Design and Analysis of Hemispherical Electrostatic Micro Deformable Focusing Mirror

Volume 3 ◽  
2004 ◽  
Author(s):  
Shang-Wei Tsai ◽  
Meng-Ju Lin
Keyword(s):  
Applied Voltage ◽  
Electrostatic Force ◽  
Focal Length ◽  
Length Change ◽  
Least Square ◽  
Limit Values ◽  
Etching Depth ◽  
Isotropic Etching ◽  
Length Changes ◽  
Structure Layer

For uniform deformation, based on bulk microfabrication with isotropic etching, two types of hemispherical electrostatic micro deformable focusing mirror are designed. One of the focusing mirrors is center-anchored, and the other is circular clamped. Using theory of shells, theoretical solution of deformation under uniform electrostatic force is derived. For more detail analysis of the electrostatic and elastic forces coupling problem, finite element is used to analyze the deformation of the mirror structure. Applying electrostatic force, the profile of micro focusing mirror will be not the spherical and change to become a curve like parabolic surface. Using least square method, the curve is fitted as a parabolic curve and the focal lengths of the focusing micro mirror are obtained. The result shows the focal length without applying electrostatic force can be determined by different micro mirror radius and isotropic etching depth. When the electrostatic forces are applied, the deformation and the focal length change differently between the two types of focusing mirror. For circular clamped micro mirror, the deformation is larger near circular clamped region and uniform in the center regime. Therefore, the relation of focal length and applying voltage is a concave curve with minimum values. That is, the focusing length decreasing as the applying voltage increasing and reaches a limit values. When the applying voltage continues increasing after reaching the minimum value, the focal length increases fast. It also shows the thicker structure layer needs larger applied voltage. But the focal length changes in larger stroke. The pull-in voltage is about 100 volt when the structure layer are both 2 μm. However, the pull-in voltage increases nonlinearly as gap increasing. When the gap increases to 4 μm, the pull-in voltage is about 300 volt. The result shows center-anchored micro mirror has better performance. The deformation is more uniform and the focal length increases nonlinearly as applied voltage increasing. It is found the stroke of focal length is larger and the applied voltage is less. The results shows even when the gap and structure layer is 4 and 2 μm, the pull-in voltage is about 62 volts. However, the stoke changes from 990 to about 1320 μm when applying voltage is from 0 to 60 volts. Therefore, with low applied voltage and large focal length stoke, the center-anchored micro mirror has good performance.

Design and Analysis of Micro Electrostatic Deformable Focusing Mirror Actuated by Hemispherical Electrode

2006 ◽  
Vol 306-308 ◽  
pp. 1235-1240
Author(s):  
Pen-Lun Chang ◽  
Meng Ju Lin
Keyword(s):  
Wafer Bonding ◽  
Maximum Stress ◽  
Electrostatic Force ◽  
Focal Length ◽  
Least Square Method ◽  
Least Square ◽  
Mems Devices ◽  
Optical Mems ◽  
Uniform Deformation ◽  
Isotropic Etching

Deformable focusing micromirror is one of the important optical MEMS devices. The focusing length is determined by the profile of the micromirror surface. For uniform deformation, based on bulk microfabrication of isotropic etching and wafer bonding, a novel micro electrostatic deformable focusing mirror actuated by hemispherical electrode is designed and analyzed. Due to the coupling between elastic and electrostatic force, numerical method of finite element using ANASYS software is used to analyze the deformations and stresses of different structure sizes. The phenomenon that structures deform abruptly fast due to nonlinear increasing electrostatic force called pull-in is also discussed. Using the least square method, the profile of micro focusing mirror can be curve fitting as a parabola. And the focal length can be obtained. The results show deformation increases nonlinearly as applying voltages increasing. The stresses increase linearly when thickness also increase but nonlinearly when radius of mirror increases. The maximum stress happens in the region of bounded. The focal length decreases quasi-linearly as applying voltage increases. The mirror sizes and gaps have effect on pull-in voltages. Larger gap and smaller mirror radius will cause larger pull-in voltage.

scholarly journals Medial collateral ligament reconstruction graft isometry is effected by femoral position more than tibial position

2021 ◽  
Author(s):  
Christoph Kittl ◽  
James Robinson ◽  
Michael J. Raschke ◽  
Arne Olbrich ◽  
Andre Frank ◽  
...  
Keyword(s):  
Medial Collateral Ligament ◽  
Knee Flexion ◽  
Length Change ◽  
Collateral Ligament ◽  
Complex Behaviour ◽  
Femoral Attachment ◽  
Attachment Sites ◽  
Custom Made ◽  
Length Changes ◽  
Graft Length

Abstract Purpose The purpose of this study was to examine the length change patterns of the native medial structures of the knee and determine the effect on graft length change patterns for different tibial and femoral attachment points for previously described medial reconstructions. Methods Eight cadaveric knee specimens were prepared by removing the skin and subcutaneous fat. The sartorius fascia was divided to allow clear identification of the medial ligamentous structures. Knees were then mounted in a custom-made rig and the quadriceps muscle and the iliotibial tract were loaded, using cables and hanging weights. Threads were mounted between tibial and femoral pins positioned in the anterior, middle, and posterior parts of the attachment sites of the native superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL). Pins were also placed at the attachment sites relating to two commonly used medial reconstructions (Bosworth/Lind and LaPrade). Length changes between the tibiofemoral pin combinations were measured using a rotary encoder as the knee was flexed through an arc of 0–120°. Results With knee flexion, the anterior fibres of the sMCL tightened (increased in length 7.4% ± 2.9%) whilst the posterior fibres slackened (decreased in length 8.3% ± 3.1%). All fibre regions of the POL displayed a uniform lengthening of approximately 25% between 0 and 120° knee flexion. The most isometric tibiofemoral combination was between pins placed representing the middle fibres of the sMCL (Length change = 5.4% ± 2.1% with knee flexion). The simulated sMCL reconstruction that produced the least length change was the Lind/Bosworth reconstruction with the tibial attachment at the insertion of the semitendinosus and the femoral attachment in the posterior part of the native sMCL attachment side (5.4 ± 2.2%). This appeared more isometric than using the attachment positions described for the LaPrade reconstruction (10.0 ± 4.8%). Conclusion The complex behaviour of the native MCL could not be imitated by a single point-to-point combination and surgeons should be aware that small changes in the femoral MCL graft attachment position will significantly effect graft length change patterns. Reconstructing the sMCL with a semitendinosus autograft, left attached distally to its tibial insertion, would appear to have a minimal effect on length change compared to detaching it and using the native tibial attachment site. A POL graft must always be tensioned near extension to avoid capturing the knee or graft failure.

The location and mechanism of electromotility in guinea pig outer hair cells

1993 ◽  
Vol 70 (2) ◽  
pp. 549-558 ◽  
Author(s):  
R. Hallworth ◽  
B. N. Evans ◽  
P. Dallos
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Length Change ◽  
Opposite Polarity ◽  
Outer Hair Cells ◽  
Response Amplitude ◽  
Change Function ◽  
Length Changes ◽  
Diameter Change

1. The microchamber method was used to examine the motile responses of isolated guinea pig outer hair cells to electrical stimulation. In the microchamber method, an isolated cell is drawn partway into a suction pipette and stimulated transcellularly. The relative position of the cell in the microchamber is referred to as the exclusion fraction. 2. The length changes of the included and excluded segments were compared for constant sinusoidal stimulus amplitude as functions of the exclusion fraction. Both included and excluded segments showed maximal responses when the cell was excluded approximately halfway. Both segments showed smaller or absent responses when the cell was almost fully excluded or almost fully included. 3. When the cell was near to, but not at, the maximum exclusion, the included segment response amplitude was zero, whereas the excluded segment response amplitude was nonzero. In contrast, when the cell was nearly fully included, the excluded segment response amplitude was zero, but the included segment response amplitude was still detectable. A simple model of outer hair cell motility based on these results suggests that the cell has finite-resistance terminations and that the motors are restricted to a region above the nucleus and below its ciliated apex (cuticular plate). 4. The function describing length change as a function of command voltage was measured for each segment as the exclusion fraction was varied. The functions were similar at midrange exclusions (i.e., when the segments were about equal length), showing nonlinearity and saturability. The functions were strikingly different when the segment lengths were different. The effects of exclusion on the voltage to length-change functions suggested that the nonlinearity and saturability are local properties of the motility mechanism. 5. The diameter changes of both segments were examined. The segment diameter changes were always antiphasic to the length changes. This finding implies that the motility mechanism has an active antiphasic diameter component. The diameter change amplitude was a monotonically increasing function of exclusion for the included segment, and a decreasing function for the excluded segment. 6. The voltage to length-change and voltage to diameter-change functions were measured for the same cell and exclusion fraction. The voltage to diameter-change function was smaller in amplitude than the voltage to length-change function. The functions were of opposite polarity to each other, but were otherwise similar in character. Thus it is likely that the same motor mechanism is responsible for both axial and diameter deformations.

Effective Voltage Control of Liquid Crystal Lens for Rapid Focal Length Change

2021 ◽  
Author(s):  
Tsugumi Fukui ◽  
Sota Shimizu ◽  
Keigo Muryobayashi ◽  
Marenori Kawamura ◽  
Susumu Sato ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Focal Length ◽  
Voltage Control ◽  
Length Change ◽  
Effective Voltage ◽  
Liquid Crystal Lens

A Ray Transfer Matrix Model for an Elastomeric Lens

2011 ◽  
Vol 110-116 ◽  
pp. 4145-4148
Author(s):  
Johanna Mae M. Indias ◽  
Clark Kendrick C. Go
Keyword(s):  
Transfer Matrix ◽  
Matrix Model ◽  
Focal Length ◽  
Effective Focal Length ◽  
Length Changes ◽  
Variable Focus ◽  
Tunable Lens

A Ray Transfer Matrix (RTM) of a variable-focus elastomeric fluidic lens is explored and modeled in this paper. A HeNe (543.45nm wavelength) laser is incident on the tunable lens and the effective focal length changes are explored based on this model. Results show that there are two possible focal lengths and that focal lengths are independent of the elastomer thickness.

Effect of Patella Alta on the Native Anatomometricity of the Medial Patellofemoral Complex: A Cadaveric Study

2020 ◽  
Vol 48 (6) ◽  
pp. 1398-1405
Author(s):  
Adam B. Yanke ◽  
Hailey P. Huddleston ◽  
Kevin Campbell ◽  
Michael L. Redondo ◽  
Alejandro Espinoza ◽  
...  
Keyword(s):  
Attachment Site ◽  
Quadriceps Tendon ◽  
Length Change ◽  
Patellar Height ◽  
Extensor Mechanism ◽  
Patella Alta ◽  
Similar Length ◽  
Custom Made ◽  
Length Changes ◽  
Medial Patellofemoral Complex

Background: Patella alta has been identified as an important risk factor for lateral patellar instability and medial patellofemoral complex (MPFC) reconstruction failure. Purpose: To evaluate the length changes of the MPFC at multiple possible reconstruction locations along the extensor mechanism in varying degrees of patella alta throughout knee motion. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric knees were used in this study. The MPFC was identified and dissected with the patellar tendon and quadriceps tendon. A custom-made jig was utilized to evaluate lengths from 0° to 90° of flexion with physiological quadriceps loading. Length was measured with a 3-dimensional robotic arm at 4 possible reconstruction locations along the extensor mechanism: the midpoint patella (MP), the MPFC osseous center (FC), the superior medial pole of the patella (SM) at the level of the quadriceps insertion, and 1 cm proximal to the SM point along the quadriceps tendon (QT). These measurements were repeated at 0°, 20°, 40°, 60° and 90° of flexion. Degrees of increasing severity of patella alta at Caton-Deschamps index (CDI) ratios of 1.0, 1.2, 1.4, and 1.6 were then investigated. Results: Patella alta and MPFC attachment site location significantly affected changes in MPFC length from 0° to 90° of flexion ( P< .0005). Length changes at attachment MP showed no difference when CDI 1.0 was compared with all patella alta values (CDI 1.2, 1.4, 1.6; P > .05). Similarly, FC showed no difference in length change from 0° to 90° until CDI 1.6, in contrast to proximal attachments (SM, QT), which demonstrated significant changes at CDI 1.4 and 1.6. When length changes were analyzed at each degree of flexion (0°, 20°, 40°, 60°, 90°), Spearman correlation analysis showed a moderate negative linear correlation for QT at CDI 1.0 ( r= −0.484; P = .002) and 1.6 ( r = −0.692; P < .0005), demonstrating constant loosening at the QT point at normal and elevated patellar height. In contrast, no differences in length were observed for MP at CDI 1.0 throughout flexion, and at CDI 1.6, there was a difference only at 0° ( P < .05). Points FC and MP at CDI 1.6 had similar length change properties to points SM and QT at CDI 1.0 ( P > .05), suggesting that distal attachments in the setting of patella alta may provide similar length changes to proximal attachmentswith normal height. Conclusion: Anisometry of the MPFC varies not only with attachment location on the extensor mechanism but also with patellar height. Increased patellar height leads to more significant changes in anisometry in the proximal MPFC attachment point as compared with the distal component. In the setting of patella alta, including a CD ratio of 1.6, the osseous attachments of the MPFC remain nearly isometric wheras the proximal half length changes increase significantly. Clinical Significance: The results of this study support the idea that the MPFC should be considered as 2 separate entities (proximal medial quadriceps tendon femoral ligament and distal medial patellofemoral ligament) owing to their unique length change properties.

The Monitoring of Shrinkage of the PVA Cement-Plates

2013 ◽  
Vol 438-439 ◽  
pp. 280-282 ◽  
Author(s):  
Michaela Kostelecká ◽  
Jiří Kolísko
Keyword(s):  
Length Change ◽  
Free Shrinkage ◽  
Significant Difference ◽  
Length Changes ◽  
The Difference ◽  
Matrix Influence

This paper presents results of a series of shrinkage tests. Described tests were performed on asbestos-free plates. The shrinkage represents very important role in monitoring of length changes for different orientation of the fibers. The results showed that humidity significantly influenced dimensions change of tested fibrecement plates. Length change ratio of dried plates and saturated plates represented the most significant difference that reached 0.25 %. Influence of fibres orientation on the length change was not confirmed. The difference in both measured direction was the same because of varied humidity impact. Elimination of free shrinkage is predominantly given by matrix, influence of fibers is not significant.

A Novel Bi-Stable Force Sensor: Theory and Modeling

2009 ◽  
Author(s):  
Pezhman A. Hassanpour ◽  
Patricia M. Nieva ◽  
Amir Khajepour
Keyword(s):  
Analytical Model ◽  
Axial Force ◽  
Applied Voltage ◽  
Electrostatic Force ◽  
Force Sensor ◽  
Time Response ◽  
Constant Rate ◽  
New Type ◽  
Linear And Nonlinear ◽  
Theory And Modeling

In this paper, a novel sensing mechanism is introduced. This mechanism consists of a clamped-clamped beam and two parallel electrodes. An analytical model of the system, that takes into account the mechanical linear and nonlinear stiffnesses as well as the nonlinear electrostatic force, is developed. The time response of the system to a disturbance is derived while the applied voltage is increasing at a constant rate. It has been shown that the voltage, that destabilize the beam, can be used as a measure of the axial force in the beam. This technique can be used in the development of new type of sensors.

Studies of Relaxation of Metallic Glasses by Dilatometry and Density Measurements

1983 ◽  
Vol 28 ◽  
Author(s):  
R.W. Cahn ◽  
N.A. Pratten ◽  
M.G. Scott ◽  
H.R. Sinning ◽  
L. Leonardsson
Keyword(s):  
Intermediate Stage ◽  
Glass Ribbon ◽  
Length Change ◽  
Experimental Conditions ◽  
Density Measurements ◽  
Density Reduction ◽  
Before And After ◽  
Recovery Annealing ◽  
Length Changes ◽  
Glass Rods

ABSTRACTHigh-precision density measurements on coldrolled Pd77.5Cu6Si16.5 glass rods before and after relaxation anneals showed that 30 – 40% rolling leads to a density reduction of ∼0.14%, recoverable on subsequent annealing below Tg. This change is about half of the density increase attainable by recovery-annealing the as-quenched glass.Density changes in Fe40Ni40B20 glass ribbon, resulting from recovery-annealing, were studied indirectly by measuring isothermal length changes through dilatometry of foil sandwiches. The experimental conditions for reliable isothermal dilatometry, using a commercial instrument, are outlined. It was found that the kinetics of length change in the longitudinal and transverse directions were quite different, being faster in the former. Prolonged recovery-annealing prior to dilatometry removed this difference. The intermediate stage of each isotherm followed loqt kinetics.Experiments were performed with Fe40Ni40B20, Ni64Zr36 and Cu66Ti34 to search for a reversible component of length change during cyclic isothermal holds at two temperatures. Such a component probably exists but is extremely small, less than 1% of the limiting irreversible length change.The implications of the various findings are discussed in the light of recent literature.

Effect of stimulus train duration and cycle frequency on the capacity to do work in the pectoral fin muscle of the pumpkinseed sunfish, Lepomis gibbosus

1993 ◽  
Vol 71 (11) ◽  
pp. 2185-2189 ◽  
Author(s):  
Eric A. Luiker ◽  
E. Don Stevens
Keyword(s):  
Duty Cycle ◽  
Length Change ◽  
Lepomis Gibbosus ◽  
Pectoral Fin ◽  
Cycle Frequency ◽  
Pumpkinseed Sunfish ◽  
Train Duration ◽  
Stimulus Train ◽  
Length Changes ◽  
Time Required

The goal of our experiment was to elucidate the effect of stimulus duty cycle (the percentage of the cycle that the muscle was stimulated), phase (the relative timing of the imposed sinusoidal length change and stimulation), and muscle cycle frequency (the speed at which the muscle was cycled) on work and power in the pectoral fin muscle of a labriform swimmer, the pumpkinseed sunfish, Lepomis gibbosus. Stimulus train duration was varied from a twitch to a 40% duty cycle; cycle frequency was varied from 1 to 8 Hz. Work was calculated as the area of work loops produced by muscle contractions while the muscle was undergoing sinusoidal length changes. Maximum net work per cycle (6.2 J/kg) was produced at 1 Hz cycle frequency and a 32% duty cycle. Maximum power (26.7 W/kg) was produced at 5 Hz cycle frequency and a 16% duty cycle. As cycle frequency increased, the duty cycle and the stimulus train duration that produced maximum work decreased. The relatively long relaxation time compared with the length of time required to complete the whole cycle precluded the muscle from doing net positive work at high cycle frequencies.

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