Liquid droplet micro-bearings on directional circular surface ratchets

Varel, Çaǧdaş; Böhringer, K. F.

doi:10.1109/memsys.2014.6765808

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…The magnitude of friction at the linear reciprocatingsliding friction test is related to the lubrication regime, which could be roughly assessed by the lambda ratio (λ), as given by Eq. (2). The λ at the mid-stroke point was 1.6 at 8 Hz (the highest speed in the test), which means the contact is probably in mixed or boundary lubrication.…”

Section: Tribological Behavioursmentioning

confidence: 78%

“…This is particularly important for bearings running under limited lubricant supply or starved conditions. The former condition is to provide on-demand lubricant and considered to be an inspired strategy to introduce practical benefits, such as less bearing friction and wastage [1][2][3], whilst the latter is a typical problem for bearings running at high speeds [4]. Using mechanical means to enrich the oil replenishment to the track may lead to the loss of the beauty of typical bearing configurations, that is, simplicity [5].…”

Section: Introductionmentioning

confidence: 99%

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Laser pattern-induced unidirectional lubricant flow for lubrication track replenishment

et al. 2021

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Effective oil replenishment to the lubrication track of a running bearing is crucial to its sustainable operation. Reliable practical solutions are rare despite numerous theoretical studies were conducted in the last few decades. This paper proposes the use of surface effect, wettability gradient, to achieve the goal. This method is simple and can be nicely implemented using femtosecond laser ablation. A periodic comb-tooth-shaped pattern with anisotropic wetting capability is devised and its effect on the anisotropic spreading behaviour of an oil droplet is studied. Results show that the comb-tooth-shaped pattern enables the rearrangement of oil distribution, thereby escalating oil replenishment to the lubrication track. The effect is due to the unbalanced interfacial force created by the surface pattern. The influence of the shape and the pitch of teeth, which are the two governing factors, on oil transport is also reported. The effects of the newly devised surface pattern on lubrication are experimentally evaluated under the conditions of limited lubricant supply. These results are promising, demonstrating the reduction in bearing friction and the increase in lubricating film thickness.

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Section: Tribological Behavioursmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Laser pattern-induced unidirectional lubricant flow for lubrication track replenishment

et al. 2021

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“…Varel recently described a rotating table based on water droplets moving unidirectionally along a circular track micromachined onto a substrate subject to vertical oscillations [13]. A low-voltage microgripper utilizing a liquid droplet to pick up and release micro-objects is presented in [14].…”

Section: Introductionmentioning

confidence: 99%

Experimental characterization of Drobot: Towards closed-loop control

Majcherczyk

Rabenorosoa

Clevy

et al. 2014

2014 IEEE/ASME International Conference on Advanced Intelligent Mechatronics

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Abstract-This paper presents advances in the development of a microrobotic platform actuated by three liquid droplets in a gaseous environment (Drop-bot or Drobot). Drobot builds on the bubble robotics concept earlier introduced by Lenders [1]. A new platform design is described allowing three actuated degrees of freedom : one translational (vertical) and two rotational (tilt). The platform-supporting droplets are generated by pushing liquid out of a tank through linear actuators. Preliminary kinematic (output/input ratio), static (compliance) and dynamic (response time and evaporation time) characterizations of Drobot are reported, as well as promising experiments with an ionic liquid, whose negligible volatility is suitable for vacuum or hot environments. Additionally, a method to deduce the platform attitude from the measurement of the electrical resistance of the droplets is discussed. This work contributes toward the automatic control of the platform, which will be fully addressed in a following publication.

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The Fluid Joint: The Soft Spot of Micro‐ and Nanosystems

Mastrangeli

2015

Advanced Materials

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Fluid bridges are ubiquitous soft structures of finite size that conform to and link the surfaces of neighboring objects. Fluid joints, the specific type of fluid bridge with at least one extremity constrained laterally, display even more pronounced reactivity and self-restoration, which make them remarkably suited for assembly, actuation, and manipulation purposes. Their peculiar surface and bulk properties place fluid joints at the rich intersection of diverse scientific interests, and foster their widespread use throughout micro- and nanotechnology. A critical survey of the mechanics and of the manifold applications of fluid bridges and joints in micro- and nanosystems is presented here, along with current challenges and multidisciplinary perspectives.

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Liquid droplet micro-bearings on directional circular surface ratchets

Cited by 5 publications

References 7 publications

Laser pattern-induced unidirectional lubricant flow for lubrication track replenishment

Laser pattern-induced unidirectional lubricant flow for lubrication track replenishment

Experimental characterization of Drobot: Towards closed-loop control

The Fluid Joint: The Soft Spot of Micro‐ and Nanosystems

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