Scientists Use 3D Printing Technology To Develop Self-sensing PEEK

A team of engineers led by the University of Glasgow used 3D printing technology to add new properties to a plastic called polyetheretherketone or PEEK. This new lightweight, impact-resistant plastic "honeycomb" structure can sense when it is damaged and can be used in new "smart" prostheses and medical implants.

Convert non-conductive materials into conductive materials

PEEK's mechanical properties, high temperature and chemical resistance make it suitable for a wide range of applications in the aerospace, automotive, and oil and gas fields. The team added micro-sized carbon fibers to its honeycomb PEEK structure, allowing this normally non-conductive material to carry electrical charges throughout its structure.

They wanted to study whether damage to the conductive honeycomb PEEK composite material would affect its electrical resistance. If so, it can give the new material the ability to "perceive itself"—for example, allowing a hip implant to report when its conductivity has changed, indicating that it has worn out and needs to be replaced.

Different honeycomb combinations

In order to test the self-sensing ability of their design, they used 3D printing to create three different honeycomb structures: hexagonal structure, cross-shaped chiral structure, and six-sided foldback design using carbon fiber PEEK material and traditional materials.

Then, they put the cell structure under two types of loads to compare their respective energy absorption capabilities. In the squeeze test, a consistent pressure is applied before the structure collapses. Each design of carbon fiber PEEK outperforms its traditional PEEK counterparts, which can withstand higher pressures.

However, in the impact test, when a heavy object falls on the structure from a height, the three carbon fiber PEEK structures show stronger damage resistance. The hexagonal honeycomb structure of carbon fiber PEEK has the best response and can withstand greater impact than any other.

In the crush test, the researchers also measured the resistance of the carbon fiber PEEK honeycomb structure to electric charges when three different structures were strained. The change in the applied strain resistance—a measure of damage progression known as piezoresistive sensitivity—decreases as the compressive strain increases. When the structure is completely crushed, the resistance is almost completely lost. The different specification factors observed for different configurations are related to the damage growth rate related to their ability to absorb energy, which indicates that the piezoresistive properties of carbon fiber PEEK may help create a new generation of smart lightweight multifunctional structures.

Future applications in many industries

Researchers say that the unique properties of PEEK make it invaluable to many industrial sectors, and we hope that the structure of carbon fiber engineering PEEK honeycomb we can build through 3D printing will open up more possibilities.

3D printing allows us to greatly control the design and density of the honeycomb structure. Compared with solid metal alloys traditionally used for medical implants such as hip or knee replacements, this may allow us to create materials that are closer to the physiology of natural bones, which may make them more comfortable and effective .