“…Polymer electret materials have the advantages of flexibility, low density, low cost, and easy structure regulation, which have been paid extensive attention in recent years [ 23 ], especially the design, development and research of bio-based electret. Bio-based electret, such as chitosan [ 24 ], hyaluronic acid [ 25 ], polylactic acid [ 26 ], hydroxyapatite [ 27 , 28 ], natural cellulose and so on, have attracted much attention because of their better biocompatibility. However, bio-based electret polarization has some defects, such as low charge density, short life and fast discharge, which often cannot meet its application requirements.…”