The Evolution Sensors and Actuators

Over the years sensors and actuators play a crucial role in the world of industrial automation. They transformed the manual processes into highly efficient, automated systems. This is the run down of their history and evolution and how they are integral the automation industry.

A Tale of Two Components

What are Sensors?

A sensor is an electrical instrument that monitors and measures physical aspects of an environment and then sends an electrical signal to a control center when it detects pre-determined conditions. On the most basic level, sensors turn physical inputs into electrical signals that are output to the control center. Sensors can be used to monitor the health of equipment and status of a sensitive environment. One example is a sensor that can alert temperature changes to an operator if a unit gets too hot.

What are Actuators?

In contrast, actuators take electrical signals from control modules and turn them into physical outputs. They can perform a wide range of functions, from turning rotors and valves to virtually anything else. You can program them to control almost any physical action. An example of an actuator is a shutoff valve. When it receives a signal from a sensor or control module, it closes the valve. The actuator receives the input of an electrical signal and turns it into a physical action. 

The History of Sensors and Actuators

Both sensors and and actuators have their roots going as far back as the early 20th century. Basic switches and relays served as the first primitive forms of automation. These simple devices were used to detect changes in physical properties, such as temperature, pressure, and position, and to initiate mechanical actions accordingly. While this technology had very limited functionality at the time, they paved the way for the future of automation.

Pneumatic Actuators

In the early stages of automation, pneumatic actuators dominated the landscape due to their simplicity and reliability. Compressed air was used to control mechanical movements, making them ideal for industrial applications. However, the advent of electric actuators brought about a significant shift. Electric actuators, driven by motors, offered finer control, quieter operation, and the ability to integrate with digital control systems.

Sensors at the Turn of the Century

By the mid-20th century, sensors experienced a revolutionary transformation. Devices like thermocouples, strain gauges, and pressure sensors emerged, enabled precise measurements and real-time data acquisition. The integration of these sensors into industrial processes improved process control laying the foundation for more sophisticated automation systems.

Microprocessors Take the Stage

The introduction of microprocessors and microcontrollers in the 1970s and 1980s marked a turning point in sensor and actuator technology. These tiny computational devices allowed for on-board processing, enabling sensors to not only gather data but also interpret and transmit it intelligently. Smart sensors emerged, capable of self-calibration, data filtering, and communication with other devices, making them indispensable for complex automation tasks.

Sensors and Actuators Evolve

Integrating PLC’s

The 1980s brought sensors and actuators closer to the heart of industrial automation with the widespread adoption of PLCs. PLCs acted as the brain of automation systems, receiving input from sensors, processing it, and triggering actions through actuators. This integration simplified automation programming and allowed for more extensive and flexible control over industrial processes.

Internet Networking

The rise of the internet and networking technologies allowed sensors and actuators to communicate on a broader scale. Fieldbus protocols and industrial communication standards, such as Modbus, Profibus, and Ethernet/IP, facilitated seamless data exchange between devices and supervisory systems. This enhanced connectivity allowed for remote monitoring, predictive maintenance, and real-time process optimization.


From the simplicity of basic switches to the intelligence of smart devices, sensors and actuators continue to play a vital role in shaping the world of industrial automation. We can expect sensors and actuators to become even more integrated, intelligent, and indispensable, driving the industry towards unprecedented levels of efficiency and automation.

Updated on July 29, 2023 by Ken Cheng

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