Research

12 pages, 2875 KiB

Open AccessArticle

Micro Motion Amplifiers for Compact Out-of-Plane Actuation

by Xin Xie, Majid Bigdeli Karimi, Sanwei Liu, Battushig Myanganbayar and Carol Livermore

Micromachines 2018, 9(7), 365; https://doi.org/10.3390/mi9070365 - 23 Jul 2018

Cited by 4 | Viewed by 3853

Small-scale, out-of-plane actuators can enable tactile interfaces; however, achieving sufficient actuator force and displacement can require larger actuators. In this work, 2-mm² out-of-plane microactuators were created, and were demonstrated to output up to 6.3 µm of displacement and 16 mN of blocking [...] Read more.

Small-scale, out-of-plane actuators can enable tactile interfaces; however, achieving sufficient actuator force and displacement can require larger actuators. In this work, 2-mm² out-of-plane microactuators were created, and were demonstrated to output up to 6.3 µm of displacement and 16 mN of blocking force at 170 V. The actuators converted in-plane force and displacement from a piezoelectric extensional actuator into out-of-plane force and displacement using robust, microelectromechanical systems (MEMS)-enabled, half-scissor amplifiers. The microscissors employed two layers of lithographically patterned SU-8 epoxy microstructures, laminated with a thin film of structural polyimide and adhesive to form compact flexural hinges that enabled the actuators’ small area. The self-aligned manufacture minimized assembly error and fabrication complexity. The scissor design dominated the actuators’ performance, and the effects of varying scissor angle, flexure thickness, and adhesive type were characterized to optimize the actuators’ output. Reducing the microscissor angle yielded the highest actuator performance, as it maximized the amplification of the half-scissor’s displacement and minimized scissor deformation under externally applied loads. The actuators’ simultaneously large displacements and blocking forces for their size were quantified by a high displacement-blocking force product per unit area of up to 50 mN·µm/mm². For a linear force–displacement relationship, this corresponds to a work done per unit area of 25 mN·µm/mm². Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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15 pages, 2981 KiB

Open AccessArticle

Rigid-Flex PCB Technology with Embedded Fluidic Cavities and Its Application in Electromagnetic Energy Harvesters

by Yi Chiu and Hao-Chiao Hong

Micromachines 2018, 9(6), 308; https://doi.org/10.3390/mi9060308 - 19 Jun 2018

Cited by 3 | Viewed by 7402

Abstract

A technology platform based on commercial printed circuit boards (PCB) technology is developed and presented. It integrates rigid flame retardant (FR)-4 boards, flexible polyimide (PI) structures, and embedded cavities for micro- and meso-scale applications. The cavities or channels can be filled with fluids [...] Read more.

A technology platform based on commercial printed circuit boards (PCB) technology is developed and presented. It integrates rigid flame retardant (FR)-4 boards, flexible polyimide (PI) structures, and embedded cavities for micro- and meso-scale applications. The cavities or channels can be filled with fluids for microfluidic and lab-on-chip systems. In this study, an electromagnetic energy harvester with enhanced output was designed and implemented in the platform. To enhance harvester output, the embedded cavities were filled with ferrofluid (FF) to improve the overall magnetic circuit design and electromechanical coupling of the device. The fabricated PCB-based harvester had a dimension of 20 mm × 20 mm × 4 mm. Vibration tests of the harvesters were conducted with different magnet sizes and different FF. Test results showed up to a 70% enhancement of output voltage and a 195% enhancement of output power when the cavities were filled with oil-based FF as compared with harvesters without FF. When the cavities were filled with water-based FF, the enhancement of voltage and power increased to 25% and 50%, respectively. The maximum output power delivered to a matched load at a 196-Hz resonance frequency and 1 g_rms vibration was estimated to be 2.3 µW, corresponding to an area power density of 0.58 µW/cm² and a volume power density of 1.4 µW/cm³, respectively. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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14 pages, 22483 KiB

Open AccessArticle

A Micromachined Coupled-Cantilever for Piezoelectric Energy Harvesters

by Agin Vyas, Henrik Staaf, Cristina Rusu, Thorbjörn Ebefors, Jessica Liljeholm, Anderson D. Smith, Per Lundgren and Peter Enoksson

Micromachines 2018, 9(5), 252; https://doi.org/10.3390/mi9050252 - 21 May 2018

Cited by 13 | Viewed by 4862

Abstract

This paper presents a demonstration of the feasibility of fabricating micro-cantilever harvesters with extended stress distribution and enhanced bandwidth by exploiting an M-shaped two-degrees-of-freedom design. The measured mechanical response of the fabricated device displays the predicted dual resonance peak behavior with the fundamental [...] Read more.

This paper presents a demonstration of the feasibility of fabricating micro-cantilever harvesters with extended stress distribution and enhanced bandwidth by exploiting an M-shaped two-degrees-of-freedom design. The measured mechanical response of the fabricated device displays the predicted dual resonance peak behavior with the fundamental peak at the intended frequency. This design has the features of high energy conversion efficiency in a miniaturized environment where the available vibrational energy varies in frequency. It makes such a design suitable for future large volume production of integrated self powered sensors nodes for the Internet-of-Things. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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11 pages, 1642 KiB

Open AccessArticle

Energy Harvesting Combat Boot for Satellite Positioning

by Haluk Akay, Ruize Xu, Dexter Chew Xuan Han, T. Hui Teo and Sang-Gook Kim

Micromachines 2018, 9(5), 244; https://doi.org/10.3390/mi9050244 - 17 May 2018

Cited by 11 | Viewed by 5945

Abstract

Most portable electronic devices are power-limited by battery capacity, and recharging these batteries often interrupts the user’s experience with the device. The product presented in this paper provides an alternative to powering portables by converting regular human walking motion to electricity. The device [...] Read more.

Most portable electronic devices are power-limited by battery capacity, and recharging these batteries often interrupts the user’s experience with the device. The product presented in this paper provides an alternative to powering portables by converting regular human walking motion to electricity. The device harvests electric power using air bulbs, distributed in the sole of a shoe to drive a series of micro-turbines connected to small DC motors. The number and position of air bulbs is optimized to harvest the maximum airflow from each foot-strike. The system is designed to continuously drive the micro-turbines by utilizing both outflow and inflow from the air bulbs. A prototype combat boot was fitted on the right foot of a 75 kg test subject, and produced an average continuous power on the order of 10 s of mW over a 22 Ω load during walking at 3.0 mph. This combat boot provides enough electric power to a passive GPS tracker that periodically relays geographical coordinates to a smartphone via satellite without battery replacement. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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11 pages, 4879 KiB

Open AccessArticle

Gimbal-Less Two-Axis Electromagnetic Microscanner with Twist Mechanism

by Yangkyu Park, Seunghwan Moon, Jaekwon Lee, Kwanghyun Kim, Sang-Jin Lee and Jong-Hyun Lee

Micromachines 2018, 9(5), 219; https://doi.org/10.3390/mi9050219 - 06 May 2018

Cited by 10 | Viewed by 3505

Abstract

We present an electromagnetically driven microscanner based on a gimbal-less twist mechanism. In contrast to conventional microscanners using a gimbal-less leverage mechanism, our device utilizes a gimbal-less twist mechanism to increase the scan angle in optical applications requiring a large scanning mirror. The [...] Read more.

We present an electromagnetically driven microscanner based on a gimbal-less twist mechanism. In contrast to conventional microscanners using a gimbal-less leverage mechanism, our device utilizes a gimbal-less twist mechanism to increase the scan angle in optical applications requiring a large scanning mirror. The proposed gimbal-less scanner with twist mechanism increases the scan angle by 1.55 and 1.97 times for the slow and fast axes, respectively, under the same force; 3.64 and 1.97 times for the slow and fast axes, respectively, under the same maximum stress, compared to the gimbal-less leverage mechanism. The scanner with a 3-mm-diameter mirror and a current path composed of a single-turn coil was fabricated, and it showed the maximum scan angle of 5° (quasi-static) and 22° (resonant) for the slow and fast axes, respectively. The experimentally estimated crosstalk was as small as 0.47% and 0.97% for the fast and slow axes affected by the other axes, respectively, which was determined using a newly employed methodology based on fast Fourier transform. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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12 pages, 4483 KiB

Open AccessArticle

A Non-Resonant Kinetic Energy Harvester for Bioimplantable Applications

by Mustafa İ. Beyaz, Hacene C. Baelhadj, Sahar Habibiabad, Shyam S. Adhikari, Hossein Davoodi and Vlad Badilita

Micromachines 2018, 9(5), 217; https://doi.org/10.3390/mi9050217 - 05 May 2018

Cited by 3 | Viewed by 3942

Abstract

A linear non-resonant kinetic energy harvester for implantable devices is presented. The design contains a metal platform with permanent magnets, two stators with three-dimensional helical coils for increased power generation, ball bearings, and a polydimethylsiloxane (PDMS) package for biocompatibility. Mechanical excitation of this [...] Read more.

A linear non-resonant kinetic energy harvester for implantable devices is presented. The design contains a metal platform with permanent magnets, two stators with three-dimensional helical coils for increased power generation, ball bearings, and a polydimethylsiloxane (PDMS) package for biocompatibility. Mechanical excitation of this device within the body due to daily activities leads to a relative motion between the platform and stators, resulting in electromagnetic induction. Initial prototypes without packaging have been fabricated and characterized on a linear shaker. Dynamic tests showed that the friction force acting on the platform is on the order of 0.6 mN. The resistance and the inductance of the coils were measured to be 2.2 Ω and 0.4 µH, respectively. A peak open circuit voltage of 1.05 mV was generated per stator at a platform speed of 5.8 cm/s. Further development of this device offers potential for recharging the batteries of implantable biomedical devices within the body. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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25 pages, 3534 KiB

Open AccessArticle

Lattice Boltzmann Simulation of the Hydrodynamic Entrance Region of Rectangular Microchannels in the Slip Regime

by Niya Ma, Zhipeng Duan, Hao Ma, Liangbin Su, Peng Liang, Xiaoru Ning, Boshu He and Xin Zhang

Micromachines 2018, 9(2), 87; https://doi.org/10.3390/mi9020087 - 16 Feb 2018

Cited by 20 | Viewed by 4534

Abstract

Developing a three-dimensional laminar flow in the entrance region of rectangular microchannels has been investigated in this paper. When the hydrodynamic development length is the same magnitude as the microchannel length, entrance effects have to be taken into account, especially in relatively short [...] Read more.

Developing a three-dimensional laminar flow in the entrance region of rectangular microchannels has been investigated in this paper. When the hydrodynamic development length is the same magnitude as the microchannel length, entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE) to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000), channel aspect ratio (0 < ε < 1), and Knudsen number (0.001 < Kn < 0.1) on the dimensionless hydrodynamic entrance length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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7997 KiB

Open AccessArticle

Effects of the Manufacturing Process on the Reliability of the Multilayer Structure in MetalMUMPs Actuators: Residual Stresses and Variation of Design Parameters

by Jianbin Guo, Jinling Wang, Shengkui Zeng, Vadim V. Silberschmidt and Yongguang Shen

Micromachines 2017, 8(12), 348; https://doi.org/10.3390/mi8120348 - 29 Nov 2017

Cited by 3 | Viewed by 3953

Abstract

Potential problems induced by the multilayered manufacturing process pose a serious threat to the long-term reliability of MEMSCAP^® actuators under in-service thermal cycling. Damage would initiate and propagate in different material layers because of a large mismatch of their thermal expansions. In [...] Read more.

Potential problems induced by the multilayered manufacturing process pose a serious threat to the long-term reliability of MEMSCAP^® actuators under in-service thermal cycling. Damage would initiate and propagate in different material layers because of a large mismatch of their thermal expansions. In this research, residual stresses and variations of design parameters induced by metal multi-user micro electromechanical system processes (MetalMUMPs) were examined to evaluate their effects on the thermal fatigue lifetime of the multilayer structure and, thus, to improve MEMSCAP^® design. Since testing in such micro internal structure is difficult to conduct and traditional testing schemes are destructive, a numerical subdomain method based on a finite element technique was employed. Thermomechanical deformation from metal to insulator layers under in-service temperature cycling (obtained from the multiphysics model of the entire actuator, which was validated by experimental and specified analytical solutions) was accurately estimated to define failures with a significant efficiency and feasibility. Simulation results showed that critical failure modes included interface delamination, plastic deformation, micro cracking, and thermal fatigue, similarly to what was concluded in the MEMSCAP^® technical report. Full article

(This article belongs to the Special Issue Microsystems for Power, Energy, and Actuation)

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