Researchers at Polytechnique Montreal announced last fall they had developed a conductive, 3D-printable composite which, they believe, industry can use to detect and describe liquids in real time. They believe this discovery could have significant applications in hydrocarbons, aerospace, and manufacturing industries. Their paper, entitled 3D Printing of Highly Conductive Nanocomposites for the Functional Optimization of Liquid Sensors, proposes to make carbon nanotubes by using a polymer composite.
A carbon nanotube is a tube-shaped material, made of carbon, having a diameter measuring on the nanometer scale. A nanometer is one-billionth of a metre, or about 10,000 times smaller than a human hair. The nanotubes are unique because the bonding between the atoms is very strong and the tubes can have extreme ratios, with enough electrical conductivity to use in real time sensing and liquids detection.
The Montreal scientists’ 3D printed a porous cloth made of nanotube-enhanced filament which they claim, “when exposed to a liquid will swell thus altering its conductivity. The extent of alteration,” they say, “can then be used to determine both the presence and type of liquid in contact with the material.”
The paper reports the process begins as a thermoplastic which remains solid at room temperature. “This is dissolved in a solvent, and placed in a container with carbon nanotubes, supplied as a fine black powder. These are mixed together in the lab by machine according to a special, patented recipe which ensures the nanotubes are optimally dispersed for the application.”
The researchers discovered that when they adjusted the viscosity of the liquid, it produced a 3D-printable ink. So, they loaded it into a 3D printer and realized the ink quickly hardened. “When pushed through the high-precision nozzle, the solvent evaporates very rapidly and the ink becomes solid in a few seconds. It prints as a wire or filament.”
The scientists glued the wire to various surfaces and other filaments and voila, 3D geometries. When they connected the final material to an electrical connection and equipment for measuring resistance, they found it could immediately detect and characterize liquid. Pipeline specialists are interested in carbon nanotube technology as detecting spills is one of their biggest challenge.
Professor Daniel Therriault, the lead author of the paper, believes their discovery could help and suggests that a composite, calibrated to the liquid being transported, could be laid down at the flanged connection points. “In the event of a leak, and liquid touching the sensors, operators could be given very precise, instant information on its location.”
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