####### Journal 14: 218–223 Journal 14: 218–223 of Cosmetic and Laser Therapy,

## ORIGINAL RESEARCH REPORT

# Fractional vaporization of tissue with an oscillatory array Ex vivo of high temperature rods – Part I: study

MONICA FOURNIER3 SLATKINE4 MONICA FOURNIER3 SLATKINE4 NATHALIE & MICHAEL

#### GARY

1UCLA 2Beit 3CLDP, Medical School, Los Angeles, CA, USA, Harofim, Holon, Israel, Clapier, France, 4Nova-B and Ltd., Hadera, Israel

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Abstract (~0.1–5 Short pulse duration milliseconds) CO2 lasers are perceived as excellent tools for vaporization of Background: craters arrays in fractional skin resurfacing. To present a thermo-mechanical ablation technology, which affects Objectives: tissue identically to fractional CO2 lasers, however at a fraction of the size and cost of a laser. The Material and methods: 400°C new technology is based on heating an oscillating array of thin metallic rods to a temperature of and advancing the rods into tissue down to a precise pre-selected depth for a duration of 0.1–5 milliseconds. As a result, an array of crater is vaporized with identical properties of those produced by CO2 lasers. An test was performed with a thermo- ex vivo metallic rod array prototype. Arrays of 10 10 vaporized micro-craters of 350 micron diameter, 200 micron depth Results: × have been produced with lateral thermal damage of 80 micron while thermal damage below craters was 80–250 micron. (350–400°C) A resonating thermo-mechanical array of high temperature rods is capable of producing an array Conclusions: of craters identical to those produced with pulsed CO2 lasers.

Key Words: skin resurfacing, CO2 lasers, fractional, wrinkles

## Introduction

100–150 micron collateral damage, are the vaporiza- J/cm3 ~3000 tion energy of tissue which is (4) and the beam penetration in tissue (30–50 micron). In the vaporization process, temperature craters produced ~350° by a single pass laser beam attain C (5). Since thermal energy is responsible for tissue vaporization, we may expect that by bringing a metal- ~350° lic element of temperature C in contact with ~0.1–5 the skin for a duration of less than millisec- ~50–250 onds and depth micron, a clinical ablative effect which is identical to the CO2 laser effect will occur. However, such extremely fast and accurate 350° thermo-mechanical procedure with a C array enclosed in a small size comfortable handpiece requires very specific geometrical, mechanical and thermal design, which has recently been developed in our laboratory. The objective of the current article is to describe the general design principles a the new ‘ThermiXel’ thermo-mechanical technology, which acts identically to a short pulse CO2 laser and can be used in a variety of surgical applications including fractional skin resurfacing. The advantage of the

Short pulse CO2 lasers are generally considered among the best tools for high precision ablation of thin layers of tissue without bleeding and with mini- mal collateral damage (1). They are widely utilized in skin resurfacing, including fractional skin resurfacing (2,3). By operating a 10.6 micron CO2 laser with J/cm2 ~5 energy density above a threshold of and pulse duration below few milliseconds (0.1–5 milli- seconds), vaporization rate is faster than thermal dif- fusion into tissue and collateral thermal necrosis is ~100–150 micron. With only 30–50 micron penetra- tion of the 10.6 micron wavelength laser beam into tissue, it is possible to vaporize craters arrays of skin down to or deeper than the papillary dermis and achieve excellent skin resurfacing results. With an ~100–500 array of micron focused beam spots, frac- ~12–20% tional resurfacing of of the skin surface ensures fast healing. The energy responsible for the vaporization of tissue with a CO2 laser is purely ther- mal. The tissue parameters, which quantitatively dic- tate the threshold energy for vaporization with only

Correspondence: Gary Lask, MD, UCLA Medical School, Dermatology, 200 UCLA Medical Plaza, Los Angeles, CA, United States. E-mail: micslatk@ zahav.net.il

(Received 18 October 2011; accepted 5 May 2012)

ISSN 1476-4172 print/ISSN 1476-4180 online © 2012 Informa UK, Ltd. DOI: 10.3109/14764172.2012.698284