The Laboratory for Microoptics at the Institute of Microsystems Technology (IMTEK) at the University of Freiburg has developed an innovative endoscopic probe. The probe enables the examination of tissue inside the human body without causing damage and with a previously unequalled resolution (fraction of the human hair). An integrated tiltable mirror at the tip of the endoscope provides the user with an all-round view. A tunable microlens enables the user to focus on different tissue depths. The new method enables three-dimensional images to be recorded and may in future considerably increase the range of available diagnostic methods.
Endoscopy is a minimally invasive, modern medical method that has long been standard in clinical applications where it is used to examine internal tissue of the human organ. Surgery involving endoscopy is minimally invasive since the endoscope can be inserted in natural body channels or very small surgical openings. In order to make this possible, the head of the endoscope needs to be as small as possible without affecting the functionality of the endoscope. Conventional endoscopes are limited in terms of miniaturisation.
However, microsystems technology enables new dimensions to be tapped: The miniaturisation of microsystems integrated in an endoscope, for example microlenses or tiltable micromirrors, results in the significant miniaturisation of endoscopic probes. A medically highly attractive method for the minimally invasive diagnosis of diseases is optical coherence tomography (OCT). Harmless infrared light enters the body to analyse the tissue below the body surface without needing to make an incision. OCT is able to penetrate significantly deeper into the scattering medium and differentiate very fine organ structures (about ten times smaller in size than the diameter of a human hair). It is thus far superior to ultrasound examinations.
The Laboratory for Microoptics at the IMTEK couples optical coherence tomography with endoscopy and for the first time enables tissue examinations in the body using harmless optical rays. The IMTEK researchers have combined an endoscopic probe with an OCT system, including tiltable mirror and a tunable lens, whose focal distance can be changed dynamically. This enables the application of OCT in the body, which leads to three-dimensional images of a uniformly high lateral resolution and high contrast. This promises to be of value in medical diagnostics, particularly for the examination of restrictions of human arteries, the early detection of tumours without needing to remove tissue, and for obtaining cross-sectional scans of narrow body channels such as the oesophagus and intestinal tract.