• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.39-46
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• 2013

Smart material such as SMA (Shape Memory Alloy) has been studied in various ways because it can perform continuous, flexible, and complex actuation in simple structure. Smart soft composite (SSC) was developed to achieve large deformation of smart material. In this paper, a shell actuator using woven type SSC was developed to enhance stiffness of the structure while keeping its deformation capacity. The fabricated actuator consisted of a flexible polymer and woven structure which contains SMA wires and glass fibers. The actuator showed various actuation motions by controlling a pattern of applied electricity because the SMA wires are embedded in the structure as fibers. To verify the actuation ability, we measured its maximum end-edge bending angle, twisting angle, and actuating force, which were $103^{\circ}$, $10^{\circ}$, and 0.15 N, respectively.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1613-1616
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• 2007

A microgripper using thermal actuator and SU-8 polymer was designed and fabricated to manipulate cells and microparts. A chip size of a microgripper was 3 mm ${\times}$ 5 mm. The thermally actuated microgripper consisted of two couples of hot and cold arm actuators. The high thermal expansion coefficient, 52 $ppm/^{\circ}C$, of SU-8 compared to silicon and metals, allows the actuation of the microgripper. Thickness and width of SU-8 as an end-effector were 26 ${\mu}m$ and 80 ${\mu}m$, respectively. Initial gap between left jaw and right jaw was 120 ${\mu}m$. The ANSYS program as FEM tool was introduced to analyze the thermal distribution and displacement induced by thermal actuators. $XeF_2$ gas was used for isotropic silicon dry etching process to release SU-8 end-effector. Mechanical displacements of the fabricated microgripper were measured by optical microscopy in the range of input voltage from 0 V to 2.5 V. The maximum displacement between two jaws of a microgripper Type OG 1_1 was 22.4 ${\mu}m$ at 2.5 V.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.881-887
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• 2016

In this study, the vibration-based tactile actuator for smart wear applications is presented by using piezoelectric ceramic transducers. The compact wireless actuation system is constructed with a high voltage piezoelectric amplifier, a microcontroller, wireless communication module, and rechargeable lithium-polymer battery. For the wireless communication between a hardware and an operator, the bluetooth-based wireless communication system is prepared and the user interface is provided via smart phone applications. From a series of experimental user studies, it is demonstrated that the proposed vibro-tactile actuator based on piezoelectric ceramic transducers can be effectively applied to smart wear applications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.360-363
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• 2005

Biomimetic actuators composed of cellophane with an electrically conducting polyaniline(PANI) film have been fabricated and tested in air ambience conditions doped with two different counter ions such as perchlorate (${ClO_4}^-$) and tetrafluoroborate (${BF_4}^-$). Fabrication of the trilayer CP//CELLOPHANE//CP substantially enhanced the tip displacement (13.2mm) compared to the small displacement (8.3mm) of the bilaye. CP//CELLOPHANE. The ion migration among layers is the main factor behind the expansion of cellophane, while the expansion/contraction of PANI are dependent on the redox reaction of the polymer. The displacement of the composite is dominated by the humidity content. This implies that the actuation principle is possibly due to the assistance of water existing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.119-123
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• 2006

The ionic-polymer-metal-composite actuators have the best merit for bio-mimetic locomotion because of their large bending performance. Especially, they have the advantage for mimicking a fish-like motion because IPMCs are useful to be actuated in water. So we have developed IPMC actuators with multiple electrodes for realization of biomimetic motion. Generally, the IPMC actuator has been fabricated in electroless plating technique, while it needs very long fabrication time and shows poor repeatability in the actuation performance owing to the variables in chemical fabrication process. Therefore, the novel fabrication methods were investigated by combining electroless plating and electroplating techniques capable of patterning precisely. On the whole, two different methods were compared and analyzed with similar thickness level of Platinum electrodes. Present results show that mixing chemical reduction and electroplating can be a promising candidate for electrode patterning.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.709-712
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• 2003

The existing technical limitation makes engineer imitate nature to solve engineering problems. Recently Micro Air Vehicle(MAV) imitating the mechanism of birds or insects is being developed. Especially Ultra Flite supported by DARPA is studying hummingbird aerodynamics to relate that information to MAV. To drive MAV bender piezoelectric(PZT) actuators are used due to the convinience of control and the small size. But the displacement of the PZT actuators are very small, and the wing driving mechanism which amplifies the stroke generated by the PZT actuators has constraints in design and manufacture because of the small dimension. In this paper a wing design concept and a efficient driving mechanism are proposed. Electroactive polymers(EAPs) are used as wing mechanism actuators. Using OpenGL the mechanisms are simulated graphically. Also a prototype actuator is being developed and verified by digital Mockup with CATIA. Basic kinematics of the mechanism is studied.

• Journal of Aerospace System Engineering
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• v.14 no.2
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• pp.28-35
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• 2020

In this paper, we present a design for a retraction-type actuator (ReACT) that has the characteristics of both thermomechanical metamaterials and displacement amplification mechanisms. The ReACT consists of an actuating bar, a diamond-shaped displacement amplification (DA) structure, and a slot for loading thin-film heaters formed through the actuating bar. When power is supplied to the thin film heater, the actuating bars contacting the heater thermally expand, and the diamond-shaped DA structures retract in the longitudinal direction. The performance characteristics of the ReACT, such as temperature distribution and retracting displacement, were calculated with thermomechanical analysis methods using the finite element method (FEM). Subsequently, the ReACTs were fabricated using a polymer-based 3D printer that can easily execute complex structures, and the performance of the ReACT was evaluated through repeated tests under various temperature conditions. The results of the performance evaluation were compared with the results of the FEM analysis.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1910-1918
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• 2005

Characterizing electrochemical polymerization of polypyrrole film on a substrate depends on many parameters. Among them, potential difference and cumulative charges play important role. The level of potential difference affects the quality of the polypyrrole. On the contrary, cumulative charge affects the thickness of the polypyrrole. The substrate surface is adjusted physically and chemically by treating with sandblasting and the addition of thiol for surface adhesion improvement. Experimental results show that the sandblasted and thiol treated substrate provides better. adhesion than non-sandblasted and non-thiol treated substrate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.640-643
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• 2006

In this paper, electro-mechanical coupling of cellulose-based Electro-Active Paper (EAPap) actuator is investigated by measuring induced strain and mechanical properties with and without electric excitation. The maximum induced in-plane strain is measured at the orientation angle of 45? samples. The elastic modulus and strength of EAPap are increased with electric excitation and the orientation angle of $45^{\circ}$ samples shows the largest increment of mechanical properties. From the observations, shear piezoelectricity is considered as the major piezoelectric mode of EAPap.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1310-1316
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• 2008

Bi-layer and tri-layer structures of electro-active paper(EAPap) using conductive polyaniline(PANI) coating were investigated to improve bending displacement of cellulose EAPap. Two different counter ions, perchlorate($CIO_4^-$) and tetrafluoroborate($BF_4^-$), are used as dopant ions in the PANI processing. The actuation performances of hi-layer and tri-layer structure are evaluated in terms of tip displacement, blocked force, strain energy density and power output density. The actuation performance of the tri-layer actuator was better than the hi-layer structure, and the maximum displacement and blocked force of tri-layer $CIO_4^-$ doped-PANI-EAPap were 13.2 mm and 0.15 mN, respectively. Also the power output of the actuator is similar to the required power of biological muscle application.