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Micromachines, Volume 6, Issue 4 (April 2015) , Pages 409-543

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Open AccessArticle Extended Kalman Filter for Real Time Indoor Localization by Fusing WiFi and Smartphone Inertial Sensors
Micromachines 2015, 6(4), 523-543; https://doi.org/10.3390/mi6040523
Received: 12 March 2015 / Revised: 11 April 2015 / Accepted: 20 April 2015 / Published: 22 April 2015
Cited by 37 | Viewed by 3406 | PDF Full-text (1707 KB) | HTML Full-text | XML Full-text
Abstract
Indoor localization systems using WiFi received signal strength (RSS) or pedestrian dead reckoning (PDR) both have their limitations, such as the RSS fluctuation and the accumulative error of PDR. To exploit their complementary strengths, most existing approaches fuse both systems by a particle [...] Read more.
Indoor localization systems using WiFi received signal strength (RSS) or pedestrian dead reckoning (PDR) both have their limitations, such as the RSS fluctuation and the accumulative error of PDR. To exploit their complementary strengths, most existing approaches fuse both systems by a particle filter. However, the particle filter is unsuitable for real time localization on resource-limited smartphones, since it is rather time-consuming and computationally expensive. On the other hand, the light computation fusion approaches including Kalman filter and its variants are inapplicable, since an explicit RSS-location measurement equation and the related noise statistics are unavailable. This paper proposes a novel data fusion framework by using an extended Kalman filter (EKF) to integrate WiFi localization with PDR. To make EKF applicable, we develop a measurement model based on kernel density estimation, which enables accurate WiFi localization and adaptive measurement noise statistics estimation. For the PDR system, we design another EKF based on quaternions for heading estimation by fusing gyroscopes and accelerometers. Experimental results show that the proposed EKF based data fusion approach achieves significant localization accuracy improvement over using WiFi localization or PDR systems alone. Compared with a particle filter, the proposed approach achieves comparable localization accuracy, while it incurs much less computational complexity. Full article
(This article belongs to the Special Issue Next Generation MEMS-Based Navigation—Systems and Applications)
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Open AccessArticle Invariant Observer-Based State Estimation for Micro-Aerial Vehicles in GPS-Denied Indoor Environments Using an RGB-D Camera and MEMS Inertial Sensors
Micromachines 2015, 6(4), 487-522; https://doi.org/10.3390/mi6040487
Received: 27 December 2014 / Revised: 11 April 2015 / Accepted: 17 April 2015 / Published: 22 April 2015
Cited by 5 | Viewed by 3104 | PDF Full-text (2589 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a non-linear state observer-based integrated navigation scheme for estimating the attitude, position and velocity of micro aerial vehicles (MAV) operating in GPS-denied indoor environments, using the measurements from low-cost MEMS (micro electro-mechanical systems) inertial sensors and an RGB-D camera. A [...] Read more.
This paper presents a non-linear state observer-based integrated navigation scheme for estimating the attitude, position and velocity of micro aerial vehicles (MAV) operating in GPS-denied indoor environments, using the measurements from low-cost MEMS (micro electro-mechanical systems) inertial sensors and an RGB-D camera. A robust RGB-D visual odometry (VO) approach was developed to estimate the MAV’s relative motion by extracting and matching features captured by the RGB-D camera from the environment. The state observer of the RGB-D visual-aided inertial navigation was then designed based on the invariant observer theory for systems possessing symmetries. The motion estimates from the RGB-D VO were fused with inertial and magnetic measurements from the onboard MEMS sensors via the state observer, providing the MAV with accurate estimates of its full six degree-of-freedom states. Implementations on a quadrotor MAV and indoor flight test results demonstrate that the resulting state observer is effective in estimating the MAV’s states without relying on external navigation aids such as GPS. The properties of computational efficiency and simplicity in gain tuning make the proposed invariant observer-based navigation scheme appealing for actual MAV applications in indoor environments. Full article
(This article belongs to the Special Issue Next Generation MEMS-Based Navigation—Systems and Applications)
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Open AccessArticle Low Flow Liquid Calibration Setup
Micromachines 2015, 6(4), 473-486; https://doi.org/10.3390/mi6040473
Received: 27 February 2015 / Revised: 16 April 2015 / Accepted: 17 April 2015 / Published: 22 April 2015
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Abstract
This article describes a primary calibration setup, and its uncertainty, for low flow liquid calibrations at Bronkhorst High-Tech. It will be used to calibrate reference flow meters from 1 to 200 g/h. By setting up an uncertainty budget for this setup, the calibration [...] Read more.
This article describes a primary calibration setup, and its uncertainty, for low flow liquid calibrations at Bronkhorst High-Tech. It will be used to calibrate reference flow meters from 1 to 200 g/h. By setting up an uncertainty budget for this setup, the calibration of the instruments can be compared to that of NMI’s (National Metrology Institutes). The uncertainty budget consists of mass, time and mass flow uncertainties/corrections that need to be taken in to account for determining the traceable mass flow. Tests results of different flow meters/actuators measured on the setup support the calculated uncertainty. By participating in an intercomparison with NMI’s the measurement and uncertainty of this setup is traceable to European NMI’s. Full article
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Open AccessCommunication A Fast Colourimetric Assay for Lead Detection Using Label-Free Gold Nanoparticles (AuNPs)
Micromachines 2015, 6(4), 462-472; https://doi.org/10.3390/mi6040462
Received: 31 December 2014 / Revised: 27 March 2015 / Accepted: 15 April 2015 / Published: 22 April 2015
Cited by 8 | Viewed by 2552 | PDF Full-text (1696 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A sensitive colourimetric method for lead (PbII) detection is reported in this paper using a common tripeptide, glutathione (GSH), and label-free gold nanoparticles (AuNPs). A limit of detection of 6.0 ppb in water was achieved and the dynamic linear range was [...] Read more.
A sensitive colourimetric method for lead (PbII) detection is reported in this paper using a common tripeptide, glutathione (GSH), and label-free gold nanoparticles (AuNPs). A limit of detection of 6.0 ppb in water was achieved and the dynamic linear range was up to 500 ppb. Selectivity over fourteen potential interfering metal ions was tested and most of these metal ions do not interfere with the method. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Open AccessArticle Multi Parameter Flow Meter for On-Line Measurement of Gas Mixture Composition
Micromachines 2015, 6(4), 452-461; https://doi.org/10.3390/mi6040452
Received: 2 March 2015 / Revised: 25 March 2015 / Accepted: 31 March 2015 / Published: 10 April 2015
Cited by 2 | Viewed by 2615 | PDF Full-text (2897 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we describe the development of a system and model to analyze the composition of gas mixtures up to four components. The system consists of a Coriolis mass flow sensor, density, pressure and thermal flow sensor. With this system it is [...] Read more.
In this paper we describe the development of a system and model to analyze the composition of gas mixtures up to four components. The system consists of a Coriolis mass flow sensor, density, pressure and thermal flow sensor. With this system it is possible to measure the viscosity, density, heat capacity and flow rate of the medium. In a next step the composition can be analyzed if the constituents of the mixture are known. This makes the approach universally applicable to all gasses as long as the number of components does not exceed the number of measured properties and as long as the properties are measured with a sufficient accuracy. We present measurements with binary and ternary gas mixtures, on compositions that range over an order of magnitude in value for the physical properties. Two platforms for analyses are presented. The first platform consists of sensors realized with MEMS fabrication technology. This approach allows for a system with a high level of integration. With this system we demonstrate a proof of principle for the analyses of binary mixtures with an accuracy of 10%. In the second platform we utilize more mature steel sensor technology to demonstrate the potential of this approach. We show that with this technique, binary mixtures can be measured within 1% and ternary gas mixtures within 3%. Full article
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Open AccessArticle 3D Printed Unibody Lab-on-a-Chip: Features Survey and Check-Valves Integration
Micromachines 2015, 6(4), 437-451; https://doi.org/10.3390/mi6040437
Received: 6 February 2015 / Revised: 31 March 2015 / Accepted: 2 April 2015 / Published: 7 April 2015
Cited by 29 | Viewed by 3475 | PDF Full-text (5300 KB) | HTML Full-text | XML Full-text
Abstract
The unibody lab-on-a-chip (ULOC) concept entails a fast and affordable micro-prototyping system built around a single monolithic 3D printed element (unibody). A consumer-grade stereo lithography (SL) 3D printer can configure ULOCs with different forms of sample delivery, transport, handling and readout, while minimizing [...] Read more.
The unibody lab-on-a-chip (ULOC) concept entails a fast and affordable micro-prototyping system built around a single monolithic 3D printed element (unibody). A consumer-grade stereo lithography (SL) 3D printer can configure ULOCs with different forms of sample delivery, transport, handling and readout, while minimizing material costs and fabrication time. ULOC centralizes all complex fabrication procedures and replaces the need for clean room resources, delivering prototypes for less than 1 US$, which can be printed in 10 min and ready for testing in less than 30 min. Recent examples of ULOC integration of transport, chemical sensing for optical readout and flow mixing capabilities are discussed, as well as the integration of the first check-valves for ULOC devices. ULOC valves are strictly unidirectional up to 100 psi, show an exponential forward flow behavior up to 70 psi and can be entirely fabricated with the ULOC approach. Full article
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Open AccessArticle A Disposable Dispensing Valve for Non-Contact Microliter Applications in a 96-Well Plate Format
Micromachines 2015, 6(4), 423-436; https://doi.org/10.3390/mi6040423
Received: 27 February 2015 / Revised: 30 March 2015 / Accepted: 30 March 2015 / Published: 3 April 2015
Cited by 4 | Viewed by 4234 | PDF Full-text (1684 KB) | HTML Full-text | XML Full-text
Abstract
We present a miniaturized, disposable, normally-closed electromagnetic dispensing valve for the microliter range to process 96-well plates. The novel injection-molded valve is designed to fit into a 9 mm grid to realize an eight channel dispensing head, enabling the serial processing of well [...] Read more.
We present a miniaturized, disposable, normally-closed electromagnetic dispensing valve for the microliter range to process 96-well plates. The novel injection-molded valve is designed to fit into a 9 mm grid to realize an eight channel dispensing head, enabling the serial processing of well plates row-by-row. The presented dispensing valve design originates from a miniaturization study of a previously developed functional model. The outer diameter of the valve, including all actuating components, was reduced by 8 mm to an overall diameter of 8.5 mm without compromising the performance. Additionally, the actuation current of the valve could be reduced to 5 A. The valve is characterized for a volume range between 840 nL and 5.3 μL. The performance of the injection molded valve is competitive to commercially available dispensing valves, featuring the advantages of low fabrication costs, disposability, low mounting size, easy handling, and super silent actuation. Full article
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Open AccessArticle Uniform Cell Distribution Achieved by Using Cell Deformation in a Micropillar Array
Micromachines 2015, 6(4), 409-422; https://doi.org/10.3390/mi6040409
Received: 18 February 2015 / Revised: 10 March 2015 / Accepted: 10 March 2015 / Published: 1 April 2015
Cited by 3 | Viewed by 2210 | PDF Full-text (3466 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The uniform dispersion of cells in a microchamber is important to reproduce results in cellular research. However, achieving this is difficult owing to the laminar flow caused by the small dimensions of such a chamber. In this study, we propose a technique to [...] Read more.
The uniform dispersion of cells in a microchamber is important to reproduce results in cellular research. However, achieving this is difficult owing to the laminar flow caused by the small dimensions of such a chamber. In this study, we propose a technique to achieve a uniform distribution of cells using a micropillar array inside a microchamber. The cells deform when they pass through a gap between the micropillars. The deformation causes a repetitive clog-and-release process of cells at the gaps between the micropillars. The micropillar array generates random flow inside the microchamber, resulting in the uniform distribution of the cells via cell accumulation. In the experiment, the distribution of cells in the microchamber with the micropillar array is uniform from end to end, whereas that in the microchamber without the micropillar array is centered. The deviation of the cell distribution from the ideally uniform distribution in the microchamber with the micropillar array is suppressed by 63% compared with that in the microchamber without the micropillar array. The doubling time of the cells passed through the micropillar array did not change relative to that of normal N87 cells. This technique will be helpful for reproducing results in cellular research at the micro scale or for those using microfluidic devices. Full article
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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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