Additional thermodynamic feature extraction from chemoresistive carbon black-polymer composite sensors by temperature modulation

Chemoresistive responses of four different carbon black-polymer composite sensors were measured with varying a sensor temperature upon exposure to volatile organic compounds (VOCs). A new thermodynamic response was extracted from the temperature dependence of the chemoresistive responses. The thermodynamic parameter was determined by the standard enthalpy energy change during the sensing processes. It mainly reflected non-specific physical interactions between the composite materials and the analyte vapors rather than analyte-specific interactions. In order to prove its capability as a feature parameter in pattern recognition programs, principal component analyses were performed by using both the chemoresistive and the thermodynamic responses simultaneously. The resultant outcome clearly demonstrated that the use of the additional thermodynamic feature improved the classification capability between VOC classes due to the correction of the deteriorations originated from the temperature-dependent response variations.