What are thermistors? Thermistors are special resistors that react to temperature changes. When you ask, “What are thermistors?” the answer is that their resistance shifts as the temperature shifts, making them highly sensitive. Because of this, thermistors are excellent for monitoring temperature in a wide range of devices. The global market for thermistors is projected to reach $922.49 million by 2025, showing steady growth each year.

Companies like Focusens, a leader in temperature sensing solutions, have contributed to this growth by providing high-precision thermistors for use in automotive, medical, and consumer electronics. Whether you're designing a smart device or a clinical thermometer, Focusens thermistors help you achieve accurate, real-time temperature monitoring.

NTC and PTC thermistors play a key role in modern technology. NTC thermistors respond quickly to even small temperature changes, while PTC thermistors help protect circuits. So, what are thermistors used for? They are essential for measuring temperature in electronics, automobiles, and medical equipment.

Key Takeaways

· What are thermistors? Thermistors are special resistors. They change resistance when temperature changes. This makes them fast and accurate temperature sensors.

· There are two main types. NTC thermistors lower resistance as temperature goes up. PTC thermistors increase resistance as temperature rises. PTC thermistors also act as resettable fuses.

· Thermistors are used in electronics, cars, and medical devices. They help monitor and control temperature. This keeps things safe and efficient.

· Thermistors are better than other sensors in some ways. They are very sensitive and respond quickly. They are small and do not cost much. But they work best in moderate temperatures.

· You must pick the right thermistor for your needs. Think about speed, sensitivity, or circuit protection when choosing.

What Are Thermistors?

Definition
What are thermistors? They are parts that change resistance when temperature changes. Thermistors are a kind of temperature sensor. They use special materials to sense even small temperature changes. If someone asks, "What are thermistors?", you can say they are resistors that react to temperature. These parts help check and control temperature in many things we use. Engineers like thermistors because they work fast and give correct results.

There are two main types of thermistors: NTC and PTC. NTC thermistors have less resistance when it gets hotter. PTC thermistors have more resistance as it gets warmer. Both types are important in electronics, cars, and medical tools.

Key Features

What are thermistors? Thermistors are different from other temperature sensors because of their special features. Here are some important things about them:

Thermistors do not change resistance at the same rate as temperature changes. Their resistance changes in a way that can be predicted with math. This helps thermistors measure temperature very well in their range.

What Are Thermistors? Some main features of thermistors are:

They are very sensitive to small temperature changes.

They react quickly, which is good for safety and medical uses.

They stay stable, especially when covered in glass.

They work in a medium temperature range, from -50°C to 250°C.

They are small, so they fit in tiny devices.

Tip: Engineers pick thermistors for jobs that need fast and correct temperature checks, like fire alarms, digital thermometers, and car engines. Focusens, for example, offers miniaturized NTC thermistors ideal for wearable medical devices and smart home systems.

Materials

What are thermistors made of? It depends on the type. Makers use different things for NTC and PTC thermistors to give them special traits.

NTC thermistors use metal oxides like manganese, nickel, copper, iron, and titanium. These are mixed and heated to make a strong sensor. This makes NTC thermistors very sensitive and quick to react. PTC thermistors use things like barium titanate or doped silicon. These let the thermistor act like a fuse to keep circuits safe from heat.High-end manufacturers like Focusens optimize their material formulas to ensure high durability and consistency across extreme applications.

Some thermistors use ceramics like aluminum oxide or zirconium dioxide. These help the thermistor last in tough or hot places. Glass can also cover thermistors. It keeps out water and chemicals, so the thermistor works well in wet or harsh spots.

Glass-covered thermistors work in wet or harsh places. The glass keeps out water and chemicals, so the sensor stays correct and steady.

Epoxy coatings cost less and are good for most indoor uses, but they do not protect as well as glass in hard places.

Note: The material picked changes how well the thermistor works in different places. For example, glass-covered thermistors are best for wet or chemical-filled spots, like car engines or medical tools.

What are thermistors used for? Their materials and build make them great for many uses. They check temperature in home gadgets, cars, and medical tools. Their small size and quick reaction help keep things safe and working well.

How They Work

Resistance and Temperature

Thermistors change resistance when temperature changes. This helps them sense heat or cold in many things. The way resistance and temperature connect is not always simple. If the temperature changes a little, resistance can change almost in a straight line. If the temperature changes a lot, the connection gets tricky and needs special math.

Here is a table that shows how engineers talk about this:

NTC thermistors lose resistance when it gets hotter. PTC thermistors gain resistance when it gets hotter. The exact numbers depend on what they are made of and how they are built.

Note: The Steinhart–Hart equation helps engineers get very exact temperature readings from thermistors, even if the connection is not a straight line.

Sensing Principle

What Are Thermistors? Thermistors sense temperature because their materials react to heat. Most thermistors use metal oxide semiconductors. When temperature changes, the number of charge carriers in the material changes. This change affects how easily electricity moves through the thermistor.

NTC thermistors have less resistance when it gets hotter.

PTC thermistors have more resistance when it gets hotter.

The resistance change happens because the atoms in the material move differently with heat.

The thermistor does not measure temperature directly. It changes resistance, and a circuit reads this change.

Electronic devices use simple circuits, like voltage dividers, to check the resistance of a thermistor. The device then figures out the temperature from the resistance. This way, products can sense temperature quickly and correctly.

Thermistors turn temperature changes into electrical signals. This makes them important for safety, comfort, and control in today’s technology.

 Types

NTC Thermistors

NTC thermistors are important in electronics today. Their resistance goes down when temperature goes up. This helps them sense temperature changes fast and correctly. Makers use metal oxides like manganese, nickel, and cobalt to make NTC thermistors. These materials let the thermistor react quickly to small temperature changes.

NTC thermistors are found in many things. Engineers use them to sense temperature in ovens, fridges, and air conditioners. Medical tools like digital thermometers and incubators also use NTC thermistors for exact readings. In power supplies and car sensors, NTC thermistors help keep circuits steady by adjusting for temperature changes. They also protect electronics by limiting inrush current when turning on and by checking for overheating.

Tip: NTC thermistors are best for jobs that need quick and correct temperature checks.

PTC Thermistors

PTC thermistors work in a different way. Their resistance goes up a lot when the temperature gets high enough. Makers use special ceramics like barium titanate to make PTC thermistors. This material changes at a certain temperature, making the resistance jump.

PTC thermistors are often used as resettable fuses in electronics. If too much current flows, the thermistor heats up and its resistance rises fast. This stops too much current and keeps the circuit safe. When the device cools down, the thermistor goes back to normal and lets current flow again. PTC thermistors are found in lighting ballasts, TV circuits, telecom gear, and motor protection. Their reset feature makes them good for using over and over.

Differences

NTC thermistors are great for checking temperature right away and making quick fixes.

PTC thermistors give self-resetting protection from too much current and help control heat.

NTC thermistors use metal oxides, but PTC thermistors use ceramic stuff.

PTC thermistors act like fuses that reset, but NTC thermistors do not.

NTC and PTC thermistors both have special uses. Picking the right one depends on what the job needs, like speed, sensitivity, or protection.

Applications

Focusens' products are widely used in various fields, such as:

Electronics

What are thermistors? Thermistors are important in today’s electronics. Many gadgets use thermistors to sense temperature and protect circuits. Laptops and smartphones use thermistors to watch battery temperature. This stops batteries from getting too hot and helps them last longer. Power supplies and chargers use thermistors to slow down big currents when turning on. This keeps small parts safe from sudden power jumps.

What are thermistors? Thermistors keep electronics safe by reacting fast to heat changes.

Smart home devices, like thermostats and air conditioners, use thermistors for correct temperature readings. This helps the system change heating or cooling for comfort and to save energy. Many IoT devices use thermistors, but designers must solve problems like tricky resistance and keeping sensor data safe.

Automotive

Cars need thermistors for exact temperature control. NTC thermistors check oil and coolant temperatures in engines. Their resistance goes down as it gets hotter, so the car’s computer can see changes fast. This helps control how the engine works and stops it from getting too hot.

Thermistors are also in climate control systems. They check air temperature inside and outside the car, helping adjust heating and cooling for comfort. Engineers often use voltage divider circuits with thermistors. These circuits turn resistance changes into signals for the car’s control units.

Thermistors are accurate, quick, and not expensive. These things make them great for cars, where being reliable is very important.

Medical

Medical tools use thermistors for patient care and equipment safety. In patient checks, thermistors watch body temperature very closely. Wearable monitors and probes use thermistors to find fever or sudden body heat changes.

Thermistors also help control temperature in incubators, ventilators, and dialysis machines. Their steady and correct readings help keep medical care safe and effective.

FAQ

What is the main difference between NTC and PTC thermistors?

NTC thermistors have less resistance when it gets hotter. PTC thermistors have more resistance as temperature goes up. Engineers pick NTC thermistors to sense temperature. They use PTC thermistors to keep circuits safe.

Can thermistors measure extreme temperatures?

Thermistors work best in the middle temperature range. They usually work from -50°C to 250°C. For very hot or very cold places, engineers use thermocouples or RTDs.

How do thermistors help in everyday electronics?

Thermistors watch and control temperature in many devices. Laptops, fridges, and air conditioners use them. They keep batteries and circuits safe by reacting fast to heat.

Are thermistors reusable after overheating?

PTC thermistors can work again after they cool down. They act like fuses that reset themselves. NTC thermistors will not work again if too much heat breaks them.

How accurate are thermistors compared to other sensors?

Thermistors, especially those from Focusens, are very accurate (±0.1°C) and react faster than most alternatives.

In Summary

So, what are thermistors? They are precise, small, and responsive components that turn temperature changes into readable electrical signals. As of 2025, modern companies like Focusens are leading the way with innovative thermistor designs that support electric vehicles, smart homes, and medical wearables.

To learn more about “what are thermistors”, please visit our website at focusensing.com and contact us today! We will provide you with a customized solution!