Levitation of Untethered Stress-Engineered Microflyers Using Thermophoretic (Knudsen) Force

Foroutan, Vahid; Majumdar, R. K.; Mahdavipour, Omid; Ward, Spencer; Paprotny, Igor

doi:10.31438/trf.hh2014.29

Cited by 6 publications

(3 citation statements)

References 3 publications

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“…The planar steering arms can be curved out-of-plane using a stress engineering process. This process uses reconfigurable shadow masks to add (post-release) a patterned layer of a stressor material (usually Chromium, Cr) with high compressive stress to provide an upward curvature [10]. The deflection of the steering arm can be controlled by precisely defining the thickness of the deposited material and the area covered by the stressor layer.…”

Section: Microstressbotsmentioning

confidence: 99%

Tactile sensing and compliance in MicroStressBot assemblies

2014

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Microassembly is one of the applications successfully implemented by group of individually-controllable MEMS microrobots (MicroStressBots). Although the robots are controlled using a centralized optical closed-loop control systems, i.e., a camera mounted on top of a microscope, compliance and self-alignment were used to successfully reduce the control error and permit precise assembly of planar structures. In this work, we further explore the possibility of using compliance to facilitate docking between MicroStressBots. The forces generated by the docking surfaces create a local attractor (pre-image of the goal configuration) that facilitates alignment between the two structures. Through this interaction the robot senses and aligns its position to match the desired configuration. Specifically, in this work we examine two cases: a) docking of two microrobots with straight front edges that promote sliding, and b) docking of two microrobots with patterned edges that restricted sliding between the two robots. In the former case, the robots are engaged in mutual alignment, which is akin to pairwise Self Assembly (SA). This allows generation of highly accurate seed-shapes for further assembly. In the latter case, the robots with matching pattern edges can dock and successfully align. Here, the patterned edge functions as a lock-and-key mechanism, and is akin to the selective affinity in SA-systems. The difference however between a system of MicroStressBots and SA is that MicroStressBots contain active on-board propulsion compared with passive SA systems.

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Section: Microstressbotsmentioning

confidence: 99%

Tactile sensing and compliance in MicroStressBot assemblies

2014

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“…Passian 24,25 , in 2003, demonstrated a micro-cantilever suspended over a substrate, which when heated via a pulsed laser generated deflections at the cantilever tip as a consequence of the Knudsen forces in the gap between the substrate and microcantilever. Foroutan 26 , in 2014, demonstrated untethered levitation in concave micro-flying robots relying on Knudsen force. The phenomenon has been further explored in small satellite and spacecraft attitude control devices 27 and high-altitude propulsion systems 28 .…”

Section: Introductionmentioning

confidence: 99%

Quantification of thermally-driven flows in microsystems using Boltzmann equation in deterministic and stochastic contexts

et al. 2019

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When the flow is sufficiently rarefied, a temperature gradient, for example, between two walls separated by a few mean free paths, induces a gas flow-an observation attributed to the thermo-stress convection effects at microscale. The dynamics of the overall thermo-stress convection process is governed by the Boltzmann equation-an integro-differential equation describing the evolution of the molecular distribution function in six-dimensional phase space-which models dilute gas behavior at the molecular level to accurately describe a wide range of flow phenomena. Approaches for solving the full Boltzmann equation with general inter-molecular interactions rely on two perspectives: one stochastic in nature often delegated to the direct simulation Monte Carlo (DSMC) method; and the others deterministic by virtue. Among the deterministic approaches, the discontinuous Galerkin fast spectral (DGFS) method has been recently introduced for solving the full Boltzmann equation with general collision kernels, including the variable hard/soft sphere models-necessary for simulating flows involving diffusive transport. In this work, the deterministic DGFS method; Bhatnagar-Gross-Krook (BGK), Ellipsoidal statistical BGK, and Shakhov kinetic models; and the widely-used stochastic DSMC method, are utilized to assess the thermo-stress convection process in MIKRA-Micro In-Plane Knudsen Radiometric Actuator-a microscale compact low-power pressure sensor utilizing the Knudsen forces. BGK model under-predicts the heatflux, shear-stress, and flow speed; S-model over-predicts; whereas ESBGK comes close to the DSMC results. On the other hand, both the statistical/DSMC and deterministic/DGFS methods, segregated in perspectives, yet, yield inextricable results, bespeaking the ingenuity of Graeme Bird who laid down the foundation of practical rarefied gas dynamics for microsystems.

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“…Radiometric levitation of microstructures has been also proposed and theoretically analyzed [10]. Recently, untethered flight of surface micromachined structures powered by radiometric forces [11,12] have been demonstrated. These MEMS microfliers are 300µm × 300µm × 1.5µm in size and are actuated by a temperature gradient from microfabricated heaters situated underneath them.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Experimental Results of Untethered Flight of Stereolithographically Printed Mems Microfliers

Hussain¹,

Klitzke²,

Majumdar³

et al. 2016

2016 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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This paper presents modeling and experimental results of untethered flight of stereo-lithographically printed MEMS microfliers propelled by radiometric forces. Analysis of the physics behind radiometric microscale flight is presented, followed by detailed experimental results. The present work further enhances our understanding of the underlying principles of these microflier designs as well as demonstrates methods to build designs using 3-D stereo-lithography. This paper verifies that the perimeter and not the surface area of the flier is the key factor in determining the force experienced during flight. Despite differences in underlying physics, similar preference (perimeter over surface area) is observed in biological microscale flight.

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Levitation of Untethered Stress-Engineered Microflyers Using Thermophoretic (Knudsen) Force

Cited by 6 publications

References 3 publications

Tactile sensing and compliance in MicroStressBot assemblies

Tactile sensing and compliance in MicroStressBot assemblies

Quantification of thermally-driven flows in microsystems using Boltzmann equation in deterministic and stochastic contexts

Analysis and Experimental Results of Untethered Flight of Stereolithographically Printed Mems Microfliers

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