Average power control and positioning of polysilicon thermal actuators

Butler, Jeffrey T.; Bright, Victor M.; Cowan, William D.

doi:10.1016/s0924-4247(98)00211-8

Cited by 43 publications

(25 citation statements)

References 11 publications

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“…A class of new active end-effectors based on an E-T actuation principle was introduced in our earlier work [7,11]. The performance of E-T actuators is limited by the maximum operating temperature and thermal stresses [12][13][14]. The coupling of "E-T to structural" is much stronger than the "structural to E-T" coupling.…”

Section: Open Accessmentioning

confidence: 99%

“…The E-T actuator comprises a grasping mechanism and a heating element. The exponential temperature profiles, which normally take place at considerably low input voltage, have been discussed before and will be reviewed in this paper for completeness [14]. The temperature profile along the microbeams is defined by an exponential function given that (ȕ h , ȕ c , ȕ f > 0); i.e., the input current is greater than the right hand side in Equation (6) or (I h , I c and I f < 1).…”

Section: Folded or Bent Beam E-t Actuatorsmentioning

confidence: 99%

“…The current passing through the "folded beam" including flexure, cold, hot and linkage arm is (12) (R s ) and (R h ) are the overall electrical resistance of folded and bent beams in the microstructure, respectively. I is the total current drawn across the pad due to overall resistance, where I = I h + I s and I s is the current passing in each one of the (q) bent beams (13) The electrical resistances are temperature dependent and their average can be simplified into (14) Thus, the voltage across the pads is (15) Alternatively, the resistances could be estimated from resistivity calculated at some close average temperature (ȡ a ) and (16) This case is equivalent to the suspended E-T actuators which is described in Case 1 of Section 3.1, but with large air gap, i.e., the structure becomes overhanging. In such cases Equation (6b) can be replaced by Equation (17).…”

Section: Combined Bent and Folded Beam Actuatormentioning

confidence: 99%

See 2 more Smart Citations

Comprehensive Thermal Modeling of ElectroThermoElastic Microstructures

Mayyas

2012

Actuators

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Bent and folded beam configurations have been popularly used in electrothermoelastic (E-T) actuation. This paper introduces new designs of thermal end-effector with micro-grasping and micro-heating capabilities. We obtained analytical models for all possible steady state temperature responses of suspended and overhanging microstructures that constitute bent beam, folded beam, and combined actuators. Generally, the thermal response of E-T microstructures is sensitive to the boundary conditions, particularly for high power input. Thermal models have predicted the failure due to melting, which is the most common reason for failure of E-T devices, and it often occurs in the longest and the thinnest microstructure.

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Section: Open Accessmentioning

confidence: 99%

Section: Folded or Bent Beam E-t Actuatorsmentioning

confidence: 99%

Section: Combined Bent and Folded Beam Actuatormentioning

confidence: 99%

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Comprehensive Thermal Modeling of ElectroThermoElastic Microstructures

Mayyas

2012

Actuators

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“…Because of this, it is difficult to derive a closed-form solution that can adequately model device performance; however, numerical models have been used with success. These range from finite-difference approaches to full three-dimensional finite element solutions [10][11][12].…”

Section: Model Developmentmentioning

confidence: 99%

Final report : compliant thermo-mechanical MEMS actuators, LDRD #52553.

Walraven¹,

Baker²,

Headley³

et al. 2004

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Thermal actuators have proven to be a robust actuation method in surface-micromachined MEMS processes. Their higher output force and lower input voltage make them an attractive alternative to more traditional electrostatic actuation methods. A predictive model of thermal actuator behavior has been developed and validated that can be used as a design tool to customize the performance of an actuator to a specific application. This tool has also been used to better understand thermal actuator reliability by comparing the maximum actuator temperature to the measured lifetime.Modeling thermal actuator behavior requires the use of two sequentially coupled models, the first to predict the temperature increase of the actuator due to the applied current and the second to model the mechanical response of the structure due to the increase in temperature. These two models have been developed using Matlab for the thermal response and ANSYS for the structural response. Both models have been shown to agree well with experimental data. 3In a parallel effort, the reliability and failure mechanisms of thermal actuators have been studied. Their response to electrical overstress and electrostatic discharge has been measured and a study has been performed to determine actuator lifetime at various temperatures and operating conditions. The results from this study have been used to determine a maximum reliable operating temperature that, when used in conjunction with the predictive model, enables us to design in reliability and customize the performance of an actuator at the design stage. AcknowledgmentThe authors would like to thank all of the staff in the MDL for fabrication and release/dry/coat support through out this project. We would also like to thank Ken Pohl, Mark Jenkins and David Luck for their assistance in testing and characterization, Mike Rye for TEM sample preparation, and Hoshang (Amir) Shahvar and Ted Parson for their work in getting SHiMMeR operational and configured for this experiment. Also, thanks to Sean Kearney and Leslie Phinney for their work in collecting the Raman temperature data.4

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“…It is commonly used to control the speed of DC motors but it has also been used to control MEMS such as the dimming in a optical system [23], [24], the flow through a microfluidic valve [5], [25], and to control thermal actuators [26]. Such a drive scheme has a number of advantages over conventional approaches.…”

Section: Introductionmentioning

confidence: 99%

PWM as a Low Cost Method for the Analog Control of MEMS Devices

Pollock

Barrett²,

Corro³

et al. 2018

Preprint

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Abstract-In this paper we discuss the use of pulse width modulation (PWM) to control analog MEMS devices. We achieve precise linear analog control of MEMS by applying a PWM signal with a frequency well above the system's mechanical natural frequency. We first demonstrate this using a parallel plate actuator and comb-drive, then extend the technique to control a commerical deformable mirror. Such an approach allows the system designer to replace expensive drive electronics such as high precision DACs and high voltage, linear amplifiers with a simple on-off switch. Advancements in the electronics industry tend to make precise timing cheaper and faster; our approach exploits these long term trends to create low cost control circuits. We also show how PWM control can linearize the positional response of devices where typically the position would depend quadratically on the applied, analog voltage.

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Average power control and positioning of polysilicon thermal actuators

Cited by 43 publications

References 11 publications

Comprehensive Thermal Modeling of ElectroThermoElastic Microstructures

Comprehensive Thermal Modeling of ElectroThermoElastic Microstructures

Final report : compliant thermo-mechanical MEMS actuators, LDRD #52553.

PWM as a Low Cost Method for the Analog Control of MEMS Devices

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