The Research Of The Extraction Of Small Diameter Single-walled Carbon Nanotubes And Large Deformation Strain Sensor

Carbon nanotubes have showed its wonderful application prospect and attracted more attention from the scholars because of its excellent performance of mechanical,optical and thermal aspect.Single walled carbon nanotubes(SWNTs)with sub-nanometer diameter have promising properties,compared to large-diameter SWNTs because of the curvature effect.Sub-5 ? SWNTs tend to be metallic due to strong ?*–s* hybridization effects which dramatically change the band structure,and 4 ? SWNTs show superconductivity.Great efforts have been focused on creating small diameter SWNTs and their relative property research.The group of Fan in Tsinghua University has showed a super aligned carbon nanotubes arrays fabricated by CVD in 2002,which open a door from micro to macro on carbon nanotube,so that flexible devices based on the carbon nanotube got a rapid development.However,the gauge factor of the flexible device is still too small to make it great development.In view of the two major challenges,the main work is summarized as bellow.Purification of Small Diameter SWNT.The SWNTs preparation by CVD always exist in the form of carbon nanotube bundles and also contain amorphous carbon particles.Firstly,the SWNTs are solubilized by covalently binding the neutravidin,followed by centrifugation to select the solubilized,individualized,small diameter SWNTs.In this step,most of the bundled SWNTs,amorphous carbon and larger diameter SWNTs were removed.Then add atto 550 to the mixture,specific binding of the biotinylated fluorescent dye atto 550 further increases the solubility difference between the neutravidin-functionalized small diameter SWNT and large diameter SWNT.A second centrifugation step allowed for further reduction of the remaining impurities and obtaining purified individualized small diameter SWNTs.AFM characterization showed that these SWNTs have a diameter of 0.38 nm.The preparation and application of large deformation strain sensor.We designed a highly stretchable hierarchically-buckled NTS_m@rubber@fiber sheath-core strain sensor that can be reversibly stretched up to 600% to provide resistance changes of 160% with two linear ranges(GF1 = 0.5 for strain = 0% to 200%;and GF2 = 0.14 for strain = 200% to 600%;)and a twist sensor that can be twisted up to 2.2 turns/cm to provide a linear resistance change by 14% with high durability and fast response.As a real world example,our technology offers a reliable,yet non-intrusive way to monitor respiration and capture breathing patterns without adverse influence by noise,light,radiation,atmospheric pressure,or magnetic fields and utilizable around the clock.We have demonstrated a breathing monitor using our strain sensor which can not only identify the total absence of respiration but also can clearly distinguish different abnormal respiration patterns,such as obstructive,Kussmaul's,Biot's/ataxic,Cheyne-Stokes,and apneustic.The NTS-sheath-core fiber strain sensor provides a convenient means of measuring large deformations of morphing structures allowing a wide range of potential applications including health care,data glove reporting for sports and fitness monitoring in recreation and virtual reality,robotics,artificial muscle orthotics,and industrial and space engineering.