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Design and fabrication of a large-stroke deformable mirror using a gear-shape ionic-conductive polymer metal composite.

Wei HC, Su GD - Sensors (Basel) (2012)

Bottom Line: Finally, a gear shaped IPMC actuator was designed and tested.Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts.The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Section 4, Taipei 10617, Taiwan. d96941017@ntu.edu.tw

ABSTRACT
Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM) provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC) is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young's modulus and Poisson's ratio. We divided an ion exchange polymer, also known as Nafion(®), into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

No MeSH data available.


The structure and ANSYS® element model of a cantilever beam shaped IPMC with the actuation mechanisms. Red and blue arrows stand for compressive and tensile stress. This configuration shows IPMC bent toward the anode.
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f2-sensors-12-11100: The structure and ANSYS® element model of a cantilever beam shaped IPMC with the actuation mechanisms. Red and blue arrows stand for compressive and tensile stress. This configuration shows IPMC bent toward the anode.

Mentions: According to the actuation mechanism, the real internal stress inside Nafion® should be symmetric and linearly distributed along the thickness, which is positive in one layer and is negative in another layer of Nafion®. However, this real model is not easy to apply to arbitrary shapes and boundary confinements. Therefore, we developed a gray-box FEM model to simplify the simulation and prediction. The FEM model was used to perform a quick prediction for three-dimensional deformation in arbitrary shapes. Since the deformable mirror is used as a light reflector, we care about shape, instead of force or current draw. An IPMC was divided into four layers along the thickness by different materials and opposite stresses. There were two layers of metallic electrodes outside the IPMC, a layer of Nafion® with constant compressive surface stress, and a layer of Nafion® with constant tensile surface stress inside the IPMC. The total thickness was 2(hNafion + hmetal) and there was an effective bending moment, noted as Me, caused by the internal stresses. There was a neutral surface with no stress between the two Nafion® layers. Figure 2 shows the structure and element model which were designed by ANSYS® for a cantilever beam shaped IPMC. All the stresses were applied normally to the element surfaces. The stresses were positive in the upper layer and negative in the lower layer of Nafion®. Red arrows and blue arrows stand for the compressive and tensile stresses, respectively. The element type which was chosen in ANSYS® was SOLID 45, which is used for the three-dimensional modeling of solid structures. The element is defined by eight nodes each having three degrees of freedom at each node. The physical properties were follows: Young's modulus of platinum and Nafion® were 168 GPa and 275 MPa, respectively. Poisson's ratio of platinum and Nafion® were 0.38 and 0.487, respectively. All the physical parameters are listed in Table 1.


Design and fabrication of a large-stroke deformable mirror using a gear-shape ionic-conductive polymer metal composite.

Wei HC, Su GD - Sensors (Basel) (2012)

The structure and ANSYS® element model of a cantilever beam shaped IPMC with the actuation mechanisms. Red and blue arrows stand for compressive and tensile stress. This configuration shows IPMC bent toward the anode.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472876&req=5

f2-sensors-12-11100: The structure and ANSYS® element model of a cantilever beam shaped IPMC with the actuation mechanisms. Red and blue arrows stand for compressive and tensile stress. This configuration shows IPMC bent toward the anode.
Mentions: According to the actuation mechanism, the real internal stress inside Nafion® should be symmetric and linearly distributed along the thickness, which is positive in one layer and is negative in another layer of Nafion®. However, this real model is not easy to apply to arbitrary shapes and boundary confinements. Therefore, we developed a gray-box FEM model to simplify the simulation and prediction. The FEM model was used to perform a quick prediction for three-dimensional deformation in arbitrary shapes. Since the deformable mirror is used as a light reflector, we care about shape, instead of force or current draw. An IPMC was divided into four layers along the thickness by different materials and opposite stresses. There were two layers of metallic electrodes outside the IPMC, a layer of Nafion® with constant compressive surface stress, and a layer of Nafion® with constant tensile surface stress inside the IPMC. The total thickness was 2(hNafion + hmetal) and there was an effective bending moment, noted as Me, caused by the internal stresses. There was a neutral surface with no stress between the two Nafion® layers. Figure 2 shows the structure and element model which were designed by ANSYS® for a cantilever beam shaped IPMC. All the stresses were applied normally to the element surfaces. The stresses were positive in the upper layer and negative in the lower layer of Nafion®. Red arrows and blue arrows stand for the compressive and tensile stresses, respectively. The element type which was chosen in ANSYS® was SOLID 45, which is used for the three-dimensional modeling of solid structures. The element is defined by eight nodes each having three degrees of freedom at each node. The physical properties were follows: Young's modulus of platinum and Nafion® were 168 GPa and 275 MPa, respectively. Poisson's ratio of platinum and Nafion® were 0.38 and 0.487, respectively. All the physical parameters are listed in Table 1.

Bottom Line: Finally, a gear shaped IPMC actuator was designed and tested.Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts.The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Section 4, Taipei 10617, Taiwan. d96941017@ntu.edu.tw

ABSTRACT
Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM) provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC) is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young's modulus and Poisson's ratio. We divided an ion exchange polymer, also known as Nafion(®), into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

No MeSH data available.