Scientists from the Laboratory of Ultrasound and Optoacoustic Diagnostics of the Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences have created a new highly sensitive ultrasound sensor for a more accurate study of blood vessels and blood flow. This was reported to RT in the press service of the Russian Science Front. The study is supported by the Gran Foundation. The results are published in the journal Advanced Photonics Nexus.
As the authors noted, now optoacoustic imaging systems are increasingly used for the study of living tissues - the skin sample is exposed to laser pulses, which are heated by hundredths of a degree by molecular "dyes" of blood, chromophores. As a result of heating, such molecules generate ultrasonic pulses, which are recorded by the system's sensors - hydrophones. Then, with the help of an optical microscope, an image of the vessels is formed. This method allows you to determine the boundaries of cancerous tumors, as they are always surrounded by a dense network of blood vessels.
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However, according to scientists, modern sensors that are used in optoacoustic systems have disadvantages - they are not sufficiently miniature and sensitive and cannot be integrated into a number of high-precision instruments.
In the new work, the specialists created a miniature ultrasonic sensor based on the fluorine-containing polymer PVDF-TrFE. The device weighs about a gram and is a thin needle with a sensitive polymer material at the end.
Scientists installed the sensor in the optical system of a laser scanning microscope and used it to study the vessels of the brain of laboratory mice. Images of the animals' brains obtained from the microscope were corrected on the basis of signals recorded by the sensor directly in the animal's organ. The final images turned out to be more accurate and contrasting than the original ones. According to experts, their device will be able to obtain images with a high resolution of 0.5 micrometers, which is comparable to the size of bacteria.
"The miniature sensor we have developed can be easily integrated into optical microscope systems. This can be useful in the study of the development of tumors, since it will allow you to trace in detail all the features of cancer cells, the vessels and surrounding tissues that envelop them, "Pavel Subochev, head of the laboratory of ultrasound and optoacoustic diagnostics at the Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences, told RT.
In addition, scientists compared the sensitivity of the new device with the analogue on the market based on another polymer. The sensors were placed above a container of water and determined how each of them captures the ultrasound passed through the liquid. The new hydrophone turned out to be 10 times more sensitive than its competitor.
"In the future, we plan to continue to improve the ultrasonic sensor, namely, to develop a configuration that will allow us to register acoustic waves with amplitudes of less than one pascal," said Pavel Subochev.