LAUSR

Thermometers are essential sensing devices for applications ranging from health monitoring to emergency management and industrial quality control. Despite their widespread use, the COVID‐19 pandemic highlighted the need for low‐cost, continuous, user‐friendly, and reusable temperature sensors for symptoms detection and infection control. This presents here lightweight (m < 1 g), power‐free, reusable, and paper‐based temperature sensing interfaces that use biomaterial‐based thermochromic inks. These inks, screen‐printed onto various surfaces, undergo a visible color change with temperature shifts and can be paired with machine learning for continuous monitoring at a resolution of ΔT = 0.1 °C. Their affordability and adaptability to large, uneven surfaces make them a cost‐effective alternative to thermal cameras for visualizing temperature distribution on a large scale.