A non-contact technique for measuring eccrine sweat gland activity using passive thermal imaging

• A non-contact methodology for monitoring active sweat glands is described.
• The methodology relies on high resolution thermal imaging of the skin.
• Respiratory exercises were used to induce discrete Skin Conductance Responses.
• Pore activity imaged on the fingers may be a useful surrogate to Skin Conductance.

An approach for monitoring eccrine sweat gland activity using high resolution Mid-Wave Infrared (MWIR) imaging (3–5 μm wave band) is described. This technique is non-contact, passive, and provides high temporal and spatial resolution. Pore activity was monitored on the face and on the volar surfaces of the distal and medial phalanges of the index and middle fingers while participants performed a series of six deep inhalation and exhalation exercises. Two metrics called the Pore Activation Index (PAI) and Pore Count (PC) were defined as size-weighted and unweighted measures of active sweat gland counts respectively. PAI transient responses on the finger tips were found to be positively correlated to Skin Conductance Responses (SCRs). PAI responses were also observed on the face, although the finger sites appeared to be more responsive. Results indicate that thermal imaging of the pore response may provide a useful, non-contact, correlate measure for electrodermal responses recorded from related sites.