Biological Ferroelectret Property Based on β-Chitin Nanofibrils of Deep-Sea Tubeworms

The tubeworm (Lamellibrachia satsuma) exhibits unique characteristics, showcasing naturally occurring high orderliness and crystallinity in its chitin structure. Upon the removal of protein through a bleaching process, hydrogen bonds between the amide groups of β-chitin nanofibrils become apparent, alongside a spontaneous alignment in the c-axis direction. These factors contribute to the ferroelectret properties of the tubeworm, characterized by spontaneous polarization occurring within pores. Uniquely, these properties are expressed through the organism’s inherent high crystallinity and consistent directional arrangement, eliminating the need for external electric field application to achieve polarization alignment. In our study, we have successfully confirmed the mechano-electric coupling properties inherent to the tubeworm organism and have demonstrated the unique energy harvesting behavior of β-chitin in the low-frequency range.