As anybody who's emerged from a car crash in good shape can tell you, it's good to have some explosives around - they pop modern vehicles' air bags. Of course explosives are also hard to manufacture and handle, which is why researchers at Purdue University in the US tried to print them.
The boffins believe they've cracked the secret of using additive manufacturing to mix and deposit “energetic materials” (propellants and pyrotechnics as well as explosives) using inkjet printer technology.
The material – in the video below, Purdue researcher Allison Murray is depositing nanothermite – is created out of inert suspensions of copper and aluminium, minimising the risk of an unexpected boom.
Murray's professor on the project, Jeff Rhoads, explained in the university's announcement: “We can have a fuel and an oxidiser in two separate suspensions, which are largely inert. Then, with this custom inkjet printer, we can deposit the two in a specific overlapping pattern, combining them on a substrate to form nanothermite.”
In the case of thermite, the aluminium provided the fuel and the copper oxide the oxidiser.
The hard part, Rhoads said, was to get the mix right while dealing with “picolitres” of material.
Using inkjet printing as the technology template also provided 0.1 micron accuracy.
As noted in the introduction to the journal paper, the only sacrifice at this point of development is that the nanothermite mixed using the inkjet printer burned 200 K cooler than premixing thermite before printing it.
Other members of the research team included George Chiu (inkjet printing expert); and Zucrow Labs' Emre Gunduz and Steve Son to help with the stuff-that-goes-boom (formally “energetic materials”) expertise. ®