Sensors for measuring and detecting chemical and biological substances are comprehensively used and are, for the most part, unobtrusive. They can help monitor our health through alerting us to chemical or biological changes in our bodies, our environment through checking air quality or pollution levels and they can contribute towards a more sustainable future. Polymer-based sensors are the subject of much attention due to their ability to collect molecules on their flexible sensory surfaces. However, most petroleum-based polymers are not renewable, leading to problems of waste-disposal. By using renewable materials, such as paper, cotton or starch, these problems can be overcome. This book reviews the current state-of-play in renewable-material-based chemical sensors and biosensors, and suggests applications in industry, environment and biomedicine.