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Lee M, Li H, Birla MB, Li G, Wang TD, Oldham KR. Capacitive Sensing for 2-D Electrostatic MEMS Scanner in a Clinical Endomicroscope. IEEE SENSORS JOURNAL 2022; 22:24493-24503. [PMID: 37497077 PMCID: PMC10367433 DOI: 10.1109/jsen.2022.3216502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
A flexible fiber-coupled confocal laser endomicroscope has been developed using an electrostatic micro-electromechanical system (MEMS) scanner located in at distal optics to collect in vivo images in human subjects. Long transmission lines are required that deliver drive and sense signals with limited bandwidth. Phase shifts have been observed between orthogonal X and Y scanner axes from environmental perturbations, which impede image reconstruction. Image processing algorithms used for correction depend on image content and quality, while scanner calibration in the clinic can be limited by potential patient exposure to lasers. We demonstrate a capacitive sensing method to track the motion of the electrostatically driven two-dimensional MEMS scanner and to extract phase information needed for image reconstruction. This circuit uses an amplitude modulation envelope detection method on shared drive and sensing electrodes of the scanner. Circuit parameters were optimized for performance given high scan frequencies, transmission line effects, and substantial parasitic coupling of drive signal to circuit output. Extraction of phase information further leverages nonlinear dynamics of the MEMS scanner. The sensing circuit was verified by comparing with data from a position sensing detector measurement. The phase estimation showed an accuracy of 2.18° and 0.79° in X and Y axes for motion sensing, respectively. The results indicate that the sensing circuit can be implemented with feedback control for pre-calibration of the scanner in clinical MEMS-based imaging systems.
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Affiliation(s)
- Miki Lee
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Haijun Li
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mayur B Birla
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Gaoming Li
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Thomas D Wang
- Departments of Internal Medicine, Biomedical Engineering, and Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kenn R Oldham
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
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Li G, Duan X, Lee M, Birla M, Chen J, Oldham KR, Wang TD, Li H. Ultra-Compact Microsystems-Based Confocal Endomicroscope. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:2406-2414. [PMID: 32012007 PMCID: PMC7918297 DOI: 10.1109/tmi.2020.2971476] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Point-of-care medical diagnosis demands immediate feedback on tissue pathology. Confocal endomicroscopy can provide real-time in vivo images with histology-like features. The working channel in medical endoscopes are becoming smaller in dimension. Microsystems methods can produce tiny mechanical scanners. We demonstrate a flexible fiber instrument for in vivo imaging as an endoscope accessory. The optical path is folded on-axis to reduce length while allowing the beam to expand and achieve a numerical aperture of 0.41. A high-speed parametric resonance mirror produces large deflection angles > 13°, and is mounted on a 2 mm diameter chip designed with clamp structures for reduced space. A compact lens assembly provides diffraction-limited lateral and axial resolution of 1.5 and [Formula: see text], respectively. A working distance of [Formula: see text] and field-of-view of [Formula: see text] m are achieved. Miniature apparatus is fabricated to assemble and align the scanhead components. The optics and scanner are packaged in a distal tip with 2.4 mm diameter and 10 mm rigid length. These dimensions allow the endomicroscope to pass forward easily through the 2.8 mm diameter working channel in medical endoscopes commonly used in clinical practice. Fluorescence images are collected in vivo at 10 frames per second in the colon of genetically-engineered mice that spontaneously develop adenomas. A FITC-labeled peptide heterodimer is administered intravenously to provide specific contrast. Sub-cellular structures are visualized to distinguish pre-malignant from normal mucosa. These results demonstrate use of microsystems methods to produce an ultra-compact instrument with sufficiently small dimensions for broad use.
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An Electrostatic MEMS Translational Scanner with Large Out-of-Plane Stroke for Remote Axial-Scanning in Multi-Photon Microscopy. MICROMACHINES 2017. [PMCID: PMC6190275 DOI: 10.3390/mi8050159] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Duan X, Li H, Li X, Oldham KR, Wang TD. Axial beam scanning in multiphoton microscopy with MEMS-based actuator. OPTICS EXPRESS 2017; 25:2195-2205. [PMID: 29519067 PMCID: PMC5772401 DOI: 10.1364/oe.25.002195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate a remotely located microelectromechanical systems (MEMS) actuator that can translate >400 μm to perform axial beam scanning in a multiphoton microscope. We use a 2-dimensional MEMS mirror for lateral scanning, and collected multiphoton excited fluorescence images in either the horizontal or vertical plane with a field-of-view of either 270 × 270 or 270 × 200 μm2, respectively, at 5 frames per second. Axial resolution varied from 4.5 to 7 μm over the scan range. The compact size of the actuator and scanner allows for use in an endomicroscope to collect images in the vertical plane with >200 μm depth.
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Affiliation(s)
- Xiyu Duan
- Dept. of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Haijun Li
- Dept. of Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI, USA
| | - Xue Li
- Dept. of Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI, USA
| | - Kenn R. Oldham
- Dept. of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Thomas D. Wang
- Dept. of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
- Dept. of Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI, USA
- Dept. of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
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Maia AMA, Longbottom C, Gomes ASL, Girkin JM. Enamel erosion and prevention efficacy characterized by confocal laser scanning microscope. Microsc Res Tech 2014; 77:439-45. [DOI: 10.1002/jemt.22364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 03/12/2014] [Accepted: 03/21/2014] [Indexed: 11/10/2022]
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Mansoor H, Zeng H, Tai IT, Zhao J, Chiao M. A handheld electromagnetically actuated fiber optic raster scanner for reflectance confocal imaging of biological tissues. IEEE Trans Biomed Eng 2013; 60:1431-8. [PMID: 23292783 DOI: 10.1109/tbme.2012.2236326] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We present a hand-held device aimed for reflectance-mode confocal imaging of biological tissues. The device consists of a light carrying optical fiber and a miniaturized raster scanner located at the distal end of the fiber. It is fabricated by mounting a polarization maintaining optical fiber on a cantilever beam that is attached to another beam such that their bending axes are perpendicular to each other. Fiber scanner is driven by electromagnetic forces and enables large fiber deflections with low driving currents. Optical resolutions of the system are 1.55 and 8.45 μm in the lateral and axial directions, respectively. Functionality of the system is demonstrated by obtaining confocal images of a fly wing and a human colon tissue sample.
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Affiliation(s)
- Hadi Mansoor
- Department of Mechanical Engineering, University of British Columbia, Vancouver, V6T 1Z4 BC, Canada
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Qiu Z, Liu Z, Duan X, Khondee S, Joshi B, Mandella MJ, Oldham K, Kurabayashi K, Wang TD. Targeted vertical cross-sectional imaging with handheld near-infrared dual axes confocal fluorescence endomicroscope. BIOMEDICAL OPTICS EXPRESS 2013; 4:322-30. [PMID: 23412564 PMCID: PMC3567718 DOI: 10.1364/boe.4.000322] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 01/16/2013] [Accepted: 01/16/2013] [Indexed: 05/08/2023]
Abstract
We demonstrate vertical cross-sectional (XZ-plane) images of near-infrared (NIR) fluorescence with a handheld dual axes confocal endomicroscope that reveals specific binding of a Cy5.5-labeled peptide to pre-malignant colonic mucosa. This view is perpendicular to the tissue surface, and is similar to that used by pathologists. The scan head is 10 mm in outer diameter (OD), and integrates a one dimensional (1-D) microelectromechanical systems (MEMS) X-axis scanner and a bulky lead zirconate titanate (PZT) based Z-axis actuator. The microscope images in a raster-scanning pattern with a ±6 degrees (mechanical) scan angle at ~3 kHz in the X-axis (fast) and up to 10 Hz (0-400 μm) in the Z-axis (slow). Vertical cross-sectional fluorescence images are collected with a transverse and axial resolution of 4 and 5 μm, respectively, over a field-of-view of 800 μm (width) × 400 μm (depth). NIR vertical cross-sectional fluorescence images of fresh mouse colonic mucosa demonstrate histology-like imaging performance with this miniature instrument.
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Affiliation(s)
- Zhen Qiu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhongyao Liu
- Department of Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xiyu Duan
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Supang Khondee
- Department of Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Bishnu Joshi
- Department of Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Michael J. Mandella
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kenn Oldham
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Katsuo Kurabayashi
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109, USA
| | - Thomas D. Wang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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