Editing Alcohol Sensor Based on Gas-Sensitive Resistive Materials (section)

=== Sensitivity (Concentration–Response Relationship) ===

Sensitivity describes how strongly the MQ-3 sensor responds to changes in ethanol concentration. It is a key parameter used to evaluate the performance of gas sensors.

For the MQ-3 sensor, sensitivity is typically defined using resistance-based ratios, such as 
S = R<sub>air</sub>/R<sub>gas</sub> or the normalized form R<sub>s</sub>/R<sub>0</sub>, as provided in the datasheet (see Appendix A). These definitions quantify the relative change in resistance caused by the presence of ethanol.

A higher sensitivity indicates a larger change in output signal for a given change in concentration, which improves the detectability of ethanol, especially at low concentrations.

In practical applications, sensitivity is used as a primary metric to compare sensor performance and to determine the usable detection range. It also directly affects calibration accuracy and measurement resolution.