Using a new 3D printing process, researchers at the University of Nottingham have discovered how to tailor-make artificial body parts and other medical devices with built-in functionality that offers better shape and durability, while cutting the risk of bacterial infection.

The hope is that the innovative design process can be applied to 3D-print any medical device that needs customizable shapes and functions. For example, the method could be adapted to create a highly bespoke one-piece prosthetic limb or joint to replace a lost finger or leg that can fit the patient perfectly to improve their comfort and the prosthetic’s durability. Or it could be used to print customized pills containing multiple drugs (known as polypills) optimized to release into the body in a pre-designed therapeutic sequence.

Meanwhile, the aging population is increasing in the world, leading to a higher demand for medical devices in the future. Using this technique could improve the health and wellbeing of older people and ease the financial burden on the government.

For this study, the researchers applied a computer algorithm to design and manufacture – pixel by pixel – 3D-printed objects made up of two polymer materials of differing stiffness that also prevent the buildup of bacterial biofilm. By optimizing the stiffness in this way, they successfully achieved custom-shaped and custom-sized parts that offer the required flexibility and strength.

Current artificial finger joint replacements, for example, use both silicone and metal parts that offer the wearer a standardized level of dexterity, while still being rigid enough to implant into bone. However, as a demonstrator for the study, the team was able to 3D-print a finger joint offering these dual requirements in one device, while also being able to customize its size and strength to meet individual patient requirements.

Excitingly, with an added level of design control, the team was able to perform a new style of 3D-printing with multi-materials that are intrinsically bacteria-resistant and bio-functional, allowing them to be implanted and combat infection (which can occur during and after surgery) without the use of added antibiotic drugs.