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Andrus L, Camli B, Mau T, Ben-Yakar A. Ultrafast Laser Microlaryngeal Surgery for In Vivo Subepithelial Void Creation in Canine Vocal Folds. Laryngoscope 2023; 133:3042-3048. [PMID: 37096749 PMCID: PMC10754041 DOI: 10.1002/lary.30713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/20/2023] [Accepted: 04/09/2023] [Indexed: 04/26/2023]
Abstract
BACKGROUND/OBJECTIVES Tightly-focused ultrafast laser pulses (pulse widths of 100 fs-10 ps) provide high peak intensities to produce a spatially confined tissue ablation effect. The creation of sub-epithelial voids within scarred vocal folds (VFs) via ultrafast laser ablation may help to localize injectable biomaterials to treat VF scarring. Here, we demonstrate the feasibility of this technique in an animal model using a custom-designed endolaryngeal laser surgery probe. METHODS Unilateral VF mucosal injuries were created in two canines. Four months later, ultrashort laser pulses (5 ps pulses at 500 kHz) were delivered via the custom laser probe to create sub-epithelial voids of ~3 × 3-mm2 in both healthy and scarred VFs. PEG-rhodamine was injected into these voids. Ex vivo optical imaging and histology were used to assess void morphology and biomaterial localization. RESULTS Large sub-epithelial voids were observed in both healthy and scarred VFs immediately following in vivo laser treatment. Two-photon imaging and histology confirmed ~3-mm wide subsurface voids in healthy and scarred VFs of canine #2. Biomaterial localization within a void created in the scarred VF of canine #2 was confirmed with fluorescence imaging but was not visualized during follow-up two-photon imaging. As an alternative, the biomaterial was injected into the excised VF and could be observed to localize within the void. CONCLUSIONS We demonstrated sub-epithelial void formation and the ability to inject biomaterials into voids in a chronic VF scarring model. This proof-of-concept study provides preliminary evidence towards the clinical feasibility of such an approach to treating VF scarring using injectable biomaterials. LEVEL OF EVIDENCES N/A Laryngoscope, 133:3042-3048, 2023.
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Affiliation(s)
- Liam Andrus
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, 78712, United States
| | - Berk Camli
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, 78712, United States
| | - Ted Mau
- Department of Otolaryngology-Head and Neck Surgery, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390, United States
| | - Adela Ben-Yakar
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, 78712, United States
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, 78712, United States
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Erdil K, Gürcüoğlu O, Ferhanoğlu O. Electromagnetically actuated 3D-printed tunable optical slit device. APPLIED OPTICS 2023; 62:5244-5250. [PMID: 37707228 DOI: 10.1364/ao.493522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/12/2023] [Indexed: 09/15/2023]
Abstract
This paper presents the design, manufacturing, and characterization of a three-dimensional (3D)-printed and electromagnetically actuated adjustable optical slit structure. The device comprises magnet-attached slits connected to the main frame via two springs controlled by external coils. To analyze the forces acting on the springs and simulate the mechanical behavior of the device, we developed both analytical and finite-element models. After fabricating the device using fused deposition, we conducted a series of tests to evaluate its performance. These tests included (1) analyzing the opacity of the slit blade as a function of its thickness, (2) measuring the temperature increase resulting from the power applied to the coils to determine the operable range of the structure, and (3) evaluating the hysteresis, repeatability, and resolution (minimum step) of the device. The experimental works were crucial to assessing the device's practicality and optimizing its performance for specific applications, which reveals a maximum slit width of ∼450µm, with ∼6.4µm step size within this study. Overall, our developed slit device has the potential to be useful in various optics-related laboratories due to its compatibility with conventional 1-inch (25.4 mm) diameter optomechanical mounts, compact form, low power consumption, and rapid prototyping capability with hybrid materials in a cost-friendly fashion, owing to the 3D-printing technology. We discuss an application where the adjustable slit is employed in a combined laser-scanning microscope and a spectrometer, highlighting its versatility and potential for the future.
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Andrus L, Jeon H, Pawlowski M, Debord B, Gerome F, Benabid F, Mau T, Tkaczyk T, Ben-Yakar A. Ultrafast laser surgery probe for sub-surface ablation to enable biomaterial injection in vocal folds. Sci Rep 2022; 12:20554. [PMID: 36446830 PMCID: PMC9708667 DOI: 10.1038/s41598-022-24446-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/15/2022] [Indexed: 11/30/2022] Open
Abstract
Creation of sub-epithelial voids within scarred vocal folds via ultrafast laser ablation may help in localization of injectable therapeutic biomaterials towards an improved treatment for vocal fold scarring. Several ultrafast laser surgery probes have been developed for precise ablation of surface tissues; however, these probes lack the tight beam focusing required for sub-surface ablation in highly scattering tissues such as vocal folds. Here, we present a miniaturized ultrafast laser surgery probe designed to perform sub-epithelial ablation in vocal folds. The requirement of high numerical aperture for sub-surface ablation, in addition to the small form factor and side-firing architecture required for clinical use, made for a challenging optical design. An Inhibited Coupling guiding Kagome hollow core photonic crystal fiber delivered micro-Joule level ultrashort pulses from a high repetition rate fiber laser towards a custom-built miniaturized objective, producing a 1/e2 focal beam radius of 1.12 ± 0.10 μm and covering a 46 × 46 μm2 scan area. The probe could deliver up to 3.8 μJ pulses to the tissue surface at 40% transmission efficiency through the entire system, providing significantly higher fluences at the focal plane than were required for sub-epithelial ablation. To assess surgical performance, we performed ablation studies on freshly excised porcine hemi-larynges and found that large area sub-epithelial voids could be created within vocal folds by mechanically translating the probe tip across the tissue surface using external stages. Finally, injection of a model biomaterial into a 1 × 2 mm2 void created 114 ± 30 μm beneath the vocal fold epithelium surface indicated improved localization when compared to direct injection into the tissue without a void, suggesting that our probe may be useful for pre-clinical evaluation of injectable therapeutic biomaterials for vocal fold scarring therapy. With future developments, the surgical system presented here may enable treatment of vocal fold scarring in a clinical setting.
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Affiliation(s)
- Liam Andrus
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Hamin Jeon
- Department of Bioengineering, Rice University, Houston, TX, 77005, USA
| | - Michal Pawlowski
- Department of Bioengineering, Rice University, Houston, TX, 77005, USA
| | - Benoit Debord
- GPPMM Group, XLIM, CNRS-University of Limoges, Limoges, France
| | - Frederic Gerome
- GPPMM Group, XLIM, CNRS-University of Limoges, Limoges, France
| | - Fetah Benabid
- GPPMM Group, XLIM, CNRS-University of Limoges, Limoges, France
| | - Ted Mau
- Department of Otolaryngology-Head and Neck Surgery, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Tomasz Tkaczyk
- Department of Bioengineering, Rice University, Houston, TX, 77005, USA
| | - Adela Ben-Yakar
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
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Benboujja F, Hartnick C. Quantitative evaluation of the human vocal fold extracellular matrix using multiphoton microscopy and optical coherence tomography. Sci Rep 2021; 11:2440. [PMID: 33510352 PMCID: PMC7844040 DOI: 10.1038/s41598-021-82157-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/11/2021] [Indexed: 02/07/2023] Open
Abstract
Identifying distinct normal extracellular matrix (ECM) features from pathology is of the upmost clinical importance for laryngeal diagnostics and therapy. Despite remarkable histological contributions, our understanding of the vocal fold (VF) physiology remains murky. The emerging field of non-invasive 3D optical imaging may be well-suited to unravel the complexity of the VF microanatomy. This study focused on characterizing the entire VF ECM in length and depth with optical imaging. A quantitative morphometric evaluation of the human vocal fold lamina propria using two-photon excitation fluorescence (TPEF), second harmonic generation (SHG), and optical coherence tomography (OCT) was investigated. Fibrillar morphological features, such as fiber diameter, orientation, anisotropy, waviness and second-order statistics features were evaluated and compared according to their spatial distribution. The evidence acquired in this study suggests that the VF ECM is not a strict discrete three-layer structure as traditionally described but instead a continuous assembly of different fibrillar arrangement anchored by predominant collagen transitions zones. We demonstrated that the ECM composition is distinct and markedly thinned in the anterior one-third of itself, which may play a role in the development of some laryngeal diseases. We further examined and extracted the relationship between OCT and multiphoton imaging, promoting correspondences that could lead to accurate 3D mapping of the VF architecture in real-time during phonosurgeries. As miniaturization of optical probes is consistently improving, a clinical translation of OCT imaging and multiphoton imaging, with valuable qualitative and quantitative features, may have significant implications for treating voice disorders.
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Affiliation(s)
- Fouzi Benboujja
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA
| | - Christopher Hartnick
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA.
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Andrus L, Mau T, Ben-Yakar A. Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-7. [PMID: 31468749 PMCID: PMC6983523 DOI: 10.1117/1.jbo.24.8.085005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
Ultrafast laser ablation may provide a treatment for vocal fold (VF) scarring. Optical properties of VFs must be known prior to clinical implementation to select appropriate laser surgery conditions. We present scattering lengths of epithelium ℓs , ep, superficial lamina propria ℓs , SLP, and ablation thresholds Fth of human and canine VF tissues. Our experimental approach involves an image-guided, laser-ablation-based method that allows for simultaneous determination of ℓs and Fth in these multilayered tissues. Studying eight canine samples, we found ℓs , ep = 75.3 ± 5.7 μm, ℓs , SLP = 26.1 ± 1.2 μm, Fth , ep = 1.58 ± 0.06 J / cm2, and Fth , SLP = 1.55 ± 0.17 J / cm2. Studying five human samples, we found ℓs , ep = 42.8 ± 3.3 μm and Fth , ep = 1.66 ± 0.10 J / cm2. We studied the effects of cumulative pulse overlap on ablation threshold and found no significant variations beyond 12 overlapping pulses. Interestingly, our studies about the effect of sample storage on the scattering properties of porcine VF show a 60% increase in ℓs , ep for fresh porcine VF when compared to the same sample stored in isotonic solution. These results provide guidelines for clinical implementation by enabling selection of optimal laser surgery parameters for subsurface ablation of VF tissues.
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Affiliation(s)
- Liam Andrus
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Ted Mau
- University of Texas Southwestern Medical Center, Department of Otolaryngology-Head and Neck Surgery, Dallas, Texas, United States
| | - Adela Ben-Yakar
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- University of Texas at Austin, Department of Mechanical Engineering, Austin, Texas, United States
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Temperature and depth evaluation of the in vitro effects of femtosecond laser on oral soft tissue, with or without air-cooling. Lasers Med Sci 2018; 34:649-658. [PMID: 30215183 DOI: 10.1007/s10103-018-2634-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022]
Abstract
Femtosecond laser is an effective and safe tool in many surgeries, but the studies of its effect on oral soft tissue ablation are insufficient. This study aimed to investigate the effect of soft tissue ablation with a 1030-nm femtosecond laser on temperature and depth. Twenty Sprague-Dawley rat tongue specimens were obtained and flat-mounted. The 1030-nm femtosecond laser was controlled by a computer system, with a set distance of 4.7 mm between the laser aperture and soft tissue surfaces. Ten specimens were ablated for > 1 min with or without air-cooling for temperature measurement, while the other 10 specimens were ablated for depth measurements, using the following parameters: (i) 3 W, 2000 mm/s; (ii) 3 W, 4000 mm/s; (iii) 5 W, 2000 mm/s; (iv) 5 W, 4000 mm/s; (v) 8 W, 2000 mm/s; (vi) 8 W, 4000 mm/s. Temperature changes were measured using a type-K thermocouple. The depth attained using different power and scanning speed settings was measured by a three-dimensional morphology measurement laser microscope. Laser power, scanning speed, and air-cooling effects were determined. Higher energy and lower speed induced higher temperatures (p < 0.05), which were significantly decreased by air-cooling (p < 0.05). The lowest ablation depth was obtained at 3 W and 4000 mm/s (72.63 ± 6.47 μm) (p < 0.05). The greatest incision depth was achieved at 8 W and 2000 mm/s (696.19 ± 35.37 μm), or 4000 mm/s (681.16 ± 55.65 μm) (p < 0.05). The 1030-nm femtosecond laser application demonstrates clinically acceptable ablation efficiency, without marked temperature damage, in a controlled manner.
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Conkey DB, Kakkava E, Lanvin T, Loterie D, Stasio N, Morales-Delgado E, Moser C, Psaltis D. High power, ultrashort pulse control through a multi-core fiber for ablation. OPTICS EXPRESS 2017; 25:11491-11502. [PMID: 28788714 DOI: 10.1364/oe.25.011491] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ultrashort pulse ablation has become a useful tool for micromachining and biomedical surgical applications. Implementation of ultrashort pulse ablation in confined spaces has been limited by endoscopic delivery and focusing of a high peak power pulse. Here we demonstrate ultrashort pulse ablation through a thin multi-core fiber (MCF) using wavefront shaping, which allows for focusing and scanning the pulse without requiring distal end optics and enables a smaller ablation tool. The intensity necessary for ablation is significantly higher than for multiphoton imaging. We show that the ultimate limitations of the MCF based ablation are the nonlinear effects induced by the pulse in the MCFs cores. We characterize and compare the performance of two devices utilizing a different number of cores and demonstrate ultrashort pulse ablation on a thin film of gold.
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Li L, Stiadle JM, Lau HK, Zerdoum AB, Jia X, Thibeault SL, Kiick KL. Tissue engineering-based therapeutic strategies for vocal fold repair and regeneration. Biomaterials 2016; 108:91-110. [PMID: 27619243 PMCID: PMC5035639 DOI: 10.1016/j.biomaterials.2016.08.054] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 01/01/2023]
Abstract
Vocal folds are soft laryngeal connective tissues with distinct layered structures and complex multicomponent matrix compositions that endow phonatory and respiratory functions. This delicate tissue is easily damaged by various environmental factors and pathological conditions, altering vocal biomechanics and causing debilitating vocal disorders that detrimentally affect the daily lives of suffering individuals. Modern techniques and advanced knowledge of regenerative medicine have led to a deeper understanding of the microstructure, microphysiology, and micropathophysiology of vocal fold tissues. State-of-the-art materials ranging from extracecullar-matrix (ECM)-derived biomaterials to synthetic polymer scaffolds have been proposed for the prevention and treatment of voice disorders including vocal fold scarring and fibrosis. This review intends to provide a thorough overview of current achievements in the field of vocal fold tissue engineering, including the fabrication of injectable biomaterials to mimic in vitro cell microenvironments, novel designs of bioreactors that capture in vivo tissue biomechanics, and establishment of various animal models to characterize the in vivo biocompatibility of these materials. The combination of polymeric scaffolds, cell transplantation, biomechanical stimulation, and delivery of antifibrotic growth factors will lead to successful restoration of functional vocal folds and improved vocal recovery in animal models, facilitating the application of these materials and related methodologies in clinical practice.
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Affiliation(s)
- Linqing Li
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
| | - Jeanna M Stiadle
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Wisconsin-Madison, Madison, WI 53792, USA; Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Hang K Lau
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
| | - Aidan B Zerdoum
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Xinqiao Jia
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA; Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA; Delaware Biotechnology Institute, 15 Innovation Way, Newark, DE 19711, USA
| | - Susan L Thibeault
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Wisconsin-Madison, Madison, WI 53792, USA; Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI 53792, USA.
| | - Kristi L Kiick
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA; Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA; Delaware Biotechnology Institute, 15 Innovation Way, Newark, DE 19711, USA.
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Yildirim M, Quinn KP, Kobler JB, Zeitels SM, Georgakoudi I, Ben-Yakar A. Quantitative differentiation of normal and scarred tissues using second-harmonic generation microscopy. SCANNING 2016; 38:684-693. [PMID: 27111090 PMCID: PMC6050009 DOI: 10.1002/sca.21316] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 03/03/2016] [Indexed: 05/28/2023]
Abstract
The aim of this study was to differentiate normal and scarred hamster cheek pouch samples by applying a quantitative image analysis technique for determining collagen fiber direction and density in second-harmonic generation microscopy images. This paper presents a collagen tissue analysis of scarred cheek pouches of four adult male Golden Syrian hamsters as an animal model for vocal fold scarring. One cheek pouch was scarred using an electrocautery unit and the other cheek was used as a control for each hamster. A home-built upright microscope and a compact ultrafast fiber laser were used to acquire depth resolved epi-collected second-harmonic generation images of collagen fibers. To quantify the average fiber direction and fiber density in each image, we applied two-dimensional Fourier analysis and intensity thresholding at five different locations for each control and scarred tissue sample, respectively. The resultant depth-resolved average fiber direction variance for scarred hamster cheek pouches (0.61 ± 0.03) was significantly lower (p < 0.05) than control tissue (0.73 ± 0.04), indicating increased fiber alignment within the scar. Depth-resolved average voxel density measurements indicated scarred tissues contained greater (p < 0.005) fiber density (0.72 ± 0.09) compared to controls (0.18 ± 0.03). In the present study, image analysis of both fiber alignment and density from depth-resolved second-harmonic generation images in epi-detection mode enabled the quantification of the increased collagen fiber deposition and alignment typically observed in fibrosis. The epi-detection geometry is the only viable method for in vivo imaging as well as imaging thick turbid tissues. These quantitative endpoints, clearly differentiating between control and scarred hamster cheek pouches, provide an objective means to characterize the extent of vocal fold scarring in vivo in preclinical and clinical research. In particular, this non-invasive method offers advantages for monitoring scar treatments in live animals and following the effects of scarring-related treatments such as application of steroids or drugs targeting pathways involved in fibrosis. SCANNING 38:684-693, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Murat Yildirim
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas
| | - Kyle P. Quinn
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas
| | - James B. Kobler
- Department of Surgery, Harvard Medical School, Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts
| | - Steven M. Zeitels
- Department of Surgery, Harvard Medical School, Center for Laryngeal Surgery and Voice Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts
| | - Irene Georgakoudi
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts
| | - Adela Ben-Yakar
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
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Subramanian K, Gabay I, Ferhanoğlu O, Shadfan A, Pawlowski M, Wang Y, Tkaczyk T, Ben-Yakar A. Kagome fiber based ultrafast laser microsurgery probe delivering micro-Joule pulse energies. BIOMEDICAL OPTICS EXPRESS 2016; 7:4639-4653. [PMID: 27896003 PMCID: PMC5119603 DOI: 10.1364/boe.7.004639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 05/22/2023]
Abstract
We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for fast tissue microsurgery. Delivery of micro-Joules level energies to the tissue was made possible by a large, 31 μm, air-cored inhibited-coupling Kagome fiber. We overcome the fiber's low NA by using lenses made of high refractive index ZnS, which produced an optimal focusing condition with 0.23 NA objective. The optical design achieved a focused laser spot size of 4.5 μm diameter covering a 75 × 75 μm2 scan area in a miniaturized setting. The probe could deliver the maximum available laser power, achieving an average fluence of 7.8 J/cm2 on the tissue surface at 62% transmission efficiency. Such fluences could produce uninterrupted, 40 μm deep cuts at translational speeds of up to 5 mm/s along the tissue. We predicted that the best combination of speed and coverage exists at 8 mm/s for our conditions. The onset of nonlinear absorption in ZnS, however, limited the probe's energy delivery capabilities to 1.4 μJ for linear operation at 1.5 picosecond pulse-widths of our fiber laser. Alternatives like broadband CaF2 crystals should mitigate such nonlinear limiting behavior. Improved opto-mechanical design and appropriate material selection should allow substantially higher fluence delivery and propel such Kagome fiber-based scalpels towards clinical translation.
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Affiliation(s)
- Kaushik Subramanian
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- These authors contributed equally to this work
| | - Ilan Gabay
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- These authors contributed equally to this work
| | - Onur Ferhanoğlu
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
| | - Adam Shadfan
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Michal Pawlowski
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Ye Wang
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Tomasz Tkaczyk
- Department of Bioengineering, Rice University, Houston 77005, USA
| | - Adela Ben-Yakar
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA
- Department of Biomedical Engineering, The University of Texas at Austin, Texas 78712, USA
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Yildirim M, Durr N, Ben-Yakar A. Tripling the maximum imaging depth with third-harmonic generation microscopy. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:096013. [PMID: 26376941 DOI: 10.1117/1.jbo.20.9.096013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/11/2015] [Indexed: 05/05/2023]
Abstract
The growing interest in performing high-resolution, deep-tissue imaging has galvanized the use of longer excitation wavelengths and three-photon-based techniques in nonlinear imaging modalities. This study presents a threefold improvement in maximum imaging depth of ex vivo porcine vocal folds using third-harmonic generation (THG) microscopy at 1552-nm excitation wavelength compared to two-photon microscopy (TPM) at 776-nm excitation wavelength. The experimental, analytical, and Monte Carlo simulation results reveal that THG improves the maximum imaging depth observed in TPM significantly from 140 to 420 μm in a highly scattered medium, reaching the expected theoretical imaging depth of seven extinction lengths. This value almost doubles the previously reported normalized imaging depths of 3.5 to 4.5 extinction lengths using three-photon-based imaging modalities. Since tissue absorption is substantial at the excitation wavelength of 1552 nm, this study assesses the tissue thermal damage during imaging by obtaining the depth-resolved temperature distribution through a numerical simulation incorporating an experimentally obtained thermal relaxation time (τ). By shuttering the laser for a period of 2τ, the numerical algorithm estimates a maximum temperature increase of ∼2°C at the maximum imaging depth of 420 μm. The paper demonstrates that THG imaging using 1552 nm as an illumination wavelength with effective thermal management proves to be a powerful deep imaging modality for highly scattering and absorbing tissues, such as scarred vocal folds.
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Affiliation(s)
- Murat Yildirim
- The University of Texas at Austin, Department of Mechanical Engineering, 204 East Dean Keeton Street, Stop C2200, Austin, Texas 78712, United States
| | - Nicholas Durr
- The John Hopkins University, Department of Biomedical Engineering, 3400 North Charles Street, Baltimore, Maryland 21218, United StatescThe University of Texas at Austin, Department of Biomedical Engineering, 107 West Dean Keeton Street, Stop C0800, Austin
| | - Adela Ben-Yakar
- The University of Texas at Austin, Department of Mechanical Engineering, 204 East Dean Keeton Street, Stop C2200, Austin, Texas 78712, United StatescThe University of Texas at Austin, Department of Biomedical Engineering, 107 West Dean Keeton Street, Stop
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Ferhanoglu O, Yildirim M, Subramanian K, Ben-Yakar A. A 5-mm piezo-scanning fiber device for high speed ultrafast laser microsurgery. BIOMEDICAL OPTICS EXPRESS 2014; 5:2023-36. [PMID: 25071946 PMCID: PMC4102346 DOI: 10.1364/boe.5.002023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/23/2014] [Accepted: 05/26/2014] [Indexed: 05/05/2023]
Abstract
Towards developing precise microsurgery tools for the clinic, we previously developed image-guided miniaturized devices using low repetition rate amplified ultrafast lasers for surgery. To improve the speed of tissue removal while reducing device diameter, here we present a new 5-mm diameter device that delivers high-repetition rate laser pulses for high speed ultrafast laser microsurgery. The device consists of an air-core photonic bandgap fiber (PBF) for the delivery of high energy pulses, a piezoelectric tube actuator for fiber scanning, and two aspheric lenses for focusing the light. Its inline optical architecture provides easy alignment and substantial size reduction to 5 mm diameter as compared to our previous MEMS-scanning devices while realizing improved intensity squared (two-photon) lateral and axial resolutions of 1.16 μm and 11.46 μm, respectively. Our study also sheds light on the maximum pulse energies that can be delivered through the air-core PBF and identifies cladding damage at the input facet of the fiber as the limiting factor. We have achieved a maximum energy delivery larger than 700 nJ at 92% coupling efficiency. An in depth analysis reveals how this value is greatly affected by possible slight misalignments of the beam during coupling and the measured small beam pointing fluctuations. In the absence of these imperfections, self-phase modulation becomes the limiting factor for the maximum energy delivery, setting the theoretical upper bound to near 2 μJ for a 1-m long, 7-μm, air-core PBF. Finally, the use of a 300 kHz repetition rate fiber laser enabled rapid ablation of 150 µm x 150 µm area within only 50 ms. Such ablation speeds can now allow the surgeons to translate the surgery device as fast as ~4 mm/s to continuously remove a thin layer of a 150 µm wide tissue. Thanks to a high optical transmission efficiency of the in-line optical architecture of the device and improved resolution, we could successfully perform ablation of scarred cheek pouch tissue, drilling through a thin slice. With further development, this device can serve as a precise and high speed ultrafast laser scalpel in the clinic.
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Qian Z, Mordovanakis A, Schoenly JE, Covarrubias A, Feng Y, Lilge L, Marjoribanks RS. Pulsetrain-burst mode, ultrafast-laser interactions with 3D viable cell cultures as a model for soft biological tissues. BIOMEDICAL OPTICS EXPRESS 2013; 5:208-22. [PMID: 24466488 PMCID: PMC3891333 DOI: 10.1364/boe.5.000208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 12/05/2013] [Accepted: 12/07/2013] [Indexed: 05/09/2023]
Abstract
A 3D living-cell culture in hydrogel has been developed as a standardized low-tensile-strength tissue proxy for study of ultrafast, pulsetrain-burst laser-tissue interactions. The hydrogel is permeable to fluorescent biomarkers and optically transparent, allowing viable and necrotic cells to be imaged in 3D by confocal microscopy. Good cell-viability allowed us to distinguish between typical cell mortality and delayed subcellular tissue damage (e.g., apoptosis and DNA repair complex formation), caused by laser irradiation. The range of necrosis depended on laser intensity, but not on pulsetrain-burst duration. DNA double-strand breaks were quantified, giving a preliminary upper limit for genetic damage following laser treatment.
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Affiliation(s)
- Zuoming Qian
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
| | - Aghapi Mordovanakis
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
- Current address: Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109, USA
| | - Joshua E. Schoenly
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
| | - Andrés Covarrubias
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
| | - Yuanfeng Feng
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
| | - Lothar Lilge
- Princess Margaret Hospital, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto ON M5G 2M9, Canada
| | - Robin S. Marjoribanks
- Department of Physics, & Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto ON M5S 1A7, Canada
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