Engineers have developed a new method of 3D printing of conductive polymer. The extrusion of the polymer solution of PEDOT:PSS with a concentration of 7 percent, it was possible to obtain the fine structure of 30 micrometers with high reproducibility. To check the quality of the new method, the scientists printed and connected neural probe for the mouse. Article published in the journal Nature Communications.
Conductive polymeric materials may find applications in energy storage, flexible electronics and bioelectronics due to its electrical, mechanical and biocompatible properties. However, despite recent advances in the field of conductive polymers, fabrication of structures and devices based on them are still limited to traditional methods, such as inkjet and screen printing, electrochemical deposition and lithography. Each of these methods has its drawbacks and complexity. For example, these methods are limited to two-dimensional structures with low resolution, i.e. with the thickness of the yarn is at least 100 micrometers, and they are very expensive and have a complicated multistage manufacturing process. These conditions hamper the wide use of the devices with conductive polymers.
On the other hand, modern methods of 3D printing opportunities for quick programmable the production of three-dimensional structures with micron resolution. To date, the list of materials that can be used in 3D printing, has significantly increased: metals, hydrogels, biochemie of cell aggregates, glass, liquid crystal polymers and ferromagnetic elastomers. But work on the study of 3D printing of conductive polymers is limited to the printing of an isolated filament due to poor ability to print existing conductive polymers.
Yu Hyun-Woo (Hyunwoo Yuk) from the Massachusetts Institute of technology with his colleagues found capable of 3D printing a conductive polymer and printed it from multielectrode ensemble, high-density flexible electronic circuits and neural probe for murine hippocampus. This polymer has proved a long-known poly(3,4-ethylenedioxythiophene) coupled with polystyrene sulfonate (PEDOT:PSS), an aqueous solution which is widely available commercially.
To obtain a suitable paste-like conductive polymer for printing, the original aqueous solution of the polymer consistently freeze at the temperature of liquid nitrogen, freeze-dried and re-dispersed in a solution of water and organic solvent dimethyl sulfoxide. The obtained solution with a concentration of five to seven percent is acceptable for 3D printing, with lower concentrations resulting structure Rasizade, while more — stuck in the nozzle of the extruder due to high viscosity. Obtained from such strip material have a high resolution of 30 micron and a large fidelity of the 20 layers.