As this technology continues to develop, it would be interesting to understand the expected print life of the cartridges for certain types of pastes. From the articles, it seems that the current strategy is to allow quick replacement of the heads (similar to an inkjet printhead cartridge), so I'm assuming that these cartridges are currently planned on being low-cost and disposible. (By the way, the peanut butter prototype was impressive).
William, both capacitive and conductive features can be 3D printed with this technology, mentioned on the company's website. We also give a link in the story for more info on the ink's characteristics. Transistors? Not quite yet.
Printing conductors is a worthwhile thing, but to gain much functionality there need to be other parts as well. Resistors and transistors would allow some functionality, but it seems that they would need to be placed, rather than printed.
Syringe extruders have been used in medical R&D for 3D printing various types of organ-like materials. But this is a new development in industrial uses. The combination of plastics and conductive viscous ink 3D printed in one pass is still in its early stages, but the open source technology means it can be developed faster via crowdsourcing.
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