Ολοκληρωμένη συστοιχία αισθητήρων βασισμένη σε πολυμερή για την αναγνώριση πτητικών αερίων

Abstract

In this research the sensor type of planar InterDigitated Capacitors (IDCs), also known as chemcapacitors, is demonstrated and its application in the detection of Volatile Organic Compounds (VOCs) and humidity is explored. The IDC layout configuration is studied by using a dedicated electromagnetic model and the behavior of different planar IDE structures/geometries coated with different polymeric materials of different dielectric permittivity values (εp) is determined. This study leads to the optimum design geometry of the planar IDCs that will be used for the detection of analytes. In order to identify the more suitable sensing materials for the targeted application, a methodology based on swelling measurements of the polymeric material upon exposure to analytes of interest was developed and applied in the prediction of the response of a chemcapacitor upon exposure to different VOCs. The integrated sensor array is characterized by the responses of each sensor to exposure to several pure analytes, binary mixtures of analytes and complex environments. Several parameters were examined such as sensitivity, selectivity, limit of detection, aging. Also the total response of the sensor array is analyzed by conjunction of the individual responses of each sensor and the use of suitable Principal Component Analysis, PCA, models that have been developed. Fabrication of a hybrid low-power gas sensing module is presented. This module is realized with integration on the same device of the sensor array with the appropriate electronic elements. The latter provide the power, control and read-out electronics of the output signal. The proposed hybrid micro-device is characterized in terms of the response of each sensor of the sensor array upon exposure to different pure analytes and their binary mixtures. Evaluation of the results obtained by the characterization of the hybrid gas sensing module demonstrate the ability of use such a device in analytical methods under conditions of constant or alterable concentration of VOCs/humidity or their mixtures in applications either at constant temperature or at temperature changing over time simulating that way real time applications.