18. October 2016
Unobstructed views inside the human body
The novel coating means that endoscope lenses are no longer contaminated by bodily fluids which stick to the lens surface like honey. Image: Harvard University/Nicolas Vogel
A team of physicians and materials scientists headed by Harvard scholar Prof. Joanna Aizenberg, working in close cooperation with EAM Prof. Nicolas Vogel, has developed a novel coating for endoscope lenses that reduces the impairment of vision caused by body fluids. Endoscopy is frequently used in contemporary medical and diagnostic procedures. However, a fundamental problem in endoscopy is vision loss caused by contamination of the lens with body secretions. This impedes accurate control of the endoscopy device which makes a visual diagnosis difficult and can even cause injuries to the patient. As a result, treatment times are longer and there is a risk of possible complications because of the need to clean the device or even repeat the procedure. The novel coating for endoscope lenses, developed in the United States and Erlangen, efficiently minimizes the fouling of the instrument.
The inspiration for this innovative coating comes from nature. A genus of carnivorous plants called Nepenthes, more commonly known as pitcher plants, trap insects in a cavity formed by leaves which have such a smooth surface that the insects can no longer climb out. The plants achieve this smoothness by a combination of a porous surface and a suitable surface chemistry to strongly confine a thin film of water within the surface structures. This liquid water film makes the surface extremely slippery. Insects are unable to gain traction on the surface of the plant and the liquid film causes them to slip into the trap.
In the laboratory of EAM Professor Nicolas Vogel at the Institute of Particle Technology at FAU, the scientists mimic the surface properties of the pitcher plant. A thin layer of silica nanoparticles on a glass surface provided the necessary smoothness. The small size of the structures makes the coating completely transparent – an important prerequisite for its application in endoscopy. The surface of this porous layer is then processed in such a way that instead of water, a thin film of physiologically harmless silicone oil can be infused into the structure provided by the silica particles. Hence, body fluids that come into contact with a modified glass substrate will reside on a thin film of silicone oil, without directly touching the surface underneath. Coatings created in this way have been tested not only under laboratory conditions but also in real clinical practice in a procedure called bronchoscopy, used to inspect lungs. The average time taken to clean the endoscope lens during the procedures and maintain a clear field of vision was reduced from more than one minute to just a few seconds, and even in the presence of severe bleeding the coating ensured that the endoscope retained a clear field of view.
Transparent antifouling material for improved operative field
visibility in endoscopy
Research Area A1
Steffi Sunny, George Cheng, Daniel Daniel, Peter Lo, Sebastian Ochoa, Caitlin Howell, Nicolas Vogel, Adnan Majid, Joanna Aizenberg
PNAS, 2016, 113, 11676 – 11681