"SAMs meet MEMS": surface modification with self-assembled monolayers for the dry-demolding of photoplastic MEMS/NEMS

Kim, Beomjoon; Kim, G.M.; Liebau, M.; Huskens, Jurriaan; Reinhoudt, David N.; Brugger, Jürgen

doi:10.1109/memsys.2001.906490

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…After the simultanous development of the membrane and rim pattern, the fabricated shadow mask is lifted off the substrate. We used two different lift-off techniques: a) sacrificial layer etching using 1-µm-thick SiO 2 deposited by physical vapor deposition (PVD) to allow high lateral underetch rate in 50% HF, and b) dryreleasing technique using a ~1.5 nm thick organic selfassembled monolayer (SAM) as antistiction coating [10]. Figure 3 shows an optical microscope image of one of the fabricated photoplastic SU-8 shadow mask with pyramidal pin for alignment.…”

Section: Photo-plastic Shadow Maskmentioning

confidence: 99%

Transducers ’01 Eurosensors XV

Obermeier¹

2001

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SUMMARYA rapid and simple fabrication method to construct tiny shadow-masks and their use in multi-layer surface patterning with in-situ micromechanical alignment is presented. Free-standing shadow-mask membranes are made of a 5-µm-thick SU-8 based resist layer by photolithography. They are supported by a 1-mm-large and 150-µm-thick SU-8 rim. The membrane has apertures with feature sizes ranging from 6-300 µm. Multiple layer deposition by electron beam evaporation of Cr, Au and Al through the membrane apertures results in aligned multilayer patterns. By using in-situ micromechanical alignment pins or jigs we achieved an overlay precision of < 2 µm in both, x and y direction. The resistless shadow mask deposition technique eliminates photolithography processes and allows surface patterns to be made in a rapid and vacuum-clean way on arbitrary millimeter-size surfaces, and at low-cost.

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Section: Photo-plastic Shadow Maskmentioning

confidence: 99%

Transducers ’01 Eurosensors XV

Obermeier¹

2001

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“…Chemical modification by adsorption of molecularly thin organic layers can greatly alter the tribological behavior of micro/nanoscale devices. Self-assembled monolayers (SAMs) have been used to functionalize surfaces in MEMS/NEMS and can help to reduce the adhesion and friction forces between contacting parts. − On the other hand, polymer brushes, which are formed when polymer chains are tethered at one end to the substrate, while the other end freely dangles away from the surface, constrained only by its elasticity, can also present a high density of functional groups at interfaces that can be harnessed for various applications. − If strongly hydrated polymer-coated surfaces are compressed against each other, repulsive steric forces acting between the polymer brushes, osmotic and entropic in origin, maintain the surfaces separated, while preserving a high fluidity at the brush–brush interface and leading to very low friction coefficients. − If the distance between the grafted chains is smaller than the radius of the gyration; i.e., at high grafting densities, the chains maximize their steric forces, resulting in lubricious brush-like structures. However, at low grafting densities, polymer chains collapse to form mushroom-like structures, in good solvent, resulting in increased friction coefficients.…”

Section: Introductionmentioning

confidence: 99%

Adhesion and Friction Properties of Polymer Brushes on Rough Surfaces: A Gradient Approach

et al. 2013

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The effect of nanoscale surface roughness on the lubrication properties of a polymer brush in a good solvent has been investigated. Friction and adhesion forces were measured by means of polyethylene colloidal-probe AFM across a 12 nm silica particle gradient before and after the adsorption of a poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) polymer brush. The adsorption and conformation of the polymer chains were studied with multiple transmission and reflection infrared (MTR-IR) spectroscopy. The results show that prior to the adsorption of PLL-g-PEG on the gradient surface, the friction is high at the smooth end of the gradient while it decreases toward the rough end. Moreover, there is a direct correlation between friction and adhesion. Upon adsorption of the brushes, adhesion vanishes. In this case, a higher frictional force between the PEG-coated particle gradient substrate and the polyethylene sphere is observed at the rough end of the gradient in comparison to the smooth end. In spite of the increased adsorbed mass of PLL-g-PEG at the rough end of the gradient, theory and simulations show that the high curvature of the nanoparticles leads to a less swollen PEG brush in comparison to PEG brushes adsorbed on a planar surface, resulting in a lower repulsion, which can explain the observed increase in friction with particle density.

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"SAMs meet MEMS": surface modification with self-assembled monolayers for the dry-demolding of photoplastic MEMS/NEMS

Cited by 2 publications

References 6 publications

Transducers ’01 Eurosensors XV

Transducers ’01 Eurosensors XV

Adhesion and Friction Properties of Polymer Brushes on Rough Surfaces: A Gradient Approach

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