Smart hydrogels for detection of volatile organic compounds in gaseous environments

Monitoring volatile organic compounds (VOCs), e.g. acetone, in the human breath allows the detection of diseases at an very early stage. In this context, stimuli-responsive smart hydrogels emerge as promising candidates for the development of corresponding sensors due to their tailored specificity towards particular gas species of interest.
The focus in this work here is directed at several aspects that are of decisive importance for the successful utilization of smart hydrogels for VOC gas sensing. Gravimetric experiments are employed to assess the swelling behavior of hydrogel samples and, thus, to characterize its sensitivity. Continuous monitoring of this volume variation is achieved by placing patterned thin hydrogel layers on piezoresistive pressure sensor chips as sorptive-electrical transducers. By applying porogens and subsequently freeze-drying, an interconnected porous network within the hydrogel can be achieved that significantly enhances gas adsorption and desorption and, hence, accelerates sensor response.