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3 pages, 138 KiB

Open AccessEditorial

Editorial for the Special Issue on MEMS Technology for Biomedical Imaging Applications

by Qifa Zhou and Yi Zhang

Micromachines 2019, 10(9), 615; https://doi.org/10.3390/mi10090615 - 16 Sep 2019

Cited by 2 | Viewed by 2144

Abstract

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science [...] Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

Research

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23 pages, 11629 KiB

Open AccessArticle

Design and Fabrication of a Push-Pull Electrostatic Actuated Cantilever Waveguide Scanner

by Wei-Chih Wang, Kebin Gu and ChiLeung Tsui

Micromachines 2019, 10(7), 432; https://doi.org/10.3390/mi10070432 - 29 Jun 2019

Cited by 5 | Viewed by 3437

Abstract

The paper presents a novel fully integrated MEMS-based non-resonating operated 2D mechanical scanning system using a 1D push-pull actuator. Details of the design, fabrication and tests performed are presented. The current design utilizes an integrated electrostatic push-pull actuator and a SU-8 rib waveguide [...] Read more.

The paper presents a novel fully integrated MEMS-based non-resonating operated 2D mechanical scanning system using a 1D push-pull actuator. Details of the design, fabrication and tests performed are presented. The current design utilizes an integrated electrostatic push-pull actuator and a SU-8 rib waveguide with a large core cross section (4 μm in height and 20 μm in width) in broadband single mode operation (λ = 0.4 μm to 0.65 μm). We have successfully demonstrated a 2D scanning motion using non- resonating operation with 201 Hz in vertical direction and 20 Hz in horizontal direction. This non-resonating scanner system has achieved a field of view (FOV) of 0.019 to 0.072 radians in vertical and horizontal directions, with the advantage of overcoming its frequency shift caused by fabrication uncertainties. In addition, we observed two fundamental resonances at 201 and 536 Hz in the vertical and horizontal directions with corresponding displacements of 130 and 19 μm, or 0.072 and 0.0105 radian field of view operating at a +150 V input. A gradient index (GRIN) lens is placed at the end of the waveguide to focus the diverging beam output from the waveguide and a 20 μm beam diameter is observed at the focal plane. The transmission efficiency of the waveguide is slightly low (~10%) and slight tensile residual stress can be observed at the cantilever portion of the waveguide due to inherent imperfections in the fabrication process. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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11 pages, 3664 KiB

Open AccessFeature PaperArticle

Three-Dimensional Printed Piezoelectric Array for Improving Acoustic Field and Spatial Resolution in Medical Ultrasonic Imaging

by Zeyu Chen, Xuejun Qian, Xuan Song, Qiangguo Jiang, Rongji Huang, Yang Yang, Runze Li, Kirk Shung, Yong Chen and Qifa Zhou

Micromachines 2019, 10(3), 170; https://doi.org/10.3390/mi10030170 - 28 Feb 2019

Cited by 29 | Viewed by 5357

Abstract

Piezoelectric arrays are widely used in non-destructive detecting, medical imaging and therapy. However, limited by traditional manufacturing methods, the array’s element is usually designed in simple geometry such as a cube or rectangle, restricting potential applications of the array. This work demonstrates an [...] Read more.

Piezoelectric arrays are widely used in non-destructive detecting, medical imaging and therapy. However, limited by traditional manufacturing methods, the array’s element is usually designed in simple geometry such as a cube or rectangle, restricting potential applications of the array. This work demonstrates an annular piezoelectric array consisting of different concentric elements printed by Mask-Image-Projection-based Stereolithography (MIP-SL) technology. The printed array displays stable piezoelectric and dielectric properties. Compared to a traditional single element transducer, the ultrasonic transducer with printed array successfully modifies the acoustic beam and significantly improves spatial resolution. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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8 pages, 2801 KiB

Open AccessArticle

Scanning MEMS Mirror for High Definition and High Frame Rate Lissajous Patterns

by Yeong-Hyeon Seo, Kyungmin Hwang, Hyunwoo Kim and Ki-Hun Jeong

Micromachines 2019, 10(1), 67; https://doi.org/10.3390/mi10010067 - 18 Jan 2019

Cited by 37 | Viewed by 8244

Abstract

Scanning MEMS (micro-electro-mechanical system) mirrors are attractive given their potential use in a diverse array of laser scanning display and imaging applications. Here we report on an electrostatic MEMS mirror for high definition and high frame rate (HDHF) Lissajous scanning. The MEMS mirror [...] Read more.

Scanning MEMS (micro-electro-mechanical system) mirrors are attractive given their potential use in a diverse array of laser scanning display and imaging applications. Here we report on an electrostatic MEMS mirror for high definition and high frame rate (HDHF) Lissajous scanning. The MEMS mirror comprised a low Q-factor inner mirror and frame mirror, which provided two-dimensional scanning at two similar resonant scanning frequencies with high mechanical stability. The low Q inner mirror enabled a broad frequency selection range. The high definition and high frame rate (HDHF) Lissajous scanning of the MEMS mirror was achieved by selecting a set of scanning frequencies near its resonance with a high greatest common divisor (GCD) and a high total lobe number. The MEMS mirror had resonant scanning frequencies at 5402 Hz and 6702 Hz in x and y directions, respectively. The selected pseudo-resonant frequencies of 5450 Hz and 6700 Hz for HDHF scanning provided 50 frames per second with 94% fill factor in 256 × 256 pixels. This Lissajous MEMS mirror could be utilized for assorted HDHF laser scanning imaging and display applications. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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16 pages, 4747 KiB

Open AccessArticle

Remote Microwave and Field-Effect Sensing Techniques for Monitoring Hydrogel Sensor Response

by Olutosin Charles Fawole, Subhashish Dolai, Hsuan-Yu Leu, Jules Magda and Massood Tabib-Azar

Micromachines 2018, 9(10), 526; https://doi.org/10.3390/mi9100526 - 17 Oct 2018

Cited by 5 | Viewed by 3516

Abstract

This paper presents two novel techniques for monitoring the response of smart hydrogels composed of synthetic organic materials that can be engineered to respond (swell or shrink, change conductivity and optical properties) to specific chemicals, biomolecules or external stimuli. The first technique uses [...] Read more.

This paper presents two novel techniques for monitoring the response of smart hydrogels composed of synthetic organic materials that can be engineered to respond (swell or shrink, change conductivity and optical properties) to specific chemicals, biomolecules or external stimuli. The first technique uses microwaves both in contact and remote monitoring of the hydrogel as it responds to chemicals. This method is of great interest because it can be used to non-invasively monitor the response of subcutaneously implanted hydrogels to blood chemicals such as oxygen and glucose. The second technique uses a metal-oxide-hydrogel field-effect transistor (MOHFET) and its associated current-voltage characteristics to monitor the hydrogel’s response to different chemicals. MOHFET can be easily integrated with on-board telemetry electronics for applications in implantable biosensors or it can be used as a transistor in an oscillator circuit where the oscillation frequency of the circuit depends on the analyte concentration. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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12 pages, 3334 KiB

Open AccessArticle

Ultrahigh Frequency Ultrasonic Transducers Design with Low Noise Amplifier Integrated Circuit

by Di Li, Chunlong Fei, Qidong Zhang, Yani Li, Yintang Yang and Qifa Zhou

Micromachines 2018, 9(10), 515; https://doi.org/10.3390/mi9100515 - 12 Oct 2018

Cited by 9 | Viewed by 6219

Abstract

This paper describes the design of an ultrahigh frequency ultrasound system combined with tightly focused 500 MHz ultrasonic transducers and high frequency wideband low noise amplifier (LNA) integrated circuit (IC) model design. The ultrasonic transducers are designed using Aluminum nitride (AlN) piezoelectric thin [...] Read more.

This paper describes the design of an ultrahigh frequency ultrasound system combined with tightly focused 500 MHz ultrasonic transducers and high frequency wideband low noise amplifier (LNA) integrated circuit (IC) model design. The ultrasonic transducers are designed using Aluminum nitride (AlN) piezoelectric thin film as the piezoelectric element and using silicon lens for focusing. The fabrication and characterization of silicon lens was presented in detail. Finite element simulation was used for transducer design and evaluation. A custom designed LNA circuit is presented for amplifying the ultrasound echo signal with low noise. A Common-source and Common-gate (CS-CG) combination structure with active feedback is adopted for the LNA design so that high gain and wideband performances can be achieved simultaneously. Noise and distortion cancelation mechanisms are also employed in this work to improve the noise figure (NF) and linearity. Designed by using a 0.35 μm complementary metal oxide semiconductor (CMOS) technology, the simulated power gain of the echo signal wideband amplifier is 22.5 dB at 500 MHz with a capacitance load of 1.0 pF. The simulated NF at 500 MHz is 3.62 dB. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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8 pages, 2712 KiB

Open AccessArticle

High Frequency Needle Ultrasonic Transducers Based on Lead-Free Co Doped Na_0.5Bi_4.5Ti₄O₁₅ Piezo-Ceramics

by Chunlong Fei, Tianlong Zhao, Danfeng Wang, Yi Quan, Pengfei Lin, Di Li, Yintang Yang, Jianzheng Cheng, Chunlei Wang, Chunming Wang and Qifa Zhou

Micromachines 2018, 9(6), 291; https://doi.org/10.3390/mi9060291 - 10 Jun 2018

Cited by 17 | Viewed by 4226

Abstract

This paper describes the design, fabrication, and characterization of tightly focused (ƒ-number close to 1) high frequency needle-type transducers based on lead-free Na_0.5Bi_4.5Ti_3.975Co_0.025O₁₅ (NBT-Co) piezo-ceramics. The NBT-Co ceramics, are fabricated through solid-state reactions, have [...] Read more.

This paper describes the design, fabrication, and characterization of tightly focused (ƒ-number close to 1) high frequency needle-type transducers based on lead-free Na_0.5Bi_4.5Ti_3.975Co_0.025O₁₅ (NBT-Co) piezo-ceramics. The NBT-Co ceramics, are fabricated through solid-state reactions, have a piezoelectric coefficient d₃₃ of 32 pC/N, and an electromechanical coupling factor k_t of 35.3%. The high Curie temperature (670 °C) indicates a wide working temperature range. Characterization results show a center frequency of 70.4 MHz and a −6 dB bandwidth of 52.7%. Lateral resolution of 29.8 μm was achieved by scanning a 10 μm tungsten wire target, and axial resolution of 20.8 μm was calculated from the full width at half maximum (FWHM) of the pulse length of the echo. This lead-free ultrasonic transducer has potential applications in high resolution biological imaging. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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7 pages, 3797 KiB

Open AccessArticle

Miniaturized Optical Resolution Photoacoustic Microscope Based on a Microelectromechanical Systems Scanning Mirror

by Weizhi Qi, Qian Chen, Heng Guo, Huikai Xie and Lei Xi

Micromachines 2018, 9(6), 288; https://doi.org/10.3390/mi9060288 - 7 Jun 2018

Cited by 17 | Viewed by 4727

Abstract

In this paper, we report a miniaturized optical resolution photoacoustic microscopy system based on a microelectromechanical system (MEMS) scanning mirror. A two-dimensional MEMS scanning mirror was used to achieve raster scanning of the excitation optical focus. The wideband photoacoustic signals were detected by [...] Read more.

In this paper, we report a miniaturized optical resolution photoacoustic microscopy system based on a microelectromechanical system (MEMS) scanning mirror. A two-dimensional MEMS scanning mirror was used to achieve raster scanning of the excitation optical focus. The wideband photoacoustic signals were detected by a flat ultrasound transducer with a center frequency of 10 MHz and an active area of 2 mm in diameter. The size and weight of this device were 60 mm × 30 mm × 20 mm and 40 g, respectively. We evaluated this system using sharp blades, carbon fibers, and a silver strip target. In vivo experiments of imaging vasculatures in the mouse ear, brain, and human lip were completed to demonstrate its potential for biological and clinical applications. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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25 pages, 8746 KiB

Open AccessArticle

Adaptive Absolute Ego-Motion Estimation Using Wearable Visual-Inertial Sensors for Indoor Positioning

by Ya Tian, Zhe Chen, Shouyin Lu and Jindong Tan

Micromachines 2018, 9(3), 113; https://doi.org/10.3390/mi9030113 - 6 Mar 2018

Cited by 4 | Viewed by 4272

Abstract

This paper proposes an adaptive absolute ego-motion estimation method using wearable visual-inertial sensors for indoor positioning. We introduce a wearable visual-inertial device to estimate not only the camera ego-motion, but also the 3D motion of the moving object in dynamic environments. Firstly, a [...] Read more.

This paper proposes an adaptive absolute ego-motion estimation method using wearable visual-inertial sensors for indoor positioning. We introduce a wearable visual-inertial device to estimate not only the camera ego-motion, but also the 3D motion of the moving object in dynamic environments. Firstly, a novel method dynamic scene segmentation is proposed using two visual geometry constraints with the help of inertial sensors. Moreover, this paper introduces a concept of “virtual camera” to consider the motion area related to each moving object as if a static object were viewed by a “virtual camera”. We therefore derive the 3D moving object’s motion from the motions for the real and virtual camera because the virtual camera’s motion is actually the combined motion of both the real camera and the moving object. In addition, a multi-rate linear Kalman-filter (MR-LKF) as our previous work was selected to solve both the problem of scale ambiguity in monocular camera tracking and the different sampling frequencies of visual and inertial sensors. The performance of the proposed method is evaluated by simulation studies and practical experiments performed in both static and dynamic environments. The results show the method’s robustness and effectiveness compared with the results from a Pioneer robot as the ground truth. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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11 pages, 3793 KiB

Open AccessArticle

Fabrication of Electromagnetically-Driven Tilted Microcoil on Polyimide Capillary Surface for Potential Single-Fiber Endoscope Scanner Application

by Zhuoqing Yang, Jianhao Shi, Bin Sun, Jinyuan Yao, Guifu Ding and Renshi Sawada

Micromachines 2018, 9(2), 61; https://doi.org/10.3390/mi9020061 - 1 Feb 2018

Cited by 4 | Viewed by 4117

Abstract

The design and fabrication of a Micro-electromechanical Systems (MEMS)-based tilted microcoil on a polyimide capillary are reported in this paper, proposed for an electromagnetically-driven single-fiber endoscope scanner application. The parameters of the tilted microcoil were optimized by simulation. It is proved that the [...] Read more.

The design and fabrication of a Micro-electromechanical Systems (MEMS)-based tilted microcoil on a polyimide capillary are reported in this paper, proposed for an electromagnetically-driven single-fiber endoscope scanner application. The parameters of the tilted microcoil were optimized by simulation. It is proved that the largest driving force could be achieved when the tilt-angle, the pitch and the coil turns of the designed microcoil were 60°, 80 µm and 20, respectively. The modal simulation of the designed fiber scanner was carried out. The prototypes of the tilted microcoils were fabricated on the surface of polyimide capillary with 1 mm-diameter using our developed cylindrical projection lithography system. The dimensions of the two tilted microcoils were as follows: one was tilt-angle 45°, line width 10 ± 0.2 µm, coil pitch 78.5 ± 0.5 µm, and the other was tilt-angle 60°, line width 10 ± 0.2 µm, coil pitch 81.5 ± 0.5 µm. Finally, a direct mask-less electroplating process was employed to fabricate the copper microcoil with 15 µm thickness on the gold (Au) seed-layer, and the corresponding line width was expanded to 40 µm. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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Review

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18 pages, 4131 KiB

Open AccessReview

Micro-optical Components for Bioimaging on Tissues, Cells and Subcellular Structures

by Hui Yang, Yi Zhang, Sihui Chen and Rui Hao

Micromachines 2019, 10(6), 405; https://doi.org/10.3390/mi10060405 - 19 Jun 2019

Cited by 9 | Viewed by 4211

Abstract

Bioimaging generally indicates imaging techniques that acquire biological information from living forms. Among different imaging techniques, optical microscopy plays a predominant role in observing tissues, cells and biomolecules. Along with the fast development of microtechnology, developing miniaturized and integrated optical imaging systems has [...] Read more.

Bioimaging generally indicates imaging techniques that acquire biological information from living forms. Among different imaging techniques, optical microscopy plays a predominant role in observing tissues, cells and biomolecules. Along with the fast development of microtechnology, developing miniaturized and integrated optical imaging systems has become essential to provide new imaging solutions for point-of-care applications. In this review, we will introduce the basic micro-optical components and their fabrication technologies first, and further emphasize the development of integrated optical systems for in vitro and in vivo bioimaging, respectively. We will conclude by giving our perspectives on micro-optical components for bioimaging applications in the near future. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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27 pages, 5515 KiB

Open AccessReview

Advances in Capacitive Micromachined Ultrasonic Transducers

by Kevin Brenner, Arif Sanli Ergun, Kamyar Firouzi, Morten Fischer Rasmussen, Quintin Stedman and Butrus (Pierre) Khuri–Yakub

Micromachines 2019, 10(2), 152; https://doi.org/10.3390/mi10020152 - 23 Feb 2019

Cited by 124 | Viewed by 12451

Abstract

Capacitive micromachined ultrasonic transducer (CMUT) technology has enjoyed rapid development in the last decade. Advancements both in fabrication and integration, coupled with improved modelling, has enabled CMUTs to make their way into mainstream ultrasound imaging systems and find commercial success. In this review [...] Read more.

Capacitive micromachined ultrasonic transducer (CMUT) technology has enjoyed rapid development in the last decade. Advancements both in fabrication and integration, coupled with improved modelling, has enabled CMUTs to make their way into mainstream ultrasound imaging systems and find commercial success. In this review paper, we touch upon recent advancements in CMUT technology at all levels of abstraction; modeling, fabrication, integration, and applications. Regarding applications, we discuss future trends for CMUTs and their impact within the broad field of biomedical imaging. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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18 pages, 5668 KiB

Open AccessReview

MEMS Actuators for Optical Microendoscopy

by Zhen Qiu and Wibool Piyawattanametha

Micromachines 2019, 10(2), 85; https://doi.org/10.3390/mi10020085 - 24 Jan 2019

Cited by 21 | Viewed by 6739

Abstract

Growing demands for affordable, portable, and reliable optical microendoscopic imaging devices are attracting research institutes and industries to find new manufacturing methods. However, the integration of microscopic components into these subsystems is one of today’s challenges in manufacturing and packaging. Together with this [...] Read more.

Growing demands for affordable, portable, and reliable optical microendoscopic imaging devices are attracting research institutes and industries to find new manufacturing methods. However, the integration of microscopic components into these subsystems is one of today’s challenges in manufacturing and packaging. Together with this kind of miniaturization more and more functional parts have to be accommodated in ever smaller spaces. Therefore, solving this challenge with the use of microelectromechanical systems (MEMS) fabrication technology has opened the promising opportunities in enabling a wide variety of novel optical microendoscopy to be miniaturized. MEMS fabrication technology enables abilities to apply batch fabrication methods with high-precision and to include a wide variety of optical functionalities to the optical components. As a result, MEMS technology has enabled greater accessibility to advance optical microendoscopy technology to provide high-resolution and high-performance imaging matching with traditional table-top microscopy. In this review the latest advancements of MEMS actuators for optical microendoscopy will be discussed in detail. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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21 pages, 4861 KiB

Open AccessFeature PaperReview

Recent Progress on Photoacoustic Imaging Enhanced with Microelectromechanical Systems (MEMS) Technologies

by Changho Lee, Jin Young Kim and Chulhong Kim

Micromachines 2018, 9(11), 584; https://doi.org/10.3390/mi9110584 - 8 Nov 2018

Cited by 37 | Viewed by 6286

Abstract

Photoacoustic imaging (PAI) is a new biomedical imaging technology currently in the spotlight providing a hybrid contrast mechanism and excellent spatial resolution in the biological tissues. It has been extensively studied for preclinical and clinical applications taking advantage of its ability to provide [...] Read more.

Photoacoustic imaging (PAI) is a new biomedical imaging technology currently in the spotlight providing a hybrid contrast mechanism and excellent spatial resolution in the biological tissues. It has been extensively studied for preclinical and clinical applications taking advantage of its ability to provide anatomical and functional information of live bodies noninvasively. Recently, microelectromechanical systems (MEMS) technologies, particularly actuators and sensors, have contributed to improving the PAI system performance, further expanding the research fields. This review introduces cutting-edge MEMS technologies for PAI and summarizes the recent advances of scanning mirrors and detectors in MEMS. Full article

(This article belongs to the Special Issue MEMS Technology for Biomedical Imaging Applications)

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