Ultrasonic sensors find new applications in IoT

Ultrasonic sensors have been a staple in the sensing space for several decades due to their capabilities, flexibility, and low cost. As the rise of IoT finds its way into virtually every market and industry, ultrasonic sensors have continued to find new applications in the areas of smart office, industrial and healthcare.

As a quick refresher, ultrasonic sensors function by sending out ultrasonic “chirps,” or sound waves, in the range of 23 kHz to 40 kHz, well above the human audible range of 20 kHz. These “ultrasonic” chirps bounce from nearby objects and return to the sensor. By measuring the amount of time that it takes for this send-and-receive process to occur, an object’s distance from the sensor can be calculated.

Figure 1 The above diagram shows the basic operating principle of an ultrasonic sensor. Source: CUI Devices

Ultrasonic sensors offer several benefits, including very accurate object detection. And, because they are based on sound waves and not electromagnetic waves, the color and/or transparency of an object being detected has no effect on the readings, also known as effect of material. This means that in addition to general object detection, they can also be used for liquid-level sensing or to detect glass.

Ultrasonic sensors also do not produce or require light to operate, making them well suited for applications in variable light conditions. With high refresh rates (hundreds of chirps per second), relatively small footprints and lower cost compared with other technologies, such as photoelectric, laser and inductive sensors, it becomes easy to see why ultrasonic sensors are so established.

With these basic principles and benefits in mind, we will now take a look at some ultrasonic sensor application examples in the smart office, industrial and healthcare markets.

Smart office applications

Driven by the need for safety, advancements in offerings and surging demand for sensor-based networks, Allied Market Research projects the smart-office market to reach $90 billion by 2030. Due to increased energy efficiency to support industry and local regulations, ultrasonic sensors are playing an expanded role in automating various processes around the office.

Figure 2 Ultrasonic sensors can be used for HVAC and lighting controls to turn heating and cooling equipment and lighting systems on and off using people detection. Source: Shutterstock

A prime example of this is HVAC and lighting control. Ultrasonic sensors have been employed to detect populated rooms in the office throughout the day. HVAC systems can be programmed, using this data, to heat or cool rooms that are in use or turn off the systems at night and kick back on upon first arrival.

In a similar way, ultrasonic sensors can control automatic motion lighting as people enter and leave certain rooms or areas of the office. While simple in nature, the energy savings of cutting back on HVAC and lighting in unoccupied office space offers significant cost savings when powering large office buildings. To sense objects across areas this large, an ultrasonic transceiver is ideal due to its detection range of up to 15 meters and wide beam angle of 80°.

A few other smart office applications worth mentioning are touchless building entry and hygiene devices. Ultrasonic sensors have long been utilized in automatic door entries as well as touchless hygiene products, such as soap dispensers, faucets, paper towel dispensers and waste bin lids. Due to the Covid-19 pandemic, these commonly recognized applications have seen ever-increasing demand as public health and safety became crucial for local businesses and offices.

Industrial IoT applications

Industry 4.0 and its demand for real-time analytics has led to surging growth in the industrial IoT (IIoT) market as companies look to target enhancements in manufacturing and automation. One of the main goals of utilizing IIoT is targeting inefficiencies and problems sooner to save time and money and to support business intelligence.

Edge devices, which transmit data between local networks and the cloud, are being further integrated into industrial settings for optimization of process and output. These include optimized quality control, sustainability, asset tracking, gaining efficiencies and predictive maintenance.

When it comes to ultrasonic sensors, they can be used in manufacturing processes for automated process control. By detecting an object passing through the line, an ultrasonic sensor could in turn trigger certain parts of the manufacturing process. High-speed counting and box sorting are other potential use cases for ultrasonic sensors due to their high refresh rates.

In these types of applications in which precision and a close range of detection are required, an ultrasonic transceiver with its close detectable range, aluminum housing and IP68 rating to deal with the often-harsher environmental conditions of industrial systems, is a good option.

While ultrasonic sensors are perhaps most often thought of for general object detection, as mentioned earlier, their ability to accurately detect translucent objects like water makes them well suited for liquid-level sensing applications. In this scenario, an ultrasonic sensor is mounted at the top of a chemical-holding tank to monitor fluid levels. As the ultrasonic sensor sends out its chirps, it can detect the liquid levels of the tank by measuring the amount of time it takes for the chirp to return.

As the liquid level decreases, the longer it takes for the chirp to return to the sensor, and vice versa, it gives an operator real-time data on tank fluid levels used for monitoring and reporting. Again, an ultrasonic sensor carrying an IP rating is an important consideration for this type of application.

IoT in healthcare applications

Medical IoT refers to technology that collects, analyzes, alerts, and saves medical information via many different platforms and devices, with an intention to streamline patient’s health and open more accessibility to doctors and other healthcare providers in the sharing and monitoring of a patient’s care. According to Market Research Future, the IoT healthcare market is projected to reach over $320 billion in the next five years.

Intra-office communication is highly important within a facility supplying medical procedures and patient monitoring. Ultrasonic sensors have been used in tandem with wearable communication devices to open communication lines when entering a room. This works on a similar principle as motion-activated lights, only in this case, the ultrasonic sensor detects motion and triggers the communication system.

Of course, when one hears the term “ultrasonic” in the medical field, it is easy to think of ultrasonic imaging via an ultrasound machine. Ultrasound machines create images by using both the echo time of the ultrasound wave and the Doppler shift of the reflected sound to determine the distance to the targeted internal organ and its movement.

While most ultrasonic sensors typically operate at frequencies between 23 and 40 kHz, this application benefits from high-frequency ultrasonic sensors that operate at 100 kHz and above. Although higher-frequency models have a shorter detectable range, they also have a smaller “blind zone,” or area closest to the ultrasonic sensor.

For example, CUI Devices’ CUSA-TR07-008-500-TH67 has a detection range as low as 3 cm, making it well matched for an ultrasound machine in which the device is extremely close to the object it is trying to detect.

Figure 3 Higher-frequency ultrasonic sensors have a shorter detectable range, making them suited for ultrasound machines. Source: Shutterstock

Final design considerations

When searching for ultrasonic sensors, they can be acquired as independent transmitters and receivers or as a combination of the two in a single unit, known as an ultrasonic transceiver. A designer will also need to decide between an analog or digital output as well as the beam angle.

Deciding on the appropriate beam angle will ultimately depend on the intended use of the end system. Wider beam angles are great for general object detection, where perhaps less precision is required, while narrow beam angles can avoid detecting false positives over longer distances. Other considerations include whether to select a more standard or high-frequency sensor and whether the intended operating environment might benefit from a sensor with an IP rating.

The diversity of applications for ultrasonic sensors can be attributed to their straightforward operating principle, reliability, and cost-effectiveness in a range of designs. As new markets continue to emerge in IoT, automation, robotics and more, ultrasonic sensors will remain a go-to solution when object detection and monitoring come into play.

Since joining CUI Devices in 2014, Rex Hallock has been a key member of the product management team. He has overseen various product lines over the years, including the expansion of CUI Devices’ thermal management group, which now features a range of DC fans, heat sinks, Peltier modules and thermal accessories.

<!–
googletag.cmd.push(function() { googletag.display(‘div-gpt-ad-native’); });
–>

The post Ultrasonic sensors find new applications in IoT appeared first on EDN.

Become a member

Become a member

Become a subscriber

Become a sponsor