Bailibo Testing - Analysis of Piezoelectric Film Open Circuit Voltage Cyclic Force Testing Technology

As a functional material that can realize the mutual conversion of mechanical energy and electrical energy, piezoelectric film is widely used in fields such as sensors, energy harvesters and micro-actuators. In order to evaluate its reliability and durability in actual use environments, open circuit voltage cycle force testing has become one of the important performance evaluation methods.

1. Basic principles of testing

The piezoelectric effect of piezoelectric film is its core functional characteristic. When the material deforms under the action of external force, charge separation will occur inside and a voltage signal will be formed on the surface; conversely, the material will also deform when an electric field is applied. The open circuit voltage cyclic force test is based on this principle and monitors the voltage output stability of the film in the open circuit state by simulating periodic mechanical loading under actual working conditions.

During the test, the piezoelectric film was subjected to periodically changing mechanical stress, and the resulting open circuit voltage response was recorded. As the number of cycles increases, the voltage output is analyzed for attenuation or fluctuation to evaluate the material's fatigue characteristics and long-term operational reliability.

2. Testing methods and procedures

Standard open circuit voltage cyclic force testing usually includes the following key steps:

Sample preparation is required first. The polarized piezoelectric film is encapsulated and protected with polyimide film, then fixed on the rigid substrate using epoxy resin glue, and connected to the test leads to form a complete test board structure.

Secondly, build the test system. Commonly used test platforms include vibrating cantilever beam systems and constant load test devices, which can cause periodic deformation of the sample through sinusoidal signals or piezoelectric actuators. The test frequency is usually set within the first-order natural frequency range of the film or test system.

The last step is data collection and analysis. Monitor the change of the output voltage with the number of cycles in the open circuit state, and record the root mean square value, peak voltage and other parameters of the voltage. Some tests will apply different pressure levels (such as 30 MPa, 80 MPa, 100 MPa, etc.) at the same time to evaluate the performance under different load conditions.

3. Evaluation indicators and significance

The core evaluation contents of the open circuit voltage cycle force test include cycle life, voltage attenuation rate and stability indicators. Generally, the test can cover the range of 10^4 to 10^8 cycles. Under ideal conditions, the open circuit voltage should remain stable under different cycle times without an obvious downward trend.

This test can reflect the mechanical fatigue performance of the film material, electrode contact reliability and the integrity of the packaging structure. When there is a significant voltage attenuation, it may indicate problems such as micro-cracks inside the film, electrode detachment, or insulation performance degradation.

IV. Application fields

Piezoelectric film open circuit voltage cyclic force testing is widely used in the following fields:

Wearable devices and energy harvesters: Such products require frequent contact with human movement or environmental vibration, and testing ensures that their voltage output is stable and reliable during long-term operation.

Sensors and MEMS devices: Pressure sensors in industrial and medical fields have extremely high durability requirements, and testing can verify whether the product complies with relevant standards such as IEC 62047.

Consumer electronics: Vibration feedback components in portable devices such as mobile phones and smart watches need to verify their service life through cycle testing.

V. Summary

Open circuit voltage cycle force test is a key link in evaluating the performance reliability of piezoelectric films. By simulating the mechanical loading cycle under actual working conditions, it provides scientific basis for material optimization, process improvement and product design. With the rapid development of technologies such as the Internet of Things and smart wearables, this type of testing will continue to play an important role in promoting the application of piezoelectric films.