Breakthrough in flexible silver nanowire circuit printing
16/03/2018
The flexibility, stretchability and conductive properties of silver nanowires make them well suited to this application. There are significant challenges to printing highly integrated circuits using silver nanowires, however, not least that conventional printing techniques have been found not to work well with them. This is primarily due to the nanowires often clogging the printing nozzles.
The research team at NC State has managed to overcome this challenge. Jingyan Dong, co-author of a paper on the project, has explained: “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. This approach allows us to use a very wide nozzle – which prevents clogging – while retaining very fine printing resolution.”
The paper’s other co-author, Yong Zhu, adds: “Because our ink consists of a solvent containing silver nanowires that are typically more than 20 micrometres long, the resulting circuits have the desired conductivity, flexibility and stretchability.”
The researchers have also said that the size of the printing area is limited only by the size of the printer, meaning the technique could be easily scaled up.
They have used their new techniques to create prototypes that make use of the silver nanowire circuits, including a glove with an internal heater and a wearable electrode for use in electrocardiography. NC State has filed a provisional patent on the technique.
“Given the technique’s efficiency, direct writing capability, and scalability, we’re optimistic that this can be used to advance the development of flexible, stretchable electronics using silver nanowires – making these devices practical from a manufacturing perspective,” said Yong Zhu.
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