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Micromachines, Volume 6, Issue 3 (March 2015) , Pages 291-408

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Open AccessArticle A Novel Transdermal Power Transfer Device for the Application of Implantable Microsystems
Micromachines 2015, 6(3), 396-408; https://doi.org/10.3390/mi6030396
Received: 25 December 2014 / Revised: 4 March 2015 / Accepted: 18 March 2015 / Published: 23 March 2015
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Abstract
This paper presents a transdermal power transfer device for the application of implantable devices or systems. The device mainly consists of plug and socket. The power transfer process can be started after inserting the plug into the socket with an applied potential on [...] Read more.
This paper presents a transdermal power transfer device for the application of implantable devices or systems. The device mainly consists of plug and socket. The power transfer process can be started after inserting the plug into the socket with an applied potential on the plug. In order to improve the maneuverability and reliability of device during power transfer process, the metal net with mesh structure were added as a part of the socket to serve as intermediate electrical connection layer. The socket was encapsulated by polydimethylsiloxane (PDMS) with good biocompatibility and flexibility. Two stainless steel hollow needles placed in the same plane acted as the insertion part of the needle plug, and Parylene C thin films were deposited on needles to serve as insulation layers. At last, the properties of the transdermal power transfer device were tested. The average contact resistance between needle and metal mesh was 0.454 Ω after 50 random insertions, which showed good electrical connection. After NiMH (nickel-metal hydride) batteries were recharged for 10 min with current up to 200 mA, the caused resistive heat was less than 0.6 °C, which also demonstrated the low charging temperature and was suitable for charging implantable devices. Full article
(This article belongs to the Special Issue Power MEMS)
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Open AccessArticle A Compact W-Band Reflection-Type Phase Shifter with Extremely Low Insertion Loss Variation Using 0.13 µm CMOS Technology
Micromachines 2015, 6(3), 390-395; https://doi.org/10.3390/mi6030390
Received: 2 February 2015 / Revised: 23 February 2015 / Accepted: 24 February 2015 / Published: 23 March 2015
Cited by 1 | Viewed by 1871 | PDF Full-text (351 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a reflection-type phase shifter (RTPS) at W-band in a 0.13 µm complementary metal oxide semiconductor (CMOS) process. The RTPS is composed of a 90° hybrid coupler and two identical reflection loads. Lumped-distributed element transmission line is introduced in the 90° [...] Read more.
This paper presents a reflection-type phase shifter (RTPS) at W-band in a 0.13 µm complementary metal oxide semiconductor (CMOS) process. The RTPS is composed of a 90° hybrid coupler and two identical reflection loads. Lumped-distributed element transmission line is introduced in the 90° hybrid coupler to reduce the chip size. Series inductor-capacitor (LC) resonators are used as the reflective loads and parallel inductors are deployed to reduce insertion loss variation. By cascading two-stage RTPS, 90° phase shifting range and 10.5 dB insertion loss with 1 dB variations from 80 GHz to 90 GHz are achieved. An impressive 0.1 dB variation is obtained at 86 GHz. Full article
(This article belongs to the Special Issue Advances in MMICs)
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Open AccessArticle Design of a Weighted-Rotor Energy Harvester Based on Dynamic Analysis and Optimization of Circular Halbach Array Magnetic Disk
Micromachines 2015, 6(3), 375-389; https://doi.org/10.3390/mi6030375
Received: 26 December 2014 / Revised: 15 March 2015 / Accepted: 18 March 2015 / Published: 23 March 2015
Cited by 4 | Viewed by 2982 | PDF Full-text (2625 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes the design of a weighted-rotor energy harvester (WREH) in which the oscillation is caused by the periodic change of the tangential component of gravity, to harvest kinetic energy from a rotating wheel. When a WREH is designed with a suitable [...] Read more.
This paper proposes the design of a weighted-rotor energy harvester (WREH) in which the oscillation is caused by the periodic change of the tangential component of gravity, to harvest kinetic energy from a rotating wheel. When a WREH is designed with a suitable characteristic length, the rotor’s natural frequency changes according to the wheel rotation speed and the rotor oscillates at a wide angle and high angular velocity to generate a large amount of power. The magnetic disk is designed according to an optimized circular Halbach array. The optimized circular Halbach array magnetic disk provides the largest induced EMF for different sector-angle ratios for the same magnetic disk volume. This study examined the output voltage and power by considering the constant and accelerating plate-rotation speeds, respectively. This paper discusses the effects of the angular acceleration speed of a rotating wheel corresponding to the dynamic behaviors of a weighted rotor. The average output power is 399 to 535 microwatts at plate-rotation speeds from 300 to 500 rpm, enabling the WREH to be a suitable power source for a tire-pressure monitoring system. Full article
(This article belongs to the Special Issue Power MEMS)
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Open AccessArticle Fast Prototyping of Sensorized Cell Culture Chips and Microfluidic Systems with Ultrashort Laser Pulses
Micromachines 2015, 6(3), 364-374; https://doi.org/10.3390/mi6030364
Received: 10 February 2015 / Revised: 11 March 2015 / Accepted: 12 March 2015 / Published: 23 March 2015
Cited by 6 | Viewed by 2203 | PDF Full-text (1762 KB) | HTML Full-text | XML Full-text
Abstract
We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO) plating or [...] Read more.
We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO) plating or were prepared from platinum sputtering (100 nm) onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip) by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS) molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB) milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems. Full article
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Open AccessArticle Smartphone-Based Indoor Integrated WiFi/MEMS Positioning Algorithm in a Multi-Floor Environment
Micromachines 2015, 6(3), 347-363; https://doi.org/10.3390/mi6030347
Received: 22 December 2014 / Revised: 18 February 2015 / Accepted: 24 February 2015 / Published: 3 March 2015
Cited by 25 | Viewed by 2975 | PDF Full-text (1729 KB) | HTML Full-text | XML Full-text
Abstract
Indoor positioning in a multi-floor environment by using a smartphone is considered in this paper. The positioning accuracy and robustness of WiFi fingerprinting-based positioning are limited due to the unexpected variation of WiFi measurements between floors. On this basis, we propose a novel [...] Read more.
Indoor positioning in a multi-floor environment by using a smartphone is considered in this paper. The positioning accuracy and robustness of WiFi fingerprinting-based positioning are limited due to the unexpected variation of WiFi measurements between floors. On this basis, we propose a novel smartphone-based integrated WiFi/MEMS positioning algorithm based on the robust extended Kalman filter (EKF). The proposed algorithm first relies on the gait detection approach and quaternion algorithm to estimate the velocity and heading angles of the target. Second, the velocity and heading angles, together with the results of WiFi fingerprinting-based positioning, are considered as the input of the robust EKF for the sake of conducting two-dimensional (2D) positioning. Third, the proposed algorithm calculates the height of the target by using the real-time recorded barometer and geographic data. Finally, the experimental results show that the proposed algorithm achieves the positioning accuracy with root mean square errors (RMSEs) less than 1 m in an actual multi-floor environment. Full article
(This article belongs to the Special Issue Next Generation MEMS-Based Navigation—Systems and Applications)
Open AccessArticle The Effect of Biomolecular Gradients on Mesenchymal Stem Cell Chondrogenesis under Shear Stress
Micromachines 2015, 6(3), 330-346; https://doi.org/10.3390/mi6030330
Received: 2 December 2014 / Revised: 24 February 2015 / Accepted: 25 February 2015 / Published: 2 March 2015
Cited by 6 | Viewed by 2273 | PDF Full-text (4844 KB) | HTML Full-text | XML Full-text
Abstract
Tissue engineering is viewed as a promising option for long-term repair of cartilage lesions, but current engineered cartilage constructs fail to match the mechanical properties of native tissue. The extracellular matrix of adult human articular cartilage contains highly organized collagen fibrils that enhance [...] Read more.
Tissue engineering is viewed as a promising option for long-term repair of cartilage lesions, but current engineered cartilage constructs fail to match the mechanical properties of native tissue. The extracellular matrix of adult human articular cartilage contains highly organized collagen fibrils that enhance the mechanical properties of the tissue. Unlike articular cartilage, mesenchymal stem cell (MSC) based tissue engineered cartilage constructs lack this oriented microstructure and therefore display much lower mechanical strength. The goal of this study was to investigate the effect of biomolecular gradients and shear stress on MSCs undergoing chondrogenesis within a microfluidic device. Via poly(dimethyl siloxane) soft-lithography, microfluidic devices containing a gradient generator were created. Human MSCs were seeded within these chambers and exposed to flow-based transforming growth factor β1 (TGF-β1) gradients. When the MSCs were both confluent and exposed to shear stress, the cells aligned along the flow direction. Exposure to TGF-β1 gradients led to chondrogenesis of MSCs, indicated by positive type II collagen staining. These results, together with a previous study that showed that aligned MSCs produce aligned collagen, suggest that oriented cartilage tissue structures with superior mechanical properties can be obtained by aligning MSCs along the flow direction and exposing MSCs to chondrogenic gradients. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Open AccessCorrection Correction: Xu, S.; Li, Y.; Liu, Y.; Sun, J.; Ren, H.; Wu, S.-T. Fast-Response Liquid Crystal Microlens. Micromachines 2014, 5, 300–324
Micromachines 2015, 6(3), 328-329; https://doi.org/10.3390/mi6030328
Received: 9 February 2015 / Accepted: 18 February 2015 / Published: 2 March 2015
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Abstract
We have found three errors in our paper [1], and thus would like to make the following corrections to this paper:[...] Full article
Open AccessArticle A Nonlinear Suspended Energy Harvester for a Tire Pressure Monitoring System
Micromachines 2015, 6(3), 312-327; https://doi.org/10.3390/mi6030312
Received: 31 December 2014 / Revised: 17 February 2015 / Accepted: 24 February 2015 / Published: 27 February 2015
Cited by 13 | Viewed by 2310 | PDF Full-text (3442 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study is to develop and analyze a nonlinear suspended energy harvester (NSEH) that can be mounted on a rotating wheel. The device comprises a permanent magnet as a mass in the kinetic system, two springs, and two coil sets. [...] Read more.
The objective of this study is to develop and analyze a nonlinear suspended energy harvester (NSEH) that can be mounted on a rotating wheel. The device comprises a permanent magnet as a mass in the kinetic system, two springs, and two coil sets. The mass vibrates along the transverse direction because of the variations in gravitational force. This research establishes nonlinear vibration equations based on the resonance frequency variation of the energy harvester; these equations are used for analyzing the power generation and vibration of the harvester. The kinetic behaviors can be determined according to the stiffness in the two directions of the two suspended springs. Electromagnetic damping is examined to estimate the power output and effect of the kinematic behaviors on NSEH. The power output of the NSEH with a 52 Ω resistor connected in series ranged from approximately 30 to 4200 μW at wheel speeds that ranged from nearly 200 to 900 rpm. Full article
(This article belongs to the Special Issue Power MEMS)
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Open AccessArticle sBCI-Headset—Wearable and Modular Device for Hybrid Brain-Computer Interface
Micromachines 2015, 6(3), 291-311; https://doi.org/10.3390/mi6030291
Received: 25 August 2014 / Revised: 24 December 2014 / Accepted: 2 February 2015 / Published: 27 February 2015
Cited by 5 | Viewed by 3571 | PDF Full-text (2073 KB) | HTML Full-text | XML Full-text
Abstract
Severely disabled people, like completely paralyzed persons either with tetraplegia or similar disabilities who cannot use their arms and hands, are often considered as a user group of Brain Computer Interfaces (BCI). In order to achieve high acceptance of the BCI by this [...] Read more.
Severely disabled people, like completely paralyzed persons either with tetraplegia or similar disabilities who cannot use their arms and hands, are often considered as a user group of Brain Computer Interfaces (BCI). In order to achieve high acceptance of the BCI by this user group and their supporters, the BCI system has to be integrated into their support infrastructure. Critical disadvantages of a BCI are the time consuming preparation of the user for the electroencephalography (EEG) measurements and the low information transfer rate of EEG based BCI. These disadvantages become apparent if a BCI is used to control complex devices. In this paper, a hybrid BCI is described that enables research for a Human Machine Interface (HMI) that is optimally adapted to requirements of the user and the tasks to be carried out. The solution is based on the integration of a Steady-state visual evoked potential (SSVEP)-BCI, an Event-related (de)-synchronization (ERD/ERS)-BCI, an eye tracker, an environmental observation camera, and a new EEG head cap for wearing comfort and easy preparation. The design of the new fast multimodal BCI (called sBCI) system is described and first test results, obtained in experiments with six healthy subjects, are presented. The sBCI concept may also become useful for healthy people in cases where a “hands-free” handling of devices is necessary. Full article
(This article belongs to the Special Issue Mind-Controlled Robotics)
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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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