Summary: ICLASS-2006
Aug.27-Sept.1, 2006, Kyoto, Japan
1. INTRODUCTION
Laser dermatological surgery (LDS) is the treatment of
choice for vascular lesions (e.g., hemangiomas [1] and Port
Wine Stain (PWS) [2] birthmarks) as well as aesthetic
purpose (e.g., hair [3] and tattoo [4] removal). For these
conditions, cryogen spray cooling (CSC) is an essential
auxiliary method that protects the epidermis from excessive
thermal damage during laser irradiation, while the target,
such as PWS blood vessels located 100­500 µm below the
skin surface [5] are thermally photocoagulated. The only
cryogen used for this purpose thus far, approved by the
FDA [3], is Tetrafluoroethane-1,1,1,2 (R134a), with a
boiling temperature of -26 o
C at atmospheric pressure.
Short cryogen spurts (20­100 ms) [6, 7] are released from a
pressurized container through a spray valve/nozzle system.
Well-atomized cryogen droplets with diameters of 3­20 µm
[8] and velocities 10­60 m/s [9] impact onto human skin

Source: Aguilar, Guillermo - Department of Mechanical Engineering, University of California at Riverside

Collections: Engineering