A simple method to characterize the impedance of pyroelectric materials at ultra-low frequencies

作者：Shaheen Murtadha A; Erturun Ugur; Campbell Brandon; Mossi Karla^*

来源：Journal of Intelligent Material Systems and Structures, 2017, 28(2): 143-153.

DOI：10.1177/1045389X16645865

• pyroelectric cells
• equivalent circuit
• impedance matching
• power maximization

The purpose of this work is to demonstrate a new simple stand-alone method of characterizing the impedance of a pyroelectric cell. This method utilizes a pyroelectric single pole low-pass filter technique. Utilizing the properties of a pyroelectric single pole low-pass filter technique, a known input voltage is applied and using simple equations, capacitance C-p and resistance R-p at a frequency range of 1 mHz to 1 Hz can be calculated. For verification purposes, an LCR meter and an impedance analyzer were exploited at 10 and 100 Hz, respectively. Results showed that R-p values for two materials, lead zirconate titanate-5A and polyvinylidene difluoride, were within 8%, and C-p values were within 7.5%. In addition, to verify the importance of the impedance values in energy harvesting applications, output power was measured with varying impedance values. The optimal load resistances for polyvinylidene difluoride and lead zirconate titanate-5A were consistent with the measured pyroelectric impedance at the particular heat range with 10.9% and 1.4%, respectively. The pyroelectric single pole low-pass filter method presented here demonstrates that for pyroelectric materials the impedance depends on two major factors: (1) average working temperature and (2) the heating rate. Neglecting these two factors can result in inefficient and unpredictable behavior of pyroelectric materials when used in energy harvesting applications.

• 出版日期2017-1