The impulse of life: devices made of new ceramics will break kidney stones in nanoseconds

Russian specialists, as part of an international scientific team, have created a new material for energy storage capacitors capable of quickly releasing it in the form of powerful electrical impulses. The development may find application in portable medical equipment, for example, in devices for the destruction of stones in internal organs and emergency cardiac stimulation. In addition, the material is of interest to the space engine industry. The experts interviewed by "Izvestia" noted the prospects of developing for import substitution, but stressed that the material would have to be tested before being used in real devices.

How ceramic materials store electricity

Scientists at Yaroslav the Wise Novgorod State University, together with colleagues from Slovenia, Turkey, Belarus and China, have created a new ceramic material for supercapacitors, devices capable of storing energy and quickly releasing it in the form of short powerful pulses.

The development is characterized by increased energy consumption and resistance to breakdown — destruction of the material under the influence of a strong electric field. This opens up the possibility to create compact, high-power discharge medical devices. In particular, the material can be used in lithotriptors — installations for the destruction of kidney stones using nanosecond pulses — and defibrillators that restore a normal heart rhythm using an electric discharge.

— In capacitors, the ceramic layer is located between two metal surfaces. The peculiarity of the new material lies in small changes in its atomic structure, as a result of which some positions, usually occupied by oxygen atoms, remain vacant. These "voids" allow you to store more energy than the original composition. At the same time, the material can withstand a much stronger electric field," Viktor Leontiev, director of the Scientific Research Center for Semiconductor Materials Science at the Polytechnic Institute of NovSU, told "Izvestia".

According to him, this modification increased the energy intensity of the material by about a third. It can withstand an electric field of up to 45 kV/mm and is capable of returning up to 86% of the stored energy. Due to the combination of these characteristics, the new ceramics can be used to develop compact pulse devices.

— The ability to release energy quickly is particularly useful for creating short nanosecond pulses used to break down kidney stones. In such equipment, the capacitor first accumulates a large amount of energy, and then releases it almost instantly. An electric pulse passes through the coil, a magnetic field arises, which sharply repels the thin membrane and creates a pressure wave," explained Viktor Leontiev.

The material can also be used to create more compact and powerful defibrillators, the scientist noted. The main advantage of the development lies in the high density of energy storage — a large amount of it, which can be stored per unit volume of the storage device.

In the future, the new ceramics may find application in pulsed plasma engines of spacecraft. In such installations, the energy of an electric discharge is used to accelerate plasma, a gas containing charged particles. Its release creates jet thrust. High energy storage density will reduce the mass and volume of storage devices on board satellites and thereby increase the share of payload.

In addition, the material is of interest for pulsed space engines, radars, railguns, lasers and other similar equipment.

— At the same time, different devices need different pulses — in terms of energy, duration and frequency of repetition. These requirements determine the design of the drives and the test program. Therefore, in the short term, it is necessary to make sure that the material can be obtained with the same characteristics from batch to batch," said Viktor Leontiev.

The next step will be to create capacitors with a given capacity. To do this, it will be necessary to form many thin layers of ceramics separated by metal contacts, the scientist said.

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In the future, researchers will have to figure out how long the drives will be able to operate at rated voltage, withstand repeated discharges, heating, cooling and other effects. At the final stage, the prototypes will be assembled as part of a full-fledged system with energy sources, switches and control electronics, after which it will be tested in its entirety. Then it will require real-world testing, certification and access to operation.

"Modern lithotriptors are already capable of producing short, powerful pulses, so the value of the new development lies in the ability to make the energy source more compact and efficient. The new material demonstrates such properties," Albert Rizvanov, head of the Center for Excellence "Personalized Medicine" at Kazan (Volga Region) Federal University, commented on the development.

At the same time, the main limitation of the development lies in the fact that the properties of the material itself, rather than the finished medical device, have so far been demonstrated, the expert noted. The obtained characteristics will have to be confirmed in a real capacitor with multiple pulses and long-term operation. Precision and safety of energy dosing are especially important for medical equipment. Therefore, the next stage should be the creation of prototypes and their testing as part of specific devices.

— During the operation of such equipment, high currents and voltages sometimes occur, which causes leads that have to be dealt with. In addition, electrical parameters may exceed the usual nominal values, and these problems also need to be addressed," said Alexey Karfidov, Head of the Department of Technological Equipment Engineering at NUST MISIS.

According to him, lithotriptors, for example, were mass-produced in the USSR, when there were strong domestic scientific and engineering schools in this field. Therefore, the development of such technologies is relevant today from the point of view of import substitution. However, for the practical implementation of new materials, it is necessary to jointly work out their use with enterprises that design and manufacture such equipment.

— Film capacitors are currently used in space pulse engines. They are specially designed to work with high discharge currents," said Svyatoslav Gordeev, Associate professor of the Department "Aviation, Rocket Engines and Power Plants", a leading engineer at the Moscow Aviation Institute.

Ceramic capacitors allow you to store the same amount of energy with a smaller size and weight. However, based on operational experience, they can also break through, the expert noted.