4D printing: another dimension

While we are now well-versed in the capabilities of 3D printing, 4D printing is increasingly coming to the fore. What is it and what potential does it hold for the medical device sector? Stratasys sheds some light on this new approach to product manufacture.

4D printing is self-reconfiguration or self- transformation – its printed elements in a strand, sheet or 3D object that transform into another shape through the use of energy. The materials we are developing are capable of transforming themselves without human intervention. These ‘smart’ materials have properties which allow them to transform from one state into their programmed state through the use of water as an activation energy.

Of course the development of 4D printing has been dependant on 3D printing. 4D printing is fundamentally 3D printing with the added capability of materials transforming over time.

With Stratasys’ Connex technology, a single print, with multi-material features, can transform from any 1D strand into 3D shape, 2D surface into 3D shape or morph from one 3D shape into another. Using Stratasys’ Connex multi-material technology, researchers can programme different material properties into specific areas of the geometry and harness the different water-absorbing properties of the materials to activate the self-assembly process.

With water as its activation energy, this technique promises new possibilities for embedding programmability and simple decision making into non-electronic based materials. (Imagine robotics-like behaviour without the reliance on complex electro-mechanical devices). Self-assembly is addressing the development of smart, multi-functional, responsive materials.

In a research collaboration between Stratasys’ Education, R&D departments and the Massachusetts Institute of Technology’s (MIT) Self-Assembly Lab, Skylar Tibbits, Self Assembly lab director, is focussing on developing self assembly technologies for large-scale structures in our physical environment.

Tibbits’ 4D printing project is enabled by Stratasys’ Connex 3D printing technology with the added capability of embedded transformation from one shape to another, directly off the 3D printer.

With a dedicated education department within Stratasys, the company is working in collaboration with educational establishments worldwide, while looking to push the boundaries of 3D printing in search of new possibilities. In fact, this is how the 4D printing project came about.

Discussing the project with Skylar, not only is the overall concept of self-assembly intriguing but so is the challenge that producing the programmed smart materials pose. The aim here is to combine innovation with academia and push Stratasys technology to new possibilities. In collaboration with Autodesk, Stratasys was able to use Connex multi-material technology to combine two different materials simultaneously in one part, each programmed with a different reaction to water.

The goal of the project is create materials that respond to different activation energies and can repeatedly transform state. Think sportswear and sports equipment that adapts to the user and how they’re performing when the body temperature or environment changes around them. For example, their sweat levels, heart rate and body temperature, the environment around them - how hot or cold it is – we’re looking at biomedical applications and many more.

According to Skylar Tibbits 4D printing is what the DIY and maker movements look like. He highlights that the change taking place within the micro and nanoscale level is the ability to make materials change shape and properties.

Speaking at the TED 2013, Tibbits mentioned the “ability to programme physical and biological materials to change shape, change properties and even compute outside of silicone-based matter,” revealing that, “there’s even a software called cadnano that allows us to design three-dimensional shapes like nano robots or drug delivery systems and use DNA to self-assemble those functional structures.”

So how does this fit into medical device design and manufacture? Tibbits says that the requirements of materials, geometry and energy source to make 4D printing a success, mean it has a definite future in this sector – smart materials would be ideal for products such as stents and orthodontics.

“We have an opportunity to make every material a smart material that will respond to any energy source – the medical space right for this,” he says.

“There are a range of sectors showing interest in 4D printing and medical is one of them,” says Tibbits and believes that the only barriers to the uptake of 4D printing in the medical sector will be the industry itself and regulations. Although not commercially available, self-assembly is just a beginning of a whole innovative world of manufacturing with minimum energy. As environmental, economic, human and other constraints continue to fluctuate, we will eventually need dynamic systems that can respond with ease and agility. 4D printing is the first of its kind to offer this exciting capability. This is truly a radical shift in our understanding of structures, which have up to this point, remained static and rigid and will soon be dynamic, adaptable and tuneable for on-demand performance.