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: A microfluidic device includes a microfluidic chamber fluidly coupled to an inlet port and an outlet port, a semiconductor microchip including fluid active circuitry and transistor circuitry, and a bed of solid supports positioned within the microfluidic chamber fluidly positioned between the inlet port and the outlet port. The transistor circuitry in this example provides onboard logic at the semiconductor microchip to control fluid active circuitry. The semiconductor microchip also defines a portion of the microfluidic chamber.

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: A method may include maintaining a sample comprising an ionic species and an optical indicator at an elevated temperature above 25° C. on a semi-conductive microfluidic die during an incubation period, intermittently interrogating the sample with an interrogating light during the incubation period and sensing a response of the sample to the interrogating light, wherein the sample is interrogated with the interrogating light only during those times at which the sample is being sensed.

Abstract: A microfluidic reaction chamber with a reaction chamber circuit includes a microfluidic reaction chamber to contain a reaction fluid for amplification of nucleic acids, and a reaction chamber circuit disposed within the microfluidic reaction chamber. The microfluidic reaction chamber includes a base wall, a top wall parallel to the base wall and defined in part by a transparent lid, a first side wall, and a second side wall. The reaction chamber circuit is disposed within the microfluidic reaction chamber, and includes a top surface, a bottom surface, a first side wall, and a second side wall. The reaction chamber circuit is in fluidic contact with the reaction fluid and includes a photodetector to detect a fluorescence signal from a labeled fluorescent tag in the reaction fluid.

Abstract: A vertically layered fluid column can include a plurality of fluids positioned in fluid layers, a density-differential interface along which two fluids from the plurality of fluids are positioned, and a capillary force-supported interface along which two fluids from the plurality of the fluids are positioned.

Abstract: A biological component separator can include a vertically layered fluid column with a plurality of fluids positioned in fluid layers and a density-differential interface along which two fluids from the plurality of fluids are positioned. The biological component separator can also include a magnetic field generator positioned about the vertically layered fluid column and having multiple magnetic field profiles appliable across the vertically layered fluid column. The multiple magnetic field profiles can include a particle aggregating profile to concentrate magnetizing particles when present in the vertically layered fluid column and a particle sweeping profile to re-suspend and sweep the magnetizing particles when present across the vertically layered fluid column.

Abstract: A fluid preparation device can include a fluid-receiving vessel and a fluid loader with multiple fluid chambers including a first fluid chamber and a second fluid chamber. The multiple fluid chambers can partially be defined by actuator seals that are positioned on an actuator. The actuator can be moveable among a plurality of positions and the actuator seals can be positioned on the actuator to fluidically separate the first fluid chamber from the second fluid chamber when the actuator is in a closed position from the plurality of positions, allow fluidic communication between the second fluid chamber and the fluid-receiving vessel when the actuator is in a first open position from the plurality of positions, and allow fluidic communication between the first fluid chamber and the second fluid chamber when the actuator is in a second open position from the plurality of positions.

Abstract: The present disclosure includes a method of forming and loading a multi-fluid density gradient column. The method can include forming a multi-fluid density gradient column and loading magnetizing microparticles into a first fluid layer or a second fluid layer of the multi-fluid density gradient column. Forming the multi-fluid density gradient column can include loading a first fluid having a first fluid density in a multi-fluid density gradient column to form a first fluid layer and loading a second fluid having a second fluid density greater than the first fluid density in the multi-fluid density gradient column to form a second fluid layer. The multi-fluid density gradient column can be fluidly coupled to a fluid processing device. The magnetizing microparticles can be surface-activated to bind with a biological component or can be bound to the biological component.

Abstract: A biological component concentration fluid assembly includes magnetizing microparticles that are surface-activated to bind with (or are bound to) a biological component; a multi-fluid density gradient column with a first fluid layer, a second fluid layer, and a third fluid layer; and a magnet to attract and draw the magnetizing microparticles from the first fluid layer, through the second fluid layer, and into the third fluid layer. The first fluid layer has a first fluid density, and a second fluid layer has a second fluid density that is greater than the first fluid density, and is positioned beneath the first fluid layer. A third fluid layer has a third fluid density that is greater than the second fluid density and is positioned beneath the second fluid layer. The second and third fluid layers in this example are formulated to interact with the surface of the magnetizing microparticles.

Abstract: A microfluidic device includes a semiconductor microchip including fluid active circuitry and transistor circuitry, wherein the transistor circuitry provides onboard logic at the semiconductor microchip to control the fluid active circuitry. The microfluidic device further includes a microfluidic chamber fluidly coupled to an inlet port and an outlet port, wherein the microfluidic chamber is defined in part by a microchip surface with the active circuitry positioned to interact with fluid introduced into the microfluidic chamber and partially defined by an enclosing surface. The microchip surface, the enclosing surface, or both include a chemically-modified microfluidic chamber surface that is selectively interactive with a target component of the fluid.

Abstract: An apparatus includes a pipette dispenser to control dispensing of a volume to a dispensing location. A tip is operatively coupled to the pipette dispenser. The tip includes an electromechanical print head to dispense the volume from the pipette dispenser to the dispensing location based on a command from the pipette dispenser that indicates an amount of the volume to be dispensed from the print head.

Abstract: Examples herein involve amplification and detection of nucleic acids using a microfluidic reaction chamber. An example apparatus includes a reaction-chamber circuit to process a reagent and a biologic sample for amplification of nucleic acids. The apparatus further includes a plurality of capillaries to pass the reagent and the biologic sample through the microfluidic reaction chamber. A valve control system may selectively control each of a plurality of valves to cause the reagent and the biologic sample to selectively move through the microfluidic reaction chamber for the amplification of the nucleic acids according to a particular timing sequence.

Abstract: According to an example, a microfluidic apparatus may include a channel, a foyer, in which the foyer is in fluid communication with the channel and in which the channel has a smaller width than the foyer, a sensor to sense a property of a fluid passing through the channel, a nozzle in fluid communication with the foyer, and an actuator positioned in line with the nozzle. The microfluidic apparatus may also include a controller to determine whether the sensed property of the fluid meets a predetermined condition and to perform a predefined action in response to the sensed property of the fluid meeting the predetermined condition.

Abstract: The present disclosure is drawn to microfluidic chips. The microfluidic chips can include an inflexible material having an elastic modulus of 0.1 gigapascals (GPa) to 450 GPa. A microfluidic channel can be formed within the inflexible material and can connect an inlet and an outlet. A working electrode can be associated with the microfluidic channel and can have a surface area of 1 ?m2 to 60,000 ?m2 within the microfluidic channel. A bubble support structure can also be formed within the microfluidic channel such that the working electrode is positioned to electrolytically generate a bubble that becomes associated with the bubble support structure.

Abstract: An apparatus includes a media that includes an encoded pattern to indicate a location of each of a plurality of dispensing locations on a receiving area for a pipette dispenser. The encoded pattern is employed to guide the pipette dispenser to dispense a volume to a selected dispensing location from the plurality of dispensing locations based on a predetermined dispensing location on the receiving area.

Abstract: In one example in accordance with the present disclosure, an analyte capturing device is described. The analyte capturing device includes a first substrate having microfluidic channels disposed therein and a second substrate disposed on top of the first substrate. A chamber is disposed through the second substrate and captures beads therein, which beads adsorb analytes. The analyte capturing device includes at least one fluid ejection device disposed in the first substrate to draw an analyte-containing solution through the beads disposed within the chamber.

Abstract: A microfluidic device includes a microfluidic chamber fluidly coupled to an inlet port and an outlet port, a semiconductor microchip including fluid active circuitry and transistor circuitry, and a bed of solid supports positioned within the microfluidic chamber fluidly positioned between the inlet port and the outlet port. The transistor circuitry in this example provides onboard logic at the semiconductor microchip to control fluid active circuitry. The semiconductor microchip also defines a portion of the microfluidic chamber.

Abstract: A fluid testing device may include a fluid interaction element and a fluid chamber to contain a fluid to be sensed by the fluid interaction element. The fluid chamber may form a first gap through which fluid is to be wicked to a second gap that is opposite the fluid interaction element and less than the first gap.

Abstract: According to an example, a microfluidic apparatus may include a fluid slot, a foyer in fluid communication with the fluid slot via a channel having a relatively smaller width than the foyer, a sensor to detect a presence of a particle of interest in a fluid passing through the channel, a nozzle in fluid communication with the foyer, and an actuator positioned in line with the nozzle. The microfluidic apparatus may also include a controller to receive information from the sensor, determine, from the received information, whether a particle of interest has passed through the channel, and control the actuator to expel fluid in the foyer through the nozzle based upon the determination.