Scientists from Tomsk Polytechnic University and Saratov State University teamed up with colleagues from Taiwan and proposed to make a laser 'blade' for a medical scalpel with a specified curved shape using a photonic 'hook'.
Currently there are laser scalpels only with an axisymmetric focus area, i.e., with a cylindrical blade. According to scientists, changing the shape of the blade will expand the possibilities of using the laser in medicine, while it is about two times thinner than the cylindrical option.
The concept and its rationale are published in the Journal of Biophotonics (IF: 3.032; Q1).
A laser scalpel is a surgical instrument used to cut or remove biological tissues by using laser energy. In a limited area of tissue the beam sharply raises the temperature up to 400 °C, thus making the irradiated area to burn out instantly.
This way, the laser immediately 'seals' small blood vessels along the edges of an incision. The laser scalpel makes very thin incisions, reduces bleeding, and the radiation itself is absolutely sterile.
A conventional surgical scalpel has a variety of blade shapes to suit specific applications. Laser scalpels do not have such a variety, or rather, there is only one form of radiation localization - axisymmetric. Therefore, we proposed a simple way to make the tip shape curved using a photonic 'hook'. This is a new type of curved self-accelerating light beam, shaped like a hook. Earlier, we theoretically predicted and experimentally confirmed the existence of such a 'hook'."
Igor Minin, Project Manager and Professor, Department of Electronic Engineering, Tomsk Polytechnic University
An indispensable element of a laser scalpel is the fiber for transmitting laser energy. At its end, a focused laser beam of several wavelengths is formed. With its help, the surgeon performs all necessary manipulations.
"To bend the laser beam, we proposed one of the simplest possible solutions: place an amplitude or phase mask at the end of the fiber. It is a thin plate made of metal or a dielectric material like glass.
The mask redistributes the energy flow inside the fiber and forms a curved region of radiation localization at the end of the fiber, that is, a photonic 'hook'.
Through simulation, a curved blade is proved to have a length of up to 3 millimeters and a thickness of about 500 microns (100 microns is the thickness of a human hair - ed.), with a wavelength to be 1,550 nanometers.
In other words, we add one small element, without affecting the general design and performance of the device, and get changes in the area of the fiber end alone (at the tip).
The shape and thickness of the blade is changing: it is approximately two times thinner than the axisymmetric option," Igor Minin explains.
In the article, the scientists provided a theoretical basis for the concept, and now they are preparing to confirm it experimentally at National Yang-Ming University (Taiwan).
Minin, I. V., et al. (2020) Concept of photonic hook scalpel generated by shaped fiber tip with asymmetric radiation. Journal of Biophotonics. doi.org/10.1002/jbio.202000342.