As an alternative to invasive and time-consuming biopsies, scientists have fitted a microscopic image sensor in an endoscope for in vivo cancer diagnosis. The fiber transmits the laser light to the microscanner mirror. Both are fitted into the tip of the endoscope. (Image: Fraunhofer IPMS) With the hope of reducing the time and stress involved with biopsies, scientists at the Fraunhofer Institute for Photonic Microsystems (Fraunhofer IPMS) have developed a microscope head with a diameter of just 8 mm which can optically resolve and magnify tissue cells measuring just 10 to 20 µm. Fitted in the tip of an endoscope it will be used for in vivo cancer diagnosis, inserted in the body as in a minimally invasive surgical operation. The scientists envision that the micro-electro-mechanical system (MEMS) microscope head will eliminate the need for biopsies. Diagnosis in real time would enable doctors to decide on the necessary course of treatment more quickly. “Microscopic image recorders that can be used on endoscopes have not been available up to now. We have developed the first laser-based sensor for this purpose,” said Dr. Michael Scholles, business unit manager at the IPMS. “In classic endoscopy using macroscopic imaging, the job can be done by CCD or CMOS image sensors, as used in digital cameras and cell phones. For endomicroscopy, however, MEMS-based image sensors are highly advantageous because they can magnify even the smallest object fields, such as cells, without the need for a large lens. We have combined the sensor with a microscanner mirror to achieve the required resolution of 10 micrometers and can therefore massively magnify the tiniest structures.” But how does the system function? The laser itself is located in the operating theater. The laser light is conducted via a transmitting fiber to the microscanner mirror fitted in the tip of the endoscope. This deflects the laser beam and illuminates the suspicious tissue specifically. A glass-fiber bundle in the tip of the endoscope transmits the reflected light to the external sensor, which thus receives a signal containing the image information. A detector precisely measures the position of the scanner mirror, indicating which area of the scene is being illuminated at the specific point in time. A two-dimensional image can thus be completely reconstructed by combining the position and image sensor signals. “An important aspect of the development was to produce a suitable microassembly for the endoscope head. Here we faced the challenge of making the complete system suitable for installation in the endoscope, and we managed to do it. In future our microscope head will be produced in large quantities in an automated process for subsequent installation in endoscopes,” said Scholles, adding that he envisions a wide range of applications for the system. “It could be used not only in medical and biological microscopy but also in technical endoscopy, for instance to examine cavities in buildings or to inspect the insides of engines and turbines.” The microscope head has already been produced and will be demonstrated June 15-18 at the Optatec trade show in Frankfurt, Germany (Hall 3, Stand D50). For more information, visit: www.ipms.fraunhofer.de/en/