gh Z-THERMISTORS – A NEW WORD IN THERMODIAGNOSIS

The one who walked in a forest in July, cursing clouds of attacking mosquitoes, at least once thought about a surprising ability of these small creatures to find from afar “hot dinners”, i.e., warm-blooded objects that are warmer than the environment. Indeed, what ingenious natural heat-sensing devices they are! However, it took millions of years – entire biological epochs - to create these outstanding “devices”. Researchers from the V.A. Trapeznikov Institute of Information Problems, Russian Academy of Sciences, have spent much less time on creation of temperature sensors - Z-thermistors. But thermistors also function excellently. They enable to produce for example temperature regulators, temperature predetermined value signalling devices, and sensors for oncological disease thermodiagnosis.

The most important element of Z- thermistor, its “core” is the semiconductor n-p structure, silicon with minor inclusions of other elements atoms. The authors do not disclose the specific composition, technology and structure configuration, although the thermistor per se has been patented practically all over the world, i.e., in Europe, China, America and certainly Russia.

The point is that this structure (depending on the temperature) is able to change from one state (with low current) to a different (also stable) state with the current that is dozens of times higher. It is rather easy to set the temperature at which such thermoelement will work (the structure will pass from one state to another) – to this end, the element supply voltage should be changed. That is why thermistors are also called tunable temperature predetermined value signalling devices. It means that if you change supply voltage – the temperature threshold will also change, at which the current step takes place. And it is sufficient to simply record the current step, i.e., the power hit, which is the output signal, since the step’s amplitude without amplification is rather high – up to 80% of the feeding voltage value. And one more thing is important, there is no need for additional device for output signal amplification.

It is also important that the temperature interval, which can be controlled with the help of thermistors, is rather big, varying from minus forty to plus one hundred and twenty degrees centigrade. So, the thermistor field of application is indeed rather wide – these can be temperature predetermined value signaling devices for heating systems of living quarters, production or storage facilities, passenger or airplane compartments, engines, brake-gear, fire alarm, various hotbeds and greenhouses – the list can go on for ever. This does not mean of course that all these objects managed without heat-sensing devices so far. Z-sensors are such sensitive elements that exceed all temperature sensors (known in the world practice) in terms of technical capabilities (simplicity of the device and management, sensitivity, compactness, and finally, universality, cost and economy).

As per oncological disease thermodiagnosis, thermistors may become the basis for a device that is simplier and cheaper than the already known thermal imagers. The latter discover at a distance the areas of higher temperature on the patient’s body surface, judging by change of infrared signal. It has been known since 1950 that the body surface temperature is slightly higher above the area of neoplasms – it is higher approximately by 0.5-1.5 degrees centigrade. But thermal imagers are very expensive devices and very complicated in operations (although simpler modifications already appear). Thermistors enable to solve the same problem (to reveal the sections of increased temperature on the body surface near the mammary and thyroid glands area) no less efficiently but much cheaper. Besides, this can be performed independently, without consulting the polyclinic. However, the patient will have to pass the sensor over the body – the device will function by the “contact method”. But interferences and atmospheric blur will be avoided. Due to their diminutiveness and safety (compare them with glass thermometers), these thermistors may be also used for other medical purposes, for example, for endoscopic research or temperature monitoring for children and seriously ill patients. It is sufficient to stick the sensor to the require area, and the audible or electric signal will be received at the physician control panel in case of increased temperature.

Precision of temperature measuring, low power intensity, unique functional capabilities, compact size open up wide prospects for utilization of such thermistors in all spheres of human vital functions.

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