Epidermal Protection: A Comparative Analysis of Sapphire Contact and Cryogen Spray Cooling

Abstract

BACKGROUND. Laser hair removal is becoming an increasingly popular alternative to traditional methods such as shaving, waxing, depilatory creams, or electrolysis. Numerous laser systems are currently available offering different methods for protecting the epidermis from thermal injury during treatment. OBJECTIVE. To analyze the effectiveness of sapphire contact and cryogen spray cooling in the context of laser hair removal. METHODS. A detailed analysis of each technique including calculations of the skin’s thermal response to each cooling method before, during, and after the treatment pulse was performed. CONCLUSION. Sapphire contact cooling is significantly more effective than cryogen spray cooling in protecting the epidermis from unwanted thermal damage during laser hair removal treatment. Calculations show that a system using sapphire contact cooling with a 30ms pulse duration is approximately two times more effective in protecting the epidermis than cryogen cooling with 3ms pulses given equal target heating. Efficient precooling of the epidermis, compression of the skin, and concurrent heat-sinking of the epidermis with a chilled sapphire window in conjunction with a longer treatment pulse duration result in superior epidermal protection. The concurrent heat-sinking of the epidermis in conjunction with a longer treatment pulse duration is the largest contributing factor reducing the temperature rise of the epidermis by over 40%. In addition to being more effective, sapphire contact cooling provides protection of the epidermis at significantly lower cost, with no risk of freezing and maximum comfort for the patient by cooling before, during, and after the treatment pulse.