University of Minnesota
Department of Biomedical Engineering
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Taner Akkin

Taner Akkin

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Biomedical Optics and Imaging

Dr. Akkin's research interests lie in the development of interferometric techniques to image depth-resolved tissue micro-structures and function. Non-invasive or minimally invasive applications in medicine are possible, since the techniques use back-scattered light.

Transient structural changes during neural activity are directly related to the action potential propagation. Non-contact optical measurement of these fast (~1 millisecond) and small (~1 nanometer) changes has been recently reported by using differential phase contrast optical coherence tomography. The measurements do not require exogenous chemicals or reflection coatings that may harm the nerve. The optical method can also produce cross-sectional images to select a particular region of neural tissue for functional interrogation. The objective of this research is to elucidate the origin of the transient structural changes and its contributions to the optical signals of neural activity. Successful development of an optical measure may yield a non-contact diagnostic toll in the future.

Sub-nanometer resolution obtained by differential phase techniques allows quantitative phase-contrast microscopy in reflection geometry. Dynamic processes in the cell can be observed for diagnostic and therapeutic applications. Investigation of cellular and sub-cellular level events is crucial not only in tissue-drug interactions but also in certain abnormalities. For example, the nucleus is enlarged and becomes dense in cancer cells. In this case the quantitative phase microscope would detect early changes in cellular morphology with enhanced lateral and longitudinal resolution.

Optical coherence tomography, which uses amplitude of the interference, has been extensively applied to non-invasive structural imaging in ophthalmology and dermatology. Currently, real-time images of tissue microstructures can be acquired with 2-10 micrometer axial resolution. In this field, the focus of our Biomedical Optics Laboratory will be development of custom made systems for disease-oriented applications.

Selected Publications

Akkin T, Landowne D, and Sivaprakasam A; 'Detection of neural action potentials using optical coherence tomography: Intensity and phase measurements with and without dyes,' Frontiers in Neuroenergetics, 2:22:1-10 (2010).

Al-Qaisi MK, and Akkin T; ' Swept-source polarization-sensitive optical coherence tomography based on polarization-maintaining fiber,' Optics Express 18: 3392-3403 (2010).

Wang H, Al-Qaisi MK, and Akkin T; 'Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain,' Optics Letters 35: 154-156 (2010). 

Akkin T, Landowne D, and Sivaprakasam A; 'Optical Coherence Tomography Phase Measurement of Transient Changes in Squid Giant Axons During Activity,' Journal of Membrane Biology, 231: 35-46 (2009).

Al-Qaisi MK, Wang H, and Akkin T; 'Measurement of Faraday rotation using phase-sensitive low-coherence interferometry,' Applied Optics, 48: 5829-5833 (2009).

Al-Qaisi MK and Akkin T; 'Polarization-sensitive optical coherence tomography based on polarization-maintaining fibers and frequency multiplexing,' Optics Express 16: 13032-13041 (2008).

Akkin T, Joo C, and de Boer JF; 'Depth resolved measurement of transient structural changes during action potential propagation,' Biophysical Journal, 93: 1347-1353 (2007).

Joo C, Akkin T, Cense B, Park BH, and de Boer JF; ‘Spectral domain optical coherence phase microscopy for quantitative phase contrast imaging,' Optics Letters, 30: 2131-2133 (2005).

Mujat M, Chan RC, Cense B, Park BH, Joo C, Akkin T, Chen TC, and de Boer JF; ‘Retinal nerve fiber layer thickness map determined from optical coherence tomography images,' Optics Express, 13: 9480-9491 (2005).

Akkin T, Davé DP, Milner TE, and Rylander-III HG; ‘Detection of neural activity using phase-sensitive optical low-coherence reflectometry,' Optics Express, 12: 2377-2386 (2004).

Larin KV, Akkin T, Motamedi M, Esenaliev RO, and Milner TE; ‘Phase-Sensitive Optical Low-Coherence Reflectometry for Detection of Analyte Concentration,' Applied Optics, 43: 3408-3414 (2004).

Youn J, Akkin T, and Milner TE; ‘Electrokinetic measurement of cartilage using differential phase optical coherence tomography,' Physiological Measurement, 25: 85-95 (2004).

Rylander CG, Davé DP, Akkin T, Milner TE, Diller KR, and Welch AJ; ‘Quantitative phase-contrast imaging of cells with phase-sensitive optical coherence microscopy,' Optics Letters, 29: 1509-1511 (2004).

Telenkov SA, Davé DP, Sethuraman S, Akkin T, and Milner TE; ‘Differential phase optical coherence probe for depth-resolved detection of photothermal response in tissue,' Physics in Medicine and Biology, 49: 111-119 (2004).

Akkin T, Davé DP, Youn J, Telenkov SA, Rylander-III HG, and Milner TE; ‘Imaging tissue response to electrical and photothermal stimulation with nanometer sensitivity,' Lasers in Surgery and Medicine, 33: 219-225 (2003).

Davé DP, Akkin T, and Milner TE; ‘Polarization-maintaining fiber-based optical low coherence reflectometer for birefringence characterization and ranging,' Optics Letters, 28: 1775-1777 (2003).

Davé DP, Akkin T, Milner TE, and Rylander-III HG; ‘Phase-sensitive frequency-multiplexed optical low-coherence reflectometry,' Optics Communication, 193: 39-43 (2001).

Akkin T, and Saliu S; 'Estimation of evoked potentials using total least squares Prony techinque,' IEE Medical & Biological Engineering & Computing, 36: 544-548 (1998).