Vladimir N. Kurlov (1,*), Irina A. Shikunova (1), Gleb M. Katyba (1),
Sergey N. Rossolenko (1), Nikita V. Chernomyrdin (2), Andrei A. Kuznetsov (2),
Igor V. Reshetov (3), Kirill I.Zaytsev (2,4)
(1) – Institute of Solid State Physics of RAS (Chernogolovka, Russia);
(2) – Bauman Moscow State Technical University (Moscow, Russia);
(3) –Sechenov First Moscow State Medical University (Moscow, Russia);
(4) – Prokhorov General Physics Institute of RAS (Moscow, Russia);
Sapphire has a broad transmission band spanning the UV, VIS, IR, and THz ranges of electromagnetic spectrum. Sapphire possesses high hardness, good thermal conductivity, tensile strength, and thermal shock resistance . Favorable combination of excellent optical and mechanical properties, along with high chemical inertness and resistance to human body fluids, makes sapphire an attractive material for various medical applications.Numerous technologies to growth sapphire shaped crystals directly from the Al2O3-melt exist. Among them is EFG (edge-defined film-fed growth) /Stepanov technique of shaped crystal growth [2–5].
In our research, we have proposed, developed and studied theoretically, numerically, and experimentally novel medical instruments based on EFG-grown sapphire shaped crystals, including applicators and probes for optical diagnosis, photodynamic and thermal therapy, laser surgery, cryodestruction, and resection of biological tissues [6–9].
(1) Sapphire needle capillaries have been developed to deliver laser radiation into a tumor during its interstitial laser photodynamic therapy, thermotherapy, and ablation of malignancies. These needles allow (i) increasing the volume of irradiated pathological tissue, (ii) obtaining optimal volumetric temperature distribution, and (iii) preventing the need of the device cooling during the tissue exposure. The use of such sapphire irradiators allows controlling the spatial distribution of photodynamic exposure during the entire irradiation procedure. Since the sapphire effectively redistributes the realized heat, the needles decrease the possibility of overheated nuclei formation and prevent appearance of thrombi, which are non-transparent to laser radiation.
(2) Sapphire scalpels have been developed tocombine intraoperative optical diagnosis and resection of biological tissues with laser coagulation of near-lying blood vessels. The sapphire scalpels contain capillary channels, which are closed from the side of the scalpel cutting edge. Optical fibers are introduced to the capillary channels, and this allows delivering electromagnetic radiation of optical diagnosis and laser exposure directly to the cutting-edge, as well as to detect the back-scattered electromagnetic field.The scalpel employs rapid real-time feedback analysis, which makes possible on-line differentiation of healthy and pathological tissue. Moreover, during surgery, the laser radiation is coupled directly on the scalpel edge, and this allows coagulating the blood in the area if resection using intense electromagnetic field.
(3) Sapphire neuroprobes have been developed to combine aspiration of malignant brain tissue with intraoperative optical diagnosis and laser coagulation of near-lying blood vessels. The technology was integrated into the neurosurgical workflow for intraoperative real-time identification and excision of invasive brain malignancies.
(4) Sapphire cryoapplicators have been proposed. These applicators combine laser-assisted tumor cryosurgery with laser therapy and optical diagnosis of biological tissues. In comparison with conventional copper tips, sapphire cryoapplicators intensively dissipate the heat from the contact area leading to the increase of tissue cooling rate. The latter is of great importance for devitalizing the tumor cells within the selected tissue area. Furthermore, due to sapphire transparency in wide range of electromagnetic frequencies, sapphire cryoaplicatorsallow combining cryosurgery with both laser thermotherapy and optical diagnosis of tissue, such as fluorescence spectroscopy and imaging , optical coherent tomography , terahertz pulsed spectroscopy [12-14] etc.
Thereby, sapphire shaped crystals make possible a combination tissue diagnosis, therapy, destruction, and resection in a single medical instrument by employing various physical principles.
 V.N. Kurlov. Sapphire: Properties, Growth, and Applications in: Saleem Hashmi (Ed.). Reference Module in Materials Science and Materials Engineering (Elsevier, 2016), ISBN 978-0-12-803581-8.
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Dr. Vladimir Kurlov
Institute of Solid State Physics RAS
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