Substance concentration analysis methods and apparatuses

A substance concentration analysis apparatus comprising:

• a housing;
• at least one MIR detector attached to the housing;
• a heating and/or cooling element attached to the housing;
• and
• a controller configured to control the MIR detector and the heating and/or cooling element, the controller storing instructions that, when executed by the controller, cause the controller to initiate operations including:
• inducing a change in a temperature (T) of a surface of a body over time (t) by heating or cooling with the element according to a signal received by the element, then allowing temperature recovery of the surface and yielding a function for temperature (T) that varies with time (t) during the temperature recovery so as to exhibit a temperature derivative with respect to time (dT/dt);
• measuring the temperature (T) of the surface of the body over time (t) during the temperature recovery and calculating the dT/dt;
• measuring mid-infrared (MIR) radiation absorbed by or emitted from the body during the temperature recovery while the surface of the body exhibits the dT/dt;
• calculating a measured value based on the MIR radiation measurement and on the dT/dt;
• and
• calculating the concentration of the substance in the body based on a correlation with the measured value.