Detecting $\sim$10 mK Face Temperature Change Based on Lock-in Thermography Referencing Heartbeat

TL;DR

This paper introduces a method using lock-in thermography referencing heartbeat signals to detect very small face temperature changes of about 10 mK with standard thermal cameras, aiding non-contact health monitoring.

Contribution

The study presents a novel approach combining lock-in thermography with heartbeat referencing to accurately measure minute facial temperature variations.

Findings

Able to detect ~10 mK temperature changes on the forehead

Stable measurement of body temperature variation achieved

Potential application in non-contact emotion estimation

Abstract

Infrared thermography, which has widely spread particularly during the COVID-19 period, has been effectively used for research on health monitoring and emotion estimation. Nevertheless, detecting minute temperature changes with thermography is challenging as it is disturbed by not only noise but also outside temperature surrounding the object. In this study, we demonstrate detecting face temperature variation by implementing lock-in thermography using heartbeat signals as a reference. It allows us to detect minute temperature changes, as low as $\sim$10 mK, on the forehead with a commercially available thermal camera. The proposed approach enables stable measurement of body temperature variation, showing potential for non-contact emotion estimation.