A basic resistive pressure sensor is a type of transducer used to measure and convert pressure into an electrical signal. It works on the principle of changing resistance in response to applied pressure. Here's how it functions:
Sensing Element: The core of the pressure sensor is a sensing element, typically made of a resistive material such as a strain gauge or piezoresistive material. These materials exhibit changes in resistance when subjected to mechanical deformation, such as pressure.
Wheatstone Bridge Circuit: The resistive sensing element is incorporated into a Wheatstone bridge circuit, which is a configuration of four resistors arranged in a diamond shape. The bridge circuit is used to measure the change in resistance of the sensing element due to pressure.
Excitation Voltage: A constant voltage is applied across the Wheatstone bridge circuit. This voltage serves as the excitation voltage, ensuring that the circuit is energized and ready to measure pressure changes.
Pressure Application: When pressure is applied to the sensing element (e.g., through a diaphragm or other means), it undergoes mechanical deformation. This deformation causes a change in the resistance of the sensing element.
Resistance Change: The change in resistance alters the balance of the Wheatstone bridge circuit, resulting in an output voltage that is proportional to the applied pressure.
Output Signal: The output voltage from the Wheatstone bridge is measured and converted into a usable form, usually an electrical signal (e.g., 0-5V, 4-20mA) that can be easily processed by control systems, microcontrollers, or data acquisition systems.
Calibration: Before the resistive pressure sensor is used in applications, it must be calibrated to provide accurate and precise pressure measurements. Calibration involves relating the sensor's output signal to the actual applied pressure using known standards.
Resistive pressure sensors are commonly used in various applications such as automotive systems, industrial automation, aerospace, medical devices, and consumer electronics. However, it's worth noting that while they are simple and cost-effective, their accuracy and performance may not be as high as more advanced pressure sensing technologies like capacitive or piezoelectric sensors.