Abstract: An example method includes providing fluid to a chamber. The chamber feeds a first channel terminating at a first droplet ejector and a second channel terminating at a second droplet ejector. The method further includes sequencing ejection of droplets at the first droplet ejector and the second droplet ejector to induce negative pressure to provide a sequenced output flow of the fluid through the first channel to a first target microfluidic network and through the second channel to a second target microfluidic network, and controlling the first and second target microfluidic networks to perform an analytical process with the fluid.

Abstract: A microfluidic device includes a chamber having sidewalls, a floor, a ceiling, and an inlet. The microfluidic device includes pillars extending from the floor to the ceiling of the chamber. Each pillar has an orientation relative to the inlet defined by a leading surface and a trailing corner opposite the leading corner. The trailing corner has an angle less than a threshold angle that is based on a fluidic contact angle. The orientations of the pillars relative to the inlet promote fluid flow from the inlet throughout the chamber without trapping gas at the sidewalls of the chamber.

Abstract: An immiscible droplet generation system may include a chip, a microfluidic channel integrated into the chip, an input to the microfluidic channel through which the microfluidic channel is to be filled with a first fluid that is to be moved through the microfluidic channel and a droplet generator. The droplet generator is integrated into the chip to generate a droplet of a second fluid, immiscible within the first fluid, and to inject the droplet into the first fluid in the microfluidic channel.

Abstract: A microfluidic device may include at least four interconnected microfluidic channels and a set of fluid actuators. The set of fluid actuators may include a fluid actuator asymmetrically located within at least two of the at least four interconnected microfluidic channels. Each of the at least four interconnected microfluidic channels may be activated to a fluid inputting state, a fluid outputting state and a fluid blocking state in response to selective actuation of different combinations of fluid actuators of the set.

Abstract: An example self-priming microfluidic structure can include a microfluidic channel including a floor and a ceiling. A channel height is defined as a distance between the floor and the ceiling. A channel height step can be in the floor, or ceiling, or both. The channel height downstream of the channel height step can be greater than the channel height upstream of the channel height step. An interior pillar can be positioned in the microfluidic channel extending from the floor to the ceiling. The interior pillar can include a widening portion at an upstream end of the interior pillar and a tapering portion at a downstream end of the interior pillar. The interior pillar can overlap the channel height step so that the interior pillar is partially upstream of the channel height step and partially downstream of the channel height step.

Abstract: An example microfluidic mixer can include an inlet microfluidic channel portion and a fluid splitting channel portion including an overpass microfluidic channel to receive fluid from a first side of the inlet microfluidic channel portion and an underpass microfluidic channel to receive fluid from a second side of the inlet microfluidic channel portion, where the underpass microfluidic channel extends under the overpass microfluidic channel such that the channels overlap at their respective downstream ends. A fluid recombining channel portion is downstream of the fluid splitting portion and includes an angled recombining surface having an acute angle with respect to a direction of fluid flow, where the angled recombining surface is between the downstream ends of the overpass and underpass microfluidic channels. An outlet microfluidic channel portion is fluidly connected downstream from the fluid recombining channel portion.

Abstract: A reversible micro-valve device includes a main channel, a passage comprising an opening in fluid communication with the main channel, and a side chamber to house a volume of trapped gas. The side chamber is communicably attached to the passage to control flow along the main channel. The side chamber is to be larger in volume than the main channel to which the trapped gas expands and includes one of the following two states at a given time: an open state in which the main channel is open and flow proceeds through the main channel, or a closed state in which the trapped gas within the side chamber is to expand within the passage and block the flow in the main channel.

Abstract: In one example in accordance with the present disclosure, a fluid analysis system is described. The fluid analysis system includes an inlet channel to an analysis chamber. The analysis chamber is to receive a fluid sample to be analyzed. The fluid analysis system also includes a fluid branch having a fluidic junction along the inlet channel and a gas chamber to house a volume of trapped gas, the gas chamber being in fluid communication with the fluid branch. The fluid analysis system also includes a sealing fluid delivery system to fill the fluid branch with a sealing fluid and a heater adjacent the gas chamber to heat the gas chamber such that the trapped gas expands to push the sealing fluid into the inlet channel to seal the analysis chamber.

Abstract: An example microfluidic device comprises a plurality of fluidic channels and a fluidic multiplexor. The fluidic multiplexor includes a plurality of fluidic micro-valves fluidically coupled to the plurality of fluidic channels, and a plurality of control lines that cross the plurality of fluidic channels proximal to the plurality of fluidic micro-valves.

Abstract: An example microfluidic structure can include a first microfluidic channel segment in a first elevation plane, a second microfluidic channel segment in a second elevation plane, and a transverse microfluidic channel segment connecting the first microfluidic channel segment to the second microfluidic channel segment. An interior pillar can be positioned at the transverse microfluidic channel segment. The interior pillar can have a tapered downstream edge. The tapered downstream edge can be angled in the first or second elevation plane at an acute angle. A fluid cross-sectional area can increase in the fluid flow direction along the tapered downstream edge.

Abstract: An example microfluidic structure can include a first microfluidic channel segment in a first elevation plane, a second microfluidic channel segment in a second elevation plane, and a transverse microfluidic channel segment connecting the first microfluidic channel segment to the second microfluidic channel segment. An angled exterior wall segment can be at the transverse microfluidic channel segment. The angled exterior wall segment can be angled in the first or second elevation plane at an acute angle with respect to a direction of fluid flow through the first or second microfluidic channel segment. A fluid cross-sectional area can increase in the fluid flow direction along the angled exterior wall segment.

Abstract: A fluidic device may include a vertical fluid dispensing volume having a side outlet, a fluid channel connected to the vertical fluid dispensing volume below the side outlet and a fluid actuator asymmetrically located between ends of the fluid channel to form an inertial pump to vertically pump fluid within the channel to the side outlet.

Abstract: An example system includes an input channel having a first end and a second end to receive particles through the first end, a sensor to categorize particles in the input channel into one of at least two categories, and at least two output channels. Each output channel is coupled to the second end of the input channel to receive particles from the input channel, and each output channel is associated with at least one category of the at least two categories. Each output channel has a corresponding pump operable, based on the categorization of a detected particle in a category associated with a different output channel, to selectively slow, stop, or reverse a flow of particles into the output channel from the input channel.

Abstract: The present disclosure is drawn to inertial pumps. An inertial pump can include a microfluidic channel, a fluid actuator located in the microfluidic channel, and a check valve located in the microfluidic channel. The check valve can include a moveable valve clement, a narrowed channel segment located upstream of the moveable valve element, and a blocking element formed in the microfluidic channel downstream of the moveable valve element. The narrowed channel segment can have a width less than a width of the moveable valve element so that the moveable valve element can block fluid flow through the check valve when the moveable valve element is positioned in the narrowed channel segment. The blocking element can be configured such that the blocking element constrains the moveable valve element within the check valve while also allowing fluid flow when the moveable valve element is positioned against the blocking element.

Abstract: A microfluidic valve may include a first portion of a liquid conduit to contain a gas, a second portion of a liquid conduit to contain a liquid, and a constriction between the first portion and the second portion and across which a capillary meniscus is to form between the gas and the liquid. The microfluidic valve may further include a drop jetting device within the second portion to open the valve by breaking the capillary meniscus across the constriction.

Abstract: The present disclosure is drawn to inertial pumps. An inertial pump can include a microfluidic channel, a fluid actuator located in the microfluidic channel, and a check valve located in the microfluidic channel. The check valve can include a moveable valve element, a narrowed channel segment located upstream of the moveable valve element, and a blocking element formed in the microfluidic channel downstream of the moveable valve element. The narrowed channel segment can have a width less than a width of the moveable valve element so that the moveable valve element can block fluid flow through the check valve when the moveable valve element is positioned in the narrowed channel segment. The blocking element can be configured such that the blocking element constrains the moveable valve element within the check valve while also allowing fluid flow when the moveable valve element is positioned against the blocking element.

Abstract: An example system includes an input channel having a first end and a second end to receive particles through the first end, a sensor to categorize particles in the input channel into one of at least two categories, and at least two output channels Each output channel is coupled to the second end of the input channel to receive particles from the input channel, and each output channel is associated with at least one category of the at least two categories. Each output channel has a corresponding pump operable, based on the categorization of a detected particle in a category associated with a different output channel, to selectively slow, stop, or reverse a flow of particles into the output channel from the input channel.

Abstract: A microfluidic flow sensor may include a substrate having a microfluidic channel, an inert particle source to supply a fluid carrying an inert particle to the microfluidic channel and a sensor element along the microfluidic channel and spaced from the inert particle source. The sensor element outputs a signal based upon a sensed passage of the inert particle with respect to the sensor element. Portions of the microfluidic channel proximate the sensor element have a first size and wherein the inert particle provided by the inert particle source is to have a second size greater than one half the first size.

Abstract: An example microfluidic device comprises a plurality of fluidic channels and a fluidic multiplexor. The fluidic multiplexor includes a plurality of fluidic micro-valves fluidically coupled to the plurality of fluidic channels, and a plurality of control lines that cross the plurality of fluidic channels proximal to the plurality of fluidic micro-valves.

Abstract: An example device includes a droplet ejector including a nozzle to eject droplets of a fluid and a target medium to receive the droplets of the fluid. The target medium is separated from the droplet ejector by a gap to be traversed by the droplets. The example device further includes a frame affixing the target medium to the droplet ejector. The target medium is immovably held with respect to the droplet ejector.