Spray layer-by-layer assembly of POSS functionalized CNT quantum chemo-resistive sensors with tuneable selectivity and ppm resolution to VOC biomarkers

vQRS Based on Hybrids of CNT with PMMA-POSS and PS-POSS Copolymers to Reach the Sub-PPM Detection of Ammonia and Formaldehyde at Room Temperature Despite Moisture

“…POSS molecules bring a clear boosting effect to the chemo-resistive responses of all CPC transducers. as already found in a previous work on CNT-based vQRS [51]. …”

“…A similar behaviour was observed with PMMA-co-POSS that exhibited a very low crystallinity [69] and presented a decreased T g compared to the homopolymer [70]. Therefore, the introduction of POSS in CNT-based CPC is expected to boost their sensitivity [51] by modifying the molecular mobility of polymers without causing any segregation thanks to their copolymerization in the same chain. The cage structure of POSS molecules and their tailorable organic functionalities should also provide additional means of discrimination of vapours, complementary to those resulting from molecular interaction of analytes with polymer chains and carbon nanotubes.…”

“…However, it can also be concluded that there is still a challenge to develop vapour sensors: highly-sensitive and -selective to CH 2 O and NH 3 , operating at room temperature to minimize consumption, working in high moisture environments, and easily up-scalable into e-nose applications. In this context, we have used our experience in the design of quantum resistive vapour sensors (vQRS) that already proved their sub-ppm sensitivity to VOCs [50] and robustness towards 50% moisture [51] to investigate their performances in this new frame and, accordingly, develop new sensors eventually integrable in an e-nose. Carbon nanotubes were chosen to build the sensors' conducting architecture because of their exceptional aspect ratio, electrical conductivity, and ability to form light and easily-switchable interconnected networks [52].…”

“…Carbon nanotubes were chosen to build the sensors' conducting architecture because of their exceptional aspect ratio, electrical conductivity, and ability to form light and easily-switchable interconnected networks [52]. Polyhedral oligomeric silsesquioxane (POSS) was selected in this study because it recently proved to be an effective nanobrick to provide a nano-assembled conducting architecture with chemical and geometrical functionalities [51]. POSS is a molecule of generic formula Si n O 1.5n composed of eight silicon atoms forming a cage of 0.53 nm diameter [53].…”

“…The resulting organic-inorganic hybrid is expected to have enhanced properties compared to the organic homopolymer, such as an increased specific surface, and a larger flexibility [58,59]. POSS-related materials meet applications in polymer based electrolytes [60,61], biomaterials [62,63], hybrid nanocomposites [64], polymer-based optoelectronic devices [65], and sensitivity enhancers in vapour sensing application [51]. In order to maximize the effect of POSS it was decided to incorporate it directly in the polymer chains from the matrix.…”