On the piezoelectricity of collagen-chitosan film

We studied the physicochemical, piezoelectric and dielectric properties of collagen-chitosan films, with regard to the development of new biomaterials which have potential applications in the coating of cardiovascular prosthe ses, support for cellular growth and in systems for controlled drug deliver y. The piezoelectric strain tensor element d(14), the elastic constant s(55 ), and the relative permittivity epsilon (11) were obtained for the collage n and collagen-chitosan films. Resonance measurement of the piezoelectric s train constant d(14) of collagen gives 0.096 pC N-1, which is in good agree ment with values reported in the literature, measured using other technique s. It was observed that addition of 15% of chitosan increased the piezoelec tricity to 0.212 pC N-1. The frequency constant f L and the piezoelectric s train element d(14), obtained for this sample, present the highest value fo r the samples under study (427.24 kHz m and 0.212 pC N-1). This value for t he d(14) element is of the same order as that obtained for bovine bone (d(1 4) = 0.2 pC N-1) (T.G. Netto and R.L. Ziemmerman, Biophys..T.,1975,15, 573) , which is about one-tenth of the piezoelectric constant d(11) of quartz cr ystal. Our results also show that the presence of chitosan contributes to a n increase in the thermal stability of the collagen films, which is associa ted with an increase in the denaturation temperature of the collagen-chitos an samples compared with the collagen sample. We believe that the increase in the organization of the microscopic structure of the sample, results in an increase in the piezoelectricity. These high values for the frequency co nstant and piezoelectricity, give the possibility of using these films in e lectronic devices based on acoustic waves (e.g. surface acoustic wave devic es (SAW)) which operate in the MHz frequency range using piezoelectric subs trates.