Single-mask microfabrication of three-dimensional objects from strained bimorphs

Moiseeva, Evgeniya; Senousy, Yehya; McNamara, Shamus; Harnett, C. K.

doi:10.1088/0960-1317/17/9/n01

Cited by 39 publications

(35 citation statements)

References 26 publications

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“…We fabricated a stressed Cr thin film by thermal evaporation (15)(16)(17)(18) and subsequently evaporated a minimally stressed Cu film to form the bilayer. The flexing of the bimetallic joints (to close the gripper) was driven by the release of residual tensile stress within the Cr thin film, and similar bending behavior of stressed thin films has been previously observed (8,(19)(20)(21)(22)(23)(24). We found both experimentally and theoretically (Fig.…”

supporting

confidence: 84%

Tetherless thermobiochemically actuated microgrippers

Leong¹,

Randall

Benson³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

382

321

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We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a selfcontained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy).actuator ͉ biochemical ͉ robotics ͉ thin films B iological function in nature is often achieved by autonomous organisms and cellular components triggered en masse by relatively benign cues, such as small temperature changes and biochemicals. These cues activate a particular response, even among large populations of spatially separated biological components. Chemically triggered activity is also often highly specific and selective in biological machinery. Additionally, mobility of autonomous biological entities, such as pathogens and cells, enables easy passage through narrow conduits and interstitial spaces.As a step toward the construction of autonomous microtools, we describe mass-producible, mobile, thermobiochemically actuated microgrippers. The microgrippers can be remotely actuated when exposed to temperatures Ͼ40°C or selected chemicals. The temperature trigger is in the range experienced by the human body at the onset of a moderate-to-high fever, and the chemical triggers include biologically benign reagents, such as cell media. Using these microgrippers, we achieved a diverse set of functions, such as picking up beads off substrates and removing cells from tissue samples.Conventional microgrippers are usually tethered and actuated by mechanical or electrical signals (1-6). Recently developed actuation mechanisms using pneumatic (7), thermal (8), and electrochemical triggers (9, 10) have also used tethered operation. Because the functional response of currently available microgrippers is usually controlled through external wires or tubes, direct connections need to be made between the gripper and the control unit. These connections restrict device miniaturization and maneuverability. For example, a simple task such as the retrieval of an object from a tube is challenging at the millimeter and submillimeter scale, because tethered microgrippers must be threaded through the tube. Moreover, many of the schemes used to drive actuation in microscale tools use biologically incompatible cues, such as high temperature or nonaqueous media, which limit their utility. There are novel, untethered tools based on shape memory alloys that use low temperature heating, but they have limited mobility and must rely solely on thermal actuation (11,12). The ability of our gripper design to use biochemical actuation, in addition to thermal actuation, represents a paradigm shift in engineering and suggests a strategy for designing mobile microtools that function in a variety of environments with high specif...

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supporting

confidence: 84%

Tetherless thermobiochemically actuated microgrippers

Leong¹,

Randall

Benson³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

382

321

View full text Add to dashboard Cite

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“…Deposition of bilayers consisting of materials with markedly different expansion coefficients can be used to introduce internal strains when the bilayers are deposited at low or high temperatures and the films are released from the substrate at room temperature. This technique was used by Moiseeva et al [43] to fabricate sophisticated cages from the patterns of magnetic films on top of thermal oxide with large compressive stresses. Some magnetic alloys called INVARs (Fe 64 Ni 36 ) take advantage of magnetostrictive properties to reduce their linear coefficient of thermal expansion by more than one order of magnitude as compared to other metals.…”

Section: E E H H H H E H E H E E H H E E H H E E H Hmentioning

confidence: 99%

“…Even much smaller selectivity of 1:80 for Si/SiGe system etched by the 3.7 wt% of NH 4 OH allowed fabrication of high-quality microorigami patterns. Reactive gases, such as xenon difluoride (XeF 2 ) vapor and CHF 3 /O 2 , were used to etch Si substrate [43] and to remove Ge layer [36], respectively. Polycrystalline magnetic films can be grown on a photoresist layer which can be dissolved by acetone [52].…”

Section: A Sacrificial Layermentioning

confidence: 99%

Magnetic Micro-Origami

Małkiński¹,

Eskandari²

2016

Magnetic Materials

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Microscopic origami figures can be created from thin film patterns using surface tension of liquids or residual stresses in thin films. The curvature of the structures, direction of bending, twisting, and folding of the patterns can be controlled by their shape, thickness, and elastic properties and by the strength of the residual stresses. Magnetic materials used for micro-and nano-origami structures play an essential role in many applications. Magnetic force due to applied magnetic field can be used for remote actuation of microrobots. It can also be used in targeted drug delivery to direct cages loaded with drugs or microswimmers to transport drugs to specific organs. Magnetoelastic properties of free-standing micro-origami patterns can serve for stress or magnetic field sensing. Also, the stress-induced anisotropy and magnetic shape anisotropy provide a convenient method of tuning magnetic properties by designing a shape of the microorigami figures instead of varying the composition of the films. Micro-origami figures can also serve as building blocks for two-and three-dimensional meta-materials with unique properties such as negative index of refraction. Micro-origami techniques provide a powerful method of self-assembly of magnetic circuits and integrating them with microelectro-mechanical systems or other functional devices.

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“…Careful control of the folding sequence adds the ability to make sophisticated multi-axis structures from a single photomask [25]. Width differences of 1 J.lm, readily accessible by contact photolithography, have been used to control the release order.…”

Section: Possible Application and Conclusionmentioning

confidence: 99%

“…[17]. Self-folding due to magnetic [18] and surface forces [19], pneumatics [20], swelling of polymers [21], photosensitive polymers [22], stressed thin films [23], [24], [25] thennal and shape memory alloy actuation [11], [26], [27], and muscular actuation [28], are other ways to manipulate micro-and nano-objects to create new objects of various shapes, sizes, and complexities.…”

Section: Introductionmentioning

confidence: 99%

Incorporating nanomaterials with MEMS devices.

Moiseeva¹

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DEDICATION To my Mom and Dadiii ACKNOWLEDGEMENTS I would like to thank my professor, Dr. Cindy Harnett, for her guidance, endless support and patience. I am grateful to her for being a continuous source of motivation and inspiration. I would also like to thank my lab members: Yehya Senousy, Tom Lucas, Silpa Kona, and Jasmin Beharic who put their efforts in making the lab very exciting place to work. This dissertation demonstrates an elegant method, known as 'micro-origami' or strain architecture to design and fabricate three-dimensional MEMS structures which are assembled using actuation of a metal-oxide bilayer with conventional planar lithography.Folding allows creating complex, robust, three-dimensional shapes from two-dimensional material simply by choosing folds in the right order and orientation, small disturbances of the initial shape may also be used to produce different final shapes. These are referred to as "pop-up structures" in this work.The scope of this work presented the deposition of colloidal gold nanoparticles (GNPs) into conformal thin films using a microstenciling technique. Results illustrated that the gold nanoparticle deposition process can easily be integrated into current MEMS microfabrication processes. Thin films of GNPs deposited onto the surfaces of siliconbased bistable MEMS and test devices were shown to have a significant effect on the heating up of microstructures that cause them to fold.The dissertation consists of four chapters, covering details of fabrication methods, theoretical simulations, experimental work, and existing and potential applications.Chapter II illustrates how control of the folding order can generate complex threev dimensional objects from metal-oxide bilayers using this approach. By relying on the fact that narrower structures are released from the substrate first, it is possible to create multiaxis loops and interlinked objects with several sequential release steps, using a single photomask. The structures remain planar until released by dry silicon etching, making it possible to integrate them with other MEMS and microelectronic devices early in the process.Chapter III depicts the fabrication process of different types of bistable structures.It describes the principle of functioning of such structures, and simulations using CoventorWare are used to support the concept. We talk over about advantages and disadvantages of bistable structures, and discuss possible applications.Chapter IV describes fabrication procedure of nanoparticle-MEMS hybrid device.We introduce a convenient synthesis of GNPs with precisely controlled optical absorption in the NIR region by a single step reaction ofHAuCl 4 and Na2S203. We take a look at different techniques to pattern gold nanoparticles on the surface of MEMS structures, and also provide a study of their thermal properties under near IR stimulation.We demonstrate the first approach of laser-driven bistable MEMS actuators for bioapplications.

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Single-mask microfabrication of three-dimensional objects from strained bimorphs

Cited by 39 publications

References 26 publications

Tetherless thermobiochemically actuated microgrippers

Tetherless thermobiochemically actuated microgrippers

Magnetic Micro-Origami

Incorporating nanomaterials with MEMS devices.

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