Boundary conditioning concept applied to the synthesis of microsystems using fuzzy logic approach

The burgeoning field of MicroSystems Technology (MST) has a tremendous potential for sensing and actuation of industrial systems in almost every field of human interest. This thesis proposes a synthesis of microsystems in order to explore the advantage of miniaturization by developing a technology suitable for fabricating integrated systems that consist of sensing, actuating and computing elements at the. micro level. The synthesis involves development of fabrication strategies using industrial CMOS process and design strategies, in order to manipulate the effect of inherent limitations of fabrication and other limitations due to structural configuration and environment on dynamic behavior of microsystems. Towards the success of fabrication synthesis, micromechanical components are fabricated through an industrial CMOS process, namely, the Mitel 1.5 om Double-Poly-Double-Metal process, and by post-releasing with gas phase xenon difluoride etching. The etching is described along with the details of the setup, the etching procedure and the effect of etching on end conditions of the fabricated structure. The types of structures fabricated show that they can be adopted for both piezoresistive and capacitive devices. The different factors that influence the elastic properties of both macro and micro systems include variations in structural geometry, process parameters and operational environment. A concept of boundary conditioning is proposed in this thesis as a unified approach for the quantification of the influence of structural geometry, support conditions, fabrication process and environmental influence on the dynamic behavior of the system. The influence of all the above parameters is represented by replacing the elastic influence with the equivalent spring stiffnesses. The modeling of boundary conditioning is carried out using artificial springs and boundary characteristic orthogonal polynomials in the Rayleigh-Ritz method. The eigenvalues are predicted for plate type structures with stiffeners and cutouts using this approach. The concept of boundary conditioning is applied to structural tuning and localization of vibrational response. The results obtained for manipulation of harmonic combinations and vibrational response using artificial springs are useful and interesting. The boundary conditioning conceptualizes micro or macro system into equivalent elastic system. The equivalent stiffnesses which can be estimated through experiment or other methods may include uncertainties and vagueness. The fuzzy system identification technique is applied for modeling such micro or macro systems with fuzziness on input and output parameters. Automatic fuzzy system identification is carried out using subtractive clustering method. A higher order fuzzy system identification technique is proposed for modeling complicated systems with fewer number of rules. The structural tuning of elastic systems is identified by expert modeling and subtractive clustering. The influence of structural variations of microsystems on dynamic behavior is modeled using the method of artificial springs. The static and dynamic behavior of free standing microsystems under the influence of electrostatic field and residual stress are also presented. The comparison between predicted and experimental values of snapping voltage for capacitive type systems shows a good agreement. The non-classical end conditions resulting from micromachining processes are modeled using boundary conditioning technique. The application of fuzzy system identification of the boundary conditioning of microsystems, shows a potential for direct and indirect design of microsytems for the required dynamic behavior

BioMEMS

As technological advancements widen the scope of applications for biomicroelectromechanical systems (BioMEMS or biomicrosystems), the field continues to have an impact on many aspects of life science operations and functionalities. Because BioMEMS research and development require the input of experts who use different technical languages and come from varying disciplines and backgrounds, scientists and students can avoid potential difficulties in communication and understanding only if they possess a skill set and understanding that enables them to work at the interface of engineering and biosciences. Keeping this duality in mind throughout, BioMEMS: Science and Engineering Perspectives supports and expedites the multidisciplinary learning involved in the development of biomicrosystems. Divided into nine chapters, it starts with a balanced introduction of biological, engineering, application, and commercialization aspects of the field. With a focus on molecules of biological interest, the book explores the building blocks of cells and viruses, as well as molecules that form the self-assembled monolayers (SAMs), linkers, and hydrogels used for making different surfaces biocompatible through functionalization. The book also discusses: Different materials and platforms used to develop biomicrosystems Various biological entities and pathogens (in ascending order of complexity) The multidisciplinary aspects of engineering bioactive surfaces Engineering perspectives, including methods of manufacturing bioactive surfaces and devices Microfluidics modeling and experimentation Device level implementation of BioMEMS concepts for different applications. Because BioMEMS is an application-driven field, the book also highlights the concepts of lab-on-a-chip (LOC) and micro total analysis system (μTAS), along with their pertinence to the emerging point-of-care (POC) and point-of-need (PON) applications

BioMEMS

As technological advancements widen the scope of applications for biomicroelectromechanical systems (BioMEMS or biomicrosystems), the field continues to have an impact on many aspects of life science operations and functionalities. Because BioMEMS research and development require the input of experts who use different technical languages and come from varying disciplines and backgrounds, scientists and students can avoid potential difficulties in communication and understanding only if they possess a skill set and understanding that enables them to work at the interface of engineering and biosciences. Keeping this duality in mind throughout, BioMEMS: Science and Engineering Perspectives supports and expedites the multidisciplinary learning involved in the development of biomicrosystems. Divided into nine chapters, it starts with a balanced introduction of biological, engineering, application, and commercialization aspects of the field. With a focus on molecules of biological interest, the book explores the building blocks of cells and viruses, as well as molecules that form the self-assembled monolayers (SAMs), linkers, and hydrogels used for making different surfaces biocompatible through functionalization. The book also discusses: Different materials and platforms used to develop biomicrosystems Various biological entities and pathogens (in ascending order of complexity) The multidisciplinary aspects of engineering bioactive surfaces Engineering perspectives, including methods of manufacturing bioactive surfaces and devices Microfluidics modeling and experimentation Device level implementation of BioMEMS concepts for different applications. Because BioMEMS is an application-driven field, the book also highlights the concepts of lab-on-a-chip (LOC) and micro total analysis system (μTAS), along with their pertinence to the emerging point-of-care (POC) and point-of-need (PON) applications

Nano-Integrated Suspended Polymeric Microfluidics (SPMF) Platform for Ultra-Sensitive Bio-Molecular Recognition of Bovine Growth Hormones

The development of sensitive platforms for the detection of biomolecules recognition is an extremely important problem in clinical diagnostics. In microcantilever (MC) transducers, surface-stress is induced upon bimolecular interaction which is translated into MC deflection. This paper presents a cost-effective and ultra-sensitive MC-based biosensing platform. To address these goals, the need for costly high-resolution read-out system has been eliminated by reducing the cantilever compliance through developing a polymer-based cantilever. Furthermore a microfluidic system has been integrated with the MC in order to enhance sensitivity and response time and to reduce analytes consumption. Gold nanoparticles (AuNPs) are synthesized on the surface of suspended microfluidics as the selective layer for biomolecule immobilization. The biosensing results show significant improvement in the sensitivity of the proposed platform compared with available silicon MC biosensor. A detection limit of 2 ng/ml (100pM) is obtained for the detection of bovine growth hormones. The results validated successful application of suspended polymeric microfluidics (SPMF) as the next generation of biosensing platforms which could enable femtomolar (fM) biomolecular recognition detection

Microfluidic coupler for hybrid integrated lab-on-a-chip

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Lab-on-chips (LOCs) or miniaturized total analytical systems (μTAS) are attractive to perform chemical and biological analysis using small amounts of samples in a short time. Micro machined fluidics and optical devices are integral components of LOCs, which are fabricated monolithically or by hybrid integration in order to perform various analytical process in a single chip. In this work, simulation and implementation of a microfluidic coupler for the hybrid integration of an optical microfluidic system by using silica-on-silicon waveguides and polydimethylsiloxane (PDMS) microfluidic chips are demonstrated. The presented microfluidic coupler simplifies the fabrication of optical microfluidic systems by coupling the fluid from the PDMS chip to the micro channel in the silica-onwaveguide. The micro-flow behavior through the coupler is investigated by the simulations carried out using the COMSOL multiphysics and the experiments as well.dc201

Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions

Plasmonic Gold Decorated MWCNT Nanocomposite for Localized Plasmon Resonance Sensing

The synergism of excellent properties of carbon nanotubes and gold nanoparticles is used in this work for bio-sensing of recombinant bovine growth hormones (rbST) by making Multi Wall Carbon Nanotubes (MWCNT) locally optically responsive by augmenting it optical properties through Localized Surface Plasmon Resonance (LSPR). To this purpose, locally gold nano particles decorated gold–MWCNT composite was synthesized from a suspension of MWCNT bundles and hydrogen chloroauric acid in an aqueous solution, activated ultrasonically and, then, drop-casted on a glass substrate. The slow drying of the drop produces a “coffee ring” pattern that is found to contain gold–MWCNT nanocomposites, accumulated mostly along the perimeter of the ring. The reaction is studied also at low-temperature, in the vacuum chamber of the Scanning Electron Microscope and is accounted for by the local melting processes that facilitate the contact between the bundle of tubes and the gold ions. Biosensing applications of the gold–MWCNT nanocomposite using their LSPR properties are demonstrated for the plasmonic detection of traces of bovine growth hormone. The sensitivity of the hybrid platform which is found to be 1 ng/ml is much better than that measuring with gold nanoparticles alone which is only 25 ng/ml

Culturing cells for life: innovative approaches in macroscopic and microfluidic cultures, with an emphasis on stem cells

In 2006, Whitesides, writing about microfluidics, said that microfluidics is in early adolescence and it is not yet clear how it will develop. Today, almost 20 years later, microfluidics became a fully developed, highly sophisticated, multidisciplinary field that had entirely honoured its early promise. Its strength stems from the knowledge and know-how, coming from multiple disciplines such as physics of fluids, engineering, and microfabrication in the beginning, followed, more recently, by cell biological research, in full bloom nowadays. In microfluidic devices, the environment of cells such as chemical and mechanical gradients can be reproduced, making biological studies even more compelling. The red thread of this review paper follows the new insights and discoveries in both traditional macro- and microfluidic cell culture brought into the cell biology field, especially in the culture of stem cells, filled with promise in the field of regenerative medicine. Microfluidic devices provide an environment that is much closer to that of in vivo cell culture than the conventional culture platforms, where large amounts of cells are cultured and the environment of individual cells cannot be distinguished. The convenience of live cell imaging, portability, and the integration of sensors to precisely, control various parameters, has expanded cell biologists’ arsenal In addition, microfluidic devices, integrated with different functionalities, that is, the automated cell culture systems, will be discussed as well

Direct Sound Printing

Photo- and thermo-activated reactions are dominant in Additive Manufacturing (AM) processes for polymerization or melting/deposition of polymers. However, ultrasound activated sonochemical reactions present a unique way to generate hotspots in cavitation bubbles with extraordinary high temperature and pressure along with high heating and cooling rates which are out of reach for the current AM technologies. Here, we demonstrate 3D printing of structures using acoustic cavitation produced directly by focused ultrasound which creates sonochemical reactions in highly localized cavitation regions. Complex geometries with zero to varying porosities and 280 μm feature size are printed by our method, Direct Sound Printing (DSP), in a heat curing thermoset, Poly(dimethylsiloxane) that cannot be printed directly so far by any method. Sonochemiluminescnce, high speed imaging and process characterization experiments of DSP and potential applications such as remote distance printing are presented. Our method establishes an alternative route in AM using ultrasound as the energy source