Fabrication of low cost and low impact RH and temperature sensors for the internet of environmental-friendly things

Given the increasing number of connected devices as a consequence of the Internet of Things (IoT) revolution, the issue of the removal and recycling of electronics is becoming more and more urgent. In this context, biodegradable electronics is expected to be one of the biggest technological revolutions to tackle this problem. Following this direction, in this work we present the fabrication and characterization of temperature and humidity sensors based on biodegradable materials with the goal of making their removal easier as well as reducing their environmental impact. In particular, these multi-sensing devices were fabricated following a screen-printing process using a carbon-based paste and a conjugated polymer, both on paper and on a water soluble substrate. The results are more than promising and show how with our biodegradable sensors it is possible to obtain a sensitivity of 1 dec/20%RH to moisture content and around 0.04%/degrees C sensitivity to temperature. It is demonstrated that the simplicity and flexibility of the fabrication approach followed in this work paves the way to a set of new "green" IoT nodes that could be extended to wide range of sensing applications.