Rapid Prototyping Of Microfluidic Packages

In the area of MEMS there exists a tremendous need for communication between the micro-device and the macro world. A standard protocol or at least multiple standards would be of great use. Electrical connections have been standardized for many uses and configurations by the integrated circuit industry. Standardization in the IC industry has created a marketplace for digital devices unprecedented. In addition to the number of off the shelf products available, there exists the possibility for consumers to mix and match many devices from many different manufacturers. This research proposes some similar solutions as those for integrated circuits for fluid connections and mechanical configurations that could be used on many different devices. In conjunction with offering the capability to facilitate communication between the micro and macro worlds, the packaging solutions should be easy to fabricate. Many devices are by nature non-standard, unique, designs that make a general solution difficult. At the same time, the micro-devices themselves will inevitably need to evolve some standardization. In BioMEMS devices the packaging issue is concerned with delivering a sample to the device, conducting the sample to the sensor or sensors, and removing the sample. Conducting the sample to the sensor or sensors is usually done with microchannels created by standard MEMS fabrication techniques. Many current designs then utilize conventional machining techniques to create the inlet and outlet for the sample. This work proposes a rapid prototyping method for creating the microchannel and inlet / outlet in simplified steps. The packages developed from this process proved to be an effective solution for many applications

Development and Packaging of Microsystems Using Foundry Services

Micro-electro-mechanical systems (MEMS) are a new and rapidly growing field of research. Several advances to the MEMS state of the art were achieved through design and characterization of novel devices. Empirical and theoretical model of polysilicon thermal actuators were developed to understand their behavior. The most extensive investigation of the Multi-User MEMS Processes (MUMPs) polysilicon resistivity was also performed. The first published value for the thermal coefficient of resistivity (TCR) of the MUMPs Poly 1 layer was determined as 1.25 x 10(exp -3)/K. The sheet resistance of the MUMPs polysilicon layers was found to be dependent on linewidth due to presence or absence of lateral phosphorus diffusion. The functional integration of MEMS with CMOS was demonstrated through the design of automated positioning and assembly systems, and a new power averaging scheme was devised. Packaging of MEMS using foundry multichip modules (MCMs) was shown to be a feasible approach to physical integration of MEMS with microelectronics. MEMS test die were packaged using Micro Module Systems MCM-D and General Electric High Density Intercounect and Chip-on-Flex MCM foundries. Xenon difluoride (XeF2) was found to be an excellent post-packaging etchant for bulk micromachined MEMS. For surface micromachining, hydrofluoric acid (HF) can be used

FLEXIBLE LOW-COST HW/SW ARCHITECTURES FOR TEST, CALIBRATION AND CONDITIONING OF MEMS SENSOR SYSTEMS

During the last years smart sensors based on Micro-Electro-Mechanical systems (MEMS) are widely spreading over various fields as automotive, biomedical, optical and consumer, and nowadays they represent the outstanding state of the art. The reasons of their diffusion is related to the capability to measure physical and chemical information using miniaturized components. The developing of this kind of architectures, due to the heterogeneities of their components, requires a very complex design flow, due to the utilization of both mechanical parts typical of the MEMS sensor and electronic components for the interfacing and the conditioning. In these kind of systems testing activities gain a considerable importance, and they concern various phases of the life-cycle of a MEMS based system. Indeed, since the design phase of the sensor, the validation of the design by the extraction of characteristic parameters is important, because they are necessary to design the sensor interface circuit. Moreover, this kind of architecture requires techniques for the calibration and the evaluation of the whole system in addition to the traditional methods for the testing of the control circuitry. The first part of this research work addresses the testing optimization by the developing of different hardware/software architecture for the different testing stages of the developing flow of a MEMS based system. A flexible and low-cost platform for the characterization and the prototyping of MEMS sensors has been developed in order to provide an environment that allows also to support the design of the sensor interface. To reduce the reengineering time requested during the verification testing a universal client-server architecture has been designed to provide a unique framework to test different kind of devices, using different development environment and programming languages. Because the use of ATE during the engineering phase of the calibration algorithm is expensive in terms of ATE’s occupation time, since it requires the interruption of the production process, a flexible and easily adaptable low-cost hardware/software architecture for the calibration and the evaluation of the performance has been developed in order to allow the developing of the calibration algorithm in a user-friendly environment that permits also to realize a small and medium volume production. The second part of the research work deals with a topic that is becoming ever more important in the field of applications for MEMS sensors, and concerns the capability to combine information extracted from different typologies of sensors (typically accelerometers, gyroscopes and magnetometers) to obtain more complex information. In this context two different algorithm for the sensor fusion has been analyzed and developed: the first one is a fully software algorithm that has been used as a means to estimate how much the errors in MEMS sensor data affect the estimation of the parameter computed using a sensor fusion algorithm; the second one, instead, is a sensor fusion algorithm based on a simplified Kalman filter. Starting from this algorithm, a bit-true model in Mathworks Simulink(TM) has been created as a system study for the implementation of the algorithm on chip

Materials and methods for microstereolithography

There is an increasing requirement to fabricate ever smaller components and microdevices and incorporate them within all aspects of our lives. From a Wii controller to a car airbag, micro-technology is employed in a huge spectrum of applications. Within process control and sample analysis, micro-components are making a significant impact, driven by the desire to use smaller volumes, lower concentrations, less reagent, or simply to make the process quicker or cheaper. Currently, methods of fabrication for such devices are based predominantly on silicon processing techniques. While these techniques are suitable for mass manufacture / high volume applications, there are a number of disadvantages for situations requiring lower volumes or where the end system is continually evolving – such as for research applications. The primary drawbacks are cost, turnaround time and the requirement for expensive processing facilities. However, for these situations, additive layer manufacture presents huge promise as an alternative fabrication technology. The field of additive layer manufacture has advanced greatly since its inception 25 years ago. While such technologies are still primarily focused on the field of rapid prototyping of purely mechanical structures, it is clear that their full potential is yet to be realised. This is particularly the case for stereolithography and microstereolithography, the latter of which provides the capability to create complex, true 3D structures (as opposed to pseudo 3D/extruded 2D of silicon techniques), measureable on the micron scale. This thesis shows that microstereolithography has the potential to become an alternative fabrication method for functional micro-devices and structures. This is due to the simplicity of its single-step fabrication process and the significant time/cost savings it presents. Therefore, making it an affordable technique for low volume production where a fast turnaround is required. However, the lack of functional materials compatible with microstereolithography, and hence the lack of examples of the technology being used to produce active components, currently limits it in this respect. This project therefore focused on exploring the possibilities of using microstereolithography as an alternative to traditional silicon based techniques for the direct fabrication of functional micro-devices and sensors. This was achieved through the development of a number of microstereolithography compatible, novel materials, methods and applications. Here, presented for the first time are both conductive and magnetic composite photopolymers compatible with microstereolithography technology. The materials were developed with the use of a custom built, constrained surface system using a parallel projection method. The system used LED technology as a novel exposure source, tuned to the developed materials in an attempt to gain extra control over the curing process and hence achieve higher quality components. These materials were characterised and then used to fabricate exemplar sensing devices using microstereolithography – a method not previously used for creating such devices. Microfluidic flow sensing devices were used to demonstrate the practical application of the magnetic material. One of which, a lab-on-chip type device, was demonstrated to have a working range of 5 to 70 ml/min when tested with a liquid medium. Similarly, a practical application of the conductive material was shown through the fabrication of MSL-printed conductometirc vapour sensors. The sensors showed favourable characteristics working in range of humidites (up to 50% RH) and temperatures (up to 70°C). The sensors also demonstrated a degree of selectivity to different analyte vapours. Finally, the technology was demonstrated as a feasible method of fabricating ultrasonic beam forming apparatus. Acoustic testing of a range of materials also suggested that the composite metal materials could be used to further improve performance. The novel materials and techniques investigated, along with the exemplar devices produced, demonstrate further abilities and a wider range of applications than has been demonstrated with this technology to date. It is hoped that this research will lead to wider use of the technology and encourage further advances in the field of microstereolithography

Prototypenentwicklung eines oberflächen-integrierten Mikrosensor Systems für 3D Traktionskraftmessungen durch DHM/DIC

In times of a rapid development and growing market in robotics, high-tech protheses and the personalization of medicine, biomimicking natural materials like artificial tissue are of central interest within research and industry. To fully understand the structure-function relations within living systems, comprehensive knowledge about the smallest living block, the cell, and its biomechanics are a central topic in world-wide research. However, there is so far no comprehensive technique established that can measure 3D cell forces simultaneously and quantitatively. In this project, a novel surface-integrated mechano-optical microsensor system has therefore been conceptualized, prototyped and tested, which allows for the record of pico- to micronewton traction forces in three dimensions simultaneously. First, adequate microsensor elements were designed via topology optimization and linear static finite element analysis. These designs were fabricated by micromachining processes of biocompatible thin films of nickel-titanium and amorphous silicon. Furthermore, a plasma etching process was developed to fabricate polydimethylsiloxane sensor elements. For accurate and quantitative traction force measurements, AFM cantilever based calibrations of the out-of-plane and in-plane sensor element spring constants were established. For the first time, a diamagnetic levitation force calibrator was used as an adequate pre-calibration method for the sensor elements with a high accuracy of 1 %. For the cost-efficient, simple, compact, variable and sensitive mechano-optical readout, a setting was conceptualized and tested based on the combination of digital holography and digital image correlation. To control cell adhesion, a high-throughput micro-nano structuring method was developed based on the fusion of ink-jet printing with the established method of diblock-copolymer micelle nanolithography.In Zeiten schneller Entwicklung und wachsender Märkte in der Robotik, der high-tech Prothetik und der personalisierten Medizin ist die Biomimetik natürlicher Materialien wie beispielsweise künstliche Haut von zentralem Interesse in Forschung und Industrie. Um die Struktur-Funktions-Beziehungen in lebenden Systemen umfassend zu verstehen ist die umfangreiche Wissenserweiterung hinsichtlich des kleinsten lebenden Bausteins, der Zelle, und seiner Biomechanik Gegenstand weltweiter Forschungsprojekte. Dennoch gab es bis jetzt keine Methode, die 3D Zellkräfte simultan und quantitativ messen kann. In diesem Projekt wurde ein neuartiges, oberflächen-integriertes, mechano-optisches Mikrosensorsystem konzeptioniert, prototypisiert und getestet, das die Messung piko-bis mikronewton kleiner Zugkräfte gleichzeitig in alle drei Dimensionen ermöglicht. Die Sensorelemente wurden mittels Topologieoptimierung und linear statischer Finite Elementanalyse konzipiert. Diese Designs wurden in Mikromaterialbearbeitungsprozessen aus biokompatiblen Nickel-Titan und amorphen Silizium-Dünnschschichten hergestellt. Desweiteren wurde ein Prozess entwickelt, um Polydimethylsiloxan basierte Sensorelemente herzustellen. Für genaue, quantitative Zugkraftmessungen wurden AFM-Cantilever basierte Kalibrierungen der axialen und lateralen Sensorelement-Federkonsten etabliert. Zum ersten Mal wurde dabei ein diamagnetischer Levitationskraftkalibrator mit einer Genauigkeit von 1% als geeignete Kalibrierungsmethode für die Sensorelemente genutzt. Für eine günstige, einfache, kompakte, variable und im Nanometerbereich empfindliche mechano-optische Datenauslesung wurde ein Aufbau konzeptioniert und getestet, in dem digitale Holographie und digitale Bildkorrelation kombiniert werden. Zur Zell-Adhäsionskontrolle wurde eine Hochdurchsatz-Mikro-Nanostrukturierungsmethode entwickelt, die auf der Kombination von Ink-Jet Drucken mit der etablierten Methode der Diblock-Copolymer Mizellen Nanolithographie basiert

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

Digitally driven microfabrication of 3D multilayer embedded electronic systems

The integration of multiple digitally driven processes is seen as the solution to many of the current limitations arising from standalone Additive Manufacturing (AM) techniques. A technique has been developed to digitally fabricate fully functioning electronics using a unique combination of AM technologies. This has been achieved by interleaving bottom-up Stereolithography (SL) with Direct Writing (DW) of conductor materials alongside mid-process development (optimising the substrate surface quality), dispensing of interconnects, component placement and thermal curing stages. The resulting process enables the low-temperature production of bespoke three-dimensional, fully packaged and assembled multi-layer embedded electronic circuitry. Two different Digital Light Processing (DLP) Stereolithography systems were developed applying different projection orientations to fabricate electronic substrates by selective photopolymerisation. The bottom up projection orientation produced higher quality more planar surfaces and demonstrated both a theoretical and practical feature resolution of 110 μm. A top down projection method was also developed however a uniform exposure of UV light and planar substrate surface of high quality could not be achieved. The most advantageous combination of three post processing techniques to optimise the substrate surface quality for subsequent conductor deposition was determined and defined as a mid-processing procedure. These techniques included ultrasonic agitation in solvent, thermal baking and additional ultraviolet exposure. SEM and surface analysis showed that a sequence including ultrasonic agitation in D-Limonene with additional UV exposure was optimal. DW of a silver conductive epoxy was used to print conductors on the photopolymer surface using a Musashi dispensing system that applies a pneumatic pressure to a loaded syringe mounted on a 3-axis print head and is controlled through CAD generated machine code. The dispensing behaviour of two isotropic conductive adhesives was characterised through three different nozzle sizes for the production of conductor traces as small as 170 μm wide and 40 μm high. Additionally, the high resolution dispensing of a viscous isotropic conductive adhesive (ICA) also led to a novel deposition approach for producing three dimensional, z-axis connections in the form of high freestanding pillars with an aspect ratio of 3.68 (height of 2mm and diameter of 550μm). Three conductive adhesive curing regimes were applied to printed samples to determine the effect of curing temperature and time on the resulting material resistivity. A temperature of 80 °C for 3 hours resulted in the lowest resistivity while displaying no substrate degradation. ii Compatibility with surface mount technology enabled components including resistors, capacitors and chip packages to be placed directly onto the silver adhesive contact pads before low-temperature thermal curing and embedding within additional layers of photopolymer. Packaging of components as small as 0603 surface mount devices (SMDs) was demonstrated via this process. After embedding of the circuitry in a thick layer of photopolymer using the bottom up Stereolithography apparatus, analysis of the adhesive strength at the boundary between the base substrate and embedding layer was conducted showing that loads up to 1500 N could be applied perpendicular to the embedding plane. A high degree of planarization was also found during evaluation of the embedding stage that resulted in an excellent surface finish on which to deposit subsequent layers. This complete procedure could be repeated numerous times to fabricate multilayer electronic devices. This hybrid process was also adapted to conduct flip-chip packaging of bare die with 195 μm wide bond pads. The SL/DW process combination was used to create conductive trenches in the substrate surface that were filled with isotropic conductive adhesive (ICA) to create conductive pathways. Additional experimentation with the dispensing parameters led to consistent 150 μm ICA bumps at a 457 μm pitch. A flip-chip bonding force of 0.08 N resulted in a contact resistance of 2.3 Ω at a standoff height of ~80 μm. Flip-chips with greater standoff heights of 160 μm were also successfully underfilled with liquid photopolymer using the SL embedding technique, while the same process on chips with 80 μm standoff height was unsuccessful. Finally the approaches were combined to fabricate single, double and triple layer circuit demonstrators; pyramid shaped electronic packages with internal multilayer electronics; fully packaged and underfilled flip-chip bare die and; a microfluidic device facilitating UV catalysis. This new paradigm in manufacturing supports rapid iterative product development and mass customisation of electronics for a specific application and, allows the generation of more dimensionally complex products with increased functionality

Laser-induced forward transfer (LIFT) of water soluble polyvinyl alcohol (PVA) polymers for use as support material for 3D-printed structures

The additive microfabrication method of laser-induced forward transfer (LIFT) permits the creation of functional microstructures with feature sizes down to below a micrometre [1]. Compared to other additive manufacturing techniques, LIFT can be used to deposit a broad range of materials in a contactless fashion. LIFT features the possibility of building out of plane features, but is currently limited to 2D or 2½D structures [2–4]. That is because printing of 3D structures requires sophisticated printing strategies, such as mechanical support structures and post-processing, as the material to be printed is in the liquid phase. Therefore, we propose the use of water-soluble materials as a support (and sacrificial) material, which can be easily removed after printing, by submerging the printed structure in water, without exposing the sample to more aggressive solvents or sintering treatments. Here, we present studies on LIFT printing of polyvinyl alcohol (PVA) polymer thin films via a picosecond pulsed laser source. Glass carriers are coated with a solution of PVA (donor) and brought into proximity to a receiver substrate (glass, silicon) once dried. Focussing of a laser pulse with a beam radius of 2 µm at the interface of carrier and donor leads to the ejection of a small volume of PVA that is being deposited on a receiver substrate. The effect of laser pulse fluence , donor film thickness and receiver material on the morphology (shape and size) of the deposits are studied. Adhesion of the deposits on the receiver is verified via deposition on various receiver materials and via a tape test. The solubility of PVA after laser irradiation is confirmed via dissolution in de-ionised water. In our study, the feasibility of the concept of printing PVA with the help of LIFT is demonstrated. The transfer process maintains the ability of water solubility of the deposits allowing the use as support material in LIFT printing of complex 3D structures. Future studies will investigate the compatibility (i.e. adhesion) of PVA with relevant donor materials, such as metals and functional polymers. References: [1] A. Piqué and P. Serra (2018) Laser Printing of Functional Materials. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA. [2] R. C. Y. Auyeung, H. Kim, A. J. Birnbaum, M. Zalalutdinov, S. A. Mathews, and A. Piqué (2009) Laser decal transfer of freestanding microcantilevers and microbridges, Appl. Phys. A, vol. 97, no. 3, pp. 513–519. [3] C. W. Visser, R. Pohl, C. Sun, G.-W. Römer, B. Huis in ‘t Veld, and D. Lohse (2015) Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer, Adv. Mater., vol. 27, no. 27, pp. 4087–4092. [4] J. Luo et al. (2017) Printing Functional 3D Microdevices by Laser-Induced Forward Transfer, Small, vol. 13, no. 9, p. 1602553

NASA Tech Briefs, September 2001

Topics include: special coverage section on sensors, and sections on electronic components systems, software, materials, machinery/automation, manufacturing/fabrication, bio-medical, book and reports, and a special section of Photonics Tech Briefs

The Boston University Photonics Center annual report 2005-2006

This repository item contains an annual report that summarizes activities of the Boston University Photonics Center in the 2005-2006 academic year. The report provides quantitative and descriptive information regarding photonics programs in education, interdisciplinary research, business innovation, and technology development. The Boston University Photonics Center (BUPC) is an interdisciplinary hub for education, research, scholarship, innovation, and technology development associated with practical uses of light.This Annual Report is intended to serve as a synopsis of the Boston University Photonics Center’s wide-ranging activities for the period from July 2005 through June 2006, corresponding to the University’s fiscal year. It is my hope that the document is reflective of the Center’s core values in innovation, entrepreneurship, and education, and that it projects our shared vision, and our dedication to excellence in this exciting field. For further information, you may visit our new website at www.bu.edu/photonics. Though only recently appointed as Director, my involvement in Center activities dates back to the Center’s formation more than ten years ago. In the early years, I worked with a team of faculty and staff colleagues to design and construct the shared laboratories that now provide every Center member extraordinary capabilities for fabrication and testing of advanced photonic devices and systems. I helped launch the business incubator by forming a company around an idea that emerged from my research laboratory. While that company failed to realize its vision of transforming the compact disc industry, it did help us form a unique vision for our program of academically engaged business acceleration. I co-developed a course in optical microsystems for telecommunications that I taught to advanced undergraduates and graduate students in the new M.S. degree program in Photonics offered through the Electrical and Computer Engineering Department. And since the Center’s inception, I have contributed to its scholarly mission through my work in optical microsystem design and precision manufacturing at the Center’s core Precision Engineering Research Laboratory. Recently, I had the opportunity to lead the Provost’s Faculty Advisory Committee on Photonics, charged with broadening the Center’s mission to better integrate academic and educational programs with its more established programs for business incubation and prototype development. [TRUNCATED