A Cost Effective Direct Writing Laser System for Rapid Prototyping of Microfluidic Devices

This study is conducted to highlight the improvement in technology of manufacturing microstructures using maskless lithography technique. Direct laser writing technique was implemented, and a major section of this study is carried out on an experimental slant. Variables that were not covered experimentally were studied using lithography simulation software, GenISys – LAB. The aim of this study is to fabricate and analyze cost effective maskless lithography apparatus to ensure rapid prototyping and optimize the system to be used for at least two negative photoresist materials. A parametric study was carried out determining the best operating conditions from both perspectives of direct laser writing and material process parameters. All parameters were studied experimentally, but the impact of depth of focus was illustrated using lithography simulation. Using direct laser writing system, complex designs were manufactured. The developed system had a maximum writing speed of 0.834 mm/s. The minimum line width produced using optimized operating conditions was 3.94 μm. Experimentally, increasing laser intensity increased the line width and by increasing post bake timings, it was observed that less laser intensity was required. Simulation results showed that depth of focus plays a crucial role in manufacturing good quality 3D resist profile. We developed a cost effective direct laser writing system as a part of studying maskless lithography process for rapid manufacturing. The total cost associated to develop this system was AED 4800 ($ 1307). This system was optimized to be used with two negative photoresist materials. A significant contribution of our work is through cost effectiveness and performance to produce complex designs using a maskless lithographic process. This study will provide an opportunity for researchers to use their innovative designs with faster and cheaper methods of prototyping micro devices

Rapid prototyping of organ-on-a-chip devices using maskless photolithography

Organ-on-a-chip (OoC) and microfluidic devices are conventionally produced using microfabrication procedures that require cleanrooms, silicon wafers, and photomasks. The prototyping stage often requires multiple iterations of design steps. A simplified prototyping process could therefore offer major advantages. Here, we describe a rapid and cleanroom-free microfabrication method using maskless photolithography. The approach utilizes a commercial digital micromirror device (DMD)-based setup using 375 nm UV light for backside exposure of an epoxy-based negative photoresist (SU-8) on glass coverslips. We show that microstructures of various geometries and dimensions, microgrooves, and microchannels of different heights can be fabricated. New SU-8 molds and soft lithography-based polydimethylsiloxane (PDMS) chips can thus be produced within hours. We further show that backside UV exposure and grayscale photolithography allow structures of different heights or structures with height gradients to be developed using a single-step fabrication process. Using this approach: (1) digital photomasks can be designed, projected, and quickly adjusted if needed; and (2) SU-8 molds can be fabricated without cleanroom availability, which in turn (3) reduces microfabrication time and costs and (4) expedites prototyping of new OoC devices.Functional Genomics of Muscle, Nerve and Brain Disorder

Recent Advances on Nanocomposite Resists With Design Functionality for Lithographic Microfabrication

Nanocomposites formed by a phase-dispersed nanomaterial and a polymeric host matrix are highly attractive for nano- and micro-fabrication. The combination of nanoscale and bulk materials aims at achieving an effective interplay between extensive and intensive physical properties. Nanofillers display size-dependent effects, paving the way for the design of tunable functional composites. The matrix, on the other hand, can facilitate or even enhance the applicability of nanomaterials by allowing their easy processing for device manufacturing. In this article, we review the field of polymer-based nanocomposites acting as resist materials, i.e. being patternable through radiation-based lithographic methods. A comprehensive explanation of the synthesis of nanofillers, their functionalization and the physicochemical concepts behind the formulation of nanocomposites resists will be given. We will consider nanocomposites containing different types of fillers, such as metallic, magnetic, ceramic, luminescent and carbon-based nanomaterials. We will outline the role of nanofillers in modifying various properties of the polymer matrix, such as the mechanical strength, the refractive index and their performance during lithography. Also, we will discuss the lithographic techniques employed for transferring 2D patterns and 3D shapes with high spatial resolution. The capabilities of nanocomposites to act as structural and functional materials in novel devices and selected applications in photonics, electronics, magnetism and bioscience will be presented. Finally, we will conclude with a discussion of the current trends in this field and perspectives for its development in the near future.Fil: Martínez, Eduardo David. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Prado, A.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Gonzalez, M.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Anguiano, S.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Tosi, Leandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Salazar Alarcón, Leonardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; ArgentinaFil: Pastoriza, Hernan. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Bariloche.; Argentin

Generation of Sinusoidal Micro-Wrinkles Pattern Using Gradient Grayscale Effect

In this thesis, a new digital lithography technology with gradient grayscale level is firstly applied in Micro-wrinkles pattern fabrication. A mathematical model is developed to predict the micro-wrinkles patterns generation through various gradient grey scale effect. By comparing theoretical curing depth and grayscale level versus light intensity, a feasible and logical experiment method is discussed. The sinusoidal waves generated on a surface, i.e. the resolution, wavelength, and amplitude are characterized by optical microscopy and scanning electron microscopy. Results from this study contribute to the fundamental understanding the knowledge on how the grayscale level and surplus growth influence the curing depth on a surface. Meanwhile, the research also contributes to potential applications in optical devices, micro-fluidic device, and cell culture substrates

Rapid and mask-less laser-processing technique for the fabrication of microstructures in polydimethylsiloxane

We report a rapid laser-based method for structuring polydimethylsiloxane (PDMS) on the micron-scale. This mask-less method uses a digital multi-mirror device as a spatial light modulator to produce a given spatial intensity pattern to create arbitrarily shaped structures via either ablation or multi-photon photo-polymerisation in a master substrate, which is subsequently used to cast the complementary patterns in PDMS. This patterned PDMS mould was then used for micro-contact printing of ink and biological molecules

Optimized SU-8 processing for low-cost microstructures fabrication without cleanroom facilities

The study and optimization of epoxy-based negative photoresist (SU-8) microstructures through a low-cost process and without the need for cleanroom facility is presented in this paper. It is demonstrated that the Ultraviolet Rays (UV) exposure equipment, commonly used in the Printed Circuit Board (PCB) industry, can replace the more expensive and less available equipment, as the Mask Aligner that has been used in the last 15 years for SU-8 patterning. Moreover, high transparency masks, printed in a photomask, are used, instead of expensive chromium masks. The fabrication of well-defined SU-8 microstructures with aspect ratios more than 20 is successfully demonstrated with those facilities. The viability of using the gray-scale technology in the photomasks for the fabrication of 3D microstructures is also reported. Moreover, SU-8 microstructures for different applications are shown throughout the paper.Work supported by FEDER funds through the Eixo I do Programa Operacional Fatores de Competitividade (POFC) QREN, project reference COMPETE: FCOMP-01-0124-FEDER-020241, and by FCT- Fundação para a Ciência e a Tecnologia, project reference PTDC/EBB-EBI/120334/2010. Vânia C. Pinto thanks the FCT for the SFRH/BD/81526/2011 grant. Paulo J. Sousa thanks the FCT for the SFRH/BD/81562/2011 grant. Vanessa F. Cardoso thanks the FCT for the SFRH/BPD/98109/2013 gran

마이크로미터 이하 패턴 제작을 위한 디지털 포토리소그래피 기술

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 물리학과, 2021.8. 권여리.Digital photolithography based on digital micromirror device (DMD) is considered the next-generation low-cost lithographic technology. However, DMD-based digital photolithography has been implemented only for micrometer-scale pattern generation, whereas sophisticated photonic devices require feature sizes of submicron. In this thesis, we adopt a high-magnification imaging optical system for a custom-built digital photolithography system to generate submicron-scale patterns. We propose techniques to enhance the versatility of the digital photolithography, pattern tilting and grayscale exposure. We demonstrate that photonic crystal band-edge lasers of various lattice structures and periods can be quality-assessment testbeds. We also tried to enhance pattern uniformity. The experimentally determined pixel spread function predicted the exposure result well, which means that we can improve the pattern quality through preliminary correction.디지털 미세거울 장치에 기반한 디지털 포토리소그래피는 차세대 저비용 리소그래피 기술로 여겨진다. 그러나 디지털 미세거울 장치 기반 디지털 포토리소그래피는 주기가 1 마이크론 이상인 패턴 제작시에만 사용되었다. 광자결정레이저 등의 광소자 제작을 위해서는 패턴의 주기가 수백나노미터 수준이어야 하는데, 아직 디지털 포토리소그래피로 이러한 광소자를 제작한 사례는 없었다. 회절 한계를 계산해 보았을 때, 1 마이크론 이하 주기의 패턴 제작이 충분히 가능할 것으로 판단되어, 고배율 결상광학계를 활용하여 디지털 포토리소그래피 시스템을 구축하였다. 구축된 시스템을 사용하여 감광액이 코팅된 시편에 노광을 진행하였으며, 1 마이크론 이하 주기의 패턴 제작이 가능함을 보였다. 마이크로미터 이하 주기의 패턴을 제작할 때, 디지털 포토리소그래피의 패턴 설계 자유도를 향상시키기 위한 두 가지 방법인 패턴 기울임, 회색조 노광을 제안하였으며 실험적으로 시연하였다. 디지털 리소그래피 시스템의 검증에는 광자결정 띠 가장자리 레이저가 주로 사용되었는데, 레이저 발진 여부를 통해 노광 패턴의 품질을 파악할 수 있고 레이저 파장을 통해 노광 패턴의 주기를 파악할 수 있기 때문이다. 또한 픽셀 분산 함수를 도입하여 이미지의 회절 계산 및 패턴 품질 향상을 위한 밝기 보정을 제안하였다. 보정에 의해 패턴의 품질이 크게 향상되어, 전자빔 리소그래피로 제작한 것과 비교할 수 있는 수준이 되었다.Chapter1 Introduction 1 1.1. Photonic crystals 1 1.1.1. Introduction 1 1.1.2. Photonic crystal band-edge laser 4 1.1.3. Photonic crystal cavity laser 6 1.2. Conventional lithography techniques 8 1.3. Alternative lithography technique: digital photolithography 10 1.4. Outline of the manuscript 12 Chapter2 Submicron-scale digital photolithography 14 2.1. Introduction 14 2.1.1. Schematic of digital photolithography system 14 2.1.2. Proposed digital photolithography system 16 2.1.3. Pixel pitch at image plane 17 2.1.4. Resolving power of proposed digital photolithography system 19 2.2. Fabrication process of air-bridge photonic crystal 21 2.3. Square-lattice photonic crystal laser device 22 Chapter3 Fine-tuning the lattice constant: pattern tilting 26 3.1. Introduction 26 3.1.1. Wavelength division multiplexing application 26 3.1.2. Pattern tilting 28 3.1.3. All possible tilting configurations 30 3.2. Result and discussion 31 3.2.1. Tilting square-lattice 31 3.2.2. Tilting hexagonal-lattice 33 Chapter4 Fine structural tuning: grayscale exposure 36 4.1. Introduction 36 4.1.1. Implementation of gray pixel 36 4.2. Result and discussion 38 4.2.1. Grayscale exposed squre-lattice 38 4.2.2. Grayscale exposed hexagonal-lattice 41 Chapter5 Enhancing pattern uniformity 42 5.1. Introduction 42 5.1.1. Airy disk point spread function 42 5.1.2. Broadening factor and exposure dose profile 47 5.1.3. Experimental determination of broadening factor 49 5.2. Result and discussion 51 5.2.1. Diffraction simulation based on pixel spread function 51 5.2.2. Correction strategy 56 5.2.3. Analysis of correction result 58 Chapter6 Conclusion and perspective 61 References 63 Abstract in Korean 70박

자성 조절이 가능한 고분자-나노복합체를 이용한 미세 구조물의 제어

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 권성훈.In this dissertation, I introduce a new magnetic nanocomposite material system and in situ fabrication process that is not shape limited and allows the programming of heterogeneous magnetic anisotropy at the microscale. The key idea is to combine the self-assembling behavior of superparamagnetic nanoparticles, which have stronger magnetization than that of general paramagnetic materials, with a spatially modulated photopatterning process. By repetitively tuning the nanoparticle assembly and fixing the assembled state using photopolymerization, I fabricate microactuators for which all parts move in different directions under a homogeneous magnetic field. To show the feasibility of this concept, I demonstrate polymeric nanocomposite actuators capable of two dimensional and three-dimensional complex actuations that have rarely been achieved using conventional microactuators. This approach greatly simplifies the manufacturing process and also offers effective rules for designing novel and complex microcomponents using a nanocomposite material with engineered magnetic anisotropy. First, I investigate the self-assembling behavior of both ferromagnetic magnetite nanoparticles and superparamagnetic nanoparticles using Monte Carlo simulation. Magnetic materials used to fabricate magnetic polymer composite include ferrimagnetic magnetite nanoparticles with 50nm of averaged diameter and superparamagnetic magnetite nanoparticles with 280nm of averaged diameter. Magnetic particle interactions, that critically affect to the self-assembling behavior of the magnetic nanoparticles, such as particle-field interaction, particle-particle dipole interaction, magnetic anisotropy and steric layer repulsion are considered. I adopt cluster-moving Monte Carlo simulation method to analyze the magnetic self-assembly of magnetic nanoparticles and investigate the self-assembling behavior of the magnetite nanoparticles varying the intensity of the applied magnetic field during the chain formation and the concentration of the magnetic nanoparticles. The result shows that the well-defined magnetic chains are formed as both the intensity of the applied magnetic field and the magnetic nanoparticle concentration increase. Also, a novel method to fabricate magnetic nanoparticle embedded polymer composite microstructure is introduced. Briefly, the combination of photocurable polymer and magnetic nanoparticles is photopolymerized to immobilize the various states of magnetic nanoparticles. I especially adopt a system called optofluidic maskless lithography system to fabricate various shapes of polymeric microstructures within a second. Also, I develop a model system to describe the actuation of a magnetic polymer composite. The magnetic torque, the derivative of system energy, of the composite microstructure embedding magnetic chains is calculated based on the expanded Monte Carlo simulation result. And, the steady state elastic modulus of the magnetic composite microbeam is induced by utilizing the simulated torque and cantilever bending experiment result. The movement of cantilever type microstructure is investigated at equilibrium state that the magnetic torque equals to the mechanical restoring torque. As an application, I demonstrate multiaxial microactuators. Polymeric microcomponents are widely used in microelectromechanicalsystems (MEMS) and lab-on-a-chip devices, but they suffer from the lack of complex motion, effective addressability and precise shape control. To address these needs, I fabricated polymeric nanocomposite microactuators driven by programmable heterogeneous magnetic anisotropy. Spatially modulated photopatterning was applied in a shape independent manner to microactuator components by successive confinement of self-assembled magnetic nanoparticles in a fixed polymer matrix. By freely programming the rotational axis of each component, I demonstrate that the polymeric microactuators can undergo predesigned, complex two- and three dimensional motion. Finally I also introduce a novel color changing microactuators based on the self-assembling behavior of the magnetic nanoparticles. I propose a color-tunable microactuator utilizing the optical and magnetic behaviors of one-dimensionally assembled superparamagnetic nanoparticles that play the role of a one-dimensional Bragg reflector and establish a magnetic easy axis. By combining these properties with rapid photopolymerization, I developed red, blue, and green micropixels whose colors could be tuned by the application of an external magnetic field. This strategy offers very simple methods for the fabrication and operation of soft color tunable surfaces with high resolution.Abstract i Contents v List of Figures vii List of Tables xxi Chapter 1 Introduction 1 1.1 Polymer Nanocomposite 4 1.2 Magnetic Polymer Composite 7 1.3 Magnetic Self-assembly 11 1.4 Main Concept 15 Chapter 2 Magnetic Nanoparticle Self-assembly 18 2.1 Material Specification 19 2.1.1 Crystalline Structure of Magnetite 19 2.1.2 Synthesis of Superparamagnetic Nanoparticles 22 2.1.3 Magnetic Anisotropy of Magnetite Nanoparticles 23 2.2 Interacting Magnetic Nanoparticle with MC Simulation 27 2.2.1 Interaction Energy of Magnetic Nanoparticles 27 2.2.2 2D Cluster-moving Monte Carlo Simulation 31 2.3 Self-assembly of Magnetic Nanoparticles 34 2.3.1 Self-assembly of Ferrimagnetic Nanoparticles 36 2.3.2 Self-assembly of Superparamagnetic Nanoparticles 41 2.4 Conclusion 46 Chapter 3 Magnetic Nanoparticle Embedded Polymer Composite 47 3.1 Optofluidic Maskless Lithography 48 3.2 In-situ Fabrication Process 50 3.3 Torque on Magnetic Composite Structure 54 3.3.1 Magnetic Torque from Self-assembled Nanoparticles 54 3.3.2 Magnetic Torque on Arbitrary Structure 59 3.3.3 Elastic Modulus of Magnetic Composite Beam 61 3.4 Deisgn Principles 65 3.4.1 Simple Cantilever 66 3.5 Conclusion 70 Chapter 4 Multiaxial Microactuators 71 4.1 Fabrication 72 4.1.1 Various Types of Microfluidic Devices 74 4.1.2 Micropatterning of PDMS Thin Film on Glass Substrate 76 4.1.3 Grey Mask for Flexible Hinge 77 4.2 Microfluidic Components 79 4.3 Various Types of Multiaxial Microactuators 82 4.4 Rotating Microstructures 87 4.5 Microrobot 89 4.6 Conclusion 92 Chapter 5 Magnetochromatic Microactuators 93 5.1 Fabrication 94 5.2 Structural Color Generation 97 5.3 Color Change of Microsurface 100 5.4 Micropatterns 103 5.5 Conclusion 105 Conclusion and Future Work 106 Bibliography 109 국문 초록 119Docto