Microsystems technology: objectives

This contribution focuses on the objectives of microsystems technology (MST). The reason for this is two fold. First of all, it should explain what MST actually is. This question is often posed and a simple answer is lacking, as a consequence of the diversity of subjects that are perceived as MST. The second reason is that a map of the somewhat chaotic field of MST is needed to identify sub-territories, for which standardization in terms of system modules an interconnections is feasible. To define the objectives a pragmatic approach has been followed. From the literature a selection of topics has been chosen and collected that are perceived as belonging to the field of MST by a large community of workers in the field (more than 250 references). In this way an overview has been created with `applications¿ and `generic issues¿ as the main characteristics

A programmable integrated power supply for the electrostatic-drive micromotor

A 6-phase bipolarized, high-voltage power supply with rectangular pulse shape has been designed to study the special operational characteristics of various electrostatic-drive micromotors. In particular the design powers the variable-capacitance side-drive micromotor. This power supply provides variable frequency, variable voltage, and variable duty-cycle control. Simulation has been used extensively in the design and design verification. The bipolarization (dual voltage polarity) of each pair of the phases reduces physical clamping of the rotor to the electrical shield beneath it. Thus, bipolarization of the voltage supplied to the stator nodes reduces charge build-up on the rotor. The output frequency range varying from 1Hz to 40KHz has been achieved. This supply frequency range corresponds to motor rotational speed range of 5rpm to 200Krpm, for a micromotor with 12 stator poles and 8 rotor poles (3:2 architec-ture). The voltage amplitudes of all six phases can be varied from 20 to 200Volts. The duty cycle of each phase can be changed by means of a parallel register. The output with variable duty cycle has been obtained, changing from 50% non-overlapping to 33% overlapping. The power supply with 6-phase bipolarized output, variable frequency, and variable voltage output has been constructed with prototyping wire wrap boards, and assembled in a card cage. The power supply is shown to meet the design specification

Innovative designs and applications of Janus micromotors with (photo)-catalytic and magnetic motion

El objetivo principal de esta Tesis Doctoral es el diseño y desarrollo de micromotores Janus biocompatibles y su aplicación en ámbitos relevantes de la salud y de la protección medioambiental. Los micromotores Janus son dispositivos en la microescala autopropulsados que tienen al menos dos regiones en su superficie con diferentes propiedades físicas y químicas, lo que les convierte en una clase distintiva de materiales que pueden combinar características ópticas, magnéticas y eléctricas en una sola entidad. Como la naturaleza del micromotor Janus -el dios romano de las dos caras- los objetivos de esta Tesis Doctoral presentan naturaleza dual y comprenden desarrollos de química fundamental y de química aplicada. En efecto, por una parte, el objetivo central aborda el diseño, síntesis y ensamblaje, así como la caracterización de micromotores Janus poliméricos propulsados por mecanismos (foto)-catalíticos y/o accionados por campos magnéticos. Por otra parte, el objetivo central implica la aplicación de los micromotores desarrollados para resolver desafíos sociales relevantes en los ámbitos químico-analítico, biomédico y ambiental. Partiendo de estas premisas, en la primera parte de la Tesis Doctoral, se sintetizaron micromotores Janus de policaprolactona propulsados químicamente integrando nanomateriales para el diseño de sensores móviles para la detección selectiva de endotoxinas bacterianas. De esta forma, el movimiento autónomo del micromotor mejora la mezcla de fluidos y la eficacia de las reacciones implicadas permitiendo detectar el analito en pocos minutos, incluso en muestras viscosas y medios donde la agitación no es posible. Además, esta autopropulsión es altamente compatible con su empleo en formatos ultra-miniaturizados para el desarrollo de futuros dispositivos portátiles en el marco de la tecnología point of care para aplicaciones clínicas y agroalimentarias. Con el fin de incrementar su biocompatibilidad para aplicaciones in vivo, en una segunda etapa de la Tesis Doctoral, se diseñaron micromotores Janus con propulsión autónoma utilizando luz visible para la eliminación de toxinas relevantes en procesos inflamatorios. El fenómeno autopropulsivo del micromotor y su capacidad de interacción con agentes tóxicos condujo a metodologías más rápidas y eficaces infiriéndose un futuro prometedor de estos micromotores para el tratamiento del shock séptico o intoxicación. En una tercera etapa, se sintetizaron micromotores propulsados por campos magnéticos. Estos micromotores utilizan una aproximación elegante de propulsión, exenta del empleo de combustibles químicos tóxicos como sucede en la propulsión catalítica y, en consecuencia, biocompatible. Asimismo, este mecanismo propulsivo permite controlar e incluso programar su trayectoria para aplicaciones que requieran de un guiado y de un control preciso de esta. De manera específica, estos micromotores han sido aplicados en esta Tesis Doctoral para la liberación controlada de fármacos en el tratamiento de cáncer pancreático y como elementos de remediación ambiental en la eliminación de agentes nerviosos en aguas contaminadas

Motility study of shaped active colloids: Bacteria and Janus Particles

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Design and Simulation of a MEMS Long Distance Traveling Micro-Actuator

This thesis is primarily concerned with the design, synthesis, modeling, and simulation of a linear micro-actuator that is able to travel relatively long distances upon the application of a bias voltage. The theoretical investigation addresses the functionality of this device in a certain setting given fixed and variable parameters. The objective of this investigation is to lay out a mathematical model, which explains the physics behind the workings of this device. It is not the objective of this investigation to study all the possible different scenarios that would result by changing certain or all the variable parameters, rather to prove that the concept of a traveling linear micro-actuator is sound. Furthermore, demonstrate that this device is functional to the specifications to which it was designed. The theoretical analysis was very critical in determining reasonable approximations for the parameters and dimensions of the device used to design the layout, and the process flow necessary for the fabrication process. The detailed explanation of each fabrication step is described in this thesis. The theoretical analysis shows that this linear micro-actuator, which has a relatively similar function to a parallel comb drive, can operate due to the electrostatic force generated upon the application of a bias voltage. This analysis, also, demonstrates that several other parameters have a direct effect on the performance of the device. Parameters, such as the thickness, the width, and the length of the electrodes are mathematically proven to change the magnitude of the electrostatic force responsible for the generation of the motion of the moving part of the micro-actuator. This device is comprised of two main components: a conductive fixed support, which works as a fixed electrode, and a moving electrode that would slide over this support and works as a shuttle. It is expected that the shuttle could be used in different applications as a transportation tool for other MEMS components or devices

Gnat Robots (And How They Will Change Robotics)

A new concept in mobile robots is proposed, namely that of a gnat-sized autonomous robot with on-board sensors, brains, actuators and power supplies, all fabricated on a single piece of silicon. Recent breakthroughs in computer architectures for intelligent robots, sensor integration algorithms and micromachining techniques for building on-chip micromotors, combined with the ever decreasing size of integrated logic, sensors and power circuitry have led to the possibility of a new generation of mobile robots which will vastly change the way we think about robotics. Forget about today's first generation robots: costly, bulky machines with parts acquired from many different vendors. What will appear will be cheap, mass produced, slimmed down, integrated robots that need no maintenance, no spare parts, and no special care. The cost advantages of these robots will create new worlds of applications. Gnat robots will offer a new approach in using automation technology. We will begin to think in terms of massive parallelism: using millions of simple, cheap, gnat robots in place of one large complicated robot. Furthermore, disposable robots will even become realistic. This paper outlines how to build gnat robots. It discusses the technology thrusts that will be required for developing such machines and sets forth some strategies for design. A close look is taken at the tradeoffs involved in choosing components of the system: locomotion options, power sources, types of sensors and architectures for intelligence.MIT Artificial Intelligence Laborator

Biohybrid robotics: From the nanoscale to the macroscale

Biohybrid robotics is a field in which biological entities are combined with artificial materials in order to obtain improved performance or features that are difficult to mimic with hand-made materials. Three main level of integration can be envisioned depending on the complexity of the biological entity, ranging from the nanoscale to the macroscale. At the nanoscale, enzymes that catalyze biocompatible reactions can be used as power sources for self-propelled nanoparticles of different geometries and compositions, obtaining rather interesting active matter systems that acquire importance in the biomedical field as drug delivery systems. At the microscale, single enzymes are substituted by complete cells, such as bacteria or spermatozoa, whose self-propelling capabilities can be used to transport cargo and can also be used as drug delivery systems, for in vitro fertilization practices or for biofilm removal. Finally, at the macroscale, the combinations of millions of cells forming tissues can be used to power biorobotic devices or bioactuators by using muscle cells. Both cardiac and skeletal muscle tissue have been part of remarkable examples of untethered biorobots that can crawl or swim due to the contractions of the tissue and current developments aim at the integration of several types of tissue to obtain more realistic biomimetic devices, which could lead to the next generation of hybrid robotics. Tethered bioactuators, however, result in excellent candidates for tissue models for drug screening purposes or the study of muscle myopathies due to their three-dimensional architecture

Natural Algae-Inspired Microrobots for Emerging Biomedical Applications and Beyond

Algae-inspired microrobots (AIMs) have attracted intense research over the past decade owing to the abundant desired properties of natural microalgae, such as biocompatibility, autofluorescence, and pharmaceutical activity, which make them ideal candidates for biomedical and related applications. With the deepening and widening of applied research, the functions of AIMs have been greatly enriched and enhanced to meet the needs of demanding application scenarios including targeted drug delivery, anticancer/antibacterial therapy, cell stimulation, wound healing, and biomolecule sensing. Notwithstanding, multiple challenges remain to be tackled for transformative advances and clinical translation. In this review, we aim to provide a comprehensive survey of representative advances in AIMs accompanied by the underlying biological/technological backgrounds. We also highlight existing issues that need to be overcome in AIM developments and suggest future research directions in this field.</p

Micro- and Nanomotors as Active Environmental Microcleaners and Sensors

© 2018 American Chemical Society. The quest to provide clean water to the entire population has led to a tremendous boost in the development of environmental nanotechnology. Toward this end, micro/nanomotors are emerging as attractive tools to improve the removal of various pollutants. The micro/nanomotors either are designed with functional materials in their structure or are modified to target pollutants. The active motion of these motors improves the mixing and mass transfer, greatly enhancing the rate of various remediation processes. Their motion can also be used as an indicator of the presence of a pollutant for sensing purposes. In this Perspective, we discuss different chemical aspects of micromotors mediated environmental cleanup and sensing strategies along with their scalability, reuse, and cost associated challenges

Swimming using surface acoustic waves

Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel