Gallery of images.

Laser poration of skin

There is a whole industry of topical drug delivery using topical patches. Also, there are a variety of transdermal approaches to pharmacological testing of interstitial fluid, blood solutes, and blood gases. Both these two tasks, delivery and collection, are impeded by the stratum corneum, the thin but tough outer sheath of protein and lipid which protects our bodies from dessiciation and prevents insult or attack from the environment.

Lasers offer a means to perforate the stratum corneum thereby opening the door for delivery and collection of compounds.

References on laser poration include:

• S. L. Jacques, D. J. McAuliffe, I. H. Blank, J. A. Parrish, "Controlled removal of human stratum corneum by pulsed laser," Journal of Investigative Dermatology,88, 88- 93 (1987).
• Patent 4775361: Controlled removal of human stratum corneum by pulsed laser to enhance percutaneous transport. Inventors: Steven L. Jacques, Daniel J. McAuliffe, Irvin H. Blank, John A. Parrish, ISSUED: Oct. 4, 1988, FILED: Apr. 10, 1986. patent
• J. S. Nelson, J. L. McCullough, T. C. Glenn, W. H. Wright, L. H. Liaw, S. L. Jacques, "Mid-infrared laser ablation of stratum corneum enhances in vitro percutaneous transport of drugs," Journal of Investigative Dermatology,97, 874- 9 (1991).
• S. L. Jacques, F. E. Ejeckam, F. K. Tittel, "How micro is microdissection? Laser removal of stratum corneum of skin to expose the epidermal battery," SPIE Proceedings of Laser- Tissue Interaction IV, edited by S. L. Jacques, A. Katzir, 1882, 23-33 (1993).
• Patent 5643252: Laser perforator. Inventors: Milton Waner, Stephen T. Flock, Charles H. Vestal, ISSUED: July 1, 1997,FILED: Sep. 24, 1993. patent

A histologic section of guinea pig skin showing a laser micropore about 300 um wide in the stratum corneum, created with a pulsed ArF excimer laser. The stratum corneum was swollen by NaOH exposure to better visualize the stratum corneum, and this exposure caused some artifactual damage in the epidermis. CLICK HERE to expand figure.

Laser poration using the ArF excimer laser. The first work on laser poration of skin used the ArF (argon-fluoride) excimer laser which operates at 193 nm wavelength (very short ultraviolet) with a 14-ns pulse duration. The strong absorption of the ultraviolet laser radiation by the protein of the stratum corneum allowed as little as 0.25 um ± 10% of tissue to be removed per pulse. In other words, the laser acted like an ultrafine milling machine. About 80 pulses would create a pore in the ~15-um-thick stratum corneum. Later work used the erbium:YAG laser operating at 2.9 um wavelength which is strongly absorbed by tissue water.

Wellman Labs, Massachusetts General Hospital Steven L. Jacques, Daniel J. McAuliffe, Shinichi Watanabe, Thomas Flotte

A cross section of skin comparing a standard lancet for drawing blood with a laser micropore (see small superficial hole in the insert) for sampling interstitial fluid. CLICK HERE to expand figure.	Laser poration vs standard lancet for glucose monitoring Glucose testing requires a blood sample obtained with a standard lancet. SpectRx Inc. is developing an alternative laser poration system for sampling interstitial fluid for glucose determination.
SpectRx Inc., Norcross, GA link

A pore in the skin created by laser poration (~200 um dia.).	Interstitial fluid accumulating in pore.	Laser poration of human skin. These images from the SpectRx website illustrate interstitial fluid accumulation in a pore created by their laser poration system.
SpectRx Inc., Norcross, GA link