Cheng and his colleagues had another idea. The team mixed a gold salt with another chemical called oleylamine, and then waited a day or two. The chemical reaction forms miniscule, threadlike nanowires of gold.
They then soaked a paper-towel-like material in the nanowires, and the golden threads were automatically absorbed into the paper towel. The team then sandwiched the paper-towel material between two thin, synthetic rubber sheets.
The total thickness was about 0.02 inches (0.5 millimeters), Cheng said.
When exposed to pressure, the nanowires change how easily electrical current flows through them, and this change in current can then be detected.
Sensitive and Flexible The new devices are as sensitive as the best pressure sensors, and can withstand twisting and bending without cracking.
The device could be used as artificial skin to monitor many mechanical properties of the blood, including heartbeat. The sensor would be placed on top of a person's skin, where it would sense the acoustic and pressure changes from blood flow.