MEMS micro-contact printing engines

This thesis investigates micro-contact printing (µCP) engines using micro-electro-mechanical systems (MEMS). Such engines are self-contained and do not require further optical alignment and precision manipulation equipment. Hence they provide a low-cost and accessible method of multilevel surface patterning with sub-micron resolution. Applications include the field of biotechnology where the placement of biological ligands at well controlled locations on substrates is often required for biological assays, cell studies and manipulation, or for the fabrication of biosensors. A miniaturised silicon µCP engine is designed and fabricated using a wafer-scale MEMS fabrication process and single level and bi-level µCP are successfully demonstrated. The performance of the engine is fully characterised and two actuation modes, mechanical and electrostatic, are investigated. In addition, a novel method of integrating the stamp material into the MEMS process flow by spray coating is reported. A second µCP engine formed by wafer-scale replica moulding of a polymer is developed to further drive down cost and complexity. This system carries six complementary patterns and allows six-level µCP with a layer-to-layer accuracy of 10 µm over a 5 mm x 5 mm area without the use of external aligning equipment. This is the first such report of aligned multilevel µCP. Lastly, the integration of the replica moulded engine with a hydraulic drive for controlled actuation is investigated. This approach is promising and proof of concept has been provided for single-level patterning

Synthesis of nanometer-sized radical polymers and their arrangement on micro-fabricated substrates

制度:新 ; 文部省報告番号:甲2322号 ; 学位の種類:博士(工学) ; 授与年月日:2007/3/15 ; 早大学位記番号:新438

Incorporating nanomaterials with MEMS devices.

This dissertation demonstrates an elegant method, known as \u27micro-origami\u27 or strain architecture to design and fabricate three-dimensional MEMS structures which are assembled using actuation of a metal-oxide bilayer with conventional planar lithography. Folding allows creating complex, robust, three-dimensional shapes from two-dimensional material simply by choosing folds in the right order and orientation, small disturbances of the initial shape may also be used to produce different final shapes. These are referred to as pop-up structures in this work. The scope of this work presented the deposition of colloidal gold nanoparticles (GNPs) into conformal thin films using a microstenciling technique. Results illustrated that the gold nanoparticle deposition process can easily be integrated into current MEMS microfabrication processes. Thin films of GNPs deposited onto the surfaces of siliconbased bistable MEMS and test devices were shown to have a significant effect on the heating up of microstructures that cause them to fold. The dissertation consists of four chapters, covering details of fabrication methods, theoretical simulations, experimental work, and existing and potential applications. Chapter II illustrates how control of the folding order can generate complex three-dimensional objects from metal-oxide bilayers using this approach. By relying on the fact that narrower structures are released from the substrate first, it is possible to create multiaxis loops and interlinked objects with several sequential release steps, using a single photomask. The structures remain planar until released by dry silicon etching, making it possible to integrate them with other MEMS and microelectronic devices early in the process. Chapter III depicts the fabrication process of different types of bistable structures. It describes the principle of functioning of such structures, and simulations using CoventorWare are used to support the concept. We talk over about advantages and disadvantages of bistable structures, and discuss possible applications. Chapter IV describes fabrication procedure of nanoparticle-MEMS hybrid device. We introduce a convenient synthesis of GNPs with precisely controlled optical absorption in the NIR region by a single step reaction ofHAuCl4 and Na2S203. We take a look at different techniques to pattern gold nanoparticles on the surface of MEMS structures, and also provide a study of their thermal properties under near IR stimulation. We demonstrate the first approach of laser-driven bistable MEMS actuators for bioapplications. Finally, in Conclusion discuss the contributions of this dissertation, existent limitations and plans of the future work

Mems Accelerometer Design

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005Bu çalışmada, analog kapasitif MEMS ivme ölçer sisteminin teori, tasarım süreci ve analizi incelenmiş ve yüzey mikro makine tekniği olan MUMPS prosesi kullanılarak geniş ölçme dinamiğine sahip MEMS ivme ölçer sistemi gerçeklenmiştir. Mekanik sistemin optimizasyonu için Bölüm 2 ‘de elde edilen analitik modeller kullanılarak C++ programla dilinde MABEMS isimli görsel tabanlı bir program yazılmıştır. Mekanik sistemlerin sonlu eleman analizlerinde ticari bir yazılım olan ANSYS kullanılmıştır. Davranışsal seviyedeki simulasyonlar içinse sistemin MATLAB Simulink modeli oluşturulmuştur. Elektronik algılama kısmında, parazitik kapasitelerin etkisini azalttığı için yük kuvvetlendiricisi yapısı kullanılmıştır. İvme ölçerin Bölüm 3’te elde edilen matematik modeli, analog davranışsal modelleme kütüphanesi (ABM) kullanılarak PSPICE içerisinde gerçeklenmiş ve bu da elektronik algılama devresi ile mekanik elemanın aynı ortamda simulasyonuna olanak vermiştir. Geleneksel yöntemlerde, MEMS ivme ölçerler, ölçme dinamiği, bant genişliği ve lineerlik gibi performans ölçütlerinin iyileştirilmesi için geri beslemeli çevrimde çalıştırılır. Bu çalışmada, bu yönteme alternatif olarak ölçme hassasiyeti düşük olan bir sistemin, hassasiyeti daha yüksek olanın dinamik ofsetini (sıfırını) oluşturması prensibine dayanan ve “Kuvvet İleri Beslemesi” diye isimlendirdiğimiz yöntem önerilmiş ve kavramsal olarak tanımlanmıştır. Bu amaçla biri daha hassas fakat belli bir yer değiştirme değerinden sonra lineerliği bozulan, diğeri de daha az hassas fakat her zaman lineer çıkış veren iki farklı mekanik sistem tasarlamıştır. Tasarımlara ilişkin bütün sonuçlar Bölüm 3’te verilmiştir.In this work, the theory, design process, and analysis of analog capacitive MEMS accelerometer system is examined and a high dynamic range MEMS accelerometer system is implemented by using MUMPS surface micromachining process. For the optimization of the mechanical system, by using the analytical models obtained in Section 2, a visual software, named MABEMS, is implemented in C++ programming language. Finite element analysis of the mechanical systems are made by using a commercially available simulation package ANSYS. MATLAB Simulink model of the system is realized for the behavioral level simulations. The charge amplifier topology is used in electronic sensing interface since this configuration eliminates the effect of the parastic capacitances. Mathematical model of the accelerometer, obtained in Section 3, is implemented in PSPICE by using the Analog Behavioral Modelling (ABM) library so, this allowed the simulation of the mechanical device and electronic interface in the same environment. In conventional methods, accelerometers are operated in closed loop by applying feedback signals to increase the performance parameters like dynamic range, bandwidth, and linearity. In this work, a new method, is offered and described conceptually as an alternative to the conventional closed loop systems and this method is named as Force Feed forward Mechanism. In this method, less sensitive system, forms the dynamic offset of the more sensitive device. For this reason, two different mechanical devices are designed such that one of them has high sensitivity but nonlinear output above a certain displacement and the other one has low sensitivity but linear even for large displacements. All the results about the designed systems are given in Section 3.Yüksek LisansM.Sc

MEMS based catheter for endoscopic optical coherence tomography

Ph.DDOCTOR OF PHILOSOPH

Back-end processing of scanning mirrors with scratch drive actuators

The use of micro-electro-mechanical system (MEMS) processes in fabrication of micr- electro-mechanical devices for optical applications has been widespread. The invention of digital light processing (DLP) technology by Texas Instruments Inc. popularized the use of micro-mirrors. One of the applications of the micro-mirrors is in the form of scanners for biomedical imaging. The small size of mirrors and actuators makes them a good candidate for in vivo measurements/imaging. Various techniques in bulk- and surface-micromachining, and various actuators have been used to fabricate scanning mirrors. The scanning mirrors used in this work make use of scratch drive actuators (SDA) for their scanning motion. Both surface- and bulk-micromachining technologies are used to fabricate the devices. Surface-micromachining (Multi User MEMS Processes or MUMPs®) is used to fabricate scanning mirrors, and bulk-micromachining is used to separate dies, to create sloped sidewalls for efficient packaging and to make grooves for optical fibers. This work describes the techniques used in the post-MUMPs processing of the devices. The main features of the post-MUMPs processing are substrate etching and formation of insulating links. The presence of devices on the front side necessitates the use of a protection method in the substrate etching step. Polymers have drawn attention in recent years as protective materials due to their chemical stability as well as the ease of use. This thesis work utilizes poly dimethylsiloxane (PDMS) as a protection material, and examines the effect of PDMS process conditions on the quality of the protection. Protection for at least 10 hours was achieved in this work. The scanning mirror devices of this thesis work require non-conductive links between the actuators and the mirror. Thick photoresists such as AZ 4620, AZ 9260, SU-8 etc, are a good choice due to the ease in their patterning as well as their excellent insulating properties. This thesis documents the processes followed to achieve optimal link structures using thick photoresist (AZ 9260). The resist was optimally hard baked to make it chemically inert to common organic solvents