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Liu Y, Zhang H, Li X. Technologies for depth scanning in miniature optical imaging systems [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:6542-6562. [PMID: 38420321 PMCID: PMC10898578 DOI: 10.1364/boe.507078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 03/02/2024]
Abstract
Biomedical optical imaging has found numerous clinical and research applications. For achieving 3D imaging, depth scanning presents the most significant challenge, particularly in miniature imaging devices. This paper reviews the state-of-art technologies for depth scanning in miniature optical imaging systems, which include two general approaches: 1) physically shifting part of or the entire imaging device to allow imaging at different depths and 2) optically changing the focus of the imaging optics. We mainly focus on the second group of methods, introducing a wide variety of tunable microlenses, covering the underlying physics, actuation mechanisms, and imaging performance. Representative applications in clinical and neuroscience research are briefly presented. Major challenges and future perspectives of depth/focus scanning technologies for biomedical optical imaging are also discussed.
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Affiliation(s)
- Yuehan Liu
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Haolin Zhang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Xingde Li
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205, USA
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2
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Welton TA, George NM, Ozbay BN, Gentile Polese A, Osborne G, Futia GL, Kushner JK, Kleinschmidt-DeMasters B, Alexander AL, Abosch A, Ojemann S, Restrepo D, Gibson EA. Two-photon microendoscope for label-free imaging in stereotactic neurosurgery. BIOMEDICAL OPTICS EXPRESS 2023; 14:3705-3725. [PMID: 37497482 PMCID: PMC10368057 DOI: 10.1364/boe.492552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/26/2023] [Accepted: 06/15/2023] [Indexed: 07/28/2023]
Abstract
We demonstrate a gradient refractive index (GRIN) microendoscope with an outer diameter of ∼1.2 mm and a length of ∼186 mm that can fit into a stereotactic surgical cannula. Two photon imaging at an excitation wavelength of 900 nm showed a field of view of ∼180 microns and a lateral and axial resolution of 0.86 microns and 9.6 microns respectively. The microendoscope was tested by imaging autofluorescence and second harmonic generation (SHG) in label-free human brain tissue. Furthermore, preliminary image analysis indicates that image classification models can predict if an image is from the subthalamic nucleus or the surrounding tissue using conventional, bench-top two-photon autofluorescence.
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Affiliation(s)
- Tarah A. Welton
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Nicholas M. George
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Baris N. Ozbay
- Intelligent Imaging Innovations, Denver, Colorado, 80216, USA
| | - Arianna Gentile Polese
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Gregory Osborne
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Gregory L. Futia
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - J. Keenan Kushner
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Bette Kleinschmidt-DeMasters
- Department of Pathology, University of Colorado School of Medicine, Aurora, CO 80045, USA
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA
- Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Allyson L. Alexander
- Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
- Division of Pediatric Neurosurgery, Children’s Hospital Colorado, Aurora CO 80045, USA
| | - Aviva Abosch
- Department of Neurosurgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Steven Ojemann
- Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Diego Restrepo
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Emily A. Gibson
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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3
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Miscles EJ, Lim WY, Supekar OD, Zohrabi M, Gopinath JT, Bright VM. Axisymmetrical resonance modes in an electrowetting optical lens. APPLIED PHYSICS LETTERS 2023; 122:201106. [PMID: 37214761 PMCID: PMC10195114 DOI: 10.1063/5.0141787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 04/29/2023] [Indexed: 05/24/2023]
Abstract
Electrowetting-based adaptive optics are of great interest for applications ranging from confocal microscopy to LIDAR, but the impact of low-frequency mechanical vibration on these devices remains to be studied. We present a simple theoretical model for predicting the resonance modes induced on the liquid interface in conjunction with a numerical simulation. We experimentally confirm the resonance frequencies by contact angle modulation. They are found to be in excellent agreement with the roots of the zero-order Bessel functions of the first kind. Next, we experimentally verify that external axial vibration of an electrowetting lens filled with density mismatched liquids (Δρ = 250 kg/m3) will exhibit observable Bessel modes on the liquid-liquid interface. An electrowetting lens filled with density matched liquids (Δρ = 4 kg/m3) is robust to external axial vibration and is shown to be useful in mitigating the effect of vibrations in an optical system.
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Affiliation(s)
- Eduardo J. Miscles
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | | | - Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | | | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
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Yu X, Zhou L, Qi T, Zhao H, Xie H. MEMS Enabled Miniature Two-Photon Microscopy for Biomedical Imaging. MICROMACHINES 2023; 14:470. [PMID: 36838170 PMCID: PMC9958604 DOI: 10.3390/mi14020470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 02/07/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
Over the last decade, two-photon microscopy (TPM) has been the technique of choice for in vivo noninvasive optical brain imaging for neuroscientific study or intra-vital microendoscopic imaging for clinical diagnosis or surgical guidance because of its intrinsic capability of optical sectioning for imaging deeply below the tissue surface with sub-cellular resolution. However, most of these research activities and clinical applications are constrained by the bulky size of traditional TMP systems. An attractive solution is to develop miniaturized TPMs, but this is challenged by the difficulty of the integration of dynamically scanning optical and mechanical components into a small space. Fortunately, microelectromechanical systems (MEMS) technology, together with other emerging micro-optics techniques, has offered promising opportunities in enabling miniaturized TPMs. In this paper, the latest advancements in both lateral scan and axial scan techniques and the progress of miniaturized TPM imaging will be reviewed in detail. Miniature TPM probes with lateral 2D scanning mechanisms, including electrostatic, electromagnetic, and electrothermal actuation, are reviewed. Miniature TPM probes with axial scanning mechanisms, such as MEMS microlenses, remote-focus, liquid lenses, and deformable MEMS mirrors, are also reviewed.
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Affiliation(s)
- Xiaomin Yu
- Key Laboratory of Biological Effect of Physical Field and Instrument, Department of Electrical and Electronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China
| | - Liang Zhou
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Tingxiang Qi
- BIT Chongqing Institute of Microelectronics and Microsystems, Chongqing 401332, China
| | - Hui Zhao
- BIT Chongqing Institute of Microelectronics and Microsystems, Chongqing 401332, China
- Foshan Lightview Technology Co., Ltd., Foshan 528000, China
| | - Huikai Xie
- BIT Chongqing Institute of Microelectronics and Microsystems, Chongqing 401332, China
- Foshan Lightview Technology Co., Ltd., Foshan 528000, China
- School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing 100081, China
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5
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Zhao P, Li Y, Zappe H. Accelerated electrowetting-based tunable fluidic lenses. OPTICS EXPRESS 2021; 29:15733-15746. [PMID: 33985269 DOI: 10.1364/oe.423460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
One of the limitations in the application of electrowetting-based tunable fluidic lenses is their slow response time. We consider here two approaches for enhancing the response speed of tunable fluidic lenses: optimization of the properties of the fluids employed and modification of the time-dependent actuation voltages. Using a tubular optofluidic configuration, it is shown through simulations how one may take advantage of the interplay between liquid viscosities and surface tension to reduce the actuation time. In addition, by careful designing the actuation pulses, the response speed of both overdamped and underdamped systems may be increased by over an order of magnitude, leading to response times of several ten milliseconds. These performance improvements may significantly enhance the applicability of tunable optofluidic-based components and systems.
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Ersumo NT, Yalcin C, Antipa N, Pégard N, Waller L, Lopez D, Muller R. A micromirror array with annular partitioning for high-speed random-access axial focusing. LIGHT, SCIENCE & APPLICATIONS 2020; 9:183. [PMID: 33298828 PMCID: PMC7596532 DOI: 10.1038/s41377-020-00420-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/29/2020] [Accepted: 10/12/2020] [Indexed: 05/24/2023]
Abstract
Dynamic axial focusing functionality has recently experienced widespread incorporation in microscopy, augmented/virtual reality (AR/VR), adaptive optics and material processing. However, the limitations of existing varifocal tools continue to beset the performance capabilities and operating overhead of the optical systems that mobilize such functionality. The varifocal tools that are the least burdensome to operate (e.g. liquid crystal, elastomeric or optofluidic lenses) suffer from low (≈100 Hz) refresh rates. Conversely, the fastest devices sacrifice either critical capabilities such as their dwelling capacity (e.g. acoustic gradient lenses or monolithic micromechanical mirrors) or low operating overhead (e.g. deformable mirrors). Here, we present a general-purpose random-access axial focusing device that bridges these previously conflicting features of high speed, dwelling capacity and lightweight drive by employing low-rigidity micromirrors that exploit the robustness of defocusing phase profiles. Geometrically, the device consists of an 8.2 mm diameter array of piston-motion and 48-μm-pitch micromirror pixels that provide 2π phase shifting for wavelengths shorter than 1100 nm with 10-90% settling in 64.8 μs (i.e., 15.44 kHz refresh rate). The pixels are electrically partitioned into 32 rings for a driving scheme that enables phase-wrapped operation with circular symmetry and requires <30 V per channel. Optical experiments demonstrated the array's wide focusing range with a measured ability to target 29 distinct resolvable depth planes. Overall, the features of the proposed array offer the potential for compact, straightforward methods of tackling bottlenecked applications, including high-throughput single-cell targeting in neurobiology and the delivery of dense 3D visual information in AR/VR.
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Affiliation(s)
- Nathan Tessema Ersumo
- The University of California, Berkeley and University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, 94720, USA
- Department of Electrical Engineering & Computer Sciences, University of California, Berkeley, CA, 94720, USA
| | - Cem Yalcin
- Department of Electrical Engineering & Computer Sciences, University of California, Berkeley, CA, 94720, USA
| | - Nick Antipa
- Department of Electrical Engineering & Computer Sciences, University of California, Berkeley, CA, 94720, USA
| | - Nicolas Pégard
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27514, USA
| | - Laura Waller
- The University of California, Berkeley and University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, 94720, USA
- Department of Electrical Engineering & Computer Sciences, University of California, Berkeley, CA, 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA
| | - Daniel Lopez
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Rikky Muller
- The University of California, Berkeley and University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, 94720, USA.
- Department of Electrical Engineering & Computer Sciences, University of California, Berkeley, CA, 94720, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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7
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Electrowetting lens with large aperture and focal length tunability. Sci Rep 2020; 10:16318. [PMID: 33004850 PMCID: PMC7530674 DOI: 10.1038/s41598-020-73260-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 08/31/2020] [Indexed: 11/09/2022] Open
Abstract
The electrowetting lenses has attracted researchers in many fields, such as biology, beam shaping, and drug delivery. Previous research on electrowetting lens has focused on neither expanding the dynamic focal length range nor reducing the wavefront aberration. However, the properties with large numerical aperture and low aberration are also essential properties of lenses, and can promote their application. Therefore, we calculated the meniscus of the lens with different optical apertures, and subsequently, analyzed the relations among the focal length, wavefront aberration, and optical aperture. To expand the focal length range, we designed an electrowetting-based triple-liquid lens with a root-mean-square wavefront aberration error of less than 1/4 waves.
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8
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Malvaut S, Constantinescu VS, Dehez H, Doric S, Saghatelyan A. Deciphering Brain Function by Miniaturized Fluorescence Microscopy in Freely Behaving Animals. Front Neurosci 2020; 14:819. [PMID: 32848576 PMCID: PMC7432153 DOI: 10.3389/fnins.2020.00819] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/14/2020] [Indexed: 11/19/2022] Open
Abstract
Animal behavior is regulated by environmental stimuli and is shaped by the activity of neural networks, underscoring the importance of assessing the morpho-functional properties of different populations of cells in freely behaving animals. In recent years, a number of optical tools have been developed to monitor and modulate neuronal and glial activity at the protein, cellular, or network level and have opened up new avenues for studying brain function in freely behaving animals. Tools such as genetically encoded sensors and actuators are now commonly used for studying brain activity and function through their expression in different neuronal ensembles. In parallel, microscopy has also made major progress over the last decades. The advent of miniature microscopes (mini-microscopes also called mini-endoscopes) has become a method of choice for studying brain activity at the cellular and network levels in different brain regions of freely behaving mice. This technique also allows for longitudinal investigations while animals carrying the microscope on their head are performing behavioral tasks. In this review, we will discuss mini-endoscopic imaging and the advantages that these devices offer to research. We will also discuss current limitations of and potential future improvements in mini-endoscopic imaging.
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Affiliation(s)
- Sarah Malvaut
- CERVO Brain Research Center, Quebec City, QC, Canada
- Department of Psychiatry and Neuroscience, Universite Laval, Quebec City, QC, Canada
| | - Vlad-Stefan Constantinescu
- CERVO Brain Research Center, Quebec City, QC, Canada
- Department of Psychiatry and Neuroscience, Universite Laval, Quebec City, QC, Canada
| | | | - Sead Doric
- Doric Lenses Inc., Quebec City, QC, Canada
| | - Armen Saghatelyan
- CERVO Brain Research Center, Quebec City, QC, Canada
- Department of Psychiatry and Neuroscience, Universite Laval, Quebec City, QC, Canada
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9
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Zhou L, Yu X, Feng PXL, Li J, Xie H. A MEMS lens scanner based on serpentine electrothermal bimorph actuators for large axial tuning. OPTICS EXPRESS 2020; 28:23439-23453. [PMID: 32752341 PMCID: PMC7470678 DOI: 10.1364/oe.400363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Confocal microscopes and two-photon microscopes are powerful tools for early cancer diagnosis because of their high-resolution 3D imaging capability, but applying them for clinical use in internal organs is hindered by the lack of axially tunable lens modules with small size, high image quality and large tuning range. This paper reports a compact MEMS lens scanner that has the potential to overcome this limitation. The MEMS lens scanner consists of a MEMS microstage and a microlens. The MEMS microstage is based on a unique serpentine inverted-series-connected (ISC) electrothermal bimorph actuator design. The microlens is an aspheric glass lens to ensure optical quality. The MEMS microstage has been fabricated and the lens scanner has been successfully assembled. The entire lens scanner is circular with an outer diameter of 4.4 mm and a clear optical aperture of 1.8 mm. Experiments show that the tunable range reaches over 200 µm at only 10.5 V and the stiffness of the microstage is 6.2 N/m. Depth scan imaging by the MEMS lens scanner has also been demonstrated with a 2.2 µm resolution, only limited by the available resolution target.
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Affiliation(s)
- Liang Zhou
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Xiaomin Yu
- College of Electronic Engineering, Chengdu University of Information Technology, Chengdu 610225, Sichuan, China
| | - Philip X.-L. Feng
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Jianhua Li
- School of Mechatronical Engineering, Beijing Institute of Technology, 100081 Beijing, China
| | - Huikai Xie
- School of Information and Electronics, Beijing Institute of Technology, 100081 Beijing, China
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10
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Lim WY, Zohrabi M, Gopinath JT, Bright VM. Calibration and characteristics of an electrowetting laser scanner. IEEE SENSORS JOURNAL 2020; 20:3496-3503. [PMID: 33746623 PMCID: PMC7977153 DOI: 10.1109/jsen.2019.2959792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present a calibration method to correct for fabrication variations and optical misalignment in a two-dimensional electrowetting scanner. These scanners are an attractive option due to being transmissive, nonmechanical, having a large scan angle (±13.7°), and low power consumption (μW). Fabrication imperfections lead to non-uniform deposition of the dielectric or hydrophobic layer which results in actuation inconsistency of each electrode. To demonstrate our calibration method, we scan a 5 × 5 grid target using a four-electrode electrowetting prism and observe a pincushion type optical distortion in the imaging plane. Zemax optical simulations verify that the symmetric distortion is due to the projection of a radial scanning surface onto a flat imaging plane, while in experiment we observe asymmetrical distortion due to optical misalignment and fabrication imperfections. By adjusting the actuation voltages through an iterative Delaunay triangulation interpolation method, the distortion is corrected and saw an improvement in the mean error across 25 grid points from 43 μm (0.117°) to 10 μm (0.027°).
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Affiliation(s)
- Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309 USA
| | - Mo Zohrabi
- Department of Electrical Engineering, University of Colorado, Boulder, CO 80309 USA
| | - Juliet T Gopinath
- Department of Electrical Engineering and Department of Physics, University of Colorado, Boulder, CO 80309 USA
| | - Victor M Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309 USA
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11
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Zohrabi M, Yang Lim W, Bright VM, Gopinath JT. High extinction ratio, low insertion loss, optical switch based on an electrowetting prism. OPTICS EXPRESS 2020; 28:5991-6001. [PMID: 32225857 PMCID: PMC7347523 DOI: 10.1364/oe.381565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
An optical switch based on an electrowetting prism coupled to a multimode fiber has demonstrated a large extinction ratio with speeds up to 300 Hz. Electrowetting prisms provide a transmissive, low power, and compact alternative to conventional free-space optical switches, with no moving parts. The electrowetting prism performs beam steering of ±3° with an extinction ratio of 47 dB between the ON and OFF states and has been experimentally demonstrated at scanning frequencies of 100-300 Hz. The optical design is modeled in Zemax to account for secondary rays created at each surface interface (without scattering). Simulations predict 50 dB of extinction, in good agreement with experiment.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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12
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Chakraborty T, Chen B, Daetwyler S, Chang BJ, Vanderpoorten O, Sapoznik E, Kaminski CF, Knowles TPJ, Dean KM, Fiolka R. Converting lateral scanning into axial focusing to speed up three-dimensional microscopy. LIGHT, SCIENCE & APPLICATIONS 2020; 9:165. [PMID: 33024553 PMCID: PMC7501866 DOI: 10.1038/s41377-020-00401-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/25/2020] [Accepted: 09/02/2020] [Indexed: 05/04/2023]
Abstract
In optical microscopy, the slow axial scanning rate of the objective or the sample has traditionally limited the speed of volumetric imaging. Recently, by conjugating either a movable mirror to the image plane in a remote-focusing geometry or an electrically tuneable lens (ETL) to the back focal plane, rapid axial scanning has been achieved. However, mechanical actuation of a mirror limits the axial scanning rate (usually only 10-100 Hz for piezoelectric or voice coil-based actuators), while ETLs introduce spherical and higher-order aberrations that prevent high-resolution imaging. In an effort to overcome these limitations, we introduce a novel optical design that transforms a lateral-scan motion into a spherical aberration-free axial scan that can be used for high-resolution imaging. Using a galvanometric mirror, we scan a laser beam laterally in a remote-focusing arm, which is then back-reflected from different heights of a mirror in the image space. We characterize the optical performance of this remote-focusing technique and use it to accelerate axially swept light-sheet microscopy by an order of magnitude, allowing the quantification of rapid vesicular dynamics in three dimensions. We also demonstrate resonant remote focusing at 12 kHz with a two-photon raster-scanning microscope, which allows rapid imaging of brain tissues and zebrafish cardiac dynamics with diffraction-limited resolution.
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Affiliation(s)
- Tonmoy Chakraborty
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM USA
| | - Bingying Chen
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
| | - Stephan Daetwyler
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
| | - Bo-Jui Chang
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
| | - Oliver Vanderpoorten
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - Etai Sapoznik
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - Tuomas P. J. Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW UK
| | - Kevin M. Dean
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
| | - Reto Fiolka
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX USA
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX USA
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13
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Kindel WF, Christensen ED, Zylberberg J. Using deep learning to probe the neural code for images in primary visual cortex. J Vis 2019; 19:29. [PMID: 31026016 PMCID: PMC6485988 DOI: 10.1167/19.4.29] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Primary visual cortex (V1) is the first stage of cortical image processing, and major effort in systems neuroscience is devoted to understanding how it encodes information about visual stimuli. Within V1, many neurons respond selectively to edges of a given preferred orientation: These are known as either simple or complex cells. Other neurons respond to localized center–surround image features. Still others respond selectively to certain image stimuli, but the specific features that excite them are unknown. Moreover, even for the simple and complex cells—the best-understood V1 neurons—it is challenging to predict how they will respond to natural image stimuli. Thus, there are important gaps in our understanding of how V1 encodes images. To fill this gap, we trained deep convolutional neural networks to predict the firing rates of V1 neurons in response to natural image stimuli, and we find that the predicted firing rates are highly correlated (\begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{\overline {{\bf{CC}}} _{{\bf{norm}}}}\end{document} = 0.556 ± 0.01) with the neurons' actual firing rates over a population of 355 neurons. This performance value is quoted for all neurons, with no selection filter. Performance is better for more active neurons: When evaluated only on neurons with mean firing rates above 5 Hz, our predictors achieve correlations of \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{\overline {{\bf{CC}}} _{{\bf{norm}}}}\end{document} = 0.69 ± 0.01 with the neurons' true firing rates. We find that the firing rates of both orientation-selective and non-orientation-selective neurons can be predicted with high accuracy. Additionally, we use a variety of models to benchmark performance and find that our convolutional neural-network model makes more accurate predictions.
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Affiliation(s)
- William F Kindel
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Elijah D Christensen
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Joel Zylberberg
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA.,Learning in Machines and Brains Program, Canadian Institute for Advanced Research, Toronto, Canada
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14
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Anderson HE, Weir RFF. On the development of optical peripheral nerve interfaces. Neural Regen Res 2019; 14:425-436. [PMID: 30539808 PMCID: PMC6334609 DOI: 10.4103/1673-5374.245461] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 09/19/2018] [Indexed: 11/04/2022] Open
Abstract
Limb loss and spinal cord injury are two debilitating conditions that continue to grow in prevalence. Prosthetic limbs and limb reanimation present two ways of providing affected individuals with means to interact in the world. These techniques are both dependent on a robust interface with the peripheral nerve. Current methods for interfacing with the peripheral nerve tend to suffer from low specificity, high latency and insufficient robustness for a chronic implant. An optical peripheral nerve interface may solve some of these problems by decreasing invasiveness and providing single axon specificity. In order to implement such an interface three elements are required: (1) a transducer capable of translating light into a neural stimulus or translating neural activity into changes in fluorescence, (2) a means for delivering said transducer and (3) a microscope for providing the stimulus light and detecting the fluorescence change. There are continued improvements in both genetically encoded calcium and voltage indicators as well as new optogenetic actuators for stimulation. Similarly, improvements in specificity of viral vectors continue to improve expression in the axons of the peripheral nerve. Our work has recently shown that it is possible to virally transduce axons of the peripheral nerve for recording from small fibers. The improvements of these components make an optical peripheral nerve interface a rapidly approaching alternative to current methods.
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Affiliation(s)
- Hans E. Anderson
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
| | - Richard F. ff. Weir
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
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15
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Fontaine AK, Segil JL, Caldwell JH, Weir RFF. Real-Time Prosthetic Digit Actuation by Optical Read-out of Activity-Dependent Calcium Signals in an Ex Vivo Peripheral Nerve. INTERNATIONAL IEEE/EMBS CONFERENCE ON NEURAL ENGINEERING : [PROCEEDINGS]. INTERNATIONAL IEEE EMBS CONFERENCE ON NEURAL ENGINEERING 2019; 2019:143-146. [PMID: 38566861 PMCID: PMC10984832 DOI: 10.1109/ner.2019.8717033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Improved neural interfacing strategies are needed for the full articulation of advanced prostheses. To address limitations of existing control interface designs, the work of our laboratory has presented an optical approach to reading activity from individual nerve fibers using activity-dependent calcium transients. Here, we demonstrate the feasibility of such signals to control prosthesis actuation by using the axonal fluorescence signal in an ex vivo mouse nerve to drive a prosthetic digit in real-time. Additionally, signals of varying action potential frequency are streamed post hoc to the prosthesis, showing graded motor output and the potential for proportional neural control. This proof-of-concept work is a novel demonstration of the functional use of activity-dependent optical read-out in the nerve.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado | Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Jacob L Segil
- Engineering Plus Program, University of Colorado Boulder, Boulder, CO, 80309 USA
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado | Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Richard F Ff Weir
- Department of Bioengineering, University of Colorado | Anschutz Medical Campus, Aurora, CO 80045 USA
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16
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Zohrabi M, Lim WY, Cormack RH, Supekar OD, Bright VM, Gopinath JT. Lidar system with nonmechanical electrowetting-based wide-angle beam steering. OPTICS EXPRESS 2019; 27:4404-4415. [PMID: 30876059 PMCID: PMC6410924 DOI: 10.1364/oe.27.004404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 05/27/2023]
Abstract
A light detection and ranging (lidar) system with ±90° of steering based on an adaptive electrowetting-based prism for nonmechanical beam steering has been demonstrated. Electrowetting-based prisms provide a transmissive, low power, and compact alternative to conventional adaptive optics as a nonmechanical beam scanner. The electrowetting prism has a steering range of ±7.8°. We demonstrate a method to amplify the scan angle to ±90° and perform a one-dimensional scan in a lidar system.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
| | - Wei Yang Lim
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Robert H. Cormack
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
| | - Omkar D. Supekar
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado Boulder, Colorado 80309,
USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309,
USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309,
USA
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17
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Multiscale Interface Effect on Homogeneous Dielectric Structure of ZrO₂/Teflon Nanocomposite for Electrowetting Application. Polymers (Basel) 2018; 10:polym10101119. [PMID: 30961044 PMCID: PMC6403886 DOI: 10.3390/polym10101119] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 09/28/2018] [Accepted: 10/02/2018] [Indexed: 02/06/2023] Open
Abstract
Electrowetting-on-dielectric is a preferred option in practical applications of the electrowetting phenomenon but limited by dielectric and breakdown performances of the dielectric layer. In the present work, a ceramic/polymer nanocomposite as a novel dielectric layer is developed to intensify the overall electrowetting performances by multiscale interface effect. Hereinto, surface fluoro-modified ZrO2 nanoparticles (mZrO2) are dispersed well in AF 1600 matrix to form a mZrO2@AF 1600 nanocomposite. The small addition of mZrO2 improves the dielectric constant of the nanocomposite, and the experimental value is larger than the theoretical value calculated by Maxwell–Garnett model, but fits well with the Rahaman–Khastgir model. The molecular dynamics simulations with the explicit model further verify the interfacial effect. Meanwhile, double contact angle modulation and higher breakdown field strength (Eb) are obtained. For the three-layer sandwich structure, both the top and bottom AF 1600 layer decrease the surface roughness for better electrowetting reproducibility and wider wettability modulation. The Forlani–Minnaja theory related to the empirical relationship between Eb and thickness of dielectric layer fit well with the monolayer structure, but cannot be applied in multi-layer structures. A new relationship is proposed to guide the design of dielectric multi-layers with high breakdown field strength.
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18
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Three dimensional two-photon brain imaging in freely moving mice using a miniature fiber coupled microscope with active axial-scanning. Sci Rep 2018; 8:8108. [PMID: 29802371 PMCID: PMC5970169 DOI: 10.1038/s41598-018-26326-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 05/09/2018] [Indexed: 02/06/2023] Open
Abstract
We present a miniature head mounted two-photon fiber-coupled microscope (2P-FCM) for neuronal imaging with active axial focusing enabled using a miniature electrowetting lens. We show three-dimensional two-photon imaging of neuronal structure and record neuronal activity from GCaMP6s fluorescence from multiple focal planes in a freely-moving mouse. Two-color simultaneous imaging of GFP and tdTomato fluorescence is also demonstrated. Additionally, dynamic control of the axial scanning of the electrowetting lens allows tilting of the focal plane enabling neurons in multiple depths to be imaged in a single plane. Two-photon imaging allows increased penetration depth in tissue yielding a working distance of 450 μm with an additional 180 μm of active axial focusing. The objective NA is 0.45 with a lateral resolution of 1.8 μm, an axial resolution of 10 μm, and a field-of-view of 240 μm diameter. The 2P-FCM has a weight of only ~2.5 g and is capable of repeatable and stable head-attachment. The 2P-FCM with dynamic axial scanning provides a new capability to record from functionally distinct neuronal layers, opening new opportunities in neuroscience research.
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19
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Fontaine AK, Anderson HE, Caldwell JH, Weir RF. Optical read-out and modulation of peripheral nerve activity. Neural Regen Res 2018; 13:58-61. [PMID: 29451205 PMCID: PMC5840990 DOI: 10.4103/1673-5374.224364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Numerous clinical and research applications necessitate the ability to interface with peripheral nerve fibers to read and control relevant neural pathways. Visceral organ modulation and rehabilitative prosthesis are two areas which could benefit greatly from improved neural interfacing approaches. Therapeutic neural interfacing, or ‘bioelectronic medicine’, has potential to affect a broad range of disorders given that all the major organs of the viscera are neurally innervated. However, a better understanding of the neural pathways that underlie function and a means to precisely interface with these fibers are required. Existing peripheral nerve interfaces, consisting primarily of electrode-based designs, are unsuited for highly specific (individual axon) communication and/or are invasive to the tissue. Our laboratory has explored an optogenetic approach by which optically sensitive reporters and actuators are targeted to specific cell (axon) types. The nature of such an approach is laid out in this short perspective, along with associated technologies and challenges.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - Hans E Anderson
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - Richard F Weir
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
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20
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Zohrabi M, Cormack RH, Mccullough C, Supekar OD, Gibson EA, Bright VM, Gopinath JT. Numerical analysis of wavefront aberration correction using multielectrode electrowetting-based devices. OPTICS EXPRESS 2017; 25:31451-31461. [PMID: 29245820 PMCID: PMC5941994 DOI: 10.1364/oe.25.031451] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/15/2017] [Accepted: 11/16/2017] [Indexed: 05/25/2023]
Abstract
We present numerical simulations of multielectrode electrowetting devices used in a novel optical design to correct wavefront aberration. Our optical system consists of two multielectrode devices, preceded by a single fixed lens. The multielectrode elements function as adaptive optical devices that can be used to correct aberrations inherent in many imaging setups, biological samples, and the atmosphere. We are able to accurately simulate the liquid-liquid interface shape using computational fluid dynamics. Ray tracing analysis of these surfaces shows clear evidence of aberration correction. To demonstrate the strength of our design, we studied three different input aberrations mixtures that include astigmatism, coma, trefoil, and additional higher order aberration terms, with amplitudes as large as one wave at 633 nm.
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Affiliation(s)
- Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309,
USA
| | - Robert H. Cormack
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309,
USA
| | - Connor Mccullough
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045,
USA
| | - Omkar D. Supekar
- Department of Mechanical Engineering, University of Colorado Boulder, CO 80309,
USA
| | - Emily A. Gibson
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045,
USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado Boulder, CO 80309,
USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309,
USA
- Department of Physics, University of Colorado, Boulder, CO 80309,
USA
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21
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Supekar OD, Ozbay BN, Zohrabi M, Nystrom PD, Futia GL, Restrepo D, Gibson EA, Gopinath JT, Bright VM. Two-photon laser scanning microscopy with electrowetting-based prism scanning. BIOMEDICAL OPTICS EXPRESS 2017; 8:5412-5426. [PMID: 29296477 PMCID: PMC5745092 DOI: 10.1364/boe.8.005412] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/31/2017] [Accepted: 11/02/2017] [Indexed: 05/24/2023]
Abstract
Laser scanners are an integral part of high resolution biomedical imaging systems such as confocal or 2-photon excitation (2PE) microscopes. In this work, we demonstrate the utility of electrowetting on dielectric (EWOD) prisms as a lateral laser-scanning element integrated in a conventional 2PE microscope. To the best of our knowledge, this is the first such demonstration for EWOD prisms. EWOD devices provide a transmissive, low power consuming, and compact alternative to conventional adaptive optics, and hence this technology has tremendous potential. We demonstrate 2PE microscope imaging of cultured mouse hippocampal neurons with a FOV of 130 × 130 μm2 using EWOD prism scanning. In addition, we show simulations of the optical system with the EWOD prism, to evaluate the effect of propagating a Gaussian beam through the EWOD prism on the imaging quality. Based on the simulation results a beam size of 0.91 mm full width half max was chosen to conduct the imaging experiments, resulting in a numerical aperture of 0.17 of the imaging system.
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Affiliation(s)
- Omkar D. Supekar
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Baris N. Ozbay
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045, USA
| | - Mo Zohrabi
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Philip D. Nystrom
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Gregory L. Futia
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045, USA
| | - Diego Restrepo
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045, USA
| | - Emily A. Gibson
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045, USA
| | - Juliet T. Gopinath
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, 80309, USA
- Department of Physics, University of Colorado, Boulder, CO 80309-0390, USA
| | - Victor M. Bright
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
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22
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Fontaine AK, Gibson EA, Caldwell JH, Weir RF. Optical Read-out of Neural Activity in Mammalian Peripheral Axons: Calcium Signaling at Nodes of Ranvier. Sci Rep 2017; 7:4744. [PMID: 28720792 PMCID: PMC5516017 DOI: 10.1038/s41598-017-03541-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/28/2017] [Indexed: 12/11/2022] Open
Abstract
Current neural interface technologies have serious limitations for advanced prosthetic and therapeutic applications due primarily to their lack of specificity in neural communication. An optogenetic approach has the potential to provide single cell/axon resolution in a minimally invasive manner by optical interrogation of light-sensitive reporters and actuators. Given the aim of reading neural activity in the peripheral nervous system, this work has investigated an activity-dependent signaling mechanism in the peripheral nerve. We demonstrate action potential evoked calcium signals in mammalian tibial nerve axons using an in vitro mouse model with a dextran-conjugated fluorescent calcium indicator. Spatial and temporal dynamics of the signal are presented, including characterization of frequency-modulated amplitude. Pharmacological experiments implicate T-type CaV channels and sodium-calcium exchanger (NCX) as predominant mechanisms of calcium influx. This work shows the potential of using calcium-associated optical signals for neural activity read-out in peripheral nerve axons.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA.
| | - Emily A Gibson
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - Richard F Weir
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
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23
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Qiu Z, Piyawattanamatha W. New Endoscopic Imaging Technology Based on MEMS Sensors and Actuators. MICROMACHINES 2017; 8:mi8070210. [PMID: 30400401 PMCID: PMC6190023 DOI: 10.3390/mi8070210] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 12/14/2022]
Abstract
Over the last decade, optical fiber-based forms of microscopy and endoscopy have extended the realm of applicability for many imaging modalities. Optical fiber-based imaging modalities permit the use of remote illumination sources and enable flexible forms supporting the creation of portable and hand-held imaging instrumentations to interrogate within hollow tissue cavities. A common challenge in the development of such devices is the design and integration of miniaturized optical and mechanical components. Until recently, microelectromechanical systems (MEMS) sensors and actuators have been playing a key role in shaping the miniaturization of these components. This is due to the precision mechanics of MEMS, microfabrication techniques, and optical functionality enabling a wide variety of movable and tunable mirrors, lenses, filters, and other optical structures. Many promising results from MEMS based optical fiber endoscopy have demonstrated great potentials for clinical translation. In this article, reviews of MEMS sensors and actuators for various fiber-optical endoscopy such as fluorescence, optical coherence tomography, confocal, photo-acoustic, and two-photon imaging modalities will be discussed. This advanced MEMS based optical fiber endoscopy can provide cellular and molecular features with deep tissue penetration enabling guided resections and early cancer assessment to better treatment outcomes.
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Affiliation(s)
- Zhen Qiu
- Department of Radiology, Stanford University, Stanford, CA 94305, USA.
| | - Wibool Piyawattanamatha
- Departments of Biomedical and Electronics Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
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24
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Hou J, Ding W, Feng Y, Shui L, Wang Y, Li H, Li N, Zhou G. Electrowetting Performances of Novel Fluorinated Polymer Dielectric Layer Based on Poly(1H,1H,2H,2H-perfluoroctylmethacrylate) Nanoemulsion. Polymers (Basel) 2017; 9:polym9060217. [PMID: 30970896 PMCID: PMC6432406 DOI: 10.3390/polym9060217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 05/26/2017] [Accepted: 06/08/2017] [Indexed: 12/14/2022] Open
Abstract
In electrowetting devices, hydrophobic insulating layer, namely dielectric layer, is capable of reversibly switching surface wettability through applied electric field. It is critically important but limited by material defects in dielectricity, reversibility, film forming, adhesiveness, price and so on. To solve this key problem, we introduced a novel fluorinated polyacrylate—poly(1H,1H,2H,2H-perfluoroctylmethacrylate (PFMA) to construct micron/submicron-scale dielectric layer via facile spray coating of nanoemulsion for replacing the most common Teflon AF series. All the results illustrated that, continuous and dense PFMA film with surface relief less than 20 nm was one-step fabricated at 110 °C, and exhibited much higher static water contact angle of 124°, contact angle variation of 42°, dielectric constant of about 2.6, and breakdown voltage of 210 V than Teflon AF 1600. Particularly, soft and highly compatible polyacrylate mainchain assigned five times much better adhesiveness than common adhesive tape, to PFMA layer. As a promising option, PFMA dielectric layer may further facilitate tremendous development of electrowetting performances and applications.
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Affiliation(s)
- Jiaxin Hou
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Wenwen Ding
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Yancong Feng
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Lingling Shui
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Yao Wang
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Hao Li
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Nan Li
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, China.
| | - Guofu Zhou
- Institute of Electronic Paper Display, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, China.
- Academy of Shenzhen Guohua Optoelectronics, Shenzhen 518110, China.
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25
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Supekar OD, Zohrabi M, Gopinath JT, Bright VM. Enhanced Response Time of Electrowetting Lenses with Shaped Input Voltage Functions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4863-4869. [PMID: 28431469 DOI: 10.1021/acs.langmuir.7b00631] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Adaptive optical lenses based on the electrowetting principle are being rapidly implemented in many applications, such as microscopy, remote sensing, displays, and optical communication. To characterize the response of these electrowetting lenses, the dependence upon direct current (DC) driving voltage functions was investigated in a low-viscosity liquid system. Cylindrical lenses with inner diameters of 2.45 and 3.95 mm were used to characterize the dynamic behavior of the liquids under DC voltage electrowetting actuation. With the increase of the rise time of the input exponential driving voltage, the originally underdamped system response can be damped, enabling a smooth response from the lens. We experimentally determined the optimal rise times for the fastest response from the lenses. We have also performed numerical simulations of the lens actuation with input exponential driving voltage to understand the variation in the dynamics of the liquid-liquid interface with various input rise times. We further enhanced the response time of the devices by shaping the input voltage function with multiple exponential rise times. For the 3.95 mm inner diameter lens, we achieved a response time improvement of 29% when compared to the fastest response obtained using single-exponential driving voltage. The technique shows great promise for applications that require fast response times.
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Affiliation(s)
- Omkar D Supekar
- Department of Mechanical Engineering and §Department of Electrical, Computer, and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Mo Zohrabi
- Department of Mechanical Engineering and §Department of Electrical, Computer, and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Juliet T Gopinath
- Department of Mechanical Engineering and §Department of Electrical, Computer, and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Victor M Bright
- Department of Mechanical Engineering and §Department of Electrical, Computer, and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
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26
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Niederriter RD, Ozbay BN, Futia GL, Gibson EA, Gopinath JT. Compact diode laser source for multiphoton biological imaging. BIOMEDICAL OPTICS EXPRESS 2017; 8:315-322. [PMID: 28101420 PMCID: PMC5231301 DOI: 10.1364/boe.8.000315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/03/2016] [Accepted: 11/03/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate a compact, pulsed diode laser source suitable for multiphoton microscopy of biological samples. The center wavelength is 976 nm, near the peak of the two-photon cross section of common fluorescent markers such as genetically encoded green and yellow fluorescent proteins. The laser repetition rate is electrically tunable between 66.67 kHz and 10 MHz, with 2.3 ps pulse duration and peak powers >1 kW. The laser components are fiber-coupled and scalable to a compact package. We demonstrate >600 μm depth penetration in brain tissue, limited by laser power.
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Affiliation(s)
| | - Baris N. Ozbay
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8607, 12700 East 19th Ave, Aurora, CO 80045,
USA
| | - Gregory L. Futia
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8607, 12700 East 19th Ave, Aurora, CO 80045,
USA
| | - Emily A. Gibson
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Mail Stop 8607, 12700 East 19th Ave, Aurora, CO 80045,
USA
| | - Juliet T. Gopinath
- Department of Physics, University of Colorado, 390 UCB, Boulder, CO 80309-0390,
USA
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, 425 UCB, Boulder, CO 80309-0425,
USA
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27
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28
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Mekhail SP, Arbuthnott G, Chormaic SN. Advances in Fibre Microendoscopy for Neuronal Imaging. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/odps-2016-0003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractTraditionally, models for neural dynamics in the brain have been formed through research conducted on slices, with electrodes, or by lesions to functional areas. Recent developments in functional dyes and optogenetics has made brain research more accessible through the use of light. However, this improved accessibility does not necessarily apply to deep regions of the brain which are surrounded by scattering tissue. In this article we give an overview of some of the latest methods in development for neural measurement and imaging.We specifically address methods designed to overcome the problem of imaging invivo for regions far beyond the mean free path of photons in brain tissue. These methodswould permit previously restricted neural research.
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29
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Hinsdale T, Malik BH, Olsovsky C, Jo JA, Maitland KC. Volumetric structured illumination microscopy enabled by a tunable-focus lens. OPTICS LETTERS 2015; 40:4943-6. [PMID: 26512489 PMCID: PMC4998189 DOI: 10.1364/ol.40.004943] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present a mechanical-scan-free method for volumetric imaging of biological tissue. The optical sectioning is provided by structured illumination, and the depth of the imaging plane is varied using an electrically tunable-focus lens. We characterize and evaluate the ability of this axial-scanning mechanism in structured illumination microscopy and demonstrate its ability to perform subcellular resolution imaging in oral mucosa ex vivo. The proposed mechanism can potentially convert any wide-field microscope to a 3D-imaging platform without the need for mechanical scanning of imaging optics and/or sample.
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TEKRIWAL A, BALTUCH G. Deep Brain Stimulation: Expanding Applications. Neurol Med Chir (Tokyo) 2015; 55:861-77. [PMID: 26466888 PMCID: PMC4686449 DOI: 10.2176/nmc.ra.2015-0172] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 10/15/2015] [Indexed: 12/13/2022] Open
Abstract
For over two decades, deep brain stimulation (DBS) has shown significant efficacy in treatment for refractory cases of dyskinesia, specifically in cases of Parkinson's disease and dystonia. DBS offers potential alleviation from symptoms through a well-tolerated procedure that allows personalized modulation of targeted neuroanatomical regions and related circuitries. For clinicians contending with how to provide patients with meaningful alleviation from often debilitating intractable disorders, DBSs titratability and reversibility make it an attractive treatment option for indications ranging from traumatic brain injury to progressive epileptic supra-synchrony. The expansion of our collective knowledge of pathologic brain circuitries, as well as advances in imaging capabilities, electrophysiology techniques, and material sciences have contributed to the expanding application of DBS. This review will examine the potential efficacy of DBS for neurologic and psychiatric disorders currently under clinical investigation and will summarize findings from recent animal models.
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Affiliation(s)
- Anand TEKRIWAL
- University of Pennsylvania, Department of Neurosurgery, Philadelphia, USA
- University of Colorado School of Medicine and Graduate School of Neuroscience, MSTP, Colorado, USA (current affiliation)
| | - Gordon BALTUCH
- University of Pennsylvania, Department of Neurosurgery, Philadelphia, USA
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Terrab S, Watson AM, Roath C, Gopinath JT, Bright VM. Adaptive electrowetting lens-prism element. OPTICS EXPRESS 2015; 23:25838-45. [PMID: 26480097 DOI: 10.1364/oe.23.025838] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
An adaptive electrowetting-based element with focusing and steering capability has been demonstrated in a monolithic design. Curvature and tip-tilt variation have been demonstrated using low voltages. A steering range of up to 4.3° and lens tuning of 18 diopters have been measured at 30 V DC and 21 V DC, respectively.
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