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Micromachines, Volume 6, Issue 8 (August 2015) , Pages 969-1212

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Open AccessArticle Micro-Machined Flow Sensors Mimicking Lateral Line Canal Neuromasts
Micromachines 2015, 6(8), 1189-1212; https://doi.org/10.3390/mi6081189
Received: 4 May 2015 / Accepted: 18 August 2015 / Published: 24 August 2015
Cited by 13 | Viewed by 2379 | PDF Full-text (808 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Fish sense water motions with their lateral line. The lateral line is a sensory system that contains up to several thousand mechanoreceptors, called neuromasts. Neuromasts occur freestanding on the skin and in subepidermal canals. We developed arrays of flow sensors based on lateral [...] Read more.
Fish sense water motions with their lateral line. The lateral line is a sensory system that contains up to several thousand mechanoreceptors, called neuromasts. Neuromasts occur freestanding on the skin and in subepidermal canals. We developed arrays of flow sensors based on lateral line canal neuromasts using a biomimetic approach. Each flow sensor was equipped with a PDMS (polydimethylsiloxane) lamella integrated into a canal system by means of thick- and thin-film technology. Our artificial lateral line system can estimate bulk flow velocity from the spatio-temporal propagation of flow fluctuations. Based on the modular sensor design, we were able to detect flow rates in an industrial application of tap water flow metering. Our sensory system withstood water pressures of up to six bar. We used finite element modeling to study the fluid flow inside the canal system and how this flow depends on canal dimensions. In a second set of experiments, we separated the flow sensors from the main stream by means of a flexible membrane. Nevertheless, these biomimetic neuromasts were still able to sense flow fluctuations. Fluid separation is a prerequisite for flow measurements in medical and pharmaceutical applications. Full article
(This article belongs to the Special Issue Biomimetic Systems)
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Open AccessArticle Centrifugal Step Emulsification can Produce Water in Oil Emulsions with Extremely High Internal Volume Fractions
Micromachines 2015, 6(8), 1180-1188; https://doi.org/10.3390/mi6081180
Received: 22 July 2015 / Revised: 11 August 2015 / Accepted: 17 August 2015 / Published: 20 August 2015
Cited by 7 | Viewed by 2608 | PDF Full-text (4955 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The high throughput preparation of emulsions with high internal volume fractions is important for many different applications, e.g., drug delivery. However, most emulsification techniques reach only low internal volume fractions and need stable flow rates that are often difficult to control. Here, we [...] Read more.
The high throughput preparation of emulsions with high internal volume fractions is important for many different applications, e.g., drug delivery. However, most emulsification techniques reach only low internal volume fractions and need stable flow rates that are often difficult to control. Here, we present a centrifugal high throughput step emulsification disk for the fast and easy production of emulsions with high internal volume fractions above 95%. The disk produces droplets at generation rates of up to 3700 droplets/s and, for the first time, enables the generation of emulsions with internal volume fractions of >97%. The coefficient of variation between droplet sizes is very good (4%). We apply our system to show the in situ generation of gel emulsion. In the future, the recently introduced unit operation of centrifugal step emulsification may be used for the high throughput production of droplets as reaction compartments for clinical diagnostics or as starting material for micromaterial synthesis. Full article
(This article belongs to the Special Issue Droplet Microfluidics: Techniques and Technologies)
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Open AccessArticle Comparative Analysis of Passive Micromixers at a Wide Range of Reynolds Numbers
Micromachines 2015, 6(8), 1166-1179; https://doi.org/10.3390/mi6081166
Received: 30 June 2015 / Revised: 5 August 2015 / Accepted: 5 August 2015 / Published: 18 August 2015
Cited by 6 | Viewed by 1998 | PDF Full-text (14243 KB) | HTML Full-text | XML Full-text
Abstract
Two novel passive micromixers, denoted as the Y-Y mixer and the H-C mixer, based on split-and-recombine (SAR) principle are studied both experimentally and numerically over Reynolds numbers ranging from 1 to 100. An image analysis technique was used to evaluate mixture homogeneity at [...] Read more.
Two novel passive micromixers, denoted as the Y-Y mixer and the H-C mixer, based on split-and-recombine (SAR) principle are studied both experimentally and numerically over Reynolds numbers ranging from 1 to 100. An image analysis technique was used to evaluate mixture homogeneity at four target areas. Numerical simulations were found to be a useful support for the design phase, since a general idea of mixing of fluids can be inferred from the segregation or the distribution of path lines. Comparison with a well-known mixer, the Tear-drop one, was also performed. Over the examined range of Reynolds numbers 1 ≤ Re ≤ 100, the Y-Y and H-C mixers showed at their exit an almost flat mixing index characteristic, with a mixing efficiency higher than 90%; conversely the Tear-drop mixer showed a relevant decrease of efficiency at mid-range. Furthermore, the Y-Y and the H-C showed significantly less pressure drop than the Tear-drop mixer. Full article
(This article belongs to the Special Issue Micromixer & Micromixing)
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Open AccessArticle Tunable Focus Liquid Lens with Radial-Patterned Electrode
Micromachines 2015, 6(8), 1157-1165; https://doi.org/10.3390/mi6081157
Received: 3 July 2015 / Revised: 11 August 2015 / Accepted: 11 August 2015 / Published: 17 August 2015
Cited by 8 | Viewed by 1853 | PDF Full-text (5491 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A dielectric liquid lens is prepared based on our previous work. By optimizing the device structure, the liquid lens presents a converging focus with good resolution and changes its focal length over a broad range with a low driving voltage. For a liquid [...] Read more.
A dielectric liquid lens is prepared based on our previous work. By optimizing the device structure, the liquid lens presents a converging focus with good resolution and changes its focal length over a broad range with a low driving voltage. For a liquid lens with ~2.3 mm diameter in the relaxed state, it can resolve ~40 lp/mm. The resolution does not degrade during focus change. Its focal length can be varied from ~12 to ~5 mm when the applied voltage is changed from 0 to 28 Vrms. The response time of one cycle is ~2.5 s. Our liquid lens, with a low driving voltage for a large dynamic range, has potential applications in imaging, biometrics, optoelectronic, and lab-on-chip devices. Full article
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Open AccessArticle Insect-Inspired Micropump: Flow in a Tube with Local Contractions
Micromachines 2015, 6(8), 1143-1156; https://doi.org/10.3390/mi6081143
Received: 20 April 2015 / Revised: 26 July 2015 / Accepted: 6 August 2015 / Published: 14 August 2015
Cited by 5 | Viewed by 1958 | PDF Full-text (1590 KB) | HTML Full-text | XML Full-text
Abstract
A biologically-inspired micropumping model in a three-dimensional tube subjected to localized wall constrictions is given in this article. The present study extends our previous pumping model where a 3D channel with a square cross-section is considered. The proposed pumping approach herein applies to [...] Read more.
A biologically-inspired micropumping model in a three-dimensional tube subjected to localized wall constrictions is given in this article. The present study extends our previous pumping model where a 3D channel with a square cross-section is considered. The proposed pumping approach herein applies to tubular geometries and is given to mimic an insect respiration mode, where the tracheal tube rhythmic wall contractions are used/hypothesized to enhance the internal flow transport within the entire respiration network. The method of regularized Stokeslets-mesh-free computations is used to reconstruct the flow motions induced by the wall movements and to calculate the time-averaged net flow rate. The time-averaged net flow rates from both the tube and channel models are compared. Results have shown that an inelastic tube with at least two contractions forced to move with a specific time lag protocol can work as a micropump. The system is simple and expected to be useful in many biomedical applications. Full article
(This article belongs to the Special Issue Biomimetic Systems)
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Open AccessArticle Multiple Silicon Nanowires with Enzymatic Modification for Measuring Glucose Concentration
Micromachines 2015, 6(8), 1135-1142; https://doi.org/10.3390/mi6081135
Received: 10 July 2015 / Revised: 3 August 2015 / Accepted: 6 August 2015 / Published: 14 August 2015
Cited by 3 | Viewed by 1602 | PDF Full-text (3077 KB) | HTML Full-text | XML Full-text
Abstract
This study fabricated a multiple poly-Si nanowires sensor through a top-down method and immobilized glucose oxidase on the multiple nanowires for determining glucose concentration. The proposed sensor is 340 nm in width and uses five physically identical and parallel nanowires. The sensor contained [...] Read more.
This study fabricated a multiple poly-Si nanowires sensor through a top-down method and immobilized glucose oxidase on the multiple nanowires for determining glucose concentration. The proposed sensor is 340 nm in width and uses five physically identical and parallel nanowires. The sensor contained nanowires of various lengths (3, 5, and 10 μm). Experimental results showed that sensor sensitivity is inversely proportional to nanowire length. The sensor with 3 μm in nanowire length exhibited a theoretical resolution of 0.003 mg/dL and the highest sensitivity of 0.03 μA/(mg/dL). Furthermore, the proposed sensor retains this performance when reused for up to 10 applications. Full article
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Open AccessArticle Activity Recognition Using Fusion of Low-Cost Sensors on a Smartphone for Mobile Navigation Application
Micromachines 2015, 6(8), 1100-1134; https://doi.org/10.3390/mi6081100
Received: 1 June 2015 / Revised: 23 July 2015 / Accepted: 28 July 2015 / Published: 14 August 2015
Cited by 14 | Viewed by 2677 | PDF Full-text (25362 KB) | HTML Full-text | XML Full-text
Abstract
Low-cost inertial and motion sensors embedded on smartphones have provided a new platform for dynamic activity pattern inference. In this research, a comparison has been conducted on different sensor data, feature spaces and feature selection methods to increase the efficiency and reduce the [...] Read more.
Low-cost inertial and motion sensors embedded on smartphones have provided a new platform for dynamic activity pattern inference. In this research, a comparison has been conducted on different sensor data, feature spaces and feature selection methods to increase the efficiency and reduce the computation cost of activity recognition on the smartphones. We evaluated a variety of feature spaces and a number of classification algorithms from the area of Machine Learning, including Naive Bayes, Decision Trees, Artificial Neural Networks and Support Vector Machine classifiers. A smartphone app that performs activity recognition is being developed to collect data and send them to a server for activity recognition. Using extensive experiments, the performance of various feature spaces has been evaluated. The results showed that the Bayesian Network classifier yields recognition accuracy of 96.21% using four features while requiring fewer computations. Full article
(This article belongs to the Special Issue Next Generation MEMS-Based Navigation—Systems and Applications)
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Open AccessArticle Quantitative Analysis to the Impacts of IMU Quality in GPS/INS Deep Integration
Micromachines 2015, 6(8), 1082-1099; https://doi.org/10.3390/mi6081082
Received: 13 July 2015 / Revised: 5 August 2015 / Accepted: 6 August 2015 / Published: 11 August 2015
Cited by 11 | Viewed by 1675 | PDF Full-text (937 KB) | HTML Full-text | XML Full-text
Abstract
In the Global Positioning System (GPS)/Inertial Navigation System (INS) deep integration system, the pure negative effect of the INS aiding is mainly the INS navigation error that is independent with the motion dynamics, which determine whether the INS aiding is worthy. This paper [...] Read more.
In the Global Positioning System (GPS)/Inertial Navigation System (INS) deep integration system, the pure negative effect of the INS aiding is mainly the INS navigation error that is independent with the motion dynamics, which determine whether the INS aiding is worthy. This paper quantitatively assesses the negative effects of the inertial aiding information from different grades of INS by modeling the phase-locked loops (PLLs) based on the scalar-based GPS/INS deep integration system under stationary conditions. Results show that the largest maneuver-independent velocity error caused by the error sources of micro-electro-mechanical System (MEMS) inertial measurement unit (IMU) is less than 0.1 m/s, and less than 0.05 m/s for the case of tactical IMU during the typical GPS update interval (i.e., 1 s). The consequent carrier phase tracking error in the typical tracking loop is below 1.2 degrees for MEMS IMU case and 0.8 degrees for the tactical IMU case, which are much less than the receiver inherent errors. Conclusions can be reached that even the low-end MEMS IMU has the ability of aiding the receiver signal tracking. The tactical grade IMU can provide higher quality aiding information and has potential for the open loop tracking of GPS. Full article
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Open AccessArticle Non-Linear Piezoelectric Actuator with a Preloaded Cantilever Beam
Micromachines 2015, 6(8), 1066-1081; https://doi.org/10.3390/mi6081066
Received: 27 May 2015 / Revised: 30 July 2015 / Accepted: 4 August 2015 / Published: 11 August 2015
Cited by 4 | Viewed by 2165 | PDF Full-text (5045 KB) | HTML Full-text | XML Full-text
Abstract
Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with [...] Read more.
Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used to increase the output displacement at a lower voltage. The system is analytically modeled with Lagrangian functional and Euler–Lagrange equations, numerically simulated with MATLAB, and experimentally realized to demonstrate its enhanced capabilities. The model is validated using an experimental device with several pretensions of the loading spring, therein representing three interesting cases: a linear system, a low natural frequency system with a pre-buckled beam, and a system with a buckled beam. The motivating hypothesis for the current work is that nonlinear phenomena could be exploited to improve the effectiveness of the piezoelectric actuator’s displacement output. The most practical configuration seems to be the pre-buckled case, in which the proposed system has a low natural frequency, a high tip displacement, and a stable balanced position. Full article
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Open AccessReview Nanoelectromechanical Switches for Low-Power Digital Computing
Micromachines 2015, 6(8), 1046-1065; https://doi.org/10.3390/mi6081046
Received: 1 July 2015 / Revised: 1 July 2015 / Accepted: 4 August 2015 / Published: 10 August 2015
Cited by 31 | Viewed by 3140 | PDF Full-text (2173 KB) | HTML Full-text | XML Full-text
Abstract
The need for more energy-efficient solid-state switches beyond complementary metal-oxide-semiconductor (CMOS) transistors has become a major concern as the power consumption of electronic integrated circuits (ICs) steadily increases with technology scaling. Nano-Electro-Mechanical (NEM) relays control current flow by nanometer-scale motion to make or [...] Read more.
The need for more energy-efficient solid-state switches beyond complementary metal-oxide-semiconductor (CMOS) transistors has become a major concern as the power consumption of electronic integrated circuits (ICs) steadily increases with technology scaling. Nano-Electro-Mechanical (NEM) relays control current flow by nanometer-scale motion to make or break physical contact between electrodes, and offer advantages over transistors for low-power digital logic applications: virtually zero leakage current for negligible static power consumption; the ability to operate with very small voltage signals for low dynamic power consumption; and robustness against harsh environments such as extreme temperatures. Therefore, NEM logic switches (relays) have been investigated by several research groups during the past decade. Circuit simulations calibrated to experimental data indicate that scaled relay technology can overcome the energy-efficiency limit of CMOS technology. This paper reviews recent progress toward this goal, providing an overview of the different relay designs and experimental results achieved by various research groups, as well as of relay-based IC design principles. Remaining challenges for realizing the promise of nano-mechanical computing, and ongoing efforts to address these, are discussed. Full article
(This article belongs to the Special Issue CMOS-MEMS Sensors and Devices)
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Open AccessReview Tunnel Junction with Perpendicular Magnetic Anisotropy: Status and Challenges
Micromachines 2015, 6(8), 1023-1045; https://doi.org/10.3390/mi6081023
Received: 29 June 2015 / Revised: 29 June 2015 / Accepted: 4 August 2015 / Published: 10 August 2015
Cited by 17 | Viewed by 3121 | PDF Full-text (5008 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic tunnel junction (MTJ), which arises from emerging spintronics, has the potential to become the basic component of novel memory, logic circuits, and other applications. Particularly since the first demonstration of current induced magnetization switching in MTJ, spin transfer torque magnetic random access [...] Read more.
Magnetic tunnel junction (MTJ), which arises from emerging spintronics, has the potential to become the basic component of novel memory, logic circuits, and other applications. Particularly since the first demonstration of current induced magnetization switching in MTJ, spin transfer torque magnetic random access memory (STT-MRAM) has sparked a huge interest thanks to its non-volatility, fast access speed, and infinite endurance. However, along with the advanced nodes scaling, MTJ with in-plane magnetic anisotropy suffers from modest thermal stability, high power consumption, and manufactural challenges. To address these concerns, focus of research has converted to the preferable perpendicular magnetic anisotropy (PMA) based MTJ, whereas a number of conditions still have to be met before its practical application. This paper overviews the principles of PMA and STT, where relevant issues are preliminarily discussed. Centering on the interfacial PMA in CoFeB/MgO system, we present the fundamentals and latest progress in the engineering, material, and structural points of view. The last part illustrates potential investigations and applications with regard to MTJ with interfacial PMA. Full article
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Open AccessArticle Biomimetic-Based Output Feedback for Attitude Stabilization of Rigid Bodies: Real-Time Experimentation on a Quadrotor
Micromachines 2015, 6(8), 993-1022; https://doi.org/10.3390/mi6080993
Received: 1 June 2015 / Revised: 15 July 2015 / Accepted: 21 July 2015 / Published: 5 August 2015
Viewed by 2077 | PDF Full-text (6897 KB) | HTML Full-text | XML Full-text
Abstract
The present paper deals with the development of bounded feedback control laws mimicking the strategy adopted by flapping flyers to stabilize the attitude of systems falling within the framework of rigid bodies. Flapping flyers are able to orient their trajectory without any knowledge [...] Read more.
The present paper deals with the development of bounded feedback control laws mimicking the strategy adopted by flapping flyers to stabilize the attitude of systems falling within the framework of rigid bodies. Flapping flyers are able to orient their trajectory without any knowledge of their current attitude and without any attitude computation. They rely on the measurements of some sensitive organs: halteres, leg sensilla and magnetic sense, which give information about their angular velocity and the orientation of gravity and magnetic field vectors. Therefore, the proposed feedback laws are computed using direct inertial sensors measurements, that is vector observations with/without angular velocity measurements. Hence, the attitude is not explicitly required. This biomimetic approach is very simple, requires little computational power and is suitable for embedded applications on small control units. The boundedness of the control signal is taken into consideration through the design of the control laws by saturation of the actuators’ input. The asymptotic stability of the closed loop system is proven by Lyapunov analysis. Real-time experiments are carried out on a quadrotor using MEMS inertial sensors in order to emphasize the efficiency of this biomimetic strategy by showing the convergence of the body’s states in hovering mode, as well as the robustness with respect to external disturbances. Full article
(This article belongs to the Special Issue Next Generation MEMS-Based Navigation—Systems and Applications)
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Open AccessArticle An Electromagnetic MEMS Energy Harvester Array with Multiple Vibration Modes
Micromachines 2015, 6(8), 984-992; https://doi.org/10.3390/mi6080984
Received: 10 May 2015 / Revised: 2 July 2015 / Accepted: 10 July 2015 / Published: 24 July 2015
Cited by 22 | Viewed by 2353 | PDF Full-text (3858 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports the design, micromachining and characterization of an array of electromagnetic energy harvesters (EHs) with multiple frequency peaks. The authors present the combination of three multi-modal spring-mass structures so as to realize at least nine resonant peaks within a single microelectromechanical [...] Read more.
This paper reports the design, micromachining and characterization of an array of electromagnetic energy harvesters (EHs) with multiple frequency peaks. The authors present the combination of three multi-modal spring-mass structures so as to realize at least nine resonant peaks within a single microelectromechanical systems (MEMS) chip. It is assembled with permanent magnet to show an electromagnetic-based energy harvesting capability. This is the first demonstration of multi-frequency MEMS EH existing with more than three resonant peaks within a limited frequency range of 189 to 662 Hz. It provides a more effective approach to harvest energy from the vibration sources of multiple frequency peaks. Full article
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Open AccessArticle Experimental and Numerical Simulation Research on Micro-Gears Fabrication by Laser Shock Punching Process
Micromachines 2015, 6(8), 969-983; https://doi.org/10.3390/mi6080969
Received: 11 June 2015 / Revised: 10 July 2015 / Accepted: 14 July 2015 / Published: 23 July 2015
Cited by 9 | Viewed by 2192 | PDF Full-text (6839 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this paper is to fabricate micro-gears via laser shock punching with Spitlight 2000 Nd-YAG Laser, and to discuss effects of process parameters namely laser energy, soft punch properties and blank-holder on the quality of micro-gears deeply. Results show that dimensional [...] Read more.
The aim of this paper is to fabricate micro-gears via laser shock punching with Spitlight 2000 Nd-YAG Laser, and to discuss effects of process parameters namely laser energy, soft punch properties and blank-holder on the quality of micro-gears deeply. Results show that dimensional accuracy is the best shocked at 1690 mJ. Tensile fracture instead of shear fracture is the main fracture mode under low laser energy. The soft punch might cause damage to punching quality when too high energy is employed. Appropriate thickness and hardness of soft punch is necessary. Silica gel with 200 µm in thickness is beneficial to not only homogenize energy but also propagate the shock wave. Polyurethane films need more energy than silica gel with the same thickness. In addition, blank-holders with different weight levels are used. A heavier blank-holder is more beneficial to improve the cutting quality. Furthermore, the simulation is conducted to reveal typical stages and the different deformation behavior under high and low pulse energy. The simulation results show that the fracture mode changes under lower energy. Full article
(This article belongs to the collection Laser Micromachining and Microfabrication)
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Micromachines EISSN 2072-666X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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