Cellulose Gel Mechanoreceptors - Principles, Applications and Prospects

In order to effectively harness varieties of mechanical waves or vibrations for the purpose of monitoring and/or powering, developments in responsive materials and conversion technologies are taking place driven by the world's current and future demands. One of the most popular novelties of the last two decades is represented by hydrogel- or ionogel-based flexible iontronics which constitute a wide family of innovative smart (self-powered) mechanoreceptors relevant for various applications such as personal health care, identity and safety monitoring, intelligent human-machine operation interfaces, underwater listening and communication, and so on. Cellulosic gels (CGs), as a promising green substitute for fossil fuel-derived materials, are extensively studied due to the possibility to choose between different cellulose types and to formulate networks chemically or physically, according to the adaptability requirements for each target application. The aim of this review is to showcase the cellulose structural versatility and to provide a summary of the principles during the formulation of CGs used for mechanosensing and mechanical energy scavenging, as well as their practical applications. Such an outlook of current challenges and overall prospects will serve as a stimulus for research on CG-based mechanoreceptors in the future.