Innovative drill wins "International Bionic Award 2014"

Drilling like the wood wasps – inspired by the wood wasps: A new type of drill is designed to help surgeons insert hip prostheses. (Source: Fraunhofer IPA)

Inspired by woodwasps: A new type of drill is designed to help surgeons insert hip prostheses. It received the 2nd prize at the International Bionic Award 2014.

Every year, around 200,000 patients in Germany receive artificial hip joints. During this complex operation, the orthopedist drills a large, rectangular cross-section hole into the thigh bone. Precision is crucial to ensure the implant fits tightly and no cavities form. Because cement backing would shorten the durability of the artificial joint. Nonetheless, surgeons largely work manually with various rasps.

A team led by biotechnologist Oliver Schwarz from the Fraunhofer Institute for Production Technology and Automation IPA in Stuttgart has now developed a pneumatically operated device that could significantly ease the work and increase precision. Since the drill takes inspiration from nature, the scientist submitted it for the "International Bionic Award," where it was awarded 2nd place. This bionics prize, established in 2008 by VDI and the Schauenburg Foundation, is awarded every two years and is endowed with 10,000 euros. This year's award ceremony took place on October 24 in Bremen.

The innovative drill can bore holes with a rectangular cross-section because it operates on an unusual principle. Schwarz was inspired by parasitic wasps and, together with his team, transferred this principle into technology. Many species of wood- and parasitic wasps bore holes up to 6 centimeters deep into wood to lay their eggs. Since they cannot rotate, they carve out the cavities in the trunk in a highly clever manner. Their ovipositor consists of three separate rasps that can move independently. A guiding rail ensures the parts stay together. During drilling, the rasp trio moves back and forth in a sophisticated pendulum motion, automatically carving into the wood. Engineers refer to this as the pendulum stroke principle. While one part moves, the other hooks into the hole, providing the necessary grip. This way, the insect does not need to press its delicate stinger like a drill would.

Usable even in space or underwater

This drilling technique offers significant advantages over conventional methods, not only for surgeons. Most notably, it is not limited to round holes. Since nothing rotates, holes with three- or multi-sided cross-sections can also be created. A plug would hold much better because it cannot spin. Additionally, a pendulum stroke drill hardly needs to be pressed. It could even be used in space or underwater, where applying large counterforces is difficult. First tests have shown it is especially suitable for porous materials like bone. The bone drill for hip surgeries is expected to weigh about 1.5 kilograms and fit comfortably in the hand. The designers coordinated with doctors to find an optimal design. The multi-part rasp head can be easily replaced with a simple hand movement and swapped out for another. To sterilize the device, it can be disassembled without difficulty. Once a interested company is found, the Stuttgart team plans to build a prototype. For non-medical drilling applications, it is already being further developed for a well-known company.