Method and apparatus for measuring the heat transfer coefficient during cryogen spray cooling of tissue

A method of controlling temperature profiles of tissue subjected to cycles of cooling and heating, where said tissue is skin having a stratum corneum and epidermis, said tissue junction being an interface between said stratum corneum and epidermis, comprising:

• cooling said tissue;
• and
• heating said tissue,
• where cooling said tissue comprises controlling cooling of said tissue according to an effective heat transfer coefficient between a cooling agent at said surface of said skin and said interface between said stratum corneum and epidermis,
• where cooling is controllable by an amount of cooling applied to said skin,
• where cooling said skin according to said heat transfer coefficient comprises varying said amount of cooling according to distance from said surface of said skin to said interface between said stratum corneum and epidermis, and
• where cooling said tissue is controlled according to a heat transfer coefficient is based on determining said heat transfer coefficient using a thermally conductive metal target mounted in an insulating substrate as a standard which is exposed to said cooling.