Sensor Principles and Fundamentals
A sensor is generally defined as a device that receives and responds to a specific signal or stimulus. A stimulus refers to the quantity, property, or state that is sensed and converted into an electrical signal by the sensor.
In the broadest definition, a sensor is a device, module, machine, or subsystem capable of detecting events or changes in its environment and transmitting this information to other electronic devices (typically a computer processor).
Passive Infrared (PIR) sensors and touch sensors have been widely integrated into everyday objects, such as touch-sensitive elevator buttons (tactile sensors), lamps that adjust brightness by touching the base, and countless ubiquitous but unnoticed concealed applications. With advancements in micromachining technologies and user-friendly microcontroller platforms, sensor applications have expanded beyond the traditional domains of temperature, pressure, and flow measurement into emerging fields such as magnetic, angular rate, and gravity sensing.
Analog sensors, such as potentiometers and force-sensing resistors (FSRs), remain in widespread use today. Their applications span industrial manufacturing and machinery, aerospace, automotive, medical, robotics, and all aspects of daily life. Furthermore, a vast array of sensors is dedicated to measuring the chemical and physical properties of materials, including optical sensors for refractive index measurement, vibratory sensors for fluid viscosity measurement, and electrochemical sensors for monitoring fluid pH.
The sensitivity of a sensor characterizes the degree to which its output changes in response to a variation in the measured input quantity. For instance, if the mercury column in a thermometer moves 1 cm when the temperature changes by 1°C, its sensitivity is 1 cm/°C (assuming linear characteristics, this is intrinsically the slope of the characteristic curve, dy/dx). Some sensors can cause perturbation to the measured object during the measurement process; for example, inserting a room-temperature thermometer into a cup of hot liquid will cool the liquid while heating the thermometer itself. In engineering, sensor design is typically optimized to minimize this perturbation to the measured target. In many cases, sensor miniaturization facilitates this goal and can yield additional performance advantages.
Driven by technological progress, an increasing number of sensors can be fabricated as miniaturized devices via MEMS (Micro-Electro-Mechanical Systems) technology, commonly referred to as microsensors. In most applications, microsensors can achieve faster response times and higher sensitivity compared to macroscopic sensing schemes. Meanwhile, as modern society's demand for rapid, low-cost, and reliable information acquisition continues to grow, disposable sensors—low-cost, user-friendly sensors designed for short-term monitoring or single-use measurements—are gaining increasing prominence. Leveraging such sensors, users can acquire critical analytical measurement data anytime and anywhere, without the need for complex calibration procedures or concerns about cross-contamination.
In the broadest definition, a sensor is a device, module, machine, or subsystem capable of detecting events or changes in its environment and transmitting this information to other electronic devices (typically a computer processor).
Passive Infrared (PIR) sensors and touch sensors have been widely integrated into everyday objects, such as touch-sensitive elevator buttons (tactile sensors), lamps that adjust brightness by touching the base, and countless ubiquitous but unnoticed concealed applications. With advancements in micromachining technologies and user-friendly microcontroller platforms, sensor applications have expanded beyond the traditional domains of temperature, pressure, and flow measurement into emerging fields such as magnetic, angular rate, and gravity sensing.
Analog sensors, such as potentiometers and force-sensing resistors (FSRs), remain in widespread use today. Their applications span industrial manufacturing and machinery, aerospace, automotive, medical, robotics, and all aspects of daily life. Furthermore, a vast array of sensors is dedicated to measuring the chemical and physical properties of materials, including optical sensors for refractive index measurement, vibratory sensors for fluid viscosity measurement, and electrochemical sensors for monitoring fluid pH.
The sensitivity of a sensor characterizes the degree to which its output changes in response to a variation in the measured input quantity. For instance, if the mercury column in a thermometer moves 1 cm when the temperature changes by 1°C, its sensitivity is 1 cm/°C (assuming linear characteristics, this is intrinsically the slope of the characteristic curve, dy/dx). Some sensors can cause perturbation to the measured object during the measurement process; for example, inserting a room-temperature thermometer into a cup of hot liquid will cool the liquid while heating the thermometer itself. In engineering, sensor design is typically optimized to minimize this perturbation to the measured target. In many cases, sensor miniaturization facilitates this goal and can yield additional performance advantages.
Driven by technological progress, an increasing number of sensors can be fabricated as miniaturized devices via MEMS (Micro-Electro-Mechanical Systems) technology, commonly referred to as microsensors. In most applications, microsensors can achieve faster response times and higher sensitivity compared to macroscopic sensing schemes. Meanwhile, as modern society's demand for rapid, low-cost, and reliable information acquisition continues to grow, disposable sensors—low-cost, user-friendly sensors designed for short-term monitoring or single-use measurements—are gaining increasing prominence. Leveraging such sensors, users can acquire critical analytical measurement data anytime and anywhere, without the need for complex calibration procedures or concerns about cross-contamination.