Aerosol mixing silver and collagen to create printed biocompatible electrodes

Many medical implants, such as pacemakers and neural stimulators, transmit electrical signals to biological tissue using electrodes. Because of their application, these electrodes must fulfill additional criteria, such as flexibility and biocompatibility, in addition to conductivity. Traditional electrode materials typically fail in at least one of these categories. This can be mitigated to an extent by combining electrode materials with proteins, but integrating two materials with different properties can be challenging.

Zhou et al. used aerosol jet printing (AJP) to simultaneously print silver and collagen in a single electrode. Their approach allowed them to uniformly mix the two materials to produce an electrode that was flexible, biocompatible, and conductive.

“With AJP, you are able to take inks that might be quite difficult to print in typical situations and aerosolize them,” said author Malavika Nair. “These aerosols are then focused down allowing you to print a wide range of materials with wide ranges of viscosity.”

The team mixed silver nanoparticles, which have an extremely high electrical conductivity, with collagen, which is flexible and biocompatible. The result keeps most of the silver’s conductivity while increasing flexibility. While increasing collagen content does interfere with conductivity, it also increases biocompatibility, and the authors identified ratios of the two materials where all characteristics are satisfactory.

The researchers plan to continue to study this approach, testing other materials and particle geometries to maximize their useful properties.

“Moving towards nanorods or other geometries could help achieve even higher performance with respect to reducing the silver content while maintaining a higher degree of biocompatibility,” said Nair.

Source: “Aerosol jet co-printing for flexible and conductive protein-metal electrodes,” by Yannan Zhou, Georgina H. Burgoyne Morris, Daniel V. Bax, Sohini Kar-Narayan, and Malavika Nair, APL Electronic Devices (2026). The article can be accessed at https://doi.org/10.1063/5.0300123 .