electronics is an external device (charge amplifier), it is referred to as charge output or PE sensor. If the electronic circuit is integrated into the sensor housing, then it is referred to as a voltage output or IEPE sensor.

Other known trademarks for the IEPE technology are Piezotron®, ICP®, etc. 

When to use a piezoelectric pressure sensor with charge output (PE)?

PE pressure sensors emit a charge signal; hence the sensitivity is given as picocoulombs per unit of pressure (e.g. pC/bar or pC/psi). Pressure applied to a PE sensor produces a negative charge signal (hence the negative sensitivity of PE sensors), which then is converted into a positive voltage signal by the external charge amplifier. 

However, a low-noise high-impedance cable should be used to connect the sensor to the charge amplifier. This converts the charge into a voltage signal. There are charge amplifiers on the market with analog outputs (which can then be connected to a DAQ) as well as digital charge amplifiers with an integrated DAQ. 

Contrary to IEPE sensors, PE sensors don’t need to be powered, as a charge signal is produced when pressure is applied to the piezoelectric material.

PE (and IEPE) pressure sensors are both applicable for the measurement of dynamic pressure profiles and pressure pulsations. 

Piezoelectric pressure sensors with charge output are optimal for:

• Measurement of quasi-static pressures
• Measurement at extremely low or very high temperatures (no electronics in the sensor)
• Adjustable measuring ranges with only one pressure sensor (measuring range is adjustable at charge amplifier)

When to use a piezoelectric pressure sensor with voltage output (IEPE)?

IEPE stands for Integrated Electronics Piezo Electric and refers to an industry standard for piezoelectric sensors with integrated electronic circuits that convert a charge into a voltage signal. Pressure applied to an IEPE sensor produces a positive voltage signal (hence the positive sensitivity of IEPE sensors). So, the sensitivity is given as millivolt per unit of pressure (e.g. mV/bar or mV/psi).

Contrary to PE sensors, IEPE sensors feature built-in electronics that need to be powered. However, a standard two-wire cable is sufficient to power the sensor and transmit the voltage signal.

IEPE pressure sensors need to be connected to a current (IEPE) coupler for power supply and decoupling the voltage signal from the power supply signal.
IEPE pressure sensors can be connected with an external IEPE coupler to a DAQ or directly to IEPE-DAQ.

Piezoelectric pressure sensors with voltage output (IEPE) are optimal for:

• Measurement of dynamic pressure
• Measurement of pressure pulsations
• Measurement at moderate temperatures and a fixed measuring range

Criteria for application of piezoelectric pressure sensors: