Evolution of Biopolymers: From Bacterial Cellulose via PCL to Pullulan

This paper presents an overview of the evolutionary path of biopolymers for ionomeric generating sensors, focusing on three primary materials: bacterial cellulose, polycaprolactone, and pullulan. Bacterial cellulose, typically obtained through the fermentation process of kombucha tea, a sweetened black tea with Acetobacter strains, has garnered significant interest as a more sustainable alternative to plant-derived cellulose due to its biocompatibility, biodegradability, and renewability. Polycaprolactone, also known as PCL, has been utilized to improve the mechanical properties of composite materials and in the creation of mechanoelectrical transducers. It is a biodegradable and biocompatible polyester with various applications due to its unique properties, flexibility, and ease of processing. Pullulan, a natural polysaccharide produced by certain yeast species, finds applications across various sectors including food, pharmaceuticals, and cosmetics. In the realm of environmental-friendly sensors, pullulan, like the other aforementioned solutions, when infused with ionic liquids and layered with polymeric electrodes, can be used as mechano-electric transducers based on the piezo-ionic conversion principle. This paper will provide an overview of how to use these composites as deformation sensors with the prerogative of being green, biodegradable, and aimed at developing dissolvable devices.