Compact fiber optical interferometer technique to measure picometer displacements in biological piezoelectric materials

TL;DR

This paper presents a simple fiber optical interferometer capable of non-invasively measuring extremely small picometer-scale displacements in biological piezoelectric materials, enabling detailed study of their weak piezoelectric effects.

Contribution

A novel, robust fiber optical interferometer technique for non-contact measurement of picometer displacements in biological samples was developed and validated.

Findings

Measured displacements better than 0.5 pm

Determined biological piezoelectric constants of 0.3-0.5 pm/V

Achieved noise level of 20 fm/Hz^0.5

Abstract

A simple and robust fiber optical interferometer was developed to non-invasively study the weak piezoelectric effect from thin samples. A biological sample from inter-molt dactyl clubs obtained from the mantis shrimp was used as the test sample. The non-contact technique can measure displacements better than 0.5 picometer for samples subjected to large electric fields. The approach utilizes the phase dependent detection of an oscillating cavity at different frequencies from 0.5 kHz to 2.0 kHz. The piezoelectric constant of the biological samples was calculated from the optical interference fringes and determined to be in the range of 0.3-0.5 pm/V. The noise of 20 fm/Hz^0.5 in the setup is primarily due to thermally associated strains from current flow to the sample electrodes during the measurement.