Researchers present paper-based temperature and humidity sensors that are accurate, reliable, and eco-friendly. The team created the sensors by printing silver lines on commercially available paper through dry additive nanomanufacturing. As the paper absorbs water vapor, its capacitance change is measured to reflect the relative humidity of the environment, and as the temperature increases, the metallic conductor experiences an increase in resistivity. They successfully detected changes in relative humidity levels from 20% to 90% and temperature variations from 25 C to 50 C.