 Bio-based polymers have been gaining popularity due to their potential applications in place of traditional polymers. In particular, they can be used in electrochemical devices, where the electrolyte is a key component in determining the device's performance. Collagen has been identified as a promising material for use as a polymeric matrix for the development of gel electrolytes. This study evaluated two types of collagen membranes, uncross-linked and physically cross-linked to determine their suitability for use as an electrolyte in electrochromic devices. The membranes were tested for their stability in water and aqueous electrolyte solutions as well as their mechanical properties. The results indicated that the cross-linked membrane had better water absorption capabilities and greater resistance than the uncross-linked membrane. Additionally, the cross-linked membrane exhibited improved optical characteristics and higher ionic conductivity when immersed in sulfuric acid solution. These findings suggest that the cross-linked collagen membrane may be suitable for use as a bio-based electrolyte in electrochromic devices. This article was authored by Carmella Tanya-Prontra, Nunzia Gallo, Roberto Tinuzzi, and others. We are article.tv. Links in the description below.