SMART PILL · New optical functions for endoscopic capsules

New optical functions for endoscopic capsules

The passive endoscopic capsule (EC) was invented a decade ago and has proven a major technological breakthrough in medical technology that has facilitated an unprecedented level of patient-friendly diagnosis of small bowel diseases. The propulsion of commercially available passive ECs is provided by the natural motility of the intestine, known as peristalsis. Moreover, the EC vision system uses only white-light and a CMOS imager that collects the images (2-4 frames per second). Before ingestion of the capsule, an antenna array is taped to the patient’s anterior abdominal wall and connected to a data recorder carried by the patient. This project addresses several innovations in advanced diagnostic imaging techniques of the EC that would contribute to enhance the diagnostic: narrow band imaging (NBI) and magnification of the image (ENIM). Also, for the first time a therapeutic function, photo-dynamic therapy (PDT), which is a technique for clinical treatment of several types of Gastrointestinal (GI) cancers, can be integrated in ECs. All technical specifications were implemented by taking into account the recommendations of the medical doctors that are collaborating with the project. 1.Narrow Band Imaging (NBI) Besides the white light usually applied in the capsule endoscopic exams, it is necessary the implementation of different light sources in particular wavelengths. This can be accomplished using dedicated LEDs (Light Emitting Diodes) that illuminate the gastrointestinal (GI) mucosa at 415 nm (blue) and 540 nm (green). However, commercial available LEDs do not have this specific range of illumination. Therefore, thin-film optical filters (in this case based on Fabry-Perot interferometer) must be placed on top of green and blue LEDs to obtain the two wavelengths: 415 nm (blue) and 540 nm (green). Commercially LEDs available, as basis, were used and optical filters based on Fabry-Perot interferometer were designed, simulated and fabricated by semiconductor technology equipment. 2.Endomicroscopic imaging module (ENIM) This feature consists in the optical design of an endomicroscopic imaging module (ENIM). The integration of ENIM in the smart pill represents a breakthrough over the procedural state of the art in both capsule endoscopy and normal flexible endoscopy. ENIM function will allow high magnification imaging for the first time available to ECs. A miniaturized ENIM with total length of 12 mm and a lateral lens assembly of 3.9 mm. The development of an ENIM comprises the integration of 4 microlenses for magnification (3 commercial microlenses plus a custom-made PDMS lens). A microfabricated PDMS lens was included in the system, obtained by a hanging droplet approach, a very-low cost and effective method. A paraxial magnification between 5-14 times was achieved with a Modulation Transfer Function (MTF) around 38% at 50 lp/mm and maximum distortion about 1.8%. 3.Photodynamic therapy (PDT) An optic module of photodynamic therapy (PDT) for endoscopic applications was integrated in ECs. The integration of a PDT optic module in endoscopy instruments would be a breakthrough in minimally invasive treatment of several types of gastrointestinal cancers. The PDT uses a photosensitizer and light with specific wavelength to destroy tumor tissue. The photosensitizer considered in this work, Foscan® or meta-tetrahydroxyphenyl chlorine (mTHPC), is one of the most powerful photosensitizer currently available. This photosensitizer needs a small dose (0.15 mg/kg) and light dose (5 20 J/cm2) to obtain a very good photodynamic activity. The wavelength of light of maximum absorption of Foscan® is 652 nm. A red light source was built with commercials LEDs at 652 nm to evaluate the efficiency of Foscan® together with red light source. Impact The global capsule endoscopy market (only ‘conventional’ capsule endoscopes with whitelight vision) is the fastest growing market in the GI endoscopy sector. It is expected to rise from USD 186.9 million in 2010 to USD 323.6 million in 2017. This forecast considers increased adoption of capsule endoscopy for the present and new market segments and the availability of high definition imaging systems as driving factors for the market growth. This market is today dominated by Medtronic (after a take-over of Given Imaging-Israel in June of 2014). The Smart Pill project opened new market segments, through the implementation of advanced bio-photonic diagnostic capabilities and a therapeutic solution with PDT. The Smart Pill points a strong differentiation features and IPR protection for these new optical functions are in preparation. Most of the endoscopy industrial companies were contacted through the oriented promotion and participation in conferences and workshops with major European organization operating in medical care and vision systems. Prof. Reinoud Wolffenbuttel was the scientific responsible and his contacts: Electronic Instrumentation Laboratory Delft University of Technology Faculty of Electrical Engineering, Mathematics and Computer Science Department of Micro-electronics and Computer Engineering Mekelweg 4 2628 CD Delft The Netherlands Room: HB 15.030 Phone: +31 15 27 86287 Fax: +31 15 27 85755 http://ei.ewi.tudelft.nl/ei/index.php/research-groups/wolffenbuttel-group/sub/people-wolffenbuttel/101-reinoud-wolffenbuttel

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