A Review on Key Issues and Challenges in Devices Level MEMS Testing

The present review provides information relevant to issues and challenges in MEMS testing techniques that are implemented to analyze the microelectromechanical systems (MEMS) behavior for specific application and operating conditions. MEMS devices are more complex and extremely diverse due to the immersion of multidomains. Their failure modes are distinctive under different circumstances. Therefore, testing of these systems at device level as well as at mass production level, that is, parallel testing, is becoming very challenging as compared to the IC test, because MEMS respond to electrical, physical, chemical, and optical stimuli. Currently, test systems developed for MEMS devices have to be customized due to their nondeterministic behavior and complexity. The accurate measurement of test systems for MEMS is difficult to quantify in the production phase. The complexity of the device to be tested required maturity in the test technique which increases the cost of test development; this practice is directly imposed on the device cost. This factor causes a delay in time-to-market

A Review on Key Issues and Challenges in Devices Level MEMS Testing

The present review provides information relevant to issues and challenges in MEMS testing techniques that are implemented to analyze the microelectromechanical systems (MEMS) behavior for specific application and operating conditions. MEMS devices are more complex and extremely diverse due to the immersion of multidomains. Their failure modes are distinctive under different circumstances. Therefore, testing of these systems at device level as well as at mass production level, that is, parallel testing, is becoming very challenging as compared to the IC test, because MEMS respond to electrical, physical, chemical, and optical stimuli. Currently, test systems developed for MEMS devices have to be customized due to their nondeterministic behavior and complexity. The accurate measurement of test systems for MEMS is difficult to quantify in the production phase. The complexity of the device to be tested required maturity in the test technique which increases the cost of test development; this practice is directly imposed on the device cost. This factor causes a delay in time-to-market

MEMS Technology for Biomedical Imaging Applications

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. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Micro-Raman measurement of strain in silicon nanowires

Crystalline nanostructures such as silicon nanowires (SiNWs) may have residual mechanical stress and strain from the fabrication process, which can potentially impair their reliability as building blocks of Microelectromechanical system (MEMS). The amount of strain may be minuscule, which requires very accurate measurements to determine the strain. Micro-Raman spectroscopy is a work horse tool since it is a simple, fast and nondestructive technique that can be used to assess mechanical strain. However, a precise evaluation of residual strain for nanostructures using micro-Raman spectroscopy requires careful calibrations and theoretical calculations. This thesis describes the interrelations between Raman shift and strain in fabricated silicon nanowires. The calibration methods are used to eliminate the two dominant errors: errors in focusing, and laser heating effects, which can lead to apparent Raman shifts. Finally, the Raman measurement results are discussed and the corresponding residual strain in the [110] direction is calculated. This work is concluded with the discussion of possible causes of strain

Optical Coherence Tomography and Its Non-medical Applications

Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications

Acousto optic modulated stroboscopic interferometer for comprehensive characterization of microstructure

Mechanical and electro-mechanical advancements to the nano-scale require comprehensive and systematic testing at the micro-scale in order to understand the underlying influences that define the micro/nano-device both from fabrication and operational points of view. In this regard, surface metrology measurements, as well as static and dynamic characteristics will become very important and need to be experimentally determined to describe the system fully. These integrated tests are difficult to be implemented at dimensions where interaction with the device can seriously impact the results obtained. Hence, a characterization method to obtain valid experimental information without interfering with the functionality of the device needs to be developed. In this work, a simple yet viable Acousto Optic Modulated Stroboscopic Interferometer (AOMSI) was developed using a frequency stabilized Continuous Wave (CW) laser together with an Acousto Optic Modulator for comprehensive mechanical characterization to obtain surface, static and dynamic properties of micro-scale structures. An optimized methodology for measurement was established and sensitivity analysis was conducted. Being a whole-field technique, unlike single point or scanning interferometers, AOMSI can provide details of surface properties as well as displacements due to static/dynamic loads and modal profiles. Experiments for surface profiling were carried out on a micro-mirror, along with 2D and 3D profile measurements. The ability of AOMSI to perform dynamic measurements was tested on Micro-Cantilevers and on AFM (Atomic Force Microscopy) cantilevers. The resolution of AOMSI was identified as 10nms. The results for static deflections, 1 st and 2 nd natural frequencies and mode shapes were found to be in good agreement with results from the developed theoretical model and manufacturers specifications. The approach is a novel approach to investigate the surface, static and dynamic behavior of microstructures using a single interferometer

Engineering and Validation of Open Microfluidic Platform for Organ on a Chip

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 기계항공공학부, 2018. 2. 전누리.Open microfluidic device was developed using the open-access microfluidic device with through-hole membrane for the regenerative medicine of Peripheral arterial disease (PAD). PAD is commonly defined as narrowing of blood vessels in the lower part of arteries or arterioles. Major risk factors of occurrence of PAD include smoking, hypertension, hypercholesterolemia, atherosclerosis, and complications of diabetes. To develop safe and effective procedures for vascularized tissue injection, we focused on open microfluidic device using through-hole membrane and open-access microfluidic device system. For the transplantable tissue culture, simple fabrication method of through-hole membrane was developed for the media supply to the tissue. Due to the small scale of the fabricated pores, the construction of through-hole membranes on a large scale and with relatively large areas faces many difficulties. Novel fabrication methods for a large-area, freestanding micro/nano through-hole membrane constructed from versatile membrane materials using through-hole membranes on a microfluidic chip (THMMC) for the reconstitution of 3D tissue. The through-hole site was easily customizable from the micro to the nanoscale, with a low or high aspect ratio giving rise to reliable membranes. Also, the rigidity and biocompatibility of the through-hole membrane are easily tunable by simple injection of versatile membrane materials to obtain a large area (up to 3600 mm2). And we describe a simple, versatile method of generating open-access microfluidic device (OAMD) with possible non-destructive tissue sampling for TEM imaging. Generally, the analysis of organ-on-a-chip usually applied by optical microscope, fluorescence microscope and confocal microscopy. Although optical imaging technologies are widespread and effective observational tools, they possess functional and resolution limitations. The myelination by Schwann cells is critically important in restoring neuromuscular motor function after injury or peripheral neuropathy, and in the case of quantifying myelination, transmission electron microscope (TEM) analysis is a requisite. The proposed OAMD platform incorporated a novel biocompatible self-detachable photopolymer (BSP) substrate to provide a viable closed microphysiological system culture environment while also allowing for controllable and nondestructive tissue sampling for TEM analysis. Furthermore, We herein thesis a novel transplantable tissue engineering technique that yields functional and vascularized tissue that can be successfully transplanted into the Balb C Nu nude mouse using THMMC and OAMD technology.Chapter 1. Introduction 1 1-1. Open Microfluidic Platform 1 1-2. Novel Fabrication Process of Through-hole Membrane 3 1-3. Open-Access Microfluidic Device for TEM Analysis 6 1-4. Transplantation of 3D Tissue as Regenerative Medicine 8 Chapter 2. Rapid large area fabrication of multiscale through-hole membranes 10 2-1. Introduction 10 2-2. Materials and Method 11 2-2-1. Through-Hole Membrane by Microfluidic Chip (THMMC) 11 2-2-2. Distribute Microfluidic Channel 13 2-2-3. Micro / Nano Membrane 13 2-3. Result and Discussion 15 2-3-1. Microscale Through-hole Membrane 15 2-3-2. Nanoscale Through-hole Membrane 24 2-4. Conclusion 27 Chapter 3. Open-access microfluidic device (OAMD) for TEM analysis of 3D Reconstituted myelin sheaths 28 3-1. Introduction 28 3-2. Materials and Method 34 3-2-1. Biocompatible and Self-detachable Photopolymer 34 3-2-2. Open-Access Microfluidic Device 37 3-2-3. Contact Angle Measurements 37 3-2-4. Scanning Electron Microscope 38 3-2-5. Swelling Ratio 38 3-2-6. Nano Indentation 38 3-2-7. Live Dead Assay 39 3-2-8 Energy-dispersive X-ray spectroscopy (EDXS) 39 3-2-9 Universal Testing Machine (UTM) 39 3-2-10.MN-SC Coculture on a Microfluidic Chip 40 3-2-11. ICC: Immunocytochemistry 43 3-2-12. Western Blotting 43 3-2-13. Cryo-Transmission Electron Microscope 44 3-3. Result and discussion 45 3-3-1. Biocompatible and Self-detachable Photopolymer 45 3-3-2. Biocompatibility and Mechanical Properties. 51 3-3-3. Self-detachable for Open-Access Organ on a Chip 58 3-4. Conclusion 69 Chapter 4. Vascularized tissue transplantation from open-access microfluidic device for regenerative therapy of peripheral artery disease (PAD) 70 4-1. Introduction 70 4-2. Materials and Method 72 4-2-1. 3D Printed Microfluidic Device 72 4-2-2. Photoresin Preparation 74 4-2-3. Surface Treatment 74 4-2-4. Through-hole Membrane Integration 75 4-2-5. Cell Culture and Vasculogenesis Cell Seeding 76 4-2-6. Immunostaining and Imaging 79 4-2-7. Hindlimb Ischemia Model and in vivo Vascularized Hydrogel Implantation 80 4-2-8. Histological analysis and immunostaining 81 4-2-9. Self-detachable for Advanced Analysis of Organ on a Chip 82 4-3. Result and discussion 85 4-3-1. Vascularized Tissue Process and Self-detached Through-hole Membrane 85 4-3-2. Vascularized Tissue Analysis 88 4-3-3. Vascularized Tissue Improves Recovery of Blood Perfusion and Limb salvage in an Ischemic Hind Limb 90 4-4. Conclusion 95 Chapter 5. Concluding Remarks 97 5-1. Conclusion 97 Bibiliography 99 국문초록 112Docto

Optical coherence tomography versus microscopy for the study of Aloe Vera leaves

The aim of this study is to compare the advantages and limitations of two optical methods, namely Optical Coherence Tomography (OCT) and microscopy for minute investigation of the structure of Aloe Vera leaves. Microscopy has the advantage of a higher resolution, but the disadvantage that the object under investigation is completely damaged (as the leaf must be peeled off). On the contrary, an advantage of OCT is that it is non-invasive with the potential added benefit of on-site measurements (if portable). Depending on the OCT method used, different resolution values are achievable. In principle, Time Domain (TD) OCT can achieve lateral resolutions similar to microscopy but the method is slow for depth investigations. Spectrometer-based and Swept Source (SS) OCT trade lateral resolution for speed of acquisition. In order to acquire sufficient axial range A-scans, low numerical aperture interface optics is used, that exhibits lower transversal resolution. The main limitation of the spectrometer based and swept source OCT is therefore the achievable lateral resolution, which might not be good enough to reveal the detailed structure of noteworthy parts of leaves, for example, their stomata. The present study experimentally compares Aloe Vera data obtained using an optical microscope at different magnifications, and an in-house SS-OCT system with a 1310 nm center wavelength. For gathering additional information, an analysis of the normalized A-scan OCT images was also performed. This reveals additional parts of the leaf structure, while it still falls short of what can be obtained by using conventional microscopy

Master of Science

thesisXurography is an inexpensive rapid prototyping technology for the development of microfluidic systems. Imprecision in the xurographic tape cutting process can result in undesired changes in channel dimensions near features that require a change in cutting direction, such as 90° miter bends. An experimental study of water flow in rectangular xurographic microchannels incorporating 90° miter bends with different channel widths in each leg is reported. A set of 12 microchannels, with channel depth approximately 105 micrometers and aspect ratio ranging from 0.071 to 0.435, were fabricated from double-sided adhesive Kapton® polyimide tape and two rectangular glass plates. The channels were reinforced with a mechanical clamping system, enabling high Reynolds number Re flows (up to Re = 3200) where Re was based upon hydraulic diameter and average velocity. Reported data include friction factor and critical Reynolds number for straight microchannels and loss coefficients for flow through 90° miter bends that contain either a contraction or expansion with cross-sectional area ratios of 0.5, 0.333 and 0.2. The critical Reynolds number, Recr, ranged from 1700 to 2300 and was found to be dependent on channel defects such as sidewall roughness, adhesive droplets, and corner imperfections. Loss coefficients through 90° miter bends with expansion decrease rapidly for Re Recr. For 90° miter bends with contractions, loss coefficients gradually decrease with increasing Re for 150 < Re < 1400. In addition, the loss coefficient decreases with decreasing area ratio through the contraction or expansion. The minor loss coefficient data were found to be dependent on Reynolds numbers and area ratio of contraction/expansion at the bend. The results suggest that the effect of the contraction/expansion was the dominant mechanism for minor losses in the 90° miter bend