C&B Notes

On to 4-D Printing

A group of research scientists from MIT and a few other places, led by Skylar Tibbits under the Self Assembly Lab banner, is working to expand the definition of “programmable” material.  Using 3-D printers, the team is printing additional layers on standard materials that respond to outside stimuli like water and temperature in predictable ways.  While still early in the development process, the expectation is that these enhanced materials can be used in novel manufacturing and construction processes.

They don’t have microprocessors, gleaming titanium skeletons, or an unhealthy obsession in Sarah Connor, but the wood panels and carbon fiber Tibbits’ team fabricates combine sensors, logic, and outputs in ways that could transform everything from airplanes to clothing to flat-pack furniture.

As its name suggests, the Self-Assembly Lab focuses on making things that can, well, self-assemble. It has created a series of small wood planks, for instance, that fold into a toy elephant when exposed to moisture. Tibbits and collaborators Christophe Guberan and Erik Demaine are working on products that could morph in response to the weather.  In the future, the Lab’s research could make way for Ikea furniture that assembles itself with a splash of water — no Allen wrench required.

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Tibbits refers to these processes collectively as “4-D printing.”  It’s like 3-D printing but with a fourth dimension: time, or as Tibbits likes to call it, “dynamism.”  In the future, Tibbits thinks it will be possible to program all types of materials.  The tools Tibbits and company use are not especially novel.  In the case of the carbon fiber projects, the manufacturing process is thoroughly two-dimensional.  The team starts with a carbon fiber roll that follows the typical warp and weft pattern.  A secondary material, formulated in Tibbit’s lab to respond to changes in temperature, is spot-printed on the mesh using a CNC gantry.  As the carbon fiber is exposed to heat, the temperature-sensitive material changes shape and causes the sheet to deform in ways specified by the designer.

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A team is testing the possibility of using it to make a smarter race car spoiler.  As the driver turns, friction creates heat that could trigger the temperature-sensitive material in the carbon fiber.  As a result, the spoiler would change shape to optimize aerodynamics and eke out greater performance.  In time, the same carbon fiber trick could be used to increase a jet engine’s efficiency, lowering its carbon footprint.

The 3-D printed wood projects use a traditional fused deposition printer, like a MakerBot, paired with a specially-formulated plastic filament filled with pulverized wood fibers.  By specifying the pattern of the “wood grain” during the printing process, designers can control how it curls when wet.  Tibbits’ work isn’t about using high-end equipment.  It’s about tapping the genius-level intellect of his team, including researchers Athina Papadopoulou, Carrie McKnelly, Christopher Martin, and Filipe Campos, to consider materials in new ways. Each creation combines discordant materials into some cohesive, newly useful whole.  “We’ve gotten used to making materials our slaves, but there’s a lot of craft in material properties,” he says.