​Building complex objects

A common criticism of consumer 3D printers is they can only build simple plastic models.

However, researchers are slowly adding to the palette of materials that 3D printers can use.

A team at MIT’s Computer Science and Artificial Intelligence Laboratory have demonstrated a 3D printer that can make objects using 10 different materials in a single print. The machine was built for less than $7,000 and created using off-the-shelf components. In contrast, existing multi-material 3D printers are generally limited to three materials and priced from $150,000.

The team say the machine can also scan and build around an existing object, allowing for the possibility of building around a circuit board.

​Up to 100 times faster

Another bat used to beat up 3D printing is how long it takes to make anything – with more complex objects often taking hours to complete.

Silicon Valley start-up Carbon3D claims to have supercharged 3D printing by making objects grow out of puddles of liquid – a process which may trigger flashbacks of Terminator 2’s T-1000.

The technique uses what it calls CLIP (Continuous Liquid Interface Production) and relies on a photosensitive resin that reacts with UV light to form a solid. By carefully controlling the reaction with the resin, different shapes can be created.

3D Carbon says the technique is 25 to 100 times faster than traditional 3D printing and can create objects from a variety of materials. It says possible uses for finished objects could range from car parts to shoes.

Working with glass

The materials that 3D printed objects can be made from is growing beyond plastics, ceramics and metals and today encompasses sandstone, sugar and living tissue.

Another material that is starting to be used in 3D printing is glass. This glass vase is one of many made by researchers at Massachusetts Institute of Technology.

MIT’s Mediated Matter Group created G3DP, a 3D printer capable of spewing out molten glass. The machine heats the glass as high as 1,165 Celcius in order to melt it, but then gradually lowers temperatures to remove bubbles, reduce stresses and prevent the glass from losing its shape once printed.

​Getting to grips with graphene

Graphene has earned a reputation as something of a wonder material for its high strength, low weight and electrical conductivity.

The material is expected to have an important role to play in developing new electronics and consequently there has been much research into 3D printing graphene structures.

Here you can see graphene oxide being used to create a complex three-dimensional object, as part of work by researchers from Imperial College London and the University of Warwick.

It follows an earlier breakthrough last year, when a team in Korea managed to 3D print graphene nanowires.

​Repairing nerves

Because it is rare for nerves to regrow after injury, nerve damage is often permanent.

US researchers have 3D printed a structure they believe could help encourage damaged nerves to repair themselves.

The team 3D-printed a silicone structure that provided a scaffold for a cut nerve to grow along. Within the silicon structure were chemical cues to promote motor and sensory nerve regeneration.

The structure was implanted into rats with nerve damage, grafted to each end of the cut sciatic nerve. Within about 10 to 12 weeks the rats showed an improvement in their ability to walk again.

To make a suitable silicone guide for the nerves to grow along, researchers used a 3D scanner to model the structure of a rat’s sciatic nerve.

​Recreating living tissue

Japanese firm Cyfuse has created Regenova, a 3D bioprinter that is capable of generating living human tissue by aggregating cells.

The plan is to use these tissue cultures to test new products and, depending on future medical breakthroughs, to use future iterations of the technology to build replacement organs using stem cells.

In September, a study reported that the Regenova was used to create a tubular tissue structure out of human cells, seen above. Copies of the tube were then transplanted into rat aortas, the main arteries running from the animals’ hearts.

Image: Itoh et al

​Printing soft robots and wearables

If we want to use 3D printers to create complex products, such as wearable electronics, then printheads need to become more sophisticated.

To this end, researchers from Harvard have created a printhead that uses an impeller to mix materials before they are pushed out of the nozzle.

Carefully mixing materials in this way allowed for the creation of silicone elastomers with soft and rigid regions that could be used in flexible electronics and soft robotics. The team also demonstrated the printer mixing in conductive and resistive inks on demand, an approach which could be used to embed circuitry in 3D printed objects.

​The softer side of 3D printing

It’s not new to print items out of fabric but it is an area where progress is still being made.

This rabbit was created using a Layered Fabric 3D Printer, which was developed by Disney Research with Carnegie Mellon University.

The machine uses a laser to cut the outline of each layer from felt. This layer is placed on the print bed, where heat-sensitive glue is warmed by the print head. The process is repeated until the object is fully printed and the excess fabric is removed.

The printer can mix two types of fabric in a single object, which Disney Research says could allow for the creation of fabric objects that incorporate embedded circuits.

​Snapping to attention

What if everyday objects could build themselves? If tables could snap into shape when you got them home.

Welcome to the world of “4D printing” and programmable matter, which focuses on creating objects capable of self-assembly or repair.

At MIT’s Self-Assembly Lab researchers are building items that can reshape themselves, thanks to the specially-treated materials they’re made from.

One of the demos from the lab is this flat arrangement of 2D squares, which folds itself into a cube.