Collagen-based biopiezoelectric nanogenerator prepared from pollack skin

Collagen, protein abundantly found in living organisms, including mammals, is a natural piezoelectric material with excellent biocompatibility. Pollack skin is a representative biowaste rich in collagen. However, it contains noncollagenous substances in addition to collagen. Herein, pollack skin was treated with a sodium hydroxide solution to remove noncollagenous substances and used to fabricate a pollack skin–based piezoelectric nanogenerator (PS-PENG) with a flexible and simple structure via a simple process. Analysis of the structure and composition of pollack skin before and after alkaline treatment confirmed that the crystallinity of pollack skin increased after alkaline treatment. In addition, after alkaline treatment, the voltage and current performances of the PS-PENG improved by approximately 2.40 and 2.48 times, respectively. Furthermore, the maximum power density of the PS-PENG reached approximately 2.27 mW/m2, enabling the charging of a capacitor to approximately 0.5 V, thereby confirming the practical application of the PS-PENG. Additionally, a voltage of approximately 5.4–7.6 V was generated when the nanogenerator was actuated by various body motions such as finger tapping. Therefore, the proposed PENG based on collagen from pollack skin can be used for powering low-power devices including bioinsertion devices.