One MEMS Design Tool with Maximal Six Design Flows

This paper presents one MEMS design tool with total six design flows, which makes it possible that the MEMS designers are able to choose the most suitable design flow for their specific devices. The design tool is divided into three levels and interconnected by six interfaces. The three levels are lumped-element model based system level, finite element analysis based device level and process level, which covers nearly all modeling and simulation functions for MEMS design. The six interfaces are proposed to automatically transmit the design data between every two levels, thus the maximal six design flows could be realized. The interfaces take the netlist, solid model and layout as the data inlet and outlet for the system, device and process level respectively. The realization of these interfaces are presented and verified by design examples, which also proves that the enough flexibility in the design flow can really increase the design efficiency.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

Micro/Nano Manufacturing

Micro- and nano-scale manufacturing has been the subject of ever more research and industrial focus over the past 10 years. Traditional lithography-based technology forms the basis of micro-electro-mechanical systems (MEMS) manufacturing, but also precision manufacturing technologies have been developed to cover micro-scale dimensions and accuracies. Furthermore, these fundamentally different technology platforms are currently combined in order to exploit the strengths of both platforms. One example is the use of lithography-based technologies to establish nanostructures that are subsequently transferred to 3D geometries via injection molding. Manufacturing processes at the micro-scale are the key-enabling technologies to bridge the gap between the nano- and the macro-worlds to increase the accuracy of micro/nano-precision production technologies, and to integrate different dimensional scales in mass-manufacturing processes. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel methodological developments in micro- and nano-scale manufacturing, i.e., on novel process chains including process optimization, quality assurance approaches and metrology

Microfluidic Power Generation

This thesis includes the detailed mathematical calculations used to determine the feasibility of harnessing electrical energy from the blood flow through human capillaries. The designs are inspired by human physiology and well established electromagnetic energy harvesting techniques and the fabrication methods have been proposed for the various components of the device. The fabrication and the design of these components have also been extensively analyzed using calculations based on the governing principles of microfluidics, kinetics, and electromagnetics. The analysis has confirmed that this design can produce sufficient energy to power a MEMS device using non-standard materials and fabrication methods. The designs were based on a standard hydroelectric dam model, modified to account for the biological aspects. Nickel and gold were selected as the primary components of the electromagnetic portion of the device because of their electromagnetic properties and the ability to deposit and pattern them. Of the four portions of the device, the coil was fully fabricated, experiments were conducted for the fabrication of the stator and the microchannels and the proposed fabrication method was explained for the turbine. Three sets of the gold induction coils were fabricated, each with different thicknesses, but the same width and length. Since the resistance of the coil is determined by the resistivity of the material and the dimensions, the cross-sectional area of these coils determined the differences in resistance. As predicted, the average resistance increased as thickness decreased. However, the resistance was greater than calculated for the two thinner coil sets due to fabrication methods

Enhanced Piezoelectric Performance of Printed PZT Films on Low Temperature Substrates

Since piezoelectric effect was discovered in 1880, it has been widely used in micro-actuators, sensors, and energy harvesters. Lead Zirconate Titanate (PZT) is a commonly used piezoelectric material due to the high piezoelectric response. The basic PZT film fabrication process includes deposition, sintering, and poling. However, due to the high sintering temperature (\u3e 800 °C) of PZT, only high melting point material can be served as the substrate. Otherwise, complex film transfer approach is needed to achieve flexible and foldable PZT devices. The exploration is accordingly necessary to realize direct fabrication of PZT films on low melting point substrates without affecting the piezoelectric performance. In order to lower the PZT film sintering temperature, in this work, the effect of the powder size and sintering aid on the sintering temperature was studied. A maskless, CAD driven, non-contact direct printing system, aerosol jet printer, was used to deposit PZT thick films on the substrate. This technique allows creating features without masking and etching processes that are generally required for realizing designed features via conventional deposition approaches. Broadband, sub-millisecond, high intensity flash pulses were used to sinter the PZT films. The role of all sintering parameters was investigated to regulate the sintering quality of the PZT thick films. The photonically sintered films showed much lower substrate temperature increase mainly due to the extremely short pulse duration and temperature gradient through the film thickness. The superior piezoelectric property to thermally sintered group was also obtained. This process significantly shortens the processing duration and dramatically expands the possible substrate materials. It accordingly opens the possibility of processing PZT film directly on low melting point materials. A PZT energy harvester based on this process was directly fabricated on the polyethylene terephthalate (PET) substrate to demonstrate the capability. The relation between the load and the generated power was investigated to obtain the highest output power. Up to 0.1 μW was generated from this flexible energy harvester when connected with 10 MΩ resistive load. Photonic sintering of PZT film also creates the opportunity of processing poling during sintering. Different combinations of the sintering and poling techniques were studied. It was observed that the best piezoelectric property was obtained while performing poling during photonic sintering. Consequently, a new method of printing, sintering, and poling of micro-scaled PZT films was demonstrated in this work resulting in high performance films. This process provides the capability of realizing PZT devices on low temperature substrate, facilitates the fabrication of flexible piezoelectric devices, and enhances the piezoelectric property

Workshop on "Robotic assembly of 3D MEMS".

Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary

Complex network analysis and nonlinear dynamics

This chapter aims at reviewing complex network and nonlinear dynamical models and methods that were either developed for or applied to socioeconomic issues, and pertinent to the theme of New Economic Geography. After an introduction to the foundations of the field of complex networks, the present summary introduces some applications of complex networks to economics, finance, epidemic spreading of innovations, and regional trade and developments. The chapter also reviews results involving applications of complex networks to other relevant socioeconomic issue

Development of High-speed Photoacoustic Imaging technology and Its Applications in Biomedical Research

Photoacoustic (PA) tomography (PAT) is a novel imaging modality that combines the fine lateral resolution from optical imaging and the deep penetration from ultrasonic imaging, and provides rich optical-absorption–based images. PAT has been widely used in extracting structural and functional information from both ex vivo tissue samples to in vivo animals and humans with different length scales by imaging various endogenous and exogenous contrasts at the ultraviolet to infrared spectrum. For example, hemoglobin in red blood cells is of particular interest in PAT since it is one of the dominant absorbers in tissue at the visible wavelength.The main focus of this dissertation is to develop high-speed PA microscopy (PAM) technologies. Novel optical scanning, ultrasonic detection, and laser source techniques are introduced in this dissertation to advance the performance of PAM systems. These upgrades open up new avenues for PAM to be applicable to address important biomedical challenges and enable fundamental physiological studies.First, we investigated the feasibility of applying high-speed PAM to the detection and imaging of circulating tumor cells (CTCs) in melanoma models, which can provide valuable information about a tumor’s metastasis potentials. We probed the melanoma CTCs at the near-infrared wavelength of 1064 nm, where the melanosomes absorb more strongly than hemoglobin. Our high-speed PA flow cytography system successfully imaged melanoma CTCs in travelling trunk vessels. We also developed a concurrent laser therapy device, hardware-triggered by the CTC signal, to photothermally lyse the CTC on the spot in an effort to inhibit metastasis.Next, we addressed the detection sensitivity issue in the previous study. We employed the stimulated Raman scattering (SRS) effect to construct a high-repetition-rate Raman laser at 658 nm, where the contrast between a melanoma CTC and the blood background is near the highest. Our upgraded PA flow cytography successfully captured sequential images of CTCs in mouse melanoma xenograft model, with a significantly improved contrast-to-noise ratio compared to our previous results. This technology is readily translatable to the clinics to extract the information of a tumor’s metastasis risks.We extended the Raman laser technology to the field of brain functional studies. We developed a MEMS (micro-electromechanical systems) scanner for fast optical scanning, and incorporated it to a dual-wavelength functional PAM (fPAM) for high-speed imaging of cerebral hemodynamics in mouse. This fPAM system successfully imaged transient changes in blood oxygenation at cerebral micro-vessels in response to brief somatic stimulations. This fPAM technology is a powerful tool for neurological studies.Finally, we explored some approaches of reducing the size the PAM imaging head in an effort to translate our work to the field of wearable biometric monitors. To miniaturize the ultrasonic detection device, we fabricated a thin-film optically transparent piezoelectric detector for detecting PA waves. This technology could enable longitudinal studies on free-moving animals through a wearable version of PAM

An Optical Density Detection Platform with Integrated Microfluidics for In Situ Growth, Monitoring, and Treatment of Bacterial Biofilms

Systems engineering strategies utilizing platform-based design methodologies are implemented to achieve the integration of biological and physical system components in a biomedical system. An application of this platform explored, in which an integrated microsystem is developed capable of the on-chip growth, monitoring, and treatment of bacterial biofilms for drug development and fundamental study applications. In this work, the developed systems engineering paradigm is utilized to develop a device system implementing linear array charge-coupled devices to enable real time, non-invasive, label-free monitoring of bacterial biofilms. A novel biofilm treatment method is demonstrated within the developed microsystem showing drastic increases in treatment efficacy by decreasing both bacterial biomass and cell viability within treated biofilms. Demonstration of this treatment at the microscale enables future applications of this method for the in vivo treatment of biofilm-associated infections

Nanoporous Bi2Te3 thermoelectric based Knudsen gas pump.

This dissertation reports on the fabrication of a bi-directional Knudsen gas pump using a multifunctional nanoporous thermoelectric material. The integration of the channels into the thermoelectric material has the advantages of reducing heat losses and power consumption, improving the pump efficiency, and reducing the overall pump size. The Knudsen pump operates on the thermal transpiration principle, the phenomenon that gas molecules drift from the cold end to the hot end of a narrow channel. The gas pumping is realized in the transition or free molecular regime. The Knudsen pump is needed in a great number of applications such as gas chromatography, spectroscopy, gas manipulation, and cooling in microelectronics. Pressure and pressureless sintering techniques are used to fabricate the nanoporous thermoelectric material. The thermoelectric material was characterized by measuring the pore size distribution, electrical conductivity, and thermal conductivity, thermopower, and temperature distribution. Two Knudsen pumps are then fabricated. In the first pump, the circular thermoelectric sample is placed on a copper heat sink. When the power is turned on, one side of the thermoelectric sample gets hot, and the other side gets cold providing the necessary temperature gradient for thermal transpiration to take place. Reversing the voltage polarity reverses the hot and cold sides and therefore reverses the pumping direction. The pump generated a pressure of 300 Pa for an input power of 0.96 W. In the second design, the fabricated square-shaped thermoelectric sample is placed in a machined plastic channel. 520 Pa pressure difference and 1 µl/min flow rate are obtained for an input power of 1.33 W. Using a combination of the Sharipov and thermoelectric equations, expression for the maximum pressure difference, max P D , and maximum mass flow rate, max M & , are derived and analyzed. We conclude the following. As the thermoelectric figure of merit Z increases, max M & and max P D increases. As the pore size increases, the max P D decreases, and max M & increases. As the molecular mass of the working gas increases, max P Ddecreases, and max M & increases. As the tangential momentum accommodation coefficient increases, max P D increases, and max M &decreases. The last section of this dissertation is concerned with gas flow through track-etch Whatman nanoporous membranes. We found that the tangential momentum accommodation coefficient fails to solve the discrepancy between experimental and theoretical flow rate. A simple measurement of pressure versus the flow rate through the membranes was conducted next. Among the analyzed models from the literature, the surface flow diffusion model provides the best fit to the experimental data