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A polypyrrole-based ammonia-detection gas sensor was studied in this work. Under a 1.6 V electrodeposition potential, polypyrrole (PPy) was electrochemically synthesized from an aqueous solution of 0.1 M pyrrole and 0.1 M oxalic acid. An extension to the polypyrrole films was applied through electrochemical deposition on indium tin oxide (ITO), using the metal oxide nanoparticles of MgO and WO3. These films were investigated for their sensing behavior towards NH3 at different working temperatures and different weight percentages of nanoparticles .The measurements of A.C conductivity were conducted over a frequency range of 101-105 Hz and temperature range of 298-423 K . The highest electrical conductivity was equal to 3.67x10-1 Ω.cm-1 at a temperature of 323 K and frequency of 105H z. The experimental results showed that the sensitivity of the undoped and doped PPy with nanoparticle films to ammonia gas changes with the change in temperature and weight percentage.

Nano-silver oxide thin films with high sensitivity for NH3 gas were deposited on glass substrates by the chemical bath deposition technique. The preparations were made under different values of pH and deposition time at 70áµ' C, using silver nitrate AgNO3 and triethanolamine. XRD analysis showed that all thin films werepolycrystalline with several peaks of silver oxides such as Ag2O, AgO and Ag3O4, with an average crystallite size that ranged between 31.7 nm and 45.8 nm, depending on the deposition parameters. Atomic force microscope (AFM) technique illustrated that the films were homogenous with different surface roughness and thegrain size ranged between 55.69 nm and 86.23 nm. The UV-Vis spectrophotometer showed that the optical direct energy gap ranged between 1.66 eV to 2.12 eV. The silver oxide thin film gives a high sensitivity of 70.12 for NH3 gas at 75°C operating temperature. This study shows that different types of silver oxides can beprepared by the CBD techniques, with the nanostructure to be used in gas sensors and optoelectronic applications.

Abstract : Silicon nanowire (Si NW) sensors are very promising because of their fast, low-cost, label-free, real-time detection of chemical and biological species. They have already demonstrated outstanding sensitivity and selectivity towards a large number of analytes in both liquid and gas phases. In particular, silicon junctionless nanowire transistors (JNTs) have recently detected record low concentrations (down to the zeptomolar range) of the protein streptavidin in liquid phase. However, JNTs have not yet been tested for sensing in gas phase. Here we present the fabrication and initial electrical characterisation of JNT-based sensors for detection of atmospheric free radicals such as hydroxyl (•OH) and nitrate (•NO3), which are the main drivers of chemical processes in the atmosphere. Silicon-on-insulator wafers have been used for device fabrication. The wafers have first been doped by a chain phosphorous implantation with nine different energies to form a box-like dopant profile across the 20 nm thick top Si layer. Subsequently, flash lamp annealing has been performed for defect healing and dopant activation. Device patterning has been based mainly on electron beam lithography, inductively-coupled reactive ion etching, metal deposition and lift-off processes. Initial electrical characterisation of fabricated devices by back-gating has proven their good performance and potential suitability for detection of atmospheric free radicals. Additional Information: Sayantan Ghosh delivered this presentation for Nanonet+ Workshop 2021. RADICAL represents a 'Fundamental Breakthrough in Detection of Atmospheric Free Radicals'. Find out more on the RADICAL project website: radical-air.eu The RADICAL project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 899282.

In this work, aluminium-doped zinc oxide (AZO) nanostructure at 0.3 wt% and 0.5 wt% Al was synthesized using the pulse-laser ablation technique in liquid(PLAL) using pulsed Nd: YAG laser of a fundamental wavelength of (1064 nm). The process was done in the absence and presence of an external magnetic field. The deposited AZO nanostructures by drop-casting on etched-Si wafers were examined by different techniques. The XRD test illustrates enhancing the crystallinity of the prepared thin films by applying an external magnetic field. The FESEM images displayed the change of nanostructure to nano-sheets of high surface area after using a 77.2 mT permanent magnet placed behind the target during the ablation process. The gas sensor based on the AZO nanostructures has higher sensitivity against NO2 than H2S. Increasing the Al ratio from 0.3 wt% to 0.5 wt% changed the properties of the prepared samples to have small porosity and small surface area, which negatively affected the properties of the sensor

In this work we study the different phenomena taking place when a hydrostatic pressure is applied in the inner fluid of a suspended microchannel resonator. Additionally to pressure-induced stiffness terms, we have theoretically predicted and experimentally demonstrated that the pressure also induces mass effects which depend on both the applied pressure and the fluid properties. We have used these phenomena to characterize the frequency response of the device as a function of the fluid compressibility and molecular masses of different fluids ranging from liquids to gases. The proposed device in this work can measure the mass density of an unknown liquid sample with a resolution of 0.7 µg/mL and perform gas mixtures characterization by measuring its average molecular mass with a resolution of 0.01 atomic mass units ; This work was supported by the European Union's Horizon 2020 research and innovation program under European Research Council grant 681275-LIQUIDMASS-ERC-CoG-2015 and the Spanish Science Ministry (MINECO) through project MOMPs TEC2017-89765-R. The service from the Micro and Nanofabrication Laboratory (MiNa) and X-SEM Laboratory, is funded by MCIU (CSIC13-4E-1794) and EU (FEDER, FSE). ; Peer reviewed