Industrial Electronics

A quick look at ultrasonic sensors

04 June 2024

Ultrasonic sensors are unique devices that harness ultrasonic waves to measure distance, detect objects and analyze material properties. Their distinctive mode of operation, advantages and adaptability render them valuable in various engineering applications, from guiding robotic arms in industrial automation to enhancing automotive safety through functionalities like parking assistance and collision avoidance systems.

Given the wide range of ultrasonic sensors available today, each boasting unique technical specifications, it is important to understand the fundamentals of these devices before selecting one for a particular application.

Figure 1: Ultrasonic sensor being used for inspection on copper casting. Source: Funtay/Adobe stockFigure 1: Ultrasonic sensor being used for inspection on copper casting. Source: Funtay/Adobe stock

Working principle

Ultrasonic sensors work based on the fundamental principle of transmitting and receiving ultrasonic waves. These sensors typically feature a transmitter that emits ultrasonic waves and a receiver that detects the reflected waves. Ultrasonic sensors measure the time taken for the waves to travel to an object and back to the sensor, and this time delay is used to calculate the distance between the sensor and the object. The distance is calculated based on the speed of sound according to:

In the context of ultrasonic sensors, frequency describes the number of cycles per second of the ultrasonic waves that the sensor emits, and it is measured in hertz (Hz). Ultrasonic sensors are designed to operate at frequencies ranging between 20 kHz and several hundred kHz. The choice of frequency plays a crucial role in the characteristics and the sensor’s suitability for various applications. For instance, ultrasonic sensors that operate at high frequencies typically produce shorter wavelengths, allowing for a more precise measurement and higher resolutions. This makes them ideal for applications that require detailed detection. In contrast, sensors with lower frequencies have longer wavelengths, which generally provide less precise measurements but can cover longer distances.

[Learn more about ultrasonic sensors on GlobalSpec]

Types of ultrasonic sensors

There are several types of ultrasonic sensors, each designed for specific applications:

  1. Proximity sensors: These sensors detect the presence of an object within a certain range. They are commonly used in the manufacturing industry to detect objects on a conveyor belt or for safety applications such as collision avoidance in machinery.
  2. Distance measuring sensors: These ultrasonic sensors measure the distance to an object. They are commonly used for water level measurements in tanks, liquid level control, and in robotics for navigation and obstacle detection.
  3. Flow sensors: Ultrasonic flow meters measure the flow rate of fluids in a pipe using the Doppler effect or time-of-flight measurement. They are commonly used in chemical processing plants, HVAC systems and power generation plants.

Technical specifications and selection criteria

When selecting an ultrasonic sensor, several key parameters must be considered to ensure it meets the requirements of the specific application:

  1. Range: Describes the minimum and maximum distance the ultrasonic sensor can measure. Ultrasonic sensors with longer ranges are suitable for level measurements in large tanks, while short-range ultrasonic sensors are ideal for proximity detection.
  2. Resolution: Describes the smallest change in distance that the ultrasonic sensor can detect. High-resolution ultrasonic sensors are critical in applications that require precise measurements, such as material thickness gauging or robotics obstacle detection.
  3. Frequency: Higher frequencies offer better resolution but shorter range, while lower frequencies provide longer range but lower resolution. The choice of frequency should match the application's needs.
  4. Beam angle: Is a measure of the spread of the ultrasonic wave emitted by the sensor. Ultrasonic sensors that emit waves with a narrow beam angle are preferred for focused measurements, while wider beam angles are suitable for detecting larger areas.
  5. Environmental conditions: Ultrasonic sensors must operate reliably under varying conditions, including changes in temperature, humidity and the presence of dust or other contaminants. Some sensors are specifically designed to withstand harsh environments.

[Learn more about specifications of ultrasonic sensors on GlobalSpec]


Ultrasonic sensors are invaluable tools in modern engineering, offering a reliable, non-contact method for detecting the presence of objects and measuring distances and flow rates. Their versatility and adaptability make them suitable for a broad range of applications, including industrial automation, automotive systems and consumer electronics. However, despite the numerous advantages that ultrasonic sensors possess, their effective operation primarily depends on selecting the right sensor for the application. Therefore, it is recommended to reach out to ultrasonic sensor suppliers to discuss application requirements and learn how to effectively integrate ultrasonic sensors into specific projects.

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