1. Articles from Huikai Xie

    1-24 of 32 1 2 »
    1. Ultralow-voltage electrothermal MEMS based fiber-optic scanning probe for forward-viewing endoscopic OCT

      Ultralow-voltage electrothermal MEMS based fiber-optic scanning probe for forward-viewing endoscopic OCT

      We report an ultralow-voltage, electrothermal (ET) micro-electro-mechanical system (MEMS) based probe for forward-viewing endoscopic optical coherence tomography (OCT) imaging. The fully assembled probe has a diameter of 5.5 mm and a length of 55 mm, including the imaging optics and a 40 mm long fiber-optic cantilever attached on a micro-platform of the bimorph ET MEMS actuator. The ET MEMS actuator provides a sufficient mechanical actuation force as well as a large vertical displacement, achieving up to a 3 mm optical scanning range with only a 3

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    2. Circumferential-scanning endoscopic optical coherence tomography probe based on a circular array of six 2-axis MEMS mirrors

      Circumferential-scanning endoscopic optical coherence tomography probe based on a circular array of six 2-axis MEMS mirrors

      We present a novel circumferential-scan endoscopic optical coherence tomography (OCT) probe by using a circular array of six electrothermal microelectromechanical (MEMS) mirrors and six C-lenses. The MEMS mirrors have a 0.5 mm × 0.5 mm mirror plate and a chip size of 1.5 mm × 1.3 mm. Each MEMS mirror can scan up to 45° at a voltage of less than 12 V. Six of those mirrors have been successfully packaged to a probe head; full circumferential scans have been demonstrated. Furthermore, each scan unit is composed of a MEMS mirror and a C-lens and the six scan ...

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      Mentions: Huikai K. Xie
    3. Design and Fabrication of a 2-Axis Electrothermal MEMS Micro-Scanner for Optical Coherence Tomography

      Design and Fabrication of a 2-Axis Electrothermal MEMS Micro-Scanner for Optical Coherence Tomography

      This paper introduces an optical 2-axis Micro Electro-Mechanical System (MEMS) micromirror actuated by a pair of electrothermal actuators and a set of passive torsion bars. The actuated element is a dual-reflective circular mirror plate of 1 m m in diameter. This inner mirror plate is connected to a rigid frame via a pair of torsion bars in two diametrically opposite ends located on the rotation axis. A pair of electrothermal bimorphs generates a force onto the perpendicular free ends of the mirror plate in the same angular direction. An array of electrothermal bimorph cantilevers deflects the rigid frame around a ...

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    4. Miniature multimodal endoscopic probe based on double-clad fiber

      Miniature multimodal endoscopic probe based on double-clad fiber

      Optical coherence tomography (OCT) can obtain light scattering properties with a high resolution, while photoacoustic imaging (PAI) is ideal for mapping optical absorbers in biological tissues, and ultrasound (US) could penetrate deeply into tissues and provide elastically structural information. It is attractive and challenging to integrate these three imaging modalities into a miniature probe, through which, both optical absorption and scattering information of tissues as well as deep-tissue structure can be obtained. Here, we present a novel side-view probe integrating PAI, OCT and US imaging based on double-clad fiber which is used as a common optical path for PAI (light ...

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    5. Miniature Endoscope for Multimodal Imaging

      Miniature Endoscope for Multimodal Imaging

      A single miniature endoscope capable of concurrently probing multiple contrast mechanisms of tissue in high resolution is highly attractive, as it makes it possible for providing complementary, more complete tissue information on internal organs hard to access. Here we describe such a miniature endoscope only 1 mm in diameter that integrates photoacoustic imaging (PAI), optical coherence tomography (OCT), and ultrasound (US). The integration of PAI/OCT/US allows for high-resolution imaging of three tissue contrasts including optical absorption (PAI), optical scattering (OCT), and acoustic properties (US). We demonstrate the capabilities of this trimodal endoscope using mouse ear, human hand, and ...

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    6. Common-path optical coherence tomography using a microelectromechanical-system-based endoscopic probe

      Common-path optical coherence tomography using a microelectromechanical-system-based endoscopic probe

      This paper presents a common-path (CP) swept-source optical coherence tomography (SSOCT) system based on a special endoscopic probe design with an in-line internal reflection as the reference and a two-axis electrothermal microelectromechanical system mirror for image scanning. The rear surface of a gradient reflective index (GRIN) lens inside the probe is set as the reference reflection plane. The length of the GRIN lens is optimized to eliminate the artifacts in SSOCT images successfully. Doppler OCT is also demonstrated based on the CP endoscopic probe. The diameter of the probe is only 2.5 mm, so it can be easily inserted ...

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    7. Miniature probe integrating optical-resolution photoacoustic microscopy, optical coherence tomography, and ultrasound imaging: proof-of-concept

      Miniature probe integrating optical-resolution photoacoustic microscopy, optical coherence tomography, and ultrasound imaging: proof-of-concept

      In this Letter, we present a novel tri-modal miniature side-view probe, through which optical-resolution photoacoustic microscopy (OR-PAM), optical coherence tomography (OCT), and pulse-echo ultrasound (US) images can be coaxially acquired and displayed simultaneously. The probe consists of a common optical path for OR-PAM (light delivery) and OCT (light delivery/detection), and a 40-MHz unfocused ultrasound transducer for OR-PAM (photoacoustic detection) and US (ultrasound transmission/receiving) with an overall diameter of 2 mm. Combining OR-PAM, OCT, and US would provide complementary information including optical absorption (OR-PAM), optical back-scattering (OCT), and deep tissue structures (US) about biological tissue. Based on an integrated ...

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    8. Electrothermal microactuator for large vertical displacement without tilt or lateral shift

      Electrothermal microactuator for large vertical displacement without tilt or lateral shift

      A microactuator for displacing a platform vertically with respect to a substrate includes a first rigid frame, a first flexible bimorph beam connecting the first frame to the substrate, a second rigid frame, a second flexible bimorph beam connecting the second frame to the first frame, and a third flexible bimorph beam connecting a platform to the second frame. Activation of the first, second, and third flexible bimorph beams allows vertical displacement of the platform with respect to the substrate, with negligible lateral shift. A microactuator assembly includes a substrate, a plurality of first rigid frames, a plurality of first ...

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    9. Method and apparatus for providing high-fill-factor micromirror/micromirror arrays with surface mounting capability

      Method and apparatus for providing high-fill-factor micromirror/micromirror arrays with surface mounting capability

      Embodiments of the subject invention relate to micromirror devices and methods of fabricating a micromirror/micromirror array. According to an embodiment, micromirrors can be fabricated from a semiconductor substrate where after forming actuators and bonding pads on a front side of the semiconductor substrate, the device is flipped over to have a portion of the back side of the substrate removed and formed to become the mirror plate surface. The subject micromirrors can allow further miniaturization of endoscopes and other optical applications without sacrificing the optical aperture through their surface mounting capabilities.

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      Mentions: Huikai K. Xie
    10. Swept-source common-path optical coherence tomography with a MEMS endoscopic imaging probe

      Swept-source common-path optical coherence tomography with a MEMS endoscopic imaging probe

      A MEMS-based common-path endoscopic imaging probe for 3D swept-source optical coherence tomography (SSOCT) has been developed. The common path is achieved by setting the reference plane at the rear surface of the GRIN lens inside the probe. MEMS devices have the advantages of low cost, small size and fast speed, which are suitable for miniaturizing endoscopic probes. The aperture size of the two-axis MEMS mirror employed in this endoscopic probe is 1 mm by 1 mm and the footprint of the MEMS chip is 1.55 mm by 1.7 mm. The MEMS mirror achieves large two dimensional optical scan ...

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    11. Feature Of The Week 9/29/13: Utilizing MEMs 2-Axis Mirror Scanners in an Endoscopic OCT Probe

      Feature Of The Week 9/29/13: Utilizing MEMs 2-Axis Mirror Scanners in an Endoscopic OCT Probe

      MEMs scanning technology offers many promising features such as low-cost and small size and seem likely to impact commercial OCT probes in the not too distant future. Recently researchers from the University of Shanghai for Science and Technology, WiO Technology Company, Nanjing Medical University, and University of Florida demonstrated an endoscopic OCT probe based on a 2-axis MEMS mirror. Below is a summary of their recent work. A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a ...

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    12. Probe alignment and design issues of microelectromechanical system based optical coherence tomography endoscopic imaging

      Probe alignment and design issues of microelectromechanical system based optical coherence tomography endoscopic imaging

      Endoscopic optical coherence tomography (OCT) imaging has been demonstrated using microelectromechanical system (MEMS) technology by several research groups. The focus of this work is to study how the OCT imaging performance is affected by the radius of curvature of MEMS mirrors as well as the optical alignment accuracy inside small imaging probes. The goal of this study is to provide guidance for assembly tolerance and design optimization of OCT endoscopic probes. Gaussian beam propagation is used for theoretical analysis which is confirmed by optical simulation and verified experimentally with a time-domain OCT system as well. It has been found that ...

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    13. Correction of image distortions in endoscopic optical coherence tomography based on two-axis scanning MEMS mirrors

      Correction of image distortions in endoscopic optical coherence tomography based on two-axis scanning MEMS mirrors

      A two-axis scanning microelectromechanical (MEMS) mirror enables an optical coherence tomography (OCT) system to perform three-dimensional endoscopic imaging due to its fast scan speed and small size. However, the radial scan from the MEMS mirror causes various distortions in OCT images, namely spherical, fan-shaped and keystone distortions. In this paper, a new method is proposed to correct all of three distortions presented in OCT systems based on two-axis MEMS scanning mirrors. The spherical distortion is corrected first by directly manipulating the original spectral interferograms in the phase domain, followed by Fourier transform and three-dimensional geometrical transformation for correcting the other ...

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    14. Endoscopic swept-source optical coherence tomography based on a two-axis microelectromechanical system mirror

      Endoscopic swept-source optical coherence tomography based on a two-axis microelectromechanical system mirror

      A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a two-axis MEMS scanning mirror which has a 0.8 × 0.8     mm 2 mirror plate and a 1.6 × 1.4     mm 2 device footprint. The diameter of the endoscopic probe is only 3.5 mm. The imaging rate of the SS-OCT system is 50     frames / s . OCT images of both human suspicious oral leukoplakia tissue and normal buccal mucosa were taken in vivo and compared. The ...

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    15. A Tip-Tilt-Piston Micromirror With Symmetrical Lateral-Shift-Free Piezoelectric Actuators

      A Tip-Tilt-Piston Micromirror With Symmetrical Lateral-Shift-Free Piezoelectric Actuators

      In this paper, we present the design, fabrication, and characterization of a high-fill-factor tip-tilt-piston micromirror actuated by four symmetrical lateral-shift-free (LSF) piezoelectric actuators. Lead zirconate titanate (PZT) is the piezoelectric material deposited using a sol-gel process. The micromirror can operate in both piston and rotation modes. At the piston mode, the measured resonant frequency is 990 Hz. An 18.3-μm piston displacement is obtained by applying 5 Vdc to four symmetrical LSF (SLSF) actuators. For the rotation mode, the measured resonant frequency is 1650 Hz and an optical deflection angle of 4.2° is measured by applying 5 Vdc ...

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    16. Miniature probe combining optical-resolution photoacoustic microscopy and optical coherence tomography for in vivomicrocirculation study

      Miniature probe combining optical-resolution photoacoustic microscopy and optical coherence tomography for in vivomicrocirculation study

      Photoacoustic microscopy (PAM) is sensitive to optical absorption, while optical coherence tomography (OCT) is based on optical backscattering. Combining PAM and OCT can provide complementary information about biological tissue. Here we present a combined optical-resolution PAM (ORPAM) and OCT system that is integrated through a miniature probe with an overall diameter of 2.3 mm, suitable for insertion through a standard endoscopic or laparoscopic port during minimally invasive surgery or endoscopic exam. The hybrid probe consists of a common optical path for OCT (light delivery/detection) and ORPAM (light excitation) and a 10 MHz unfocused ultrasound transducer for photoacoustic detection ...

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    17. A 2.8-mm Imaging Probe Based On a High-Fill-Factor MEMS Mirror and Wire-Bonding-Free Packaging for Endoscopic Optical Coherence Tomography

      A 2.8-mm Imaging Probe Based On a High-Fill-Factor MEMS Mirror and Wire-Bonding-Free Packaging for Endoscopic Optical Coherence Tomography

      This paper reports a miniature optical coherence tomography (OCT) probe and high-resolution 3-D OCT imaging results obtained with this side-view probe. The probe is only 2.8 mm in diameter, enabled by a unique high-fill-factor electrothermal MEMS mirror with hidden actuators and a novel wire-bonding-free packaging technique. The MEMS mirror has a large mirror aperture of 1 mm with a chip size of only 1.55 mm $times$ 1.7 mm $times$0.5 mm. The fabricated device achieves large 2-D scan optical angles up to 46$^{circ}$ at only 4.8 V. The specific time-domain OCT system utilized is ...

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    18. Refractive index measurement of acute rat brain tissue slices using optical coherence tomography

      Refractive index measurement of acute rat brain tissue slices using optical coherence tomography
      An optical coherence tomography (OCT) system employing a microelectromechanical system (MEMS) mirror was used to measure the refractive index (RI) of anatomically different regions in acute brain tissue slices, in which viability was maintained. RI was measured in white-matter and grey-matter regions, including the cerebral cortex, putamen, hippocampus, thalamus and corpus callosum. The RI in the corpus callosum was found to be ~4% higher than the RIs in other regions. Changes in RI with tissue deformation were also measured in the cerebral cortex and corpus callosum under uniform compression (20-80% strain). For 80% strain, measured RIs increased nonlinearly by up ...
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    19. MEMS-Based Endoscopic Optical Coherence Tomography

      MEMS-Based Endoscopic Optical Coherence Tomography
      Early cancer detection has been playing an important role in reducing cancer mortality. Optical coherence tomography (OCT), due to its micron-scale resolution, has the ability to detect cancerous tissues at their early stages. For internal organs, endoscopic probes are needed as the penetration depth of OCT is about 1–3 mm. MEMS technology has the advantages of fast speed, small size, and low cost, and it has been widely used as the scanning engine in endoscopic OCT probes. Research results have shown great potential for OCT in endoscopic imaging by incorporating MEMS scanning mirrors. Various MEMS-OCT designs are introduced, and ...
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    20. Single fiber endoscopic full-field optical coherence tomography (OCT) imaging probe

      Single fiber endoscopic full-field optical coherence tomography (OCT) imaging probe
      A single fiber full-field optical coherence tomography (OCT) imaging probe (300) includes a hollow tube (301), and a single fiber (305) disposed within the tube for transmitting light received from a broadband light source to a beam splitter (350) in the tube optically coupled to the single fiber (305). The beam splitter (350) splits the light into a first and a second optical beam, wherein the first beam is optically coupled to a reference arm including a MEMS reference micromirror (335) which provides axial scanning and the second beam is optically coupled to a sample arm for probing a sample ...
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    21. Miniature endoscopic optical coherence tomography probe employing a two-axis microelectromechanical scanning mirror with through-silicon vias

      Miniature endoscopic optical coherence tomography probe employing a two-axis microelectromechanical scanning mirror with through-silicon vias
      We present the design and experimental results of a new MEMS-based endoscopic optical coherence tomography (OCT) probe. The uniqueness of this miniature OCT imaging probe is a two-axis MEMS mirror with through-silicon vias (TSVs) for interconnecting. The TSV interconnection enables ultracompact probe design, successfully reducing the probe size to only 2.6 mm in diameter. The MEMS mirror is actuated by an electrothermal actuator that is capable of scanning ±16° at only 3.6 V DC. Two-dimensional and three-dimensional OCT images of microspheres embedded in PDMS and acute rat brain tissue have been obtained with this miniature probe in a ...
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    22. 3D In Vivo optical coherence tomography based on a low-voltage, large-scan-range 2D MEMS mirror

      3D In Vivo optical coherence tomography based on a low-voltage, large-scan-range 2D MEMS mirror
      3D in vivo optical imaging on a mouse has been obtained using a 2D MEMS mirror for lateral scanning in a time-domain optical coherence tomography (OCT) system. The MEMS mirror aperture size is 1 × 1 mm2, and the device footprint is 2 × 2 mm2. The MEMS mirror scans ± 30° optical angles about both x and y-axis at only 5.5V DC voltage. An endoscopic probe with an outer diameter of 5.8 mm has been designed, manufactured and packaged. The probe scans an average transverse area of 2 mm × 2 mm. The imaging speed of the probe is about 2 ...
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    23. The potential of optical coherence tomography for diagnosing meniscal pathology

      The potential of optical coherence tomography for diagnosing meniscal pathology
      Meniscal tears are often associated with anterior cruciate ligament (ACL) injury and may lead to pain and discomfort in humans. Maximal preservation of meniscal tissue is highly desirable to mitigate the progression of osteoarthritis. Guidelines of which meniscal tears are amenable to repair and what part of damaged tissues should be removed are elusive and lacking consensus. Images of microstructural changes in meniscus would potentially guide the surgeons to manage the meniscal tears better, but the resolution of current diagnostic techniques is limited for this application. In this study, we demonstrated the feasibility of using optical coherence tomography (OCT) for ...
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    24. Optical micro-endoscopes for 3D in-vivo imaging

      Optical micro-endoscopes for 3D in-vivo imaging

      Electrothermal micromirrors and a flexible printed circuit board permit fast, small optical coherence tomography of internal organs. Optical coherence tomography (OCT) is a medical optical imaging technique that can achieve high-resolution 3D images (1-15μm)1 by detecting infrared light scattered by body tissue. It has an imaging depth range of about 3mm in highly-scattered tissue and has already been widely used for external imaging, e.g., for eye diseases and skin cancer diagnosis. It would be useful to apply OCT to internal imaging, since about 85% of all cancers originate from the surface layers of internal organs. As these ...

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    1-24 of 32 1 2 »
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    1. (31 articles) Huikai K. Xie
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