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20.06.2022

How do temperature sensors work? They are devises to measure temperature readings through electrical signals. The Medical Temperature Sensor is made up of two metals, which generate electrical voltage or resistance once it notices a change in temperature. The temperature sensor plays a critical role in maintaining a specific temperature within any equipment used to make anything from medicine to beer. To produce these types of content, the accuracy and responsiveness of the temperature and temperature control are critical to ensuring the end product is perfect. Temperature is the most common physical measurement type in industrial applications. Accurate measurements are vital in ensuring the success of these processes. There are many applications that are not-so-obvious, which use temperature sensors. Melting chocolate, using a blast furnace, controlling a hot air balloon, freezing substances in a lab, running a motor vehicle, and firing a kiln.


The below contact temperature sensors:

A thermometer is generally what we think of when we think of temperature – particularly the mercury-filled glass tube. However, there are several types of thermometers available: Glass Thermometer: as above mercury/ ethanol glass tube. Ethanol is now the main liquid used in these thermometers.

Bi-Metal Thermometer: this thermometer type consists of a connected gauge and stem. The tip of the sensor has a spring that is attached to a rod, leading up to the gauge needle. The spring sits inside the stems sensing the end. When heat is applied to the sensing coil, movement in the coil is created which causes the needle in the gauge to move – thus displaying the temperature.

Gas-filled & Liquid Thermometer: These thermometers are similar in terms of how they work. There is a bulb either filled with gas or liquid. This is situated inside the sensing end of the probe. When heated, the gas expands/liquid heats up which signals the attached rod to move the needle to the temperature being measured.

Digital Thermometer: A digital thermometer uses a probe such as a thermocouple or a resistance temperature detector (RTD). The temperature is measured using the probe (sensing end) and displayed as a digital reading.


The below is a Non-contact temperature sensor

Infrared sensors determine temperatures from a distance, by measuring the thermal radiation emitted by an object or heat source. The applications for these are often in high temperatures or hazardous environments where you need to maintain a safe distance away from a particular body. ; Thermal imaging and infrared sensors are the most common type of non-contact temperature sensors, and are used in the following circumstances: Fever detection or when the target object is moving (such as on a conveyor belt or within moving machinery), if it’s a great distance away if there’s a dangerous surrounding environment (such as high voltages) or at extremely high temperatures where a contact sensor would not function appropriately.


What is a Thermistor and how does it work?
Thermistors are a type of semiconductor, meaning they have greater resistance than conducting materials, but lower resistance than insulating materials. The relationship between a thermistor’s temperature and its resistance is highly dependent upon the materials from which it’s composed. The manufacturer typically determines this property with a high degree of accuracy, as this is the primary characteristic of interest to thermistor buyers. ;

Thermistors are made up of metallic oxides, binders and stabilizers, pressed into wafers and then cut to chip size, left in disc form, or made into another shape. The precise ratio of the composite materials governs their resistance/temperature “curve.” ;

Thermistors are available in two types: those with Negative Temperature Coefficients (NTC thermistors) and those with Positive Temperature Coefficients (PTC thermistors). NTC thermistors’ resistance decreases as their temperature increases, while PTC thermistors’ resistance increases as their temperature increases. Only NTC thermistors are commonly used in temperature measurement. ;

Thermistors are composed of materials with known resistance. As the temperature increases, an NTC thermistor’s resistance will increase in a non-linear fashion, following a particular “curve.” The shape of this resistance vs. temperature curve is determined by the properties of the materials that make up the thermistor. ;

Thermistors are often selected for applications where ruggedness, reliability, and stability are important. They’re well suited for use in environments with extreme conditions, or where electronic noise is present. They’re available in a variety of shapes: the ideal shape for a particular application depends on whether the thermistor will be surface-mounted or embedded in a system, and on the type of material being measured. ;


Using Epoxy to Protect NTC Thermistors
An Epoxy Bead NTC Thermistor temperature sensor appears as a tear-drop-shaped bead with two radial wire leads. Very often these types of NTC thermistor temperature sensors are used with applications in proximity to moisture. Some of these applications include medical devices that measure the airflow and air temperature. Epoxy bead thermistors are also frequently used in automotive applications to monitor and control air conditioning and seat warming for passenger cabins.

It is critical that NTC thermistors are protected from direct exposure to fluids, such as water or oil. To accomplish this, thermally conductive epoxy is used as an encapsulant, called “potting,” to seal the NTC thermistor temperature sensors in a stainless steel housing. This epoxy not only protects the NTC sensor from moisture but enables good thermal conduction from the medium being measured to the thermistor sensor. The thermally conductive epoxy provides operating effectiveness without degradation.


Thin Film NTC Thermistor
NTC thermistorThermal Component Technologies has released a new Thin Film NTC Thermistor. The Thin Film Type NTC Thermistor is frequently used for applications where space is a concern and the standard design is not thin enough. A typical thickness of 0.55mm offers the solution engineers have been looking for. They are an ideal choice for precise temperature measurement between flat surfaces where quick time response is critical. The thermistor chip is loaded between 2 conductors and then sandwiched with polyimide insulation. This provides excellent moisture resistance, along with flexibility. All the usual benefits of thermistors where sensitivity to temperature change is paramount.


Applications Thin Flim NTC Thermistor

where this type will suit is in the medical industry such as blood bag temperature monitoring for refrigerated storage. Small battery packs will also demand this type where space is particularly limited and a quick response is needed to prevent heating during charging cycles. The surface temperature of pipes can also be monitored using thin-film technology.


GLASS TYPE B - GLASS-COATED BEAD
Thermometrics Type B Glass Bead NTC Thermistors consist of glass-coated bead thermistors on fine diameter platinum alloy lead wires. The special thin glass coatings provide a hermetic seal making these thermistors unaffected by severe environmental exposures. They are suitable for most low-cost temperature measurement, control, and compensation, such as self-heated applications, including liquid level sensing and gas flow measurement.

Features

Fast thermal response times

Special thin glass coating provides a hermetic seal

Unaffected by severe environmental exposures, including nuclear radiation

The intermittent operation to 600°C


Temperature Sensor Types
A temperature sensor is a device that detects and measures hotness and coolness and converts it into an electrical signal. At TE Connectivity (TE), we design and manufacture a broad portfolio of temperature sensors – including our NTC thermistors, RTDs, thermocouples, and thermopiles – designed for efficiency and easy installation, ; with the capacity to reliably integrate technology that responds to human behavior.

In HVAC/R systems, our digital temperature sensors help monitor industrial heating and cooling systems and control smart thermostats while thermocouples provide feedback to boiler controls in the home. In commercial aircraft, our NTC thermistors measure air and gas temperature, in a miniature and lightweight design that save space in small systems. In household stoves and appliances, our platinum temperature sensor can help amateur chefs prepare a meal perfectly – and ensure they store it safely. In microwave ovens, our thermopile sensors can measure temperature without making contact with food. ;

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