Contact Burn Injuries: Analytical Assessments of Thermal Damage in a Perfused Tissue

Burn hazard from consumer electronics and wearables is growing more common as we maintain increasingly constant contact with these technologies. Trends in consumer electronics show that consumers are spending more time in contact with devices that dissipate heat. This long duration, low temperature contact with objects of relatively low thermal mass has the potential, under more severe exposure conditions, to cause thermal damage to the skin tissue. However, much of the regulatory guidance is more suited to evaluating burns sustained by short duration contact with hot objects that do not dissipate internal heat. In general, the accurate prediction of the time-temperature response of the skin tissue can be a complicated task due to complexities such as device contact area, skin geometry, skin properties, and heat transfer in the skin due to blood perfusion and metabolic heat generation. However, for most of the contact scenarios, the time-temperature response of the skin can be characterized by (1) initial time-dependent phases controlled by the object thermal mass and initial temperature followed by (2) a steady state phase that is controlled by the heat dissipation inside the device and the thermal and physiological properties of the skin. In the context of wearables or consumer electronics devices with low thermal mass, low initial temperatures and long duration exposures, the amount of energy transferred to the skin during the initial time-dependent phases can be neglected, and a preliminary hazard assessment can be conducted relying on simplified heat transfer calculations for a perfused tissue. This paper presents a number of novel closed form heat transfer solutions to simulate the behavior of a perfused tissue in contact with an object that dissipates heat.