A growing number of surgical procedures are being performed with minimally invasive techniques. Surgeons make an incision just a few centimeters long and then use long, thin instruments and needles to reach the target tissue, with their movements guided by imaging technology. However, even the most careful surgeons often have to adjust the needle’s trajectory as they go along, pulling it out and repositioning it. In some cases, the tissue can be extremely hard to reach because it’s tucked away behind an organ, for example. Such probing with a stiff needle can make surgeries last longer and increase the risk of trauma or infection. Now, researchers have developed a new kind of flexible needle (ARC) that addresses this problem. A button on the needle’s handle allows surgeons to correct the needle’s trajectory on the fly, enabling them to reach diseased tissue more quickly and, if needed, explore nearby tissue without pulling the needle out.

The innovative surgical needle developed by engineers from EPFL (Lausanne, Switzerland and the University of Strasbourg (Strasbourg, France) is intended for use in image-guided surgery, and offers greater precision in surgeon’s movements as well as reduces the risk for patients. The needle has the stiffness to make it easier for surgeons to move the instrument exactly as they want along with a tip that surgeons can curve as needed. The entire system is mechanical. When a surgeon slides the button, the inner tube translates and releases one, two or three tiny segments that move in the direction indicated by the bevel of the needle and therefore by the orientation of the surgeon's hand. For now, only the first few centimeters of the tip are flexible, but the system could be modified to extend that.

Using a high-precision process, the engineers were able to make customized needles with diameters of 0.9-4.5 mm so as to cover a wide range of surgical applications. The researchers tested two different types of materials: stainless steel and glass. The stainless steel version is the most advanced because "glass technology is emerging and still requires development. Nevertheless needles are intended for soft-tissue surgery, meaning they won’t have to withstand shocks,” according to the researchers. The flexible needles are almost ready for preclinical trials, and the engineers are actively seeking companies to partner with. The researchers plan to eventually connect high-precision systems to their device in order to give doctors smarter medical equipment.

“We performed resistance tests in silicone which showed that the kind of glass we selected offers numerous benefits: it’s biocompatible, hard to deform, can be used with MRI machines, and doesn’t create reflections that could interfere with images of the area being operated on,” said Charles Baur, an engineer at EPFL’s Instant-Lab (School of Engineering). "It is possible to add additional functions to ensure specific surgical procedures such as electrostimulation, administration of medication on demand or biopsies, to name a few." 

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