Load cells are mainly classified into resistance strain gauge, capacitive, piezoelectric, electromagnetic, and hydraulic types. Among these, resistance strain gauge is the most widely used due to its high accuracy, moderate cost, and strong adaptability, making it widely applicable in electronic scales, weighbridges, and industrial automation.
Based on different structures and working principles, common types are as follows:
Resistance Strain Gauge Sensors: These utilize metal or semiconductor strain gauges bonded to an elastic body. When subjected to force and deformation, the resistance value changes, which is converted into a voltage signal via a Wheatstone bridge. They feature high accuracy and good stability, suitable for most static and dynamic weighing scenarios.
Capacitive Sensors: These consist of two parallel plates. The weight of the object causes a change in the distance between the plates, thus changing the capacitance. They have advantages such as low power consumption, fast response, and simple structure, making them suitable for use in harsh environments, but are susceptible to interference from distributed capacitance.
Piezoelectric Sensors: Based on the piezoelectric effect of quartz or ceramic materials, they generate an electrical charge output when subjected to force. Especially suitable for high-speed dynamic weighing, such as vehicle axle load detection and automated sorting on assembly lines, but not suitable for static measurement.
Electromagnetic force sensors achieve non-contact measurement by balancing the weight of the object being measured with electromagnetic force. Extremely high accuracy (up to 1/60000), commonly used in high-precision balances and micro-weighing equipment, but with a relatively small measuring range.
Hydraulic sensors utilize the principle of liquid pressure transmission; weight increases oil pressure, and the value is measured by a pressure gauge. Robust structure and large measuring range, but lower accuracy (generally not exceeding 1/100), mostly used in heavy industrial applications.