Selective dip-coating of chemically micropatterned surfaces

We characterize the selective deposition of liquid microstructures on chemically heterogeneous surfaces by means of dip coating processes. The maximum deposited film thickness depends critically on the speed of withdrawal as well as the pattern size, geometry, and angular orientation. For vertically oriented hydrophilic strips, we derive a hydrodynamic scaling relation for the deposited film thickness which agrees very well with interferometric measurements of dip-coated liquid lines. Due to the lateral confinement of the liquid, our scaling relation differs considerably from the classic Landau–Levich formula for chemically homogeneous surfaces. Dip coating is a simple method for creating large area arrays of liquid microstructures for applications involving chemical analysis and synthesis, biochemical assays, or wet printing of liquid polymer or ink patterns

PHENOMENOLOGICAL THEORIES OF QUASICRYSTAL FORMATION

Nous discutons la classe de théories de champ moyen récemment proposées pour expliquer la formation et stabilité des quasicristaux.We survey the class of mean field theories which have recently been proposed to explain the formation and stability of quasicrystals

Offset printing of liquid microstructures for high resolution lithography

We have investigated the direct printing of polymer solutions from a chemically patterned stamp onto a hydrophilic target substrate as a new high-throughput alternative to optical lithography. The patterns on the stamp, which are typically in the micron size range, define regions of alternating wettability. They are produced by patterning a hydrophobic self-assembled monolayer previously deposited onto a hydrophilic surface, typically a glass slide or silicon wafer with a natural oxide coating. Polar liquids or aqueous polymeric solutions are then deposited only onto the hydrophilic surface patterns by dip-coating the stamp in a liquid reservoir. The deposited film thickness depends critically on the speed of withdrawal and the feature size and shape. For vertically oriented hydrophilic stripes dipped in a reservoir containing a polar liquid, we have developed a theoretical model whose prediction for the maximum deposited film thickness agrees exceptionally well with experimental measurements. After deposition, the wetted stamp is pressed against a target substrate by means of a motion controlled press. In this way we have so far printed 5µm wide polyethylene oxide lines onto a silicon wafer

Morphology of liquid microstructures on chemically patterned surfaces

We study the equilibrium conformations of liquid microstructures on flat but chemically heterogeneous substrates using energy minimization computations. The surface patterns, which establish regions of different surface energy, induce deformations of the liquid–solid contact line. Depending on the geometry, these deformations either promote or impede capillary breakup and bulge formation. The contact angles of the liquid on the hydrophilic and hydrophobic regions, as well as the pattern geometry and volume of liquid deposited, strongly affect the equilibrium shapes. Moreover, due to the small scale of the liquid features, the presence of chemical or topological surface defects significantly influence the final liquid shapes. Preliminary experiments with arrays of parallel hydrophilic strips produce shapes resembling the simulated forms. These encouraging results provide a basis for the development of high resolution lithography by direct wet printing

Process simulation for contact print microlithography

Using a combination of experiment and simulations, we have studied the conformation of liquid microstructures on both at and corrugated, chemically heterogeneous substrates. The arti??cial surface patterns, which defi??ne regions of di??erent surface energy, induce deformations of the liquid-solid contact line, which can either promote or impede capillary break-up and the formation of bulges. We study numerically the in uence of the adhesion energies on the hydrophilic and hydrophobic surface areas, the pattern geometry and the deposited fluid volume on the liquid surface pro??les. Moreover, we investigate the transfer of these microscopic ink patterns from the stamp surface to the target substrate during the printing process

Morphology of liquid microstructures on chemically patterned surfaces

We study the equilibrium conformations of liquid microstructures on flat but chemically heterogeneous substrates using energy minimization computations. The surface patterns, which establish regions of different surface energy, induce deformations of the liquid–solid contact line. Depending on the geometry, these deformations either promote or impede capillary breakup and bulge formation. The contact angles of the liquid on the hydrophilic and hydrophobic regions, as well as the pattern geometry and volume of liquid deposited, strongly affect the equilibrium shapes. Moreover, due to the small scale of the liquid features, the presence of chemical or topological surface defects significantly influence the final liquid shapes. Preliminary experiments with arrays of parallel hydrophilic strips produce shapes resembling the simulated forms. These encouraging results provide a basis for the development of high resolution lithography by direct wet printing

Process simulation for contact print microlithography

Using a combination of experiment and simulations, we have studied the conformation of liquid microstructures on both at and corrugated, chemically heterogeneous substrates. The arti??cial surface patterns, which defi??ne regions of di??erent surface energy, induce deformations of the liquid-solid contact line, which can either promote or impede capillary break-up and the formation of bulges. We study numerically the in uence of the adhesion energies on the hydrophilic and hydrophobic surface areas, the pattern geometry and the deposited fluid volume on the liquid surface pro??les. Moreover, we investigate the transfer of these microscopic ink patterns from the stamp surface to the target substrate during the printing process

Generation of high-resolution surface temperature distributions

We have performed numerical calculations to study the generation of arbitrary temperature profiles with high spatial resolution on the surface of a solid. The characteristics of steady-state distributions and time-dependent heating and cooling cycles are examined, as well as their dependence on material properties and device geometry. Ideally, low-power consumption and fast response times are desirable. The simulations show that the achievable spatial resolution is on the order of the substrate thickness and that the response time t1 depends on the width of the individual heating elements. Moreover, the rise time t1 can be significantly shortened by deposition of a thermal insulation layer, which also reduces the power consumption and increases lateral resolution

Selective dip-coating of chemically micropatterned surfaces

We characterize the selective deposition of liquid microstructures on chemically heterogeneous surfaces by means of dip coating processes. The maximum deposited film thickness depends critically on the speed of withdrawal as well as the pattern size, geometry, and angular orientation. For vertically oriented hydrophilic strips, we derive a hydrodynamic scaling relation for the deposited film thickness which agrees very well with interferometric measurements of dip-coated liquid lines. Due to the lateral confinement of the liquid, our scaling relation differs considerably from the classic Landau–Levich formula for chemically homogeneous surfaces. Dip coating is a simple method for creating large area arrays of liquid microstructures for applications involving chemical analysis and synthesis, biochemical assays, or wet printing of liquid polymer or ink patterns