By using silver nanowires, circuits can be printed on flexible, stretchable substrates. This technique is credited to researchers at North Carolina State University, and may integrate into a variety of electronic devices.
Since silver nanowires are conductive, stretchable, and flexible, they’ve made their way into many medical devices, such as wearable health sensors. Although they possess considerable benefits, researchers have found it difficult to print highly integrated circuits using the material. For example, they often clog the printing nozzles of conventional systems.
There has been some success printing with silver nanoparticles, however the final output is fragile and less conductive than their silver nanowire counterpart.
“Our approach uses electrohydrodynamic printing, which relies on electrostatic force to eject the ink from the nozzle and draw it to the appropriate site on the substrate,” says Jingyan Dong, associate professor in NC State’s Edward P. Fitts Department of Industrial & Systems Engineering, and co-corresponding author of a paper. “This approach allows us to use a very wide nozzle —which prevents clogging—while retaining very fine printing resolution.”
“And because our ‘ink’ consists of a solvent containing silver nanowires that are typically more than 20 micrometers long, the resulting circuits have the desired conductivity, flexibility, and stretchability,” says Yong Zhu, co-corresponding author of the paper, and professor of mechanical engineering at NC State.
The team uses a nontoxic, water-soluble solvent in their design, meaning that once the circuit has been printed, the solvent can be easily washed away.
A few prototypes utilizing silver nanowire circuits were made from this technique, including a wearable electrode for use in electrocardiography applications, and a glove fitted with an internal heater.
To learn more, read the full research details in the paper, “Electrohydrodynamic Printing of Silver Nanowires for Flexible and Stretchable Electronics,” published in the journal Nanoscale.