Flawless. Precise. Intricate. Detailed. With no right or wrong answer, what do those words bring to mind? For some it may conjure up images of a beautiful art masterpiece, others may picture a brilliant-cut diamond, and yes, some may envision medical devices and equipment. A large MRI machine wouldn’t come to mind, but how about a dental implant, a femoral stem, a bone screw, or microstent?
The aging population together with increasing life expectancy represent some of the top drivers for the industry – from implants to wheelchairs, MRI machines, and everything in-between – but demand for smaller, less intrusive devices continues to push the boundaries of design and manufacture. As those boundaries get pushed, the challenge to produce smaller components to fit into smaller places means manufacturing to tighter tolerances and looking at different technologies. There are a lot of examples throughout this issue.
This month’s Medical Innovations section highlights Swiss researchers who produced a 0.05mm x 0.50mm microstent with highly detailed structures measuring 100µm in diameter. While not ready for real-world application, these stents are 40x smaller than any manufactured to date.
The researchers use heat from a laser beam to cut a three-dimensional template – 3D negative – into a micro-mold layer that can be dissolved with a solvent. They then fill the negative with a shape-memory polymer and set the structure using ultraviolet (UV) light. Finally, they dissolve the template in a solvent bath and the three-dimensional stent is finished.
It’s the stent’s shape-memory properties that give it its fourth dimension. Even if the material is deformed, it remembers its original shape and returns to this shape when warm. The extra dimension generated the process’ name – indirect 4D printing. Pediatric surgeon Gaston De Bernardis explains how this would work to address urinary tract constrictions in gestating fetuses. First compressed, the stent can be pushed through the affected area and once in place, it returns to its original shape, widening the constricted area of the urinary tract.
However, in utero surgery on gestating fetuses is not the only place small devices are needed. What about those living with Parkinson’s disease? Deep brain stimulation (DBS) implantable devices, such as Boston Scientific’s Vercise directional DBS, deliver mild electrical stimulation to specific regions in the brain through implants powered by an implantable pulse generator (IPG) inside the person’s chest. And everything in the systems needs to be small, as Boston Scientific’s Vercise uses eight individually controlled electrodes on each lead to better manage the stimulation field.
Now, while the smart, customizable knee orthosis featured on our cover this month isn’t tiny, combining mechanical design elements with embedded electronics – microcontrollers, sensors, radio frequency (RF) connectivity – forms smart parts that enable customized products.
As medical manufacturers continue to push the envelope on how small devices can go, advancements such as memory materials open up more opportunities. So give it time, parts will continue to get smaller.
Elizabeth Engler Modic, Editor