Resistive Sensors: Advantages and Disadvantages

This page covers the basics of resistive sensors, highlighting their advantages and disadvantages.

What is a Resistive Sensor?

A sensor is an electronic component, module, or subsystem that detects events or changes in its environment and sends information to other electronics, such as microcontrollers (µC) or microprocessors (µP). Resistive sensors are a type of sensor that detects changes in resistance. These changes are monitored and used to perform specific tasks.

Resistance, measured in Ohms, quantifies how a device or material reduces the flow of current.

The figure depicts different sensors available in the market which use different factors in order to detect their resistance.

Common types of resistive sensors include:

• Photoresistor: Detects the presence of light, infrared (IR), and/or ultraviolet (UV) energy. Its resistance changes based on brightness levels or the presence/absence of light.
• Thermistor: Its resistance depends on temperature. Thermistors are made of semiconductor material and exhibit a significant resistance change relative to temperature changes.
• Flex Sensor: Measures the amount of deflection or bending. When attached to a surface, its resistance changes based on the surface’s bending.
• RTDs (Resistive Temperature Detectors): Used to measure temperature. Many RTDs consist of a fine wire wrapped around a ceramic or glass core. They operate on the principle that a metal’s resistance increases with temperature and vice versa.
• Strain Gauge: A thin film with a metal pattern that changes resistance when strained.
• Piezoresistive Element: Pressure on the element causes material to compress and change its resistance.

Benefits or Advantages of Resistive Sensors

Here’s a look at the good side of using resistive sensors:

• Simple Construction: They are relatively easy to manufacture.
• Durable: Resistive sensors tend to be robust and long-lasting.
• Good Dynamic Range: They can accurately measure over a wide range of resistance values.
• Low Noise: Resistive sensors typically produce minimal electrical noise.
• Low Cost: They are generally inexpensive compared to other types of sensors.
• Sensitive: They can detect even small changes in resistance.

Drawbacks or Disadvantages of Resistive Sensors

Like any technology, resistive sensors also have some downsides:

• Non-Linear Response: The relationship between the measured quantity and the resistance change is often non-linear.
• Hysteresis Characteristic: They may exhibit hysteresis, meaning the resistance value depends on the history of the applied quantity.
• Lower Sensitivity: Compared to some other sensor types, their sensitivity can be limited in certain applications.
• High Power Consumption: Some resistive sensors can consume a significant amount of power.
• Usually Detects Single Contact Point: This is relevant in resistive touch screen applications.