The present invention relates to phaseguide patterns for use in fluid systems such as channels, chambers, and flow through cells. In order to effectively control filling and/or emptying of fluidic chambers and channels, techniques for a controlled overflowing of phaseguides are proposed. In addition, techniques of confined liquid patterning in a larger fluidic structure, including approaches for patterning overflow structures and the specific shape of phaseguides, are provided. The invention also proposes techniques to effectively rotate the advancement of a liquid/air meniscus over a certain angle. In particular, a phaseguide pattern for guiding a flow of a liquid contained within a compartment is provided, wherein an overflow of the phaseguide by a moving liquid phase is controlled by a local change in capillary force along the phaseguide, wherein said overflow by the liquid over the phaseguide is provoked at the position of the local change in capillary force.

Fluidic diodes are disclosed that have a housing defining an inlet and an outlet and a divided fluid passageway therebetween defined by mirror image partitions generally tear-drop shaped spaced apart a first distance from one another by a constant width primary fluid pathway with the tip thereof pointed generally toward the outlet and spaced apart a second distance from an interior wall of the housing to define a constant width secondary fluid pathway. Fluid flow from the inlet to the outlet is through the primary fluid pathway with some additional flow through the secondary fluid pathways joining the primary fluid pathway proximate the outlet for flow together in the same direction, and fluid flow from the outlet to the inlet through the secondary fluid pathways exits the secondary fluid pathways into the primary fluid pathway, proximate the inlet, in a direction substantially opposite the flow in the primary fluid pathway.

The present invention is directed to an improved fluid diode using topology optimization with Finite Element Method (FEM). Topology optimization as a flexible optimization method has been extended to the fluid field. For given boundary conditions and constraints, it distributes a specific amount of pores (or remove materials to get channel) in the design domain to minimize/maximize an objective function. In this design, inlet and outlet ports are aligned and inflow and outflow are in the same direction. The present invention features an intricate network of fluid channels having optimized fluid connectivity and shapes, which significantly improves the diodicity of fluidic passive valves.

We describe a method of layer-by-layer deposition of a plurality of layers of material onto the wall or walls of a channel of a microfluidic device, the method comprising: loading a tube with a series of segments of solution, a said segment of solution bearing a material to be deposited; coupling said tube to said microfluidic device; and injecting said segments of solution into said microfluidic device such that said segments of solution pass, in turn, through said channel depositing successive layers of material to perform said layer-by-layer deposition onto said wall or walls of said channel. Embodiments of the methods are particularly useful for automated surface modification of plastic, for example PDMS (Poly(dimethylsiloxane)), microchannels. We also describe methods and apparatus for forming double-emulsions.