Formula & Calculator
Sensor Sensitivity
Quantifies how much a sensor's output changes for a given change in the measured input quantity.
Interpretation
Sensor sensitivity S = Δoutput / Δinput is the change in sensor output per unit change in the measured quantity.
Higher sensitivity gives better resolution and smaller detectable changes.
Example: A thermocouple with S=40µV/°C gives 40µV output for every 1°C change.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| S | Sensor sensitivity | (Output unit)/(Input unit) |
| ΔOutput | Change in output signal | V, mV, mA, Ω, etc. |
| ΔInput | Change in input measurand | °C, kPa, kg, mm, Gauss, etc. |
What it means
Sensor sensitivity S is the change in output per unit change in the measured physical quantity. It is defined as S = Δoutput / Δinput. Higher sensitivity means the sensor can detect smaller changes, providing better resolution. Sensitivity is often specified in the sensor’s datasheet. For example, a thermocouple has sensitivity in µV/°C; a strain gauge has sensitivity in terms of GF; a pressure transducer may have sensitivity in mV/psi. Sensitivity is usually linear over the operating range, but non‑linearities may require calibration. Example: A temperature sensor with sensitivity 10 mV/°C produces 10mV output for every 1°C change. If the output changes by 50mV, the temperature change is 5°C. Understanding sensitivity helps in selecting a sensor for a given measurement range and accuracy.
Worked example
Sensor Sensitivity – Practical Example
Real‑World| Parameter | Value |
|---|---|
| ΔOutput | 10 mV |
| ΔInput | 1 °C |
| Formula | S = ΔOutput / ΔInput |
Common mistakes
Watch unit consistency and the assumptions behind the formula; misapplying it outside its valid conditions is the most frequent error.Applications
Sensor sensitivity S = Δoutput/Δinput is the change in sensor output per unit of measured quantity. It determines the resolution and signal‑to‑noise ratio. Engineers use it to select sensors for applications, to calibrate measurement systems, and to compare sensor performance. Higher sensitivity gives better detection but may also increase noise. This is a fundamental sensor parameter.
- Sensor selection and specification
- Calibration and uncertainty analysis
- Measurement system design and optimisation
- Performance comparison of sensors
- Educational understanding of sensor characteristics
Frequently Asked Questions
Sensitivity is the ratio of change in output signal to change in input measured quantity: S = Δoutput / Δinput. It indicates how responsive the sensor is.
The units depend on the sensor. For example, a pressure sensor might have mV/kPa; a temperature sensor might have mV/°C; a photodiode might have A/W.
Higher sensitivity means a larger output change for a given input change, which can improve resolution (if the noise level is low). However, sensitivity alone does not determine resolution; noise and linearity also matter.
Common errors: 1) confusing sensitivity with accuracy, 2) using the wrong units, 3) ignoring the effect of temperature on sensitivity (temperature coefficient), 4) applying sensitivity outside the linear range.
Apply known input changes and record the output change; the slope of the calibration curve gives the sensitivity.
When choosing a sensor for a measurement, a higher sensitivity may be desirable to amplify the signal, but it may also amplify noise. A trade‑off exists.
Sensitivity is the ratio of output change to input change; resolution is the smallest detectable change in the input. Resolution depends on noise and sensitivity.
If the sensor is non‑linear, the sensitivity may vary with the input level. Often, an average sensitivity is specified over the operating range.