How to choose a sensor - Solutions - Huaqiang Electronic Network

Modern sensors come in a wide variety of designs and working principles. Choosing the right sensor for a specific measurement task depends on several factors, including the object being measured, the environment, and the intended application. Once the sensor is selected, the appropriate measurement method and equipment can be determined. The overall success of the measurement process largely relies on whether the chosen sensor is suitable for the given conditions.

1. Determine the Sensor Type Based on the Measured Object and Environment

Before starting any measurement, it's essential to understand the sensor’s principle and analyze various factors that might affect its performance. Even when measuring the same physical quantity, there are multiple sensor options available. The best choice depends on specific characteristics like the measurement range, position, contact or non-contact method, signal extraction technique, and whether the sensor is domestic or imported. Additionally, cost and development capabilities should also be considered.

Once these factors are evaluated, you can identify the most suitable sensor type and then assess its detailed performance specifications.

2. Sensitivity Selection

In general, within the linear operating range of a sensor, higher sensitivity is preferable. This ensures that even small changes in the measured quantity produce a noticeable output signal, which is beneficial for signal processing. However, high sensitivity can also make the sensor more susceptible to external noise, which may be amplified by the system and reduce measurement accuracy. Therefore, the sensor must have a good signal-to-noise ratio, and external disturbances should be minimized as much as possible.

Sensitivity is directional. If the measurement involves a single vector with strict directional requirements, sensors with lower sensitivity might be better. For multi-dimensional measurements, low cross-sensitivity is important to avoid interference between different axes.

3. Frequency Response Characteristics

The frequency response of a sensor determines the range of frequencies it can accurately measure. It’s crucial that the sensor maintains an undistorted response within the required frequency range. In practice, all sensors have some delay, and the shorter the delay, the better. A higher frequency response allows the sensor to capture a wider range of signals. However, due to mechanical inertia, low-frequency sensors typically have a lower measurable frequency range.

When dealing with dynamic measurements, the sensor’s response characteristics should match the nature of the signal (steady-state, transient, random, etc.) to avoid errors caused by over-response or under-response.

4. Linear Range

The linear range refers to the input range where the sensor output is directly proportional to the input. Within this range, the sensitivity remains relatively constant. A wider linear range means a larger measurement range and better accuracy. When selecting a sensor, it's important to check if its range meets the requirements of the application.

However, no sensor is perfectly linear. The linearity is relative, and for applications with lower accuracy demands, a slightly nonlinear sensor can often be approximated as linear, making the measurement process simpler and more efficient.

5. Stability

Stability refers to the sensor’s ability to maintain consistent performance over time. While the design of the sensor itself plays a role, environmental factors such as temperature, humidity, and vibration significantly affect long-term stability. To ensure reliability, the sensor must be able to withstand these environmental challenges.

Before selection, it’s important to evaluate the working environment and choose a sensor that fits the conditions. In some cases, additional protective measures may be necessary to reduce environmental impact.

Stability is a quantifiable parameter. After a period of use, recalibration is recommended to verify that the sensor’s performance hasn’t changed. For applications requiring long-term operation without easy replacement or calibration, the sensor must meet stricter stability standards to ensure reliable performance over time.

6. Accuracy

Accuracy is a key performance metric of a sensor and directly impacts the overall accuracy of the measurement system. Higher accuracy usually comes at a higher cost. Therefore, it’s advisable to select a sensor that meets the required accuracy level of the system without unnecessary overspecification. This allows for cost-effective and simple solutions among available options.

If the measurement is for qualitative analysis, a sensor with high repeatability is sufficient. Absolute precision is not always necessary. For quantitative analysis, precise measurement values are essential, so a sensor with the appropriate accuracy level should be used.

In special cases where standard sensors don’t fit the needs, custom-designed sensors may be required. These should be developed to meet the specific performance requirements of the application.