Grove - weather sensors

Temperature sensors - different designs, one goal

The purpose of measurements made with temperature sensors is to obtain information about the degree of cooling or heating of the object of measurement. One of the most common designs of temperature measurement sensors are thermistor sensors, which can be found in medical thermometers. A change in body temperature causes a change in the current flowing through the thermistor, whose resistance can also change. A thermistor is made of semiconductor materials that are particularly sensitive to temperature changes. The resistance of the thermistor decreases as the temperature of the object of measurement increases. Thermocouple sensors, on the other hand, use wires made from an alloy of two pieces of metal to measure temperature. The design of a thermocouple sensor uses the Seebeck effect as its operating principle. The difference in thermodynamic characteristics of metals, in which the alloy of the measuring wire is made, causes the creation of a strong potential difference, proportional to the temperature of the measuring environment. The use of a thermocouple allows for wide measuring ranges. The thermocouple sensor reads the thermoelectric voltage, which is its output signal. In infrared temperature sensors, a beam of infrared light is sent toward the measurement object and reflected back to the sensor. The signal from the IR sensor is converted into a voltage proportional to the emissivity of the object of measurement and dependent on the calibration of the sensor.

Measuring the humidity of the environment

Humidity sensors are among the most important devices that are used in home appliances, as well as in industry, medical instruments and environmental engineering. Humidity determines the water content present in the atmosphere, which affects, among other things, the well-being of living organisms, electronic devices sensitive to humid atmospheres, as well as the operation of electrical isolation systems in transformers and power lines, especially those operating at high and highest voltages. One popular design of humidity sensors, is the capacitive sensor, which measures relative humidity. They use a capacitor whose dielectric is made of a hygroscopic polymer and is sensitive to changes in humidity, which causes changes in the capacitance of the measuring capacitor. Such sensors are used, among other things, in observing changes in the frequency of electrical oscillations of an LC oscillator, when testing pharmaceutical products. The drug in the form of the test preparation acts as a dielectric, which is inserted between the measuring electrodes. The frequency of the electrical oscillator changes with the humidity surrounding the test preparation.