6 Key Factors for Sensor Selection: Type, Sensitivity, Stability…

6 Core Sensor Selection Factors: Explained in One Article

Modern sensors vary greatly in principle and structure. How to reasonably select sensors according to the specific purpose of measurement, the measurement object, and the measurement environment, is the first problem to be solved in measurement. When the sensor is determined, the matching measurement method and measurement equipment can also be determined. The success or failure of the measurement results, to a large extent, depends on whether the sensor selection is reasonable.

01/Starting with Sensor Principle
Based on the measurement object and the measurement environment, to determine the type of sensor for a specific measurement, the first consideration is the principle of the sensor to be used. This requires analyzing a number of factors before making a decision. Because, even for measuring the same physical quantity, there are various principles of sensors that can be selected. To determine which principle of the sensor is more appropriate, it is necessary to consider the following specific issues based on the characteristics of the sensor and the conditions of use: the range size; the volume requirements of the sensor at the measured position; whether the measurement is contact or non-contact; the source of the sensor, whether domestic or imported, affordable, or self-developed. After considering the above issues, one will be able to determine what type of sensor to use, and then consider the specific performance indicators of the sensor.

02/Choice of Sensitivity
Usually, within the linear range of the sensor, it is desirable for the sensor's sensitivity to be as high as possible. Because only when the sensitivity is high, and the change in the measured value corresponds to a relatively large change in the output signal, is it conducive to signal processing. However, it should be noted that a high sensor sensitivity also makes it easy for unrelated external noise to mix in, which will also be amplified by the amplification system, affecting measurement accuracy. Therefore, the sensor itself should have a high signal-to-noise ratio to minimize the introduction of interference signals from the outside world. The sensitivity of the sensor is directional. When the measurement is of a unidirectional quantity with high directional requirements, then the sensor should have a small sensitivity in the other direction; if the measurement is of a multi-dimensional vector, then the sensor is required to have a sensitivity that is as small as possible.

03/Response Characteristics (Response Time)
The frequency response characteristics of the sensor determine the frequency range to be measured. It must be maintained within the allowable frequency range without distortion of the measurement conditions. In fact, there is always a delay in the response of the sensor - a certain amount of delay. It is desirable for the delay time to be as short as possible. A high sensor frequency response allows for a wider measurable signal frequency range. However, due to the impact of structural characteristics, the mechanical system's inertia is large, so the lower the frequency of the sensor, the lower the measurable signal frequency. In dynamic measurements, the response characteristics should be based on the characteristics of the signal (steady state, transient, random, etc.) to avoid producing overshoot errors.

04/Linear Range
The linear range of the sensor is the range in which the output is proportional to the input. In theory, within this range, the sensitivity maintains a fixed value. The wider the linear range of the sensor, the larger the measurable range, and it can ensure a certain degree of measurement accuracy. When selecting sensors, once the type of sensor is determined, the first thing to check is whether the range meets the requirements. But in fact, no sensor can guarantee absolute linearity; its linearity is relative. When the required measurement accuracy is relatively low, within a certain range, the nonlinear error of the sensor can be approximated as linear, which will bring great convenience to the measurement.

05/Stability
The ability of a sensor to maintain its performance over a period of time without changing is called stability. Factors affecting the long-term stability of the sensor, in addition to the structure of the sensor itself, are mainly the environment in which the sensor is used. Therefore, to make the sensor have good stability, it must have a strong ability to adapt to the environment. Before selecting the sensor, the use environment should be investigated, and the right sensor should be chosen based on the specific use environment, or appropriate measures should be taken to reduce the impact of the environment. There are quantitative indicators of sensor stability. After being used for a period of time, the sensor should be recalibrated to determine whether its performance has changed. In some applications where the sensor must be used for a long time and cannot be easily replaced or calibrated, the stability requirements for the selected sensor are more stringent, to be able to withstand a long period of use.

06/Precision
Accuracy is an important performance indicator of the sensor, and it is an important part of the entire measurement system related to measurement accuracy. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor should only be as high as required to meet the precision demands of the entire measurement system, and it is not necessary to choose too high an accuracy. In this way, it is possible to choose a cheaper and simpler sensor among the many sensors that meet the same measurement purpose. If the purpose of the measurement is qualitative analysis, the choice of sensor repeatability can be high, and the absolute value of high precision should not be chosen; if it is for quantitative analysis, and accurate measured values are needed, then a sensor with an accuracy level that meets the requirements must be chosen. For some special occasions where the right sensor cannot be chosen, one needs to design and manufacture their own sensors. The performance of homemade sensors should meet the requirements of use.

Warm Reminder
There’s no need to blindly pursue "maxed-out parameters" when choosing a sensor: it’s sufficient for the accuracy to match the measurement system—no need for excessive expense. For stability, you must consider the usage environment in advance; for scenarios like humid or high-temperature conditions, prioritize selecting environment-resistant models. During dynamic measurement, don’t forget to match the sensor’s response characteristics based on signal characteristics (e.g., transient or steady-state) to avoid the issue of excessive errors too!

If you need more specific sensor selection advice (e.g., for specific scenarios like industrial testing or environmental monitoring), feel free to leave a comment with your usage scenario. We will specifically break down the corresponding selection tips for everyone later!