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: The present disclosure is drawn to microfluidic devices. A microfluidic device can include a substrate, a lid mounted to the substrate, and a microchip mounted to the substrate. The lid mounted to the substrate can form a discrete microfluidic chamber between structures including an interior surface of the lid and a portion of the substrate. The lid can include an inlet and a vent positioned relative to one another to facilitate loading of fluid to the discrete microfluidic chamber via capillary action. A portion of the microchip can be positioned within the discrete microfluidic chamber.

Abstract: In some examples, a fluid dispensing device includes a fluid chamber, a heating element adjacent the fluid chamber, and an orifice adjacent the fluid chamber. A ratio of an area of a surface of the heating element to an orifice area of the orifice is greater than or equal to 3, where the surface of the heating element faces the fluid chamber.

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: In one example in accordance with the present disclosure, a device for conducting a reaction with a fluid sample is described. The device includes: a microfluidic channel; a number of heating elements along the microfluidic channel; and an inertial pump at each of opposite ends of the microfluidic channel to oscillate the fluid sample along the microfluidic channel.

Abstract: In one example in accordance with the present disclosure, a thermal cycling device is described. The thermal cycling device includes a fluid chamber to retain a fluid. A heating element is disposed around multiple sides of a cross-sectional perimeter of the fluid chamber and an insulator is disposed around multiple sides of a cross-sectional perimeter of the heating element. The thermal cycling device also includes a conductive body disposed around multiple sides of a cross-sectional perimeter of the insulator.

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: 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: 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: Examples include microfluidic devices. Example microfluidic devices include a first microfluidic channel, a second microfluidic channel, and a third microfluidic channel fluidly coupled to the first microfluidic channel and the second microfluidic channel via a fluid junction. A fluid actuator is disposed in the third microfluidic channel to actuate to thereby pump a first fluid and a second fluid into the third microfluidic channel.

Abstract: A fluid recirculation channel for dispensing a plurality of fluid drop weights includes a number of sub-channels. The sub-channels include at least one pump channel, and a plurality of drop generator channels fluidically coupled to the at least one pump channel. The fluid recirculation channel further includes a number of pump generators incorporated into the at least one pump channel, a number of drop generators incorporated into drop generator channels, and a plurality of nozzles defined within the drop generator channels, the nozzles being at least as numerous as the number of drop generators.

Abstract: One example includes a device that may include a heating element and a molecular binding site. The heating element may heat a fluid volume, interfaced with the heating element, in response to a voltage being applied to the heating element, the heat transforming the fluid volume from a liquid state into a vaporized state to generate fluid motion within the fluid volume. The molecular binding site may be disposed proximate to the heating element, in which a portion of the fluid volume expands when the fluid volume transforms from the liquid state into the vaporized state, the vaporized state of the fluid volume generating the fluid motion within a target fluid that is disposed within the molecular binding site.

Abstract: Example fluidic channels for microfluidic devices are disclosed. In examples disclosed herein, an example microfluidic device includes a body having a microfluidic network. The microfluidic network includes a main fluid channel to transport a biological fluid from a first cavity of the microfluidic network to a second cavity of the microfluidic network. An auxiliary fluid channel is in fluid communication with to the main fluid channel. The auxiliary fluid channel has a first end and a second end. The first end is in fluid communication with the main fluid channel and the second end is spaced from the main fluid channel. A fluid actuator is positioned in the auxiliary fluid channel to induce fluid flow in the main fluid channel.

Abstract: In one example in accordance with the present disclosure, a fluid analysis device is described. The device includes a substrate, a die adhered to the substrate, and at least one fluid analysis element disposed on the die. A lid is adhered to the substrate and includes a channel formed thereinto be seated over the die. The device also includes an inlet port to the channel and an outlet from the channel. The inlet port and the outlet port are formed on at least one of the substrate and the lid. A number of electrical traces couple the die to a controller.

Abstract: A fluid ejection device may include a first channel having a first end and a second end, a first drop ejector along the first channel, a second channel having a first end and a second end, a second drop ejector along the second channel, a third channel extending between and connecting the first end of the first channel and the first end of the second channel, a fourth channel extending between and connecting the second end of the firs channel and the second end of the second channel and a fifth channel extending between and connecting the third channel and the fourth channel.

Abstract: An example system includes an input channel having a first end and a second end to receive particles through the first end, a separation chamber, at least two output channels, and an integrated pump to facilitate flow through the separation chamber. The separation chamber is in fluid communication with the second end of the input channel. The separation chamber has a passive separation structure, the passive separation structure including an array of columns spaced apart to facilitate separation of particles in a flow based on a size of the particles. Each output channel is in fluid communication with the separation chamber to receive separated particles. The integrated pump is positioned within at least one of the input channel or one of the at least two output channels.

Abstract: A microfluidic valve comprises a first reservoir, a second reservoir, an inertial pump and a channel connecting the first reservoir to the second reservoir. The second reservoir is to receive fluid from the first reservoir through the channel under a pressure gradient. The inertial pump is within the channel proximate the second reservoir and distant the first reservoir.

Abstract: Examples include a fluid ejection die embedded in a molded panel. The fluid ejection die comprises a substrate, and the substrate includes an army of nozzles extending therethrough. The substrate has a first surface in which nozzle orifices are formed and a second surface, opposite the first surface, in which nozzle inlet openings are formed. The fluid ejection die is embedded in the molded panel such that the first surface of the substrate is approximately planar with a top surface of the molded panel. The molded panel has a fluid channel formed therethrough in fluid communication with the nozzle inlet openings of the array of nozzles.