scholarly journals MEMS Ultrasound Transducers for Endoscopic Photoacoustic Imaging Applications

Micromachines ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 928 ◽  
Author(s):  
Haoran Wang ◽  
Yifei Ma ◽  
Hao Yang ◽  
Huabei Jiang ◽  
Yingtao Ding ◽  
...  

Photoacoustic imaging (PAI) is drawing extensive attention and gaining rapid development as an emerging biomedical imaging technology because of its high spatial resolution, large imaging depth, and rich optical contrast. PAI has great potential applications in endoscopy, but the progress of endoscopic PAI was hindered by the challenges of manufacturing and assembling miniature imaging components. Over the last decade, microelectromechanical systems (MEMS) technology has greatly facilitated the development of photoacoustic endoscopes and extended the realm of applicability of the PAI. As the key component of photoacoustic endoscopes, micromachined ultrasound transducers (MUTs), including piezoelectric MUTs (pMUTs) and capacitive MUTs (cMUTs), have been developed and explored for endoscopic PAI applications. In this article, the recent progress of pMUTs (thickness extension mode and flexural vibration mode) and cMUTs are reviewed and discussed with their applications in endoscopic PAI. Current PAI endoscopes based on pMUTs and cMUTs are also introduced and compared. Finally, the remaining challenges and future directions of MEMS ultrasound transducers for endoscopic PAI applications are given.

2012 ◽  
Vol 220-223 ◽  
pp. 915-920
Author(s):  
Jeng Haur Horng ◽  
Jen Fin Lin ◽  
Shin Yuh Chern ◽  
Chin Chung Wei ◽  
Chun Yueh Chen

With the rapid development of microelectromechanical systems (MEMS) technology, materials such as silicon, metal, and polymers are widely used in the MEMS field. One of the reliability concerns related to Si MEMS is unwanted wear and adhesion. Therefore, SiC film is a possible choice for surfaces because of its favorable friction and wear properties such as used in cutting tool and transmission system of wind turbine. In this study, biocompatible SAM film (ODS) was used to decrease the adhesion force and the friction coefficient of SiC surface. Experimental results show that ODS can increase the contact angle and decrease the surface roughness value of SiC surfaces for the different roughness values and roughness directions. For Si, SiC film and SAMs film on surfaces, larger normal forces lead to smaller friction coefficients and cross roughness pattern have a smaller friction coefficient than that of straight roughness pattern. In addition, ODS film can decrease the friction coefficient on cross topography with relative small roughness value more effectively than can straight topography of SiC surfaces.


Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1257
Author(s):  
Haoran Wang ◽  
Yifei Ma ◽  
Qincheng Zheng ◽  
Ke Cao ◽  
Yao Lu ◽  
...  

Facilitated by microelectromechanical systems (MEMS) technology, MEMS speakers or microspeakers have been rapidly developed during the past decade to meet the requirements of the flourishing audio market. With advantages of a small footprint, low cost, and easy assembly, MEMS speakers are drawing extensive attention for potential applications in hearing instruments, portable electronics, and the Internet of Things (IoT). MEMS speakers based on different transduction mechanisms, including piezoelectric, electrodynamic, electrostatic, and thermoacoustic actuation, have been developed and significant progresses have been made in commercialization in the last few years. In this article, the principle and modeling of each MEMS speaker type is briefly introduced first. Then, the development of MEMS speakers is reviewed with key specifications of state-of-the-art MEMS speakers summarized. The advantages and challenges of all four types of MEMS speakers are compared and discussed. New approaches to improve sound pressure levels (SPLs) of MEMS speakers are also proposed. Finally, the remaining challenges and outlook of MEMS speakers are given.


Author(s):  
J-B Li ◽  
K Jiang ◽  
G J Davies

A novel die-sinking micro-electro discharge machining (EDM) process is presented for volume fabrication of metallic microcomponents. In the process, a high-precision silicon electrode is fabricated using deep reactive ion etching (DRIE) process of microelectromechanical systems (MEMS) technology and then coated with a thin layer of copper to increase the conductivity. The metalized Si electrode is used in the EDM process to manufacture metallic microcomponents by imprinting the electrode onto a flat metallic surface. The two main advantages of this process are that it enables the fabrication of metallic microdevices and reduces manufacturing cost and time. The development of the new EDM process is described. A silicon component was produced using the Surface Technology Systems plasma etcher and the DRIE process. Such components can be manufactured with a precision in nanometres. The minimum feature of the component is 50 μm. In the experiments, the Si component was coated with copper and then used as the electrode on an EDM machine of 1 μm resolution. In the manufacturing process, 130 V and 0.2 A currents were used for a period of 5 min. The SEM images of the resulting device show clear etched areas, and the electric discharge wave chart indicates a good fabrication condition. The experimental results have been analysed and the new micro-EDM process is found to be able to fabricate 25 μm features.


Author(s):  
Nidhi Singh ◽  
Emmanuel Cherin ◽  
Yohannes Soenjaya ◽  
Maninder Matharoo ◽  
Brandon Brisbane ◽  
...  

2001 ◽  
Author(s):  
Emily J. Pryputniewicz ◽  
John P. Angelosanto ◽  
Gordon C. Brown ◽  
Cosme Furlong ◽  
Ryszard J. Pryputniewicz

Abstract Using recent advances in microelectromechanical systems (MEMS) technology, a new multivariable sensor was developed. This MEMS sensor, capable of measuring temperature, absolute pressure, and differential pressure on a single chip, is particularly suitable for applications in process control industry. However, functional operation of the sensor depends on validation of its performance under specific test conditions. We have developed a hybrid methodology, based on analysis and measurements, that allows such validation. In this paper, the MEMS multivariable sensor is described, the hybrid methodology is outlined, and its use is illustrated with representative results.


2012 ◽  
Vol 81 ◽  
pp. 65-74 ◽  
Author(s):  
Jacopo Iannacci ◽  
Giuseppe Resta ◽  
Paola Farinelli ◽  
Roberto Sorrentino

MEMS (MicroElectroMechanical-Systems) technology applied to the field of Radio Frequency systems (i.e. RF-MEMS) has emerged in the last 10-15 years as a valuable and viable solution to manufacture low-cost and very high-performance passive components, like variable capacitors, inductors and micro-relays, as well as complex networks, like tunable filters, reconfigurable impedance matching networks and phase shifters, and so on. The availability of such components and their integration within RF systems (e.g. radio transceivers, radars, satellites, etc.) enables boosting the characteristics and performance of telecommunication systems, addressing for instance a significant increase of their reconfigurability. The benefits resulting from the employment of RF-MEMS technology are paramount, being some of them the reduction of hardware redundancy and power consumption, along with the operability of the same RF system according to multiple standards. After framing more in detail the whole context of RF MEMS technology, this paper will provide a brief introduction on a typical RF-MEMS technology platform. Subsequently, some relevant examples of lumped RF MEMS passive elements and complex reconfigurable networks will be reported along with their measured RF performance and characteristics.


2019 ◽  
Vol 40 (5) ◽  
pp. 313-326 ◽  
Author(s):  
Andrew Martin Cox ◽  
Stephen Pinfield ◽  
Sophie Rutter

Purpose The purpose of this paper is to conceptualise the issues of alignment for changing academic libraries by using and extending McKinsey’s 7S model. Design/methodology/approach Theoretical work was conducted to consider and extend the 7S model for the situation of academic libraries. Empirical data were then used to confirm the value of these extensions and suggest further changes. The data to support the analysis were drawn from 33 interviews with librarians, library and non-library academics and experts, and a survey of UK library staff. Findings In the academic library context, the 7S model can be usefully extended to include three library functions (stuff, space and services) and users. It can also include institutional influences and stakeholders, and aspects of the external environment or situation, including suppliers and allies. The revised model then provides a useful framework within which data about library change can be analysed. Perceived barriers to successful performance fit the model and enable the identification of seven challenges of alignment. Research limitations/implications The resulting model has potential applications such as in the structuring analysis of academic library performance, mapping future directions of development and for exploring variations across the sector and internationally. Practical implications The revised model can be used by practitioners to think through their own strategic position and to act to shape their future, in the light of seven major areas of alignment. Originality/value The paper extends a well-known model used in strategy, to produce a more comprehensive, sector-specific analytic tool.


2014 ◽  
Vol 11 (99) ◽  
pp. 20140573 ◽  
Author(s):  
H. Droogendijk ◽  
R. A. Brookhuis ◽  
M. J. de Boer ◽  
R. G. P. Sanders ◽  
G. J. M. Krijnen

Flies use so-called halteres to sense body rotation based on Coriolis forces for supporting equilibrium reflexes. Inspired by these halteres, a biomimetic gimbal-suspended gyroscope has been developed using microelectromechanical systems (MEMS) technology. Design rules for this type of gyroscope are derived, in which the haltere-inspired MEMS gyroscope is geared towards a large measurement bandwidth and a fast response, rather than towards a high responsivity. Measurements for the biomimetic gyroscope indicate a (drive mode) resonance frequency of about 550 Hz and a damping ratio of 0.9. Further, the theoretical performance of the fly's gyroscopic system and the developed MEMS haltere-based gyroscope is assessed and the potential of this MEMS gyroscope is discussed.


2001 ◽  
Author(s):  
Ryszard J. Pryputniewicz

Abstract Advances in microelectromechanical systems (MEMS) technology are based on understanding of the issues involved in design, analysis, fabrication, characterization, and use of the finished products. Although this understanding is being developed “on the job” to satisfy immediate needs of rapid advances in the emerging MEMS technology, there is also growing demand for “academic” education in MEMS. Whether on-the-job or academic, development of the required understanding is no easy task because the MEMS field is very multidisciplinary. Those involved should be able to work simultaneously with topics relating to physics, chemistry, materials, computer science, engineering, as well as other relevant disciplines. To facilitate preparation of future engineers for work with MEMS, we have developed undergraduate and graduate courses addressing some of the crucial issues relating to MEMS. These courses are based on case studies that we have developed in our laboratories. The courses include lectures, laboratory experiments, student projects, and presentations. This paper describes selected case studies used in our courses as they relate to design education with MEMS.


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