Jian Zhu pulls a cotton thread out of the nano¬tube solution, where it’s been soaking for about two minutes. Zhu will allow the thread to dry and then repeat the process about nine times to maximize the thread’s electrical properties.Visible in this image from a scanning electron microscope, the microscale fibers that make up a cotton thread provide a structural template for the nanotubes to adhere to.
Treated threads are attached to electrodes on five light-emitting diodes and to a power source (by the red and black clips). The threads carry enough current to light all five LEDs.
Zhu holds small patches of cotton cloth treated with the nanotube-Nafion solution. The dipping technique used on individual threads can also turn whole cloth into an electronic textile.When antibodies to human albumin are added to the nanotube solution, the treated threads can sensitively detect blood. In a solution containing a small amount of human blood (dye added for visual emphasis), the thread becomes much less resistant to the flow of electrical current. A solution with just a tiny amount of albumin in it causes the thread’s resistance to drop significantly.