Background and objective: A common assumption made in the thermal response of biological materials due to laser irradiation is the constancy of the specific heat capacity at constant pressure, CP. In this investigation, CP of pure hydrated Type I collagen films is measured in time during laser irradiation.
Study design/materials and methods: A Nd:YAG laser scanning calorimeter is developed and used to test the constant heat capacity assumption by monitoring transient, laser-induced thermal transitions in the collagen films.
Results: Results of preliminary studies on the irreversible, laser induced thermal denaturation of collagen with heating rates of up to 110 K/sec show a broad CP transition that can attain large values (20 J/g K).
Conclusion: The magnitude of the CP change that occurs in response to laser irradiation shows that the assumption of a constant CP when modeling heat transport in tissues is not always valid.