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Catheters are of paramount importance for minimally invasive surgery. They allow interventions such as the removal of blood clots, the placement of implants or the targeted administration of drugs, and are intended to be particularly gentle on patients. In general, the less invasive the catheter procedure, the lower the risk of medical complications and the shorter the recovery time.

However, there are limits. For example, previously developed sensors and actuators were still hand-integrated into electronic catheters. Additionally, control and placement of catheters in the body is limited, as the tiny instruments must be externally maneuvered by the surgeon in a complex environment or placed with robotic assistance. This has significant drawbacks for miniaturization and the use of flexible structures that must adapt to the body for particularly gentle use in surgery. It has also been difficult to integrate additional sensors and functions into microcatheters, which hampers their potential applications.

Under the supervision of Teacher. Dr. Oliver G. Schmidt, Head of the Chair of Materials Systems for Nanoelectronics, appointed Scientific Director of the Center for Materials, Architectures and Integration of Nanomembranes (MAIN) at Chemnitz University of Technology and former director of the Leibniz Institute for Solid State and Materials Research (IFW Dresden), scientists at IFWDresden in collaboration with the Max Planck Institute for Molecular Cell Biology and Genetics (CBG) have now introduced the world’s smallest flexible microelectronic microcatheter.

Smart functions – as thin as a hair
In this smart microelectronic tool for minimally invasive surgery, the electronics for sensors and actuators are already integrated into the catheter wall from the start. “Due to the special manufacturing method, the on-board electronics have no effect on the size of our catheters, which can thus be as thin as a single hair,” says Boris Rivkin, lead author of the study, who is pursuing his doctoral studies. at Chemnitz University of Technology and his thesis at Leibniz IFW Dresden. The instruments have a small diameter of only 0.1 mm and are also characterized by their flexibility, resilience and high biocompatibility. “Using microchip technologies to manufacture microcatheters allows us to generate completely new types of biomedical and multifunctional tools,” adds Professor Schmidt. These smart tools could be used, for example, in minimally invasive treatments for aneurysms, vascular malformations or pancreatic surgery.

The research team reports on the world’s smallest microelectronic catheter in a publication titled “Electronically integrated microcatheters based on self-assembling polymer films” in the current issue of the prestigious journal Scientists progress.

Flexible and equipped for various applications
Professor Schmidt and his team integrated magnetic sensors for navigation and positioning into the micro-catheter. Like a compass, this tracking relies on weak magnetic fields instead of harmful radiation or contrast agents, and would therefore be applicable in deep tissues and under dense materials such as skull bones.

The microelectronic microcatheter incorporates a fluid channel. Using this microfluidic system, drugs or liquid embolic agents could be delivered directly to the point of use. The tip of the catheter is fitted with a tiny grasping instrument that allows the catheter to grasp and move microscopic objects. Removal of tiny tissue samples or blood clots are suggested as potential applications. This very flexible use of embedded microelectronics is made possible by integrated electronic components based on Swiss-Roll Origami technology. Using this technology, the team can build highly complex microelectronic sensor and actuator circuits on a chip, which are then triggered to roll themselves into a Swiss-Roll microtube structure. The multiple windings of the Swiss-Roll architecture dramatically increase usable surface area and monolithically integrate sensors, actuators, and microelectronics into the compact wall of the tubular microcatheter.

Professor Schmidt and his team have been pioneering this technology for some time. Extremely thin and shapeable polymer films have proven useful for microtube architecture that can geometrically adapt to other objects, for example, cuff implants like bioneural interfaces. Another application scenario targeted by this technology are catalytic micromotors and electronic component platforms to create microelectronic swimming robots.

The microelectronic microcatheter bridges the gap between electronically enhanced instruments and the size requirements of vascular interventions in sub-millimeter anatomy. In the future, additional sensor functions can be integrated, thus expanding the range of potential applications. For example, sensors for blood gas analysis, detection of biomolecules and detection of physiological parameters such as pH, temperature and blood pressure are conceivable. Entirely new and flexible applications for minimally invasive surgery enter the realm of possibilities.