We live in a world where every environment represents some kind of analog property, like the intensity of sunlight or the wind-blow rate. Yet technology is advancing more toward the digital side due to the ease with which digital signals can be reproduced and transmitted. For bridging the gap between these two domains, a sensor comes into play to convert these physical properties from one field to another.
Due to the recent rise of work-from-home culture, almost everyone now has a set of microphones, speakers, and webcams. While they vary in purpose, these devices are nothing but sensors that have become an essential part of our lives and impacted us significantly.
This article will brief you about sensors and a few applications in which sensor technologies play a significant role. We will also consider some of the industry-grade sensors as an example for each application, which will help you understand the technology better.
What is a sensor?
Sensors, sometimes referred to as ”transducers,” help us interact with the world around us through an electrical or a mechanical device. The technology measures or detects some property of the environment or changes to that property over time. With one of the first temperature sensors based on copper resistor developed in the late 1800s, there has been rapid advancement in sensor technologies. Nowadays, even if you look around you, you’ll see different forms of sensors everywhere. Smartphones, laptops, cars, microwave ovens — you name it, and it will probably have at least one sensor in it.
What types of sensors are there?
There are two types of sensors depending on what kind of property they record. If the sensor captures data about the environment outside the system in which it is present, it is an exteroceptive sensor. “Extero” means outside or from the surroundings, and some common examples are camera, LiDAR, radar, and ultrasonic/sonar sensors. Contrary to that, a sensor is proprioceptive if it records data about the system itself. “Proprios” means internal or one’s own, and some common examples include GPS, inertial measurement unit (IMU), and position sensors. Sensors also categorize as digital or analog based on the type of output they provide.
What is a sensor used for? Industry applications
Sensors can be used anywhere one can think of. “Sensors can improve the world through diagnostics in medical applications; improved performance of energy sources like fuel cells and batteries and solar power; improved health and safety and security for people; sensors for exploring space and the known universe; and improved environmental monitoring,” says The Electrochemical Society. Let us now look into some of the applications in which sensors play a vital role.
Manufacturing industry
With the ongoing Fourth Industrial Revolution (Industry 4.0), sensing technologies have become a core part of the manufacturing process. Sensors enable industries to monitor, control, and automate the process and increase safety. Sensors bring forth various benefits in manufacturing like improved operational efficiency, improved asset management, and more responsive product development.
The different types of sensors used for manufacturing are:
These are some of the most common in the manufacturing industry. A temperature sensor is a crucial component that measures the temperature change and allows us to monitor and control the heat flow in the process. These sensors help us by providing freeze protection in water lines by constantly tracing the heat supplied to the pipes or by limiting the heat generated in loaded electrical machines, which can be lethal, both for the device and humans, if not monitored.
Some standard temperature-sensing technologies indicate temperature according to a change in the output voltage or resistance. Infrared sensors are also employed for measuring the temperature at a large scale, as they detect temperature by intercepting a portion of emitted infrared energy of the object or substance without being in contact with the surface.
A pressure sensor is a device that measures the pressure in an environment and converts it into an electrical signal. This signal is variable voltage or current, and the range differs for different manufacturers. Potential applications include monitoring pressure in compressors, cylinder tanks, and hydraulics. They also play a pivotal role in detecting leaks in equipment, thereby helping to avoid unnecessary loss of assets.
For such purposes, the MLH08KPSB01A Industrial Pressure Sensors from Honeywell serve as a perfect example. These are heavy-duty pressure sensors that work in the range of 6 bar to 550 bar and have multiple output options, making them much more flexible and compatible with existing systems. The MLH series sensors come with application-specific integrated-circuit technology, increasing the value and performance. Together with industry-standard electrical connectors and pressure ports, they offer enhanced reliability and user flexibility.
These sensors measure the flow rate for a liquid or a gas in a tube or a pipe. Flow sensors measure changes in the fluid’s physical attributes and calculate its flow using electrical or mechanical subsystems. They are essential for applications in which the flow rate needs to be maintained (e.g., pumping fuel into IC engines). Medical industries, HVAC, and various intelligent energy applications extensively use flow sensors.
Learn about the top sensors used in smart manufacturing.
Automotive industry
According to a report by Argonne National Laboratory, the automotive sensor market is driven by increased demand for convenience, comfort, safety, efficiency, and environmental protection. With the rise in electric-vehicle technology these days, systems like autonomous driving are being implemented, relying entirely on sensors.
Some of the essential types of sensors used in the automotive industry are:
LiDAR
LiDAR sensing involves shooting light beams into the environment and measuring the reflected return to map the environment completely. LiDAR usually includes a spinning element with multiple stacked light sources and outputs a 3D point-cloud map, which is excellent for assessing scene geometry. It is an active sensor with a light source and therefore is not affected by the environment’s lighting. So LiDAR does not face the same challenges as cameras when operating in poor or variable lighting conditions.
Sometimes also referred to as ultrasonic sensors, these are used as parking assists, helping to park a vehicle safely and conveniently. Proximity sensors emit high-frequency sound pulses, which are then reflected by any obstacle near the car. The sensor receives the reflected pulse, and the time taken for the bounceback is calculated.
Prototyping such technologies before actually implementing them as a product in real life is essential, and for that, sensors like the MOD_CH101-03-01 Proximity Sensor from InvenSense are used. Its sensing distance ranges from 300 to 1,200 mm and operates at a maximum voltage of just 1.98 V. The module’s electronic interface is via a standard eight-pin flat flex cable and comes with a 45˚ field of view.
Oxygen sensors
For automotive applications, oxygen sensors evaluate the measurement of oxygen gas levels in the vehicle’s exhaust system. By comparing the oxygen concentration in exhaust gas and oxygen in the air, these sensors indirectly compute the air-fuel ratio entering the engine. Like the previous sensors we saw, oxygen sensors provide variable voltage levels as output proportional to the oxygen level. Oxygen sensor applications are not just limited to automotive but are also used immensely in medical applications.
Learn more about sensor technologies used in the modern vehicle.
AI-enabled internet of things
Thanks to recent advancements in sensor technologies, we are witnessing a new era of smart sensors. These “smart sensors” contain a base sensor along with a dedicated microprocessor that filters or processes the collected data to then provide a highly reliable output signal. By combining AI-based software with these sensors, we can perform edge computing with ease after collecting the sensor data locally. These sensors comply with various communication standards such as Wi-Fi, Bluetooth, and ZigBee, thus making its way into AIoT.
Some of the sensors used for these applications are:
Image sensors are solid-state devices that can convert photons into electrical signals for displaying or storing optical images electronically. In the IoT, these are used for remote surveillance through cameras, and when combined with AI, these cameras can detect human faces and track them as long as they are within the camera frame.
An excellent example of one such sensor is OV04686-H67A Image Sensor from OmniVision Technologies. This 1/3-inch sensor supports 1080p resolution with 120 fps and delivers best-in-class low-light and infrared performance. The OV04686 operates with a maximum voltage of 3 V and consumes 163 mA in active mode and as low as 1 mA in standby mode.
IMU sensors
IMU sensors measure the acceleration experienced by an object due to inertial forces or mechanical excitation. They usually consist of an accelerometer, a gyroscope, and sometimes a magnetometer. They provide indications of the pitch, roll, and heading of a moving system using these three sensors. IMU sensors are widely used in smartwatches and smartphones to track the user’s fitness activities and leverages IoT to display the information and statistics in a user-friendly format like charts or graphs.
The BHI260AP AI Smart Sensor from Bosch is an example of how IMU sensors are integrated with AI. This smart sensor includes a 32-bit programmable microcontroller along with a six-axis IMU, all in one package. It automatically tracks a wide variety of fitness movements and can provide relative and absolute orientation. All this is possible because of the support of a self-learning AI software platform for fitness tracking. BHI260AP operates at 1.8 V with an ultra-low power consumption of 386-μA rating.
Humidity sensors detect moisture levels in the environment. Capacitive, resistive, and thermal conductive types are some of the more common humidity sensors. They are used where controlled moisture levels are necessary, like for medical equipment, including pharmaceutical processing. Weather-monitoring systems also use these sensors for remote monitoring of humidity through IoT or other technologies.
Future of sensor technologies
As sensor applications continue to grow, so does the demand for sensors. One thing to note is that a lack of reliable sensors would cripple most automation industries. So producing high-quality sensors is essential, and with the increase in competition among manufacturers, sensors are becoming cheaper than ever before. The data collection of the physical parameters with precision will also be a deciding factor for sensors used in automation. Hence, reliability factor would be given a prior requirement for sensors, even if the cost factor increases significantly.
Additionally, advancements in AI technologies will demand a precise dataset generated from the sensors. This data will be used for training AI models for classification and regression problems, and thus, sensors will become smarter and more accurate in the future.
