A sensor is a device that converts non-electrical signals into electrical signals; it serves as a fundamental component in achieving automatic detection and control, finding widespread application in industrial and agricultural production as well as in daily life. Currently, the course "Principles and Applications of Sensors" has become a compulsory subject for majors in electronics and automatic control at institutions of higher learning, garnering increasing attention from both faculty and students. In particular, integrating sensor studies with courses on microcontrollers enables the design and construction of simple yet practical intelligent measurement and control systems; this not only stimulates student interest but also enhances their hands-on capabilities, making effective instruction in this field of significant practical importance.
Sensors come in a wide variety of types based on diverse operating principles; while it is impossible to cover every single one during instruction, explaining classic or commonly used sensors is essential. Based on their operating principles, common sensors can be categorized into several major groups, such as resistive, capacitive, inductive, thermoelectric, photoelectric, and magnetoelectric types. Regardless of the specific type, a sensor's structure generally consists of three components: the sensing element, the transduction element, and the conversion circuit. Within the same category of sensors, different functions may require different sensing elements, even if the transduction elements and conversion circuits remain identical. Therefore, instruction can focus on a detailed analysis of a specific sensor category—covering its operating principle, the selection of the sensing element, the design of the transduction element and conversion circuit, and temperature error compensation—before applying this same framework to explain other types of sensors.Take the resistive strain-gauge sensor as an example for detailed study: its sensing element is an elastic body, its transduction element is a resistive strain gauge, and its conversion circuit is a Wheatstone bridge. Furthermore, to mitigate temperature-induced errors, multiple strain gauges can be configured into a temperature-compensating bridge; this approach not only corrects for temperature errors but also enhances detection sensitivity. Subsequently, when studying capacitive and inductive sensors, one can use the resistive sensor as a model and follow the same logical progression—moving from the sensing element to the transduction element, then to the conversion circuit, and finally to error correction and compensation. This method highlights key points and strikes an appropriate balance between detail and conciseness, thereby improving efficiency and facilitating student understanding.
Many traditional sensor types date back to the 1960s and 1970s; some no longer meet the demands of modern production practices, and students often show little interest in studying them. Consequently, it is essential to expand the curriculum by introducing students to innovative sensors frequently used in real-world applications. This approach enhances the course's practicality and stimulates students' desire to explore the field. Examples include widely used PVDF piezoelectric film sensors, Hall-effect sensors, biosensors, and smart sensors. These devices not only have broad applications but also incorporate newly developed sensing materials or advanced microelectronic technologies, representing the future direction of sensor development.Multimedia teaching is characterized by a wealth of information and intuitive clarity, significantly enhancing classroom efficiency. Courses on sensors involve numerous schematic diagrams and circuit layouts; utilizing multimedia can effectively save time and expand the scope of the lesson. In particular, multimedia images and animations can vividly illustrate the physical structure and operating principles of sensors, thereby enlivening the teaching process, stimulating student interest, and improving instructional outcomes.
Although there is a wide variety of sensors, structurally they primarily consist of three components: the sensing element, the transduction element, and the signal conditioning circuit; explaining every section in this manner would likely strike students as monotonous and tedious. In teaching practice, four to six class periods can be dedicated to discussion-based learning, where students work in groups to explore the working principles, structure, and circuit design of specific sensors—as well as issues such as mitigating temperature errors, real-world applications, and the specific systems in which these sensors are utilized. This approach not only boosts student engagement but also stimulates their desire to explore the subject matter.Project-based learning involves students managing the entire lifecycle of a project under the guidance of an instructor, thereby mastering the curriculum content through hands-on experience. Since the combination of sensors and microcontrollers enables the creation of intelligent measurement and control systems, instructors can assign projects for students to complete—either individually or in groups—step by step. While much of the work is typically done outside of class hours, the successful completion of such a project ensures a clear understanding of sensor technology. For instance, students might be tasked with designing a scale capable of measuring weights up to 200 kilograms using a resistive strain gauge sensor. This project requires addressing several key stages: selecting the strain gauge, designing a suitable elastic element, creating a signal conversion circuit, amplifying the converted electrical signal, converting the analog signal to a digital one, and using a microcontroller to process the digital signal for display on a screen.
