Technical Insights > Benchtop

Sensor Types and Their Applications

2019-01-24  |  8 min read 

Sensors make the world go round. They are inside all the electronic devices we use at home, at work, in our cars, and practically everywhere else. Today, we cannot imagine living without our devices, and those devices are enabled by sensors.

We live in the information age where we want to know everything immediately – and we want to access information remotely via any device, anywhere, any time. For example, before I go to work each day, I use an app on my smartphone to check the weather. Before I can do that, I need to use the biometric sensor on my phone to unlock it.

There are hundreds of weather sensors – wind, humidity, and temperature sensors – at various geographic locations to determine the weather. There are sensors in my car such as the tire pressure monitoring sensors (TPMS) that ensure the tires are properly inflated, and temperature sensors to ensure the engine’s cooling system works properly. The point is that sensors are important and ever-present in our everyday lives.

What are the distinct types of sensors in the market?

There are many distinct types of sensors, and for each distinct type, there are sub-types. For example, in Figure 1, you can see a list of sensor types. A temperature sensor is a distinct type of sensor, but it has many different sub-types such as resistor temperature detector (RTD), thermocouple, and thermistor sensors. The boxes surrounding the sensor types represent key markets driving sensor usage and growth.

Sensor types and sensor markets
Figure 1: Specific sensor types and key sensor markets

What are the types of sensor applications?

Sensors permeate everything we touch in our daily lives. Figure 1 shows key markets that use sensors in applications. Below, we will look at two key markets.

Automotive

There are hundreds of sensors in our cars that we may not even be aware of. These built-in sensors provide useful information for drivers to take appropriate action. Figure 2 shows examples of some of the indicators on our car dashboards that turn on or off based on built-in sensors. For example, when the gas tank is almost empty, a yellow light indicates we are low on fuel. If the engine is too hot, a red light thermometer icon lights up. That is because there is a level and a thermometer sensor built into cars for these applications.

Vehicles are becoming more intelligent with new types of sensors that enhance environmental perception such as long-range and short-range radar sensors, 3-D vision sensors, 3-D laser sensors, ultrasonic sensors, and more.

Indicators on car dashboard using sensors
Figure 2: Some familiar indicators on your car dashboard that require sensors

Medical Devices

Biosensors, ultrasonic sensors, magnetic resonance sensors, thermal sensors, and many other kinds of sensors play important roles in monitoring and diagnosing a patient’s medical condition. Figure 3 shows a monitor that records a patient’s vital signs such as heart rate, body temperature, oxygen saturation level in the blood, blood pressure, and more.

Indicators from medical devices that require sensors
Figure 3: Vital display indicators from medical devices that require sensors

The examples of sensor applications in cars and in medical devices show just how important sensors are in our daily lives. Modern applications pose more challenges for sensors. Most products are portable and battery-powered so, sensors must not consume too much power. However, today’s applications pose more challenges for sensors and products which, while small, are growing more complicated. The small footprint means sensors are packed closely together. This poses a challenge because the sensors cannot interfere with each other or any electrical circuits.  We typically document and measure this as EMI (electromagnetic interference) or noise interference.

How important is accurate sensor testing?

The need for accurate testing of sensors depends on the application. Generally, the output of the sensors is electrical in nature such as voltage, current, resistance, or capacitance. Sensors need to be:

  • Properly characterized – temperature sensors, pressure sensors, and many types of sensors are typically not linear. They need to be properly characterized so that product designers can perform error corrections to ensure the sensors behave within specifications and with better accuracy.
  • Conditioned – this sometimes involves noise reduction, signal amplification, attenuation, low pass filtering, bandpass filtering or high pass filtering, and more. Conditioning normally comes in the form of additional electronic components at the sensors’ output and before the input of the measuring system.

To characterize your sensors, you need versatile and accurate test instruments. Versatile, because the instruments need to be able to measure many types of electrical signals such as voltage, current, resistance, and capacitance. Accurate, because you need to characterize the smallest intricate behavior of your sensors fully. In addition, the test instruments must have a wide measurement range to ensure they cover all of the sensors’ output range.

Our Solution

Keysight’s 34465A and 34470A Truevolt Series Digital Multimeters (DMMs) offer exactly what you will need for accurate sensor testing and characterization. Truevolt Series DMMs provide:

  • The versatility of up to 12 measurement functions – DC and AC Voltage, DC and AC Current, 2- and 4-wire Resistance, Frequency, Period, Capacitance, Diode test, Continuity test, and Temperature.
  • Wide measurement ranges, especially to measure low power devices, and the ability to measure very low current, 1 μA range with pA resolution, which allows you to make measurements on very low power devices.

Keysight 34470A Truevolt Digital Multimeter

Summary

This blog post explains the importance and role of sensors in our daily lives. There are many specific types of sensors that are used in various global markets. This post focuses on the automotive and medical device markets and their applications that rely on various types of sensors.

The post also described challenges for sensors with respect to application development. Two of those challenges include low power consumption requirements and product space constraints.

To find out more about Keysight’s 34460A and 34470A Truevolt series DMMs, please visit our website at www.keysight.com/find/truevolt.

To learn more before you purchase your next DMM, read 10 Things You Must Know Before Buying Your Next Benchtop Digital Multimeter.