Researchers in the Netherlands have come up with a new advance in the science of metamaterials -composite materials with unique properties not found naturally in their parts- one of which is likely to have applications in the fields of prosthetics, robotics and wearable technology among others.
Using 3D printing, the team created a set of squishable rubber cubes 1 cm 3 in size that when stacked together can be programmed to change shape when compressed by an outside force. These cubic building blocks, called voxels, are specially designed so that they work in concert when compressed. Basically, as one block gets deformed (or squished, really) in a particular way, other blocks around it respond by reforming their shapes as well so as to collectively produce a specified result. In this case, the team programmed the blocks to form a smiley face on one side of the cube stack when compressed, with a mirroring indented smiley face appearing on the opposite side.
“Our building blocks are precisely designed such that, given the polarization of one brick, the polarization of an adjacent brick can be adapted so that the pair have a tight fit, irrespective of their mutual orientation,” say the study’s authors whose work appears in the scientific journal Nature.
The team sees their new textured, shape-sensing and shape-shifting metamaterial to potentially have applications in areas such as prosthetics where materials need to be able to interplay with a person’s body shape to a very high degree, forming complex shapes and making fittings and joint sockets specially designed for a particular individual.
“This type of programmable ‘machine material’ could be ideal for prostheses or wearable technology in which a close fit with the body is important,” says study so-author Yair Shokef from Tel Aviv University in Israel. “If we can make the building blocks even more complex or produce these from other materials, the possibilities really are endless.”
Other recent advances in prosthetics design include a new type of plastic skin that can detect pressure and send electric signals to a person’s brain. Researchers at Stanford University in Palo Alto, California, created a material which combines a unique rubber-like substratum that can sense differing degrees of pressure and a latticework of nanowires that can bend and stretch while still transmitting a signal. Also the product of an advance in printing technology, the electronic skin uses a souped up version of an inkjet printer to create its pressure-sensitive material.
“When we apply small pressure there are only a few spikes are produced. Whereas when we apply larger pressure spikes are produced more frequently, which is the way the human brain encodes information from pressure,” Stanford researcher Alex Chortos said.
The long-term goal is to develop a material that can be placed over a person’s prosthetic hand or arm and then connected to neurons in the person’s brain, giving the user a new way to sense their surroundings. “When someone uses their prosthetic limb, they’ll have an indication of how much force is being applied when they’re grasping something,” says Stanford researcher Amanda Nguyen.