A polymeric microgripper with integrated thermal actuators

Nguyen, Nam‐Trung; Ho, Soon-Seng; Low, Cassandra Lee-Ngo

doi:10.1088/0960-1317/14/7/018

Cited by 156 publications

(102 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Owing to their electrical and thermal insulating properties, most polymers require integrated heaters to enable electrical activation. 2,5 The heaters are normally made of surface metallic films and may induce nonuniform heating across the polymeric thickness. This may inevitably cause out-of-plane bending to the polymeric layers.…”

mentioning

confidence: 99%

Powerful polymeric thermal microactuator with embedded silicon microstructure

Lau

Goosen

Keulen

et al. 2007

Applied Physics Letters

View full text Add to dashboard Cite

A powerful and effective design of a polymeric thermal microactuator is presented. The design has SU-8 epoxy layers filled and bonded in a meandering silicon ͑Si͒ microstructure. The silicon microstructure reinforces the SU-8 layers by lateral restraint. It also improves the transverse thermal expansion coefficient and heat transfer for the bonded SU-8 layers. A theoretical model shows that the proposed SU-8/Si composite can deliver an actuation stress of 1.30 MPa/ K, which is approximately 2.7 times higher than the unconstrained SU-8 layer, while delivering an approximately equal thermal strain. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2742599͔ Thermal actuators feature relatively high actuation stress or strain. However, they have shortcomings in terms of high power consumption and high operating temperatures. 1,2 To a large extent, their performance depends on the selected thermal expansion materials. 3 For example, silicon and metals with high moduli of elasticity produce high actuation stresses, but polymers with high thermal expansion coefficients ͑CTEs͒ deliver relatively high actuation strains. According to Ashby, 4 the linear CTE ͑␣͒ is almost inversely proportional to Young's modulus ͑E͒. This means that compliant but high-CTE polymers may not be ideal for generating large actuation stress and strain simultaneously. Owing to their electrical and thermal insulating properties, most polymers require integrated heaters to enable electrical activation. 2,5 The heaters are normally made of surface metallic films and may induce nonuniform heating across the polymeric thickness. This may inevitably cause out-of-plane bending to the polymeric layers.In this letter, we present a design of polymeric thermal actuators to accomplish enhanced in-plane actuation. This design combines multiple materials for effective thermal actuation. It consists of an aluminum film heater, a silicon ͑Si͒ microstructure, and polymeric epoxy ͑SU-8͒ encapsulant ͑see Fig. 1͒. The silicon microstructure is meandering in shape and has a high aspect ratio. Its gaps and surrounding areas are filled and encapsulated with SU-8 epoxy, whereas its top is covered with the aluminum ͑Al͒ heater. The Si "skeleton" serves to conduct heat and to reinforce the SU-8 encapsulant; the Al line is responsible for resistive heating; whereas, the SU-8 epoxy serves to expand and open the spacing of the Si skeleton.The proposed design has been fabricated using bulk micromachining of silicon and casting of SU-8-2002 polymer. 6 Testing shows that a 530-m-long sample device ͑consisting of a 0.675-m-thick Al film and a 50-m-high Si microstrcutrure͒ delivers a 2.5% in-plane longitudinal strain at 2 V, while consuming less than 27 mW ͓see Fig. 1͑b͔͒, and shows no noticeable out-of-plane motion. The actuation using this composite design is efficient. This motivates investigation into its potential actuation capabilities. The normal activation of the actuator design by resistive heating causes an unknown and nonuniform temperature distribution. This ma...

show abstract

mentioning

confidence: 99%

Powerful polymeric thermal microactuator with embedded silicon microstructure

Lau

Goosen

Keulen

et al. 2007

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…A greater maximum deflection of 100 μm could be obtained from a double u-shaped electrothermal design [6]. The design employs asymmetrical heating and thermal expansion of two arms of a pseudo-bimorph actuator structure.…”

Section: Introductionmentioning

confidence: 99%

The static and dynamic response of SU-8 electrothermal microgrippers of varying thickness

Dodd

Ward

Cooke

et al. 2015

Microelectronic Engineering

View full text Add to dashboard Cite

Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in the Journal of microelectronic engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in the Journal of microelectronic engineering, 145, 2015, 10.1016/j.mee.2015.03.028 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThis work presents an investigation into the effect on dynamic response of SU-8 microgrippers due to varying thickness, and subsequent validation via COMSOL Multiphysics simulations and thermal camera profiling during actuation. The tweezer-like microgrippers can easily manipulate, with a high degree of control, cells and particles with diameters as small as 10 µm, without using an impractical operating voltage or generating excessive heat. However, in order to fully exploit the versatility of the devices, their response characteristics must be fully understood as material and/or dimension parameters change. Therefore an investigation took place to determine the effects of device thickness on functionality of the device, including the drive current required to actuate the gripper and the speed of actuation. Furthermore, an infrared camera was used to characterize the thermal response of the device. Finally, a simulation of the temperature profile and deflection dimension has been developed in order to verify the findings and further investigate and predict the effects of design variations.

show abstract

“…Various microactuators such as piezoelectric [ 1,2], electrostatic [3], and electro-thermal [4,5,6,7] are developed using MEMS technology for microgripper applications. Generally, electro-thermal actuators are preferred as they require lower driving voltages.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, electro-thermal actuators are preferred as they require lower driving voltages. Especially the polymeric electro-thermal microgrippers have been widely investigated as they are capable of producing larger displacements at a lower driving voltage and operating temperature [5,6,7]. However, most of the developed polymeric microgrippers employ two-material structures.…”

Section: Introductionmentioning

confidence: 99%

Integrated Silicon-Polymer Laterally Stacked Bender for Sensing Microgrippers

Due

Wei

Sarro

et al. 2006

2006 5th IEEE Conference on Sensors

View full text Add to dashboard Cite

-This paper presents a novel electro-thermal microgripper based on integrated silicon-polymer laterally stacked microactuators. The device consists of a serpentineshape deep silicon structure with a thin film aluminum heater on the top and filling polymer in the trenches among the vertical silicon parts. The fabrication is based on deep reactive ion etching of silicon, aluminum sputtering and SU8 filling. The actuator is 500 pm long, 65 pm wide and 50 pm high. The microgripper generates a large motion up to 52 pm at a driving voltage of only 2 V and with a power consumption of 50 mW. The maximum working temperature is 164°C at 2 V.

show abstract

A polymeric microgripper with integrated thermal actuators

Cited by 156 publications

References 13 publications

Powerful polymeric thermal microactuator with embedded silicon microstructure

Powerful polymeric thermal microactuator with embedded silicon microstructure

The static and dynamic response of SU-8 electrothermal microgrippers of varying thickness

Integrated Silicon-Polymer Laterally Stacked Bender for Sensing Microgrippers

Contact Info

Product

Resources

About