How to make the body transparent
If human tissues were transparent, it would greatly facilitate the detection and treatment of various diseases, primarily tumors. A partial solution to this problem was proposed by scientists at the California Institute of Technology, working under the guidance of Dr. Changhuei Yang.
It is known that light scattering, which ensures the opacity of the material, is not a random process and occurs according to certain patterns. This means that the movement of light through the thickness of the tissue and the direction of its reflection from individual cells is absolutely predictable. If you pass a ray of light through the same cell complex several times, it will be scattered in the same way each time.
In addition, the described process is reversible. If individual photons scattered by the fabric are collected and sent in the opposite direction, they will follow their trajectories and return to the point of emission. The authors decided to use this phenomenon to overcome the opacity of human tissues.
The effective and reproducible technique developed as a result was called "opacity suppression by optical wavefront reversal" (turbidity suppression by optical phase conjugation, TSOPC). In demonstrating the method, the authors used a holographic crystal to record a model of scattered light passing through a 0.46 mm thick slice of chicken breast. After that, they passed a three-dimensional model of the light flux in the opposite direction and as a result received an identical beam of light to the original one. This process can be compared to an attempt to return billiard balls rolled on the table back into the frame.
The authors suggest using their technique to expand the possibilities of photodynamic therapy, which is mainly used to treat skin and mucous tumors.
Light-reflecting particles coated with antitumor drug molecules can be injected into neoplasms located in the thickness of tissues. When a beam of light passes through the fabric, photons will be reflected from light scattering particles. Part of the reflected light will return to the point of its emission, where it will be registered in the form of a hologram.
This hologram will contain information about the path by which light penetrated into the tissue, and, accordingly, about the optimal "reverse" path to light-scattering molecules and antitumor drugs. The emission of a reverse three-dimensional high-intensity light stream using a hologram activates therapeutic drugs that destroy the tumor.
In addition, the technique will minimize the size of various implants, which are currently quite large due to the built-in power supplies. A modern heart rate driver, for example, is comparable in size to a mobile phone. The authors believe that the approach they have developed will ensure effective penetration of light to miniature implants that will receive energy from photovoltaic receivers.
Article by Zahid Yaqoob et al. Optical phase conjugation for turbidity suppression in biological samples is published in the February issue of Nature Photonics.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
14.02.2008