Highly stretchable, sensitive, and flexible strain sensors based on Ag@Cu/PDMS composites

With the rapid development of electronic devices and wearable electronic products, flexible conductive materials have attracted more and more attention. Metal/polymer composite is a kind of functional electronic material to realize the conductivity and interoperability of flexible electronic devices. Ultrafine metal copper powders have high electrical conductivity, however, the powders are extremely prone to oxidation, which greatly limits their practical applications. In this article, the silver plated copper (Ag@Cu) powders were prepared and had excellent electrical conductivity and well antioxidative stability even after exposure in air for 12 months without any obvious oxidation. The Ag@Cu powders were added into polydimethylsiloxane (PDMS) polymer matrix to form an elastic conductive film (Ag@Cu/PDMS conductive film) using the Mayer rod process. The Ag@Cu/PDMS conductive film exhibits super stretchability, flexible, twisting, bending ability, and repeatability. The sensor has good strain-resistance response performance when attached to the finger under the cycles of bending and releasing indicates that the sensor has high sensitivity. The Ag@Cu/PDMS conductive paste can be printed on different substrates with different conductive patterns. Low cost, high conductivity, sensitivity, good mechanical flexibility and electrical stability make it have a good potential application in the field of flexible conductor, flexible printed circuit, and human health monitoring.