Techniques for forming nanostructured materials are provided. In one aspect of the invention, a method for forming nanotubes on a buried insulator includes the steps of: forming one or more fins in a SOI layer of an SOI wafer, wherein the SOI wafer has a substrate separated from the SOI layer by the buried insulator; forming a SiGe layer on the fins; annealing the SiGe layer under conditions sufficient to drive-in Ge from the SiGe layer into the fins and form a SiGe shell completely surrounding each of the fins; and removing the fins selective to the SiGe shell, wherein the SiGe shell which remains forms the nanotubes on the buried insulator. A nanotube structure and method of forming a nanotube device are also provided.

A device includes an upper metallic layer, a lower layer, and a nano sensor array positioned between the upper and lower layers to detect a presence of a gas, a chemical, or a biological object, wherein each sensor's electrical characteristic changes when encountering the gas, chemical or biological object.

A flexible nitrogen dioxide sensor based on tungsten trioxide nanoparticles-loaded multi-walled carbon nanotubes-reduced graphene oxide (WO.sub.3 NPs-loaded MWCNTs-RGO) hybrid on a polyimide/polyethylene terephthalate substrate. A viscous gel of the hybrid materials can be prepared by the assistance of -terpineol. The fabricated sensor shows excellent sensing performance toward NO.sub.2 which may have a maximum response of 17% (to 5 ppm), a limit of detection of 1 ppm, and relatively short response/recovery time (7/15 min). The sensor may exhibit excellent mechanical flexibility and sensing properties at room temperature without any significant performance degradation even at a curvature angle of 90 and after 10.sup.6 times of bending/relaxing processes. Low cost, light weight and mechanical robustness of the proposed WO.sub.3 NPs-MWCNTs-RGO hybrid based sensor can be a promising element for the development of flexible NO.sub.2 gas sensors having higher performance.

A process for ultrasensitive in vitro detection and/or quantification of a substance of interest in a sample is performed by detecting the luminescence emission by photoluminescent inorganic nanoparticles. The process includes (i) use of photoluminescent particles comprising a photoluminescent inorganic nanoparticle consisting of a crystalline matrix having at least 10.sup.3 rare-earth ions, and coupled to a targeting agent for the substance to be analyzed, under conditions conducive to their association with the sample substance to be analyzed; (ii) exciting the rare-earth ions of the particles by an illumination device having a power of at least 50 mW and an excitation intensity of at least 1 W/cm.sup.2; (iii) detecting the luminescence emission by the particles after single-photon absorption; and (iv) determining the presence and/or concentration of the substance by interpreting said luminescence measurement. This process can be used for in vitro diagnostic purposes and as an in vitro diagnostic kit.