Catheters are of paramount
importance for minimally invasive surgery. They enable interventions such as
the removal of blood clots, the insertion of implants, or the targeted
administration of drugs, and are intended to be particularly gentle for
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 instance, previously developed
sensors and actuators were still integrated by hand into electronic catheters.
In addition, control, and placement of catheters in the body are limited,
because the tiny instruments have to be maneuvered externally by the surgeon in
a complex environment or placed with robotic assistance. This has significant
disadvantages for miniaturization and the use of flexible structures that need
to adapt to the body for particularly gentle use in surgery. It has also been
difficult to integrate additional sensors and functions into micro-catheters,
which hampers their potential applications.
Under the supervision of Prof. Dr. Oliver G. Schmidt, head of
the Professorship for Material Systems for Nanoelectronics, designated
Scientific Director of the Center for Materials, Architectures and Integration of Nanomembranes (MAIN) at Chemnitz University of Technology and
former Director at the Leibniz Institute for Solid State and Materials Research
(IFW Dresden), scientists at IFWDresden in cooperation with the Max Planck Institute for Molecular Cell Biology and Genetics (CBG) have now presented the world's tiniest
flexible, microelectronic microcatheter.
Smart
functions – as thin as a hair
In this smart microelectronic tool for minimally invasive
surgery, the electronic components for sensors and actuators are already
integrated into the catheter wall from the outset. "Due to the special
manufacturing method, the embedded electronic components 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 graduation
at Chemnitz University of Technology and his dissertation at Leibniz IFW
Dresden. The instruments have a tiny diameter of only 0.1 mm and are also
characterized by their flexibility, resilience, and high biocompatibility.
"Using microchip technologies to manufacture the microcatheters allows us
to generate completely new types of biomedical and multifunctional tools,"
adds Prof. Schmidt. Such smart tools could be used, for example, in minimally
invasive treatments of aneurysms, vascular malformations, or pancreatic
surgery.
The research team reports on the World’s smallest
Microelectronic Catheter in a publication entitled "Electronically
integrated microcatheters based on self-assembling polymer films" in the current issue of the prestigious journal Science Advances.
Flexible
and equipped for diverse applications
Prof. 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 thus be applicable in deep tissue and under dense
materials such as skull bones.
The microelectronic microcatheter integrates a channel for
fluids. Through this microfluidic system drugs or liquid embolic agents could
be delivered directly to the point of use. The catheter tip is equipped with a
tiny gripping instrument that allows the catheter to grasp and move microscopic
objects. The removal of minute tissue samples or blood clots are suggested as
potential applications. This highly flexible use of embedded microelectronics
is made possible by integrated electronic components based on the Swiss-Roll
Origami Technology. By this technology the team can construct highly complex
microelectronic sensor and actuator circuits on a chip, which are then
triggered to roll up by themselves into a Swiss-Roll microtube structure. The
multiple windings of the Swiss-Roll architecture significantly increase the
usable surface area and monolithically integrate sensors, actuators and
microelectronics into the compact wall of the tubular microcatheter.
Prof. Schmidt and his team have pioneered this technology for
some time. Extremely thin, shapeable polymer films have proven useful for a
microtube architecture that can geometrically adapt to other objects, for
example, cuff implants as bioneural interfaces. Another
application scenario targeted by this technology are catalytic micromotors and
platforms for electronic components to create microelectronic swimming robots.
The microelectronic microcatheter bridges the gap between
electronically enhanced instruments and the size requirements of vascular
interventions in submillimeter anatomies. In the future, additional sensor
functions can be integrated, expanding the range of potential applications. For
example, sensors for blood gas analysis, biomolecule detection, and sensing
physiological parameters such as pH, temperature, and blood pressure are
conceivable. Entirely new and flexible applications for minimally invasive
surgery are coming into the realm of possibilities.