A method, comprising: providing a substrate having present thereon a pattern of hydrophobic and hydrophilic regions; contacting a polymerizable composition to the substate so as to confer the pattern of hydrophobic and hydrophilic regions onto the polymerizable composition; and polymerizing the polymerizable composition. A device, comprising a polymeric substrate, the poly-meric substrate having disposed thereon pattern of hydrophobic and hydrophilic regions, the polymeric substrate comprising a first component that is comparatively hydrophobic relative to a second component of the composition, and a hydrophobic region of the polymeric substrate being comparatively rich in the first component relative to the second component. A method, comprising using a microfluidic device according to the present disclosure to form an emulsion.

A microdroplet/bubble-generating device comprising a slit and a row of a plurality of microflow paths is constructed, in such a manner that either a continuous phase or dispersion phase is supplied to the slit, and so that the end of the slit, the other supply port for the continuous phase or dispersion phase and the liquid recovery port are connected. The plurality of microflow paths each have a narrow part where the cross-sectional area of the flow channel is locally narrowed adjacent to or near the connection point between the slit and the microflow path. The continuous phase and dispersion phase that have met at the connection points flow into the narrow parts, and the dispersion phase is sheared at the narrow parts with the continuous phase flow as the driving force, forming droplets or gas bubbles of the dispersion phase. The product is recovered from the liquid recovery port.

A flow reactor that mixes a first and a second fluid, wherein the first fluid flows toward a first tip between an inner wall of a first inner tubular portion and an outer wall of a second inner tubular portion, the second fluid flows toward a second tip inside the second inner tubular portion, a third fluid having low affinity for the first and the second fluid flows toward a downstream end between an outer wall of the first inner tubular portion and an inner wall of an outer tubular portion, the second tip of the second inner tubular portion does not protrude further to the side of the downstream end than the first tip of the first inner tubular portion, and the first tip is located closer to the side of the upstream end than the downstream end when viewed from a direction orthogonal to the flow direction.