How do temperature sensors work

We learnt about how do they work also. To buy such type of temperature sensors click here! India's biggest robotics E-commerce company. Click here to explore range of Robotics products available at Robu.

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The blog covers, how moisture sensor works and step by step guide of interfacing sensor with Arduino Your email address will not be published. Great post well explained working principle to different types of sensor available and its uses. The best i found in Non contact infrared thermometer. The cooler the temperature, lesser will be the resistance, and vice-versa. The resistance across the diode is measured and converted into readable units of temperature Fahrenheit, Celsius, Centigrade, etc.

In geotechnical monitoring field, these temperature sensors are used to measure the internal temperature of structures like bridges, dams, buildings, power plants, etc. Well, there are many types of temperature sensors, but, the most common way to categorise them is based upon the mode of connection which includes, contact and non-contact temperature sensors.

Contact sensors include thermocouples and thermistors because they are in direct contact with the object they are to measure. Whereas, the non-contact temperature sensors measure the thermal radiation released by the heat source. Such temperature meters are often used in hazardous environments like nuclear power plants or thermal power plants. In geotechnical monitoring, temperature sensors measure the heat of hydration in mass concrete structures.

They can also be used to monitor the migration of groundwater or seepage. One of the most common areas where they are used is while curing the concrete because it has to be relatively warm in order to set and cure properly.

The seasonal variations cause structural expansion or contraction thereby, changing its overall volume. The basic principle of working of the temperature sensors is the voltage across the diode terminals. If the voltage increases, the temperature also rises, followed by a voltage drop between the transistor terminals of base and emitter in a diode. Besides this, Encardio-Rite has a vibrating wire temperature sensor that works on the principle of stress change due to temperature change.

The vibrating wire temperature meter is designed on the principle that dissimilar metals have a different linear coefficient of expansion with temperature variation. It primarily consists of a magnetic, high tensile strength stretched wire, the two ends of which are fixed to any dissimilar metal in a manner that any change in temperature directly affects the tension in the wire and, thus, its natural frequency of vibration.

The dissimilar metal, in the case of the Encardio-Rite temperature meter, is aluminium Aluminum has a larger coefficient of thermal expansion than steel.

As the temperature signal is converted into frequency, the same read-out unit which is used for other vibrating wire sensors can also be used for monitoring temperature also. The change in temperature is sensed by the specially built Encardio-rite vibrating wire sensor and is converted to an electrical signal which is transmitted as a frequency to the read-out unit.

Temperature sensors are available of various types, shapes, and sizes. The two main types of temperature sensors are:. Contact Type Temperature Sensors : There are a few temperature meters that measure the degree of hotness or coolness in an object by being in direct contact with it. Such temperature sensors fall under the category contact-type.

They can be used to detect solids, liquids or gases over a wide range of temperatures. Non-Contact Type Temperature Sensors : These types of temperature meters are not in direct contact of the object rather, they measure the degree of hotness or coolness through the radiation emitted by the heat source. A thermostat is a contact type temperature sensor consisting of a bi-metallic strip made up of two dissimilar metals such as aluminium, copper, nickel, or tungsten.

Thermistors or thermally sensitive resistors are the ones that change their physical appearance when subjected to change in the temperature.

The thermistors are made up of ceramic material such as oxides of nickel, manganese or cobalt coated in glass which allows them to deform easily.

Most of the thermistors have a negative temperature coefficient NTC which means their resistance decreases with an increase in the temperature. But, there are a few thermistors that have a positive temperature coefficient PTC and, their resistance increases with a rise in the temperature.

RTDs are precise temperature sensors that are made up of high-purity conducting metals such as platinum, copper or nickel wound into a coil. The electrical resistance of an RTD changes similar to that of a thermistor. One of the most common temperature sensors includes thermocouples because of their wide temperature operating range, reliability, accuracy, simplicity, and sensitivity.

A thermocouple usually consists of two junctions of dissimilar metals, such as copper and constantan that are welded or crimped together. One of these junctions, known as the Cold junction, is kept at a specific temperature while the other one is the measuring junction, known as the Hot junction.

A thermistor is basically a sensitive temperature sensor that reacts precisely to even the minute temperature changes. It provides a huge resistance at very low temperatures. Different varieties such as handheld , pocket , and black or red-colored reading liquid are available. Another thermometer variety makes use of a bi-metal coil which is attached to a faceplate with a needle dial and graduations for the temperature reading. Each metal used in the bimetallic strip has a different thermal coefficient of expansion with temperature, which results in the coil unwinding and winding as the temperature changes.

This rotary movement positions the needle against the faceplate to reflect the current temperature reading. Infrared thermometers are non-contact electronic thermometers that display a digital reading of temperature as opposed to reading an analog scale. The devices sense the level of black body radiation emitted by the object and convert that radiation level into a reading of temperature.

The thermometer focuses the energy through a lens onto a thermopile which produces an electrical output that is proportionate to the amount of heat absorbed. Infrared thermometers can record and store values, useful to safe time and make procedures more efficient.

Infrared thermometers are used to record patient temperatures in areas such as the tympanic membrane eardrum which is too sensitive for the use of a standard contact thermometer.

They are also valuable for firefighters to use as they can sense the temperature of walls to assess how fire has spread without needing to tear the wall apart to physically inspect it or check for hot spots in a burning building. The fact that the unit can take readings on a non-contact basis means that the devices are also useful in applications where direct contact would be hazardous to personnel or equipment.

While thermometers are useful, they are limited by the fact that many models require manual operation, are slow to record and recover from a reading, are not extremely accurate, and have a limited range in temperature over which readings may be made.

In spite of these limitations, there are many different models of thermometers on the market and they find application in a variety of uses, including:. Vibrating wire temperature sensors consist of a magnetic, high tensile strength wire that is stretched between and whose ends are attached to a dissimilar metal. The tension that exists in the wire is directly impacted by temperature.

As the temperature changes, the wire tension changes, which alters the natural resonant frequency of the suspended wire. The frequency is proportional to temperature and can be used to establish the temperature of the sensor.

Vibrating wire temperature sensors are used for measuring the temperature of water, soil, and concrete structures. This article provided information on temperature sensors, including the different types, how they work, and their applications.

For information on other topics, consult our additional guides or visit the Thomas Supplier Discovery Platform where you can locate potential sources of supply for over 70, different product and service categories, including over 1, suppliers of temperature sensors. Guides Ed Edwards Share:. Melting chocolate, using a blast furnace, controlling a hot air balloon, freezing substances in a lab, running a motor vehicle, and firing a kiln. Temperature sensors come in different forms, which are used for different methods of temperature management.

There are two categories of temperature sensors which are contact and non-contact. Contact sensors are used mainly in hazardous areas. The below are contact temperature sensors:. The metal can be made of different materials including platinum, nickel, or copper.

However, platinum is the most accurate and therefore carries a higher cost. The Thermocouple is a sensor made up of two wires with two different metals connected at two points.