Functionalization of APTES modified tin dioxide gas sensor

Communication présentée dans la session "Metal Oxide Gas Sensor".International audienceSummary In the present work, commercial SnO2 powder was used for sensor thick film fabrication. The film was produced using screen printing technology. The SnO2 functionalization was done with 3-aminopropyltriethoxysilane (APTES) in liquid phase as an intermediate step, followed by functionalization using hexanoyl chloride exhibiting an alkyl end functional (CH3) group. The SnO2 sensor modified with alkyl end group was found to be sensitive to ammonia gas at 100°C. The advantages are the reduction of the power consumption by decreasing the operating temperature, and the enhancement of the selectivity and sensitivity to the gas with respect to pure SnO2 sensor.MotivationMolecularly modified metal oxide gas sensors have shown to be promising devices for selective gas sensor related to disease diagnosis. Those sensors can be used to detect the gas emanated from the human body for breath analysis application. Tin dioxide sensors have lack of selectivity and work at high temperature (350-500°C). The need of selective sensors with high sensitivity at low gases concentration pushes us to modify SnO2 sensing element in order to change its interactions with gas. The modification with organic functional groups with different polarities change the sensor response to specific gases depending on their polarity. A SnO2 functionalization based on APTES combined with hexanoyl chloride was investigated. Another objective is to reduce the power consumption by decreasing the operating temperature

Etude du système hybride constitué par l ensemble film d oxyde semi-conducteur/oligonucléotides de conformation hairpin /nanoparticules d or

GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Detection of DNA using Silicon carbide nanowire based Field effect transistor

International audienc

Substrats SERS Ag°/ TiO2 pour la détection de molécules organiques

National audienc

Study of sol-gel ZnO thin films – A 1st step toward ZnO nanowire growth and their integration into DNA biosensors

National audienc

ZnO nanowire networks: Fabrication and application to label-free electrical DNA biosensors

International audienc

Superior long term stability of SiC nanowires over Si nanowires under physiological conditions

International audienceSemiconducting nanowires (NWs) are raising a growing interest in nanoelectronic devices. While silicon is the most widely used material in this field, it lacks long-term stability in aqueous solution. The usage of Si must hence be reconsidered for specific applications such as devices operating in biological media with high ionic strength. Silicon carbide is a wide bandgap semiconductor that can efficiently replace Si for applications in harsh environments or high temperature thanks to its high chemical stability and thermal conductivity. Here, we compare the long term stability of Si and SiC NWs under mimicked physiological conditions. The degradation kinetics of both types of NWs was studied from accurate monitoring of their cross-sectional geometry by transmission electron microscopy (TEM) over a period of 4 weeks. Results show a linear dissolution of Si NWs whereas SiC NWs exhibit much slower degradation kinetics confirming the superior chemical stability of SiC nanostructures over Si. After 32 days, NWs with an initial diameter of 20 nm are expected to dissolve completely in the case of Si NWs while SiC NWs would shrink by only 16%

A Label-Free Impedimetric DNA Sensor Based on a Nanoporous SnO2 Film: Fabrication and Detection Performance

International audienceNanoporous SnO2 thin films were elaborated to serve as sensing electrodes for label-free DNA detection using electrochemical impedance spectroscopy (EIS). Films were deposited by an electrodeposition process (EDP). Then the non-Faradic EIS behaviour was thoroughly investigated during some different steps of functionalization up to DNA hybridization. The results have shown a systematic decrease of the impedance upon DNA hybridization. The impedance decrease is attributed to an enhanced penetration of ionic species within the film volume. Besides, the comparison of impedance variations upon DNA hybridization between the liquid and vapour phase processes for organosilane (APTES) grafting on the nanoporous SnO2 films showed that vapour-phase method is more efficient. This is due to the fact that the vapour is more effective than the solution in penetrating the nanopores of the films. As a result, the DNA sensors built from vapour-treated silane layer exhibit a higher sensitivity than those produced from liquid-treated silane, in the range of tested target DNA concentration going to 10 nM. Finally, the impedance and fluorescence response signals strongly depend on the types of target DNA molecules, demonstrating a high selectivity of the process on nanoporous SnO2 films

DNA Detection Using SiC Nanowire Based Transistor

International audienceThe fast and direct detection of small quantities of biomolecules improves early medical diagnosis of certain serious diseases as cancers and can be used to detect in situ the presence of pathogenic viruses or GMOs for food industry, protection environmental and bio-defense. Numerous research projects are conducted on nanoelectronic devices that can perform such detection with high sensitivity using nanostructures. Currently, these devices are made from Silicon nanowires [1]. For these applications, Silicon Carbide (SiC) material can advantageously replace Silicon as this semiconductor is now known to be biocompatible and to show a high chemical inertness [2]. Here, we present the electrical detection of DNA using a SiC Nanowire Field Effect Transistor (NWFET). The NWFETs are fabricated and then functionalized with DNA molecules. Between each step of the functionalization process, I-V characteristic measurements are performed. Comparative and simultaneous measurements are carried out on two SiC NWFETs: one is the sensor and the second one is used as a reference. Some interesting properties of the sensor are studied for the first time which opens the way to future developments of SiC nanowire based sensors

Electrochemical impedance spectroscopy and surface plasmon resonance studies of DNA hybridization on gold/SiO_<i>x</i> interfaces

International audienceThe use of Au/SiOx interfaces for the investigation of DNA hybridization using electrochemical impedance spectroscopy (EIS) and surface plasmon resonance (SPR) simultaneously is demonstrated. Standard glass chemistry was used to link single-stranded DNA (ss-DNA) on aldehyde-terminated Au/SiOx interfaces. The layer thickness and amount of grafted oligonucleotides (ODNs) were calculated from SPR on the basis of a multilayer system of glass/Ti/Au/SiOx/grafted molecule. Capacitance and resistance values of the modified interface before and after hybridization were calculated from EIS data using an equivalent circuit and allowed the affinity rate constant, KA = 4.07 × 105 M-1, to be determined. The EIS results were comparable to those obtained by SPR hybridization kinetics recorded in parallel