36 research outputs found
Medical Robotics
The first generation of surgical robots are already being installed in a number of operating rooms around the world. Robotics is being introduced to medicine because it allows for unprecedented control and precision of surgical instruments in minimally invasive procedures. So far, robots have been used to position an endoscope, perform gallbladder surgery and correct gastroesophogeal reflux and heartburn. The ultimate goal of the robotic surgery field is to design a robot that can be used to perform closed-chest, beating-heart surgery. The use of robotics in surgery will expand over the next decades without any doubt. Minimally Invasive Surgery (MIS) is a revolutionary approach in surgery. In MIS, the operation is performed with instruments and viewing equipment inserted into the body through small incisions created by the surgeon, in contrast to open surgery with large incisions. This minimizes surgical trauma and damage to healthy tissue, resulting in shorter patient recovery time. The aim of this book is to provide an overview of the state-of-art, to present new ideas, original results and practical experiences in this expanding area. Nevertheless, many chapters in the book concern advanced research on this growing area. The book provides critical analysis of clinical trials, assessment of the benefits and risks of the application of these technologies. This book is certainly a small sample of the research activity on Medical Robotics going on around the globe as you read it, but it surely covers a good deal of what has been done in the field recently, and as such it works as a valuable source for researchers interested in the involved subjects, whether they are currently âmedical roboticistsâ or not
Microelectromechanical Systems and Devices
The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators
MACHINE LEARNING AUGMENTATION MICRO-SENSORS FOR SMART DEVICE APPLICATIONS
Novel smart technologies such as wearable devices and unconventional robotics have been enabled by advancements in semiconductor technologies, which have miniaturized the sizes of transistors and sensors. These technologies promise great improvements to public health. However, current computational paradigms are ill-suited for use in novel smart technologies as they fail to meet their strict power and size requirements. In this dissertation, we present two bio-inspired colocalized sensing-and-computing schemes performed at the sensor level: continuous-time recurrent neural networks (CTRNNs) and reservoir computers (RCs). These schemes arise from the nonlinear dynamics of micro-electro-mechanical systems (MEMS), which facilitates computing, and the inherent ability of MEMS devices for sensing. Furthermore, this dissertation addresses the high-voltage requirements in electrostatically actuated MEMS devices using a passive amplification scheme.
The CTRNN architecture is emulated using a network of bistable MEMS devices. This bistable behavior is shown in the pull-in, the snapthrough, and the feedback regimes, when excited around the electrical resonance frequency. In these regimes, MEMS devices exhibit key behaviors found in biological neuronal populations. When coupled, networks of MEMS are shown to be successful at classification and control tasks. Moreover, MEMS accelerometers are shown to be successful at acceleration waveform classification without the need for external processors.
MEMS devices are additionally shown to perform computing by utilizing the RC architecture. Here, a delay-based RC scheme is studied, which uses one MEMS device to simulate the behavior of a large neural network through input modulation. We introduce a modulation scheme that enables colocalized sensing-and-computing by modulating the bias signal. The MEMS RC is tested to successfully perform pure computation and colocalized sensing-and-computing for both classification and regression tasks, even in noisy environments.
Finally, we address the high-voltage requirements of electrostatically actuated MEMS devices by proposing a passive amplification scheme utilizing the mechanical and electrical resonances of MEMS devices simultaneously. Using this scheme, an order-of-magnitude of amplification is reported. Moreover, when only electrical resonance is used, we show that the MEMS device exhibits a computationally useful bistable response.
Adviser: Dr. Fadi Alsalee
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Towards Ultra-High Resolution Mode-localised MEMS Sensors
Sensors employing mode localisation in weakly coupled resonators have been increasingly viewed as an alternative to resonant frequency shift based sensing. Much theory has been proposed highlighting the advantages of these sensors including the increased sensitivity and the promise of common mode rejection to first order environmental variations. This has led to the development of proof-of-concept sensors to sense physical quantities such as displacement, charge, mass, and acceleration. However, practical aspects of developing a sensor starting from design of a closed-loop implementation to understanding different operating regions with the aim of resolution analysis and noise optimisation have yet to be explored in depth. This work delves into these practical aspects of developing ultra-high resolution mode-localised MEMS sensors.
First, the mechanical sensor is integrated with a prototype closed-loop oscillator along with the interface electronics on a printed circuit board. Key aspects of sensors such as stability, noise floor, and bandwidth are analysed using this integrated sensor system. A critical observation is made on the improvement of stability of the amplitude ratio output metric over its frequency shift counterpart at large integration times therefore, highlighting the advantage of common mode rejection to environmental factors. The common mode rejection abilities of both mechanically and electrically coupled devices are next studied at different operating regions. These are then compared to the state-of-the-art differential frequency measurements. Amplitude ratio measurements in an electrically coupled device showed an order of magnitude better rejection to temperature variations over a mechanically coupled device. Furthermore, amplitude ratio measurements in the electrically coupled device were on par with the rejection offered by the differential frequency output in the same device. This result highlights the advantage of amplitude ratio measurements that are able to achieve the same common mode rejection with the help of a single oscillator instead of the two oscillators required in differential frequency output measurements.
The resolution of the mode-localised sensor is then explored with the purpose of optimising operating regions to achieve the best noise figure. A detailed theoretical analysis is first undertaken to optimise the amplitude ratio noise in different noise dominant regimes. It is predicted that the resonator-based noise (such as thermo-mechanical noise) can be optimised be operating at an amplitude ratio of and the electronic sourced noises can be optimised at an amplitude ratio of in a single ended resonator drive configuration. Additionally, both sources of noise are predicted to decrease with the decrease of the coupling stiffness. This result is then validated using experimental data to verify the claim. A further noise reduction is sought by operating the coupled resonators in the nonlinear domain with interesting observations on the variations of the amplitude ratio output metric. The phase filtering offered by the bifurcation points in the nonlinear domain is utilised to further improve the noise by 4 times.
Finally, a mode-localised accelerometer design is proposed that employs a novel differential amplitude ratio output metric. Noise optimisation techniques are then used to optimise this novel output metric. A noise floor of g/\sqrt{\mbox{Hz}} with a stability of g is achieved thus, benchmarking the mode-localised accelerometer favourably with respect to other high-end commercial MEMS accelerometers. Additionally, their potential is demonstrated with a measurement of seismic activity. This measurement is then compared to reference data sourced from an accelerometer from the British Geological Survey. Lastly, suggestions are made to further optimise the resolution in the accelerometer to push the limits of amplitude ratio sensing thereby, putting mode-localised accelerometers at par with the best resonant accelerometers till date.Innovate UK
Natural Environment Research Counci
MEMS Technology for Biomedical Imaging Applications
Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community
Development of MEMS Piezoelectric Vibration Energy Harvesters with Wafer-Level Integrated Tungsten Proof-Mass for Ultra Low Power Autonomous Wireless Sensors
La gĂ©nĂ©ration dâĂ©nergie localisĂ©e et Ă petite Ă©chelle, par transformation de lâĂ©nergie vibratoire disponible dans lâenvironnement, est une solution attrayante pour amĂ©liorer lâautonomie de certains noeuds de capteurs sans-fil pour lâInternet des objets (IoT). GrĂące Ă des microdispositifs inertiels rĂ©sonants piĂ©zoĂ©lectriques, il est possible de transformer lâĂ©nergie mĂ©canique en Ă©lectricitĂ©. Cette thĂšse prĂ©sente une Ă©tude exhaustive de cette technologie et propose un procĂ©dĂ© pour fabriquer des microgĂ©nĂ©rateurs MEMS offrant des performances surpassant lâĂ©tat de lâart.
On prĂ©sente dâabord une revue complĂšte des limites physiques et technologiques pour identifier le meilleur chemin dâamĂ©lioration. En Ă©valuant les approches proposĂ©es dans la littĂ©rature (gĂ©omĂ©trie, architecture, matĂ©riaux, circuits, etc.), nous suggĂ©rons des mĂ©triques pour comparer lâĂ©tat de lâart. Ces analyses dĂ©montrent que la limite fondamentale est lâĂ©nergie absorbĂ©e par le dispositif, car plusieurs des solutions existantes rĂ©pondent dĂ©jĂ aux autres limites. Pour un gĂ©nĂ©rateur linĂ©aire rĂ©sonant, lâabsorption dâĂ©nergie dĂ©pend donc des vibrations disponibles, mais aussi de la masse du dispositif et de son facteur de qualitĂ©.
Pour orienter la conception de prototypes, nous avons rĂ©alisĂ© une Ă©tude sur le potentiel des capteurs autonomes dans une automobile. Nous avons Ă©valuĂ© une liste des capteurs prĂ©sents sur un vĂ©hicule pour leur compatibilitĂ© avec cette technologie. Nos mesures de vibrations sur un vĂ©hicule en marche aux emplacements retenus rĂ©vĂšlent que lâĂ©nergie disponible pour un dispositif linĂ©aire rĂ©sonant MEMS se situe entre 30 Ă 150 Hz. Celui-ci pourrait produire autour de 1 Ă 10 ÎŒW par gramme. Pour limiter la taille dâun gĂ©nĂ©rateur MEMS pouvant produire 10 ÎŒW, il faut une densitĂ© supĂ©rieure Ă celle du silicium, ce qui motive lâintĂ©gration du tungstĂšne.
Lâeffet du tungstĂšne sur la sensibilitĂ© du dispositif est Ă©vident, mais nous dĂ©montrons Ă©galement que lâusage de ce matĂ©riau permet de rĂ©duire lâimpact de lâamortissement fluidique sur le facteur de qualitĂ© mĂ©canique Qm. En fait, lorsque lâamortissement fluidique domine, ce changement peut amĂ©liorer Qm dâun ordre de grandeur, passant de 103 Ă 104 dans lâair ambiant. Par consĂ©quent, le rendement du dispositif est amĂ©liorĂ© sans utiliser un boĂźtier sous vide.
Nous proposons ensuite un procĂ©dĂ© de fabrication qui intĂšgre au niveau de la tranche des masses de tungstĂšne de 500 ÎŒm dâĂ©pais. Ce procĂ©dĂ© utilise des approches de collage de tranches et de gravure humide du mĂ©tal en deux Ă©tapes. Nous prĂ©sentons chaque bloc de fabrication rĂ©alisĂ© pour dĂ©montrer la faisabilitĂ© du procĂ©dĂ©, lequel a permis de fabriquer plusieurs prototypes. Ces dispositifs ont Ă©tĂ© testĂ©s en laboratoire, certains dĂ©montrant des performances records en terme de densitĂ© de puissance normalisĂ©e. Notre meilleur design se dĂ©marque par une mĂ©trique de 2.5 mW-s-1/(mm3(m/s2)2), soit le meilleur rĂ©sultat rĂ©pertoriĂ© dans lâĂ©tat de lâart. Avec un volume de 3.5 mm3, il opĂšre Ă 552.7 Hz et produit 2.7 ÎŒW Ă 1.6 V RMS Ă partir dâune accĂ©lĂ©ration de 1 m/s2. Ces rĂ©sultats dĂ©montrent que lâintĂ©gration du tungstĂšne dans les microgĂ©nĂ©rateurs MEMS est trĂšs avantageuse et permet de sâapprocher davantage des requis des applications rĂ©elles.Small scale and localized power generation, using vibration energy harvesting, is considered as an attractive solution to enhance the autonomy of some wireless sensor nodes used in the Internet of Things (IoT). Conversion of the ambient mechanical energy into electricity is most often done through inertial resonant piezoelectric microdevices. This thesis presents an extensive study of this technology and proposes a process to fabricate MEMS microgenerators with record performances compared to the state of the art. We first present a complete review of the physical and technological limits of this technology to asses the best path of improvement. Reported approaches (geometries, architectures, materials, circuits) are evaluated and figures of merit are proposed to compare the state of the art. These analyses show that the fundamental limit is the absorbed energy, as most proposals to date partially address the other limits. The absorbed energy depends on the level of vibrations available, but also on the mass of the device and its quality factor for a linear resonant generator. To guide design of prototypes, we conducted a study on the potential of autonomous sensors in vehicles. A survey of sensors present on a car was realized to estimate their compatibility with energy harvesting technologies. Vibration measurements done on a running vehicle at relevant locations showed that the energy available for MEMS devices is mostly located in a frequency range of 30 to 150 Hz and could generate power in the range of 1-10 ÎŒW per gram from a linear resonator. To limit the size of a MEMS generator capable of producing 10 ÎŒW, a higher mass density compared to silicon is needed, which motivates the development of a process that incorporates tungsten. Although the effect of tungsten on the device sensitivity is well known, we also demonstrate that it reduces the impact of the fluidic damping on the mechanical quality factor Qm. If fluidic damping is dominant, switching to tungsten can improve Qm by an order of magnitude, going from 103 to 104 in ambient air. As a result, the device efficiency is improved despite the lack of a vacuum package. We then propose a fabrication process flow to integrate 500 ÎŒm thick tungsten masses at the wafer level. This process combines wafer bonding with a 2-step wet metal etching approach. We present each of the fabrication nodes realized to demonstrate the feasibility of the process, which led to the fabrication of several prototypes. These devices are tested in the lab, with some designs demonstrating record breaking performances in term of normalized power density. Our best design is noteworthy for its figure of merit that is around 2.5 mW-s-1/(mm3(m/s2)2), which is the best reported in the state of the art. With a volume of 3.5 mm3, it operates at 552.7 Hz and produces 2.7 ÎŒW at 1.6 V RMS from an acceleration of 1 m/s2. These results therefore show that tungsten integration in MEMS microgenerators is very advantageous, allowing to reduce the gap with needs of current applications
High Aspect-ratio Biomimetic Hair-like Microstructure Arrays for MEMS Multi-Transducer Platform
Many emerging applications of sensing microsystems in health care, environment, security and transportation systems require improved sensitivity and selectivity, redundancy, robustness, increased dynamic range, as well as small size, low power and low cost. Providing all of these features in a system consisting of one sensor is not practical or possible. Micro electro mechanical microsystems (MEMS) that combine a large sensor array with signal processing circuits could provide these features.
To build such multi-transducer microsystems we get inspiration from âhairâ, a structure frequently used in nature. Hair is a simple yet elegant structure that offers many attractive features such as large length to cross-sectional area ratio, large exposed surface area, ability to include different sensing materials, and ability to interact with surrounding media in sophisticated ways. In this thesis, we have developed a microfabrication technology to build 3D biomimetic hair structures for MEMS multi-transducer platform. Direct integration with CMOS will enable signal processing of dense arrays of 100s or 1000s of MEMS transducers within a small chip area.
We have developed a new device structure that mimics biological hair. It includes a vertical spring, a proof-mass atop the spring, and high aspect-ratio narrow electrostatic gaps to adjacent electrodes for sensing and actuation. Based on this structure, we have developed three generations of 3D high aspect-ratio, small-footprint, low-noise accelerometers. Arrays of both high-sensitivity capacitive and threshold accelerometers are designed and tested, and they demonstrate extended full-scale detection range and frequency bandwidth.
The first-generation capacitive hair accelerometer arrays are based on Silicon-on-Glass (SOG) process utilizing 500âŻÂ”m thick silicon, achieving a highest sensor density of ~100 sensors/mm2 connected in parallel. Minimum capacitive gap is 5âŻÎŒm with device height of 400âŻÎŒm and spring length of 300âŻÎŒm.
A custom-designed Bosch deep-reactive-etching (DRIE) process is developed to etch ultra-deep (>âŻ500âŻÂ”m) ultra-high aspect-ratio (UHAR) features (ARâŻ>âŻ40) with straight sidewalls and reduced undercut across a wide range of feature sizes. A two-gap dry-release process is developed for the second-generation capacitive hair accelerometers. Due to the large device height at full wafer thickness of 1âŻmm and UHAR capacitive transduction gaps at 2âŻÂ”m that extend >âŻ200âŻÂ”m, the accelerometer achieves sub-”g resolution (<âŻ1”g/âHz) and high sensitivity (1pF/g/mm2), having an area smaller than any previous precision accelerometers with similar performance. Each sensor chip consists of devices with various design parameter to cover a wide range. Bonding with metal interlayers at <âŻ400âŻÂ°C allows direct integration of these devices on top of CMOS circuits.
The third-generation digital threshold hair accelerometer takes advantage of large aspect-ratio of the hair structure and UHAR DRIE structures to provide low noise (<âŻ600âŻng/âHz per mm2 footprint proof-mass due to small contact area) and low power threshold acceleration detection. 16-element (4-bit) and 32-element (5-bit) arrays of threshold devices (total chip area being <âŻ1âŻcm2) with evenly-spaced threshold gap dimensions from 1âŻÂ”m to 4âŻÂ”m as well as with hair spring cross-sectional area from 102âŻÂ”m to 302âŻÂ”m are designed to suit specific g-ranges from <âŻ100âŻmg to 50âŻg.
This hair sensor and sensor array technology is suited for forming MEMS transducer arrays with circuits, including high performance IMUs as well as miniaturized detectors and actuators that require high temporal and spatial resolution, analogous to high-density CMOS imagers.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143975/1/yemin_1.pd
Engineering Dynamics and Life Sciences
From Preface:
This is the fourteenth time when the conference âDynamical Systems: Theory
and Applicationsâ gathers a numerous group of outstanding scientists and engineers, who
deal with widely understood problems of theoretical and applied dynamics.
Organization of the conference would not have been possible without a great effort of
the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage
over the conference has been taken by the Committee of Mechanics of the Polish Academy
of Sciences and Ministry of Science and Higher Education of Poland.
It is a great pleasure that our invitation has been accepted by recording in the history
of our conference number of people, including good colleagues and friends as well as a large
group of researchers and scientists, who decided to participate in the conference for the
first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all
over the world. They decided to share the results of their research and many years
experiences in a discipline of dynamical systems by submitting many very interesting
papers.
This year, the DSTA Conference Proceedings were split into three volumes entitled
âDynamical Systemsâ with respective subtitles: Vibration, Control and Stability of Dynamical
Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and
Engineering Dynamics and Life Sciences. Additionally, there will be also published two
volumes of Springer Proceedings in Mathematics and Statistics entitled âDynamical Systems
in Theoretical Perspectiveâ and âDynamical Systems in Applicationsâ