Over the last few decades, the use of modern optics technology for biomedical research and health care has been dramatically growing so fast. It has resulted in increased attention towards the study of Biophotonics, which is a highly cross-disciplinary scientific field. Biophotonics covers a broad range of topics that rises on the generation of laser radiation and interactions between laser light and tissue for minimally invasive manipulation, detection, and monitoring of biological tissues. Besides being a cross-disciplinary research field, the translation of technologies from laser physics, optoelectronics, fiber optics, biophysics, and optical imaging into a common point to aid the development of new generation biomedical instrumentations for point-of-care diagnostics and therapy is the unique and extremely valuable part of Biophotonics.
At Translational Biophotonics and Optical Imaging Lab, our focus is to develop and translate novel optical technologies and methods (using laser-tissue interactions and noninvasive optical coherence imaging modalities) that address challenges in biomedical applications through a multi-disciplinary approach including Electrical Engineering, Optical Engineering, Physics, Biophysics and Biology, and making close professional collaborations with clinicians.
We envision that future advances in Biophotonics and Optical Imaging will be used as leverage in the development of new generation biomedical instrumentations for point-of-care diagnostics and therapy, resulting in a direct benefit to patients’ quality of life. To help reach this envision, we attach priority to translational and novel R&D through a methodology which is a multi-disciplinary approach including optics, photonics, laser physics, engineering, and biology.
Our research direction spans from basic physics of light-tissue interactions to optical coherence imaging systems. Main topics of our research interests can be summarized as follows: Development of new wavelength-stepped and wavelength-swept laser sources, Swept-source Optical Coherence Tomography, Development of optical laparoscopic probes, and Infrared laser nerve stimulation.
1) A Potential Diagnostic Technique: Optical Nerve Stimulation
Optical Nerve Stimulation that uses continuous-wave laser radiation at near-infrared (near-IR) has been reported as a potential alternative to a conventional technique called Electrical Nerves Stimulation. Optical Nerve Stimulation method may have significant advantages compared with Electrical Nerve Stimulation for both scientific studies and clinical applications. First, it is a non-contact method of stimulation because the near-IR laser radiation is delivered in a non-contact mode. Second, spatial selectivity is improved because the laser beam can be focused down smaller than a typical electrode and the problem of the electrical current spreading out in the tissue is eliminated for Optical Nerve Stimulation. Finally, when stimulating a nerve optically and measuring responses electrically, or by another means, electrical stimulation artifacts are eliminated. At Translational Biophotonics and Optical Imaging Lab, we perform development studies of nerve mapping devices and Optical Nerve Stimulation technique, which may be promising for real-time, intra-operative identification and preservation of the nerve bundles during clinic operations.
The figure shows thermal images of the rat cavernous nerve before and during Optical Nerve Stimulation. The temperature of the nerve just before laser irradiation was at a baseline level of 33.9 °C. The nerve reached a peak temperature of 43.3 °C during laser irradiation, which was just above the nerve stimulation threshold.
2) Therapy: Development of Endoscopic Therapy Device
Inflammation in the lining of the esophagus caused by chronic reflux of acid into the esophagus may result in precancerous conditions of the esophagus and may associate with esophageal cancer (adenocarcinoma of the esophagus). There are several treatment options including medication, endoscopic mucosal resection, and endoscopic ablation therapy. However, there is still a need for a device that produces minimally destructive tissue damage in the endoscopic mucosal treatment of esophagus over large areas. Our team works on new designs of endoscopic devices that are able to remove the diseased tissue layer in safe, effective, cost-effective, efficient, single-session, and a reliable manner.
Figure shows an OCT image of swine esophagus taken by newly developed endoscopic probe.
3) Optical Imaging: Swept-Source Optical Coherence Tomography
Swept-Source Optical Coherence Tomography (SS-OCT) systems operating at MHz A-line rates provide higher imaging speeds that offer new capabilities for rapid volumetric OCT angiography and blood flow imaging. With this feature, OCT technology can be leveraged to enable more extensive oversampling of each location to improve flow quantification, or to provide rapid measurement of perfusion and pulsatile dynamics within a volume. Here, we develop an angiographic system composed of a novel swept wavelength source integrated with an MEMs-based fast-axis scanner. This new generation SS-OCT system provides rapid acquisition of volumes on which a range of Doppler and intensity-based angiographic analyses can be performed. Besides the rapid imaging, the laser source and data acquisition computer can be directly phase-locked to provide an intrinsically phase stable imaging system. With this interesting feature, it is possible to support Doppler measurements without the need for individual A-line triggers or post-processing phase calibration algorithms.
The figure shows a schematic of the novel OCT system that provides MHz A-line rates while having phase coherence between each A-lines for a long period of time.
Siddiqui M, Nam AS, Tozburun S, Lippok N, Blatter C, Vakoc BJ.
High-speed optical coherence tomography by circular interferometric ranging.
Tozburun S, Blatter C, Siddiqui M, Meijer EFJ, Vakoc BJ.
Phase-stable Doppler OCT at 19 MHz using a stretched-pulse mode-locked laser.
Biomedical Optics Express.
Tokel O, Turnali A, Makey G, Elahi P, Çolakoğlu T, Ergeçen E, Yavuz Ö, Hübner R, Borra MZ, Pavlov I, Bek A, Turan R, Kesim DK, Tozburun S, Ilday S, Ilday FÖ.
In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon.
on Biophotonics and Optical Imaging
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