SU1550395A1 - Heating electrolytic converter of gas humidity - Google Patents

Abstract

This invention relates to a measurement technique, namely to hygrometry. The purpose of the invention is to improve the measurement accuracy and simplify the design of the electrolytic heating converter for the humidity of gases. The converter is formed on a dielectric substrate, on one side of which there is a film heater, made in the form of a meander of a material with a high temperature coefficient of resistance and having conclusions from the central part. An electrode is inserted into the central part of the heater. Above the heater and the electrode are dielectric and moisture-sensitive layers. The central part of the heater performs the functions of the second electrode. 3 il.

Description

The invention relates to a measuring technique, namely to electrolytic heated humidity sensors, and can be used in various areas of the national economy.

The purpose of the invention is to improve the accuracy of humidity measurements and simplify the design of the converter.

Figure 1 shows the design of a heated electrolytic moisture converter for gases; figure 2 - section aa in figure 1; FIG. 3 is a converter connection circuit.

The converter is formed on a dielectric substrate 1 of sapphire with dimensions of 0.2x3x3 mm. On the substrate

ke is located film heater 2 in the form of a meander 200 μm wide with taps 3 from its middle part. The middle part of the heater, located in the central part of the substrate, is a film thermistor. One of the electrodes is a heater. Another electrode 4 is located between the terminals 5 of the thermistor and is installed parallel to the first electrode. Conclusions 5 of gold wire with a diameter of 30 μm using conductive paste 6 on the basis of palladium and silver are connected to contact pads 7. A layer of dielectric from silicon dioxide thickness SLR

about

OO

WITH

ate

"SS &,

0.5 µm thick, above which a moisture-sensitive layer 9 is located, which is an aqueous solution of lithium chloride wetting the oxide

Figure 2 shows a converter wiring diagram. The power supply 10 is connected to the terminals of the heater 5. The current through the heater is monitored by an ammeter 1 1. An electrode 13 through a resistor 12 is connected to a generator 13 at a frequency of 1 kHz and a voltage of 1 V. The voltage at the electrode is measured with an AC voltmeter 14. The voltage at the leads to the central part of the heater is measured by a voltmeter 15.

Heated electrolytic converter of humidity of gases works as follows.

In the case where the temperature of the transducer is insufficient to dry the moisture sensitive layer 9, its resistance and voltage on electrode 4 is low. When the voltage on the heater rises, its temperature rises and at the moment the partial pressure of water vapor of the moisture sensitive substance and the measured medium reaches the surface of the moisture sensitive layer 9, water evaporates, leading to a sharp increase in its resistance and voltage on the electrode 4. The temperature of the converter at this moment is a measure of the humidity of the environment. Temperature moisture sensitive

five

0

five

0

five

This region is determined by a thermistor, the function of which is performed by the middle part of the heater.

The resistance of the moisture sensitive layer 9 is measured by a circuit consisting of a generator 13, a resistor 12, an alternating current voltmeter 14 and a circuit between electrode 4 and heater 2. The equivalent circuit of this circuit can be represented as a series connection of two capacitors, one of the plates of which electrode 4 or heater 2 and the other is the moisture sensitive layer 9, and the resistance of the moisture sensitive layer 9.

Claims (1)

Invention Formula A heated electrolytic moisture content converter for gases, consisting of a dielectric substrate, film heaters, made in the form of a square wave, a thermistor and two parallel-installed electrodes, over which a moisture-sensitive layer is located, characterized in that the thermistor is used the middle part of the heater located in the central part of the substrate, one of the electrodes is the heater, and the other is It can be between the terminals of the thermistor, between the electrodes and the moisture-sensitive layer a dielectric layer is applied. / BUT, 1 FIG. 2 ten Di fi, g. B