Electrostriction contribution to the electromechanical response of cast chitosan films

Abstract

Polysaccharides offer great potential for developing flexible and sustainable electronics due to their inherent biocompatibility and biodegradability. Among them, chitosan shows promise for biomedical applications, though its electromechanical behavior remains not fully understood. To address this, we prepared chitosan films using two different acidic solutions to promote varied interactions between chitosan chains. A comprehensive characterization of these films was conducted, examining their crystallinity, bond interactions, and microscale electromechanical response through X-ray diffraction, Fourier transform infrared spectroscopy, and piezoresponse force microscopy (PFM), respectively. Our analysis reveals that the second harmonic PFM response is greater than the first harmonic response in chitosan cast films (30–40 μm thick), suggesting that the dominant electromechanical response is electrostrictive rather than piezoelectric, although electrostatic and charge injection phenomena cannot be entirely ruled out. These findings provide new insights into the mechanisms underlying chitosan's electromechanical behavior, helping to resolve discrepancies in prior studies. This improved understanding opens opportunities to employ chitosan in functional devices, advancing the field of polysaccharide-based flexible electronics with applications in biomedicine and beyond.