Heat flux measurement system for assessing peripheral vascular function during cold provocation

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Peripheral vascular function is important for the early detection and monitoring of vibration-related disorders, such as vibration-induced white finger, yet standardized cold-provocation assessments often rely on bulky or operator-dependent methods. We present a compact heat-flux measurement system that quantifies conductive heat exchange between the fingertip and a temperature-controlled surface while monitoring contact force, a key confounder of fingertip heat transfer. A thermoelectric cooler imposes a controlled boundary temperature, and an integrated force sensor supports repeatable contact conditions. Metrological characterization under controlled conditions shows measurement variability consistent with the heat flux sensor specification. Recordings in healthy volunteers exhibit a reproducible transient well captured by a double-exponential model and reach steady state after approximately 70 s. In a comparative validation study conducted in healthy subjects, local cooling to 10 °C induced a significant reduction in finger blood flow measured by strain-gauge venous-occlusion plethysmography. Consistently, mixed-effects modeling showed that, in the total sample (n = 20, obs = 98), each 1 ml/100 ml/s increase in finger blood flow was associated with a 39.6 mW increase in mean thermal power (robust standard error 7.52, p < 0.0001 ) after adjustment for covariates. The R-squared measures showed that the proportion of the total thermal power variance explained by all predictors via fixed slopes and random slope variation was 0.57, and the whole model explained about 68% of the variability in the measured thermal power. Overall, these findings support the feasibility of heat flux-based descriptors for tracking perfusion-related changes during cold provocation in healthy individuals. The present study does not establish diagnostic utility or discrimination between healthy and pathological subjects, and further evaluation in larger cohorts, including individuals with vibration-induced white finger or Raynaud-type disorders, is required.

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