Some aspects of this disclosure involve head-mounted systems that are utilized to take thermal measurements of a user's face to detect various physiological responses, such as an allergic reaction, stress, a headache, a stroke, to name a few. Typically, these systems involve one or more head-mounted thermal cameras that may be physically coupled to a frame worn on the user's head and are utilized to take thermal measurements of one or more regions of interest (ROIs). Some of the systems described in this disclosure are intended for "real world", uncontrolled day-to-day use, in which detection of the physiological response may be hampered by "confounding factors". A confounding factor can be a cause of warming and/or cooling of certain ROIs the face, which is unrelated to a physiological response being detected, and as such, can reduce the accuracy of the detection of the physiological response.
Collecting thermal measurements of various regions on a user's face can have many health-related (and other) applications. However, movements of the user and/or of the user's head can make acquiring this data difficult with many of the known approaches. Some embodiments described herein utilize various combinations of head-mounted thermal cameras, which may be physically coupled to a frame of a head-mounted system (HMS), in order to collect the thermal measurements. In one embodiment, the thermal measurements are utilized by a computer to detect a physiological response such as stress, an allergic reaction, a headache, a stroke, or an expression of a certain emotion (e.g., joy, fear, sadness, or anger).
Described herein are various embodiments of wearable systems that collect thermal measurements related to respiration and/or brain activity. The systems may optionally include a frame that is worn on a user's head, and at least one non-contact thermal camera that is physically coupled to the frame and located close to the user's face. In one embodiment, each thermal camera takes thermal measurements of at least one of: a portion of the right side of the user's upper lip, a portion of the left side of the user's upper lip, and a portion of the user's mouth. The thermal measurements used by a computer to calculate breathing related parameters, such as breathing rate, an extent to which the breathing was done through the mouth/nostrils, and ratio between exhaling and inhaling durations. In another embodiment, a thermal camera takes measurements of the forehead, which are indicative of brain activity of the user.