Fine control of carbon nanotubes-polyelectrolyte sensors sensitivity by electrostatic layer by layer assembly (eLbL) for the detection of volatile organic compounds (VOC)

International audienceVolatile organic compounds (VOC) sensors have recently extended their field of application to medical area as they are considered as biomarkers in anticipated diagnosis of diseases such as lung cancer by breath analysis. Conductive polymer nanocomposites (CPC) have already proved their interest to fabricate sensors for the design of electronic noses (e-noses) but, for the first time to our knowledge, the present study is showing that electrostatic layer by layer assembly (eLbL) is bringing an interesting input to tailor the sensitivity of carbon nanotubes (CNT)-polyelectrolyte sensors. By this technique transducers are progressively built in 3D alternating dipping into sodium deoxycholate (DOC)-stabilized SWNT and poly(diallyldimethyl-ammonium chloride) [PDDA] solutions, respectively anionic and cationic. The precise control of transducers thicknesses (between 5 and 40 nm) resulting from this process allows a fine tuning of multilayer films resistance (between 50 and 2 kΩ) and thus of their sensitivity to VOC. Interestingly the surfactant used to disperse CNT into water, DOC is also found to enhance CNT sensitivity to vapors so is it for the polyelectrolyte PDDA. Finally it is found that transducers with 16 bilayers of PDDA/DOC-CNT provide optimum chemo-resistive properties for the detection and discrimination of the eight vapors studied (chloroform, acetone, ethanol, water, toluene, dichloromethane, tetrahydrofuran and methanol)

Electrically and thermally conductive nanocomposites: heating and sensing applications

International audienc

Selectivity of Chemoresistive Sensors Made of Chemically Functionalized Carbon Nanotube Random Networks for Volatile Organic Compounds (VOC)

Different grades of chemically functionalized carbon nanotubes (CNT) have been processed by spraying layer-by-layer (sLbL) to obtain an array of chemoresistive transducers for volatile organic compound (VOC) detection. The sLbL process led to random networks of CNT less conductive, but more sensitive to vapors than filtration under vacuum (bucky papers). Shorter CNT were also found to be more sensitive due to the less entangled and more easily disconnectable conducting networks they are making. Chemical functionalization of the CNT’ surface is changing their selectivity towards VOC, which makes it possible to easily discriminate methanol, chloroform and tetrahydrofuran (THF) from toluene vapors after the assembly of CNT transducers into an array to make an e-nose. Interestingly, the amplitude of the CNT transducers’ responses can be enhanced by a factor of five (methanol) to 100 (chloroform) by dispersing them into a polymer matrix, such as poly(styrene) (PS), poly(carbonate) (PC) or poly(methyl methacrylate) (PMMA). COOH functionalization of CNT was found to penalize their dispersion in polymers and to decrease the sensors’ sensitivity. The resulting conductive polymer nanocomposites (CPCs) not only allow for a more easy tuning of the sensors’ selectivity by changing the chemical nature of the matrix, but they also allow them to adjust their sensitivity by changing the average gap between CNT (acting on quantum tunneling in the CNT network). Quantum resistive sensors (QRSs) appear promising for environmental monitoring and anticipated disease diagnostics that are both based on VOC analysis

Electrically and thermally conductive nanocomposites: heating and sensing applications

International audienc

Composites Polymères Conducteurs pour la détection de température & de vapeur

FOTON, Lannio

Référé pour 36 journaux internationaux : R 1 : Macromolecules, Polymer Engineering & Science, Biomacromolecules, Journal of Applied Polymer Science, Journal of Polymer Science B: chemical, Journal of non Crystalline Solids, Macromolecular Chemistry & Physics, Smart Materials & Structure, Sensors & Actuators B: Chemical, Polymer, Thermochica Acta, Analitica Chimica Acta, Synthetic Metals, Polymers for Advanced Technologies

Journal of Physic & Chemistry of Solids, Electroanalysis, Sensors, Thin solid Films, Composites Science & Technolog

Structures, Propriétés Applications des Composites Polymères Conducteurs

LPI, Évr

Thermoelectrical and Chemoelectrical Properties of Conductive Polymer NanoComposites (CPC): Different Strategies for Conducting Network Structuring

International audienc

Conductive Polymer nanoComposites (CPC) for temperature sensing applications

Center of Energy Studies, Indian Institut of Technology, Delhi, India