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: 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 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: Examples include polymerase chain reaction (PCR) devices. Example PCR devices comprise a fluid input, ejection nozzles, and a set of microfluidic channels that fluidly connect the fluid input and the ejection nozzles. Each microfluidic channel comprises a reaction chamber, and examples further comprise at least one heating element, where the at least one heating element is positioned in the reaction chamber of each microfluidic channel. The at least one heating element is to heat fluid in the reaction chamber of each fluid channel. The device may eject fluid via the ejection nozzles.

Abstract: The present disclosure is drawn to microfluidic devices. In one example, a microfluidic device can include a microfluidic channel. A vent chamber can be in fluid communication with the microfluidic channel. A capillary break can be located between the microfluidic channel and the vent chamber. The capillary break can include a tapered portion and a narrowed opening with a smaller width than a width of the microfluidic channel. A vent port can vent gas from the vent chamber. The vent port can be located a distance away from the capillary break so that a fluid in the capillary break does not escape through the vent port.

Abstract: According to an example, a microfluidic device may include a transport channel having an inlet and an outlet and a plurality of pump loops extending along the transport channel. Each of the plurality of pump loops may include a first branch, a second branch, and a connecting section connecting the first branch and the second branch. The first branch may include a first opening and the second branch may include a second opening, in which the first opening and the second opening are in direct fluid communication with the transport channel. The pump loops may also each include an actuator positioned in the first branch, in which the actuators in the pump loops are to be activated to induce a traveling wave that is to transport the fluid through the transport channel from the inlet to the outlet.

Abstract: Examples include polymerase chain reaction (PCR) devices. Example PCR devices comprise a fluid input, a fluid output, and a set of microfluidic channels that fluidly connect the fluid input and the fluid output. Each microfluidic channel comprises a reaction chamber, and examples further comprise at least one heating element, where the at least one heating element is positioned in the reaction chamber of each microfluidic channel. The at least one heating element is to heat fluid in the reaction chamber of each fluid channel, and the at least one heating element is to pump fluid to the reaction chamber and from the reaction chamber of each microfluidic channel.

Abstract: A fluid ejection device includes a fluid slot, a first fluid ejection chamber communicated with the fluid slot and including a first drop ejecting element, a second fluid ejection chamber communicated with the fluid slot and including a second drop ejecting element, a fluid circulation path communicated with the first fluid ejection chamber and the second fluid ejection chamber, and a fluid circulating element within the fluid circulation path.

Abstract: A fluid ejection device includes a fluid slot, three laterally adjacent fluid ejection chambers each having a drop ejecting element therein, a fluid circulation path communicated with each of the three laterally adjacent fluid ejection chambers, and a fluid circulating element within the fluid circulation path, with at least two laterally adjacent fluid ejection chambers of the three laterally adjacent fluid ejection chambers to substantially simultaneously eject drops of fluid therefrom such that the drops of fluid are to coalesce during flight.

Abstract: A fluid exit passage is at a location along a microfluidic channel. A fluid displacement device is proximate the location along the microfluidic channel. A constituent locator distinguishes a target constituent in a fluid within the microfluidic channel from remaining non-target constituents and locate the target constituent proximate the fluid exit passage. A controller selectively actuates the fluid displacement device when the target constituent is proximate the fluid exit passage to discharge the target constituent from the microfluidic channel through the fluid exit passage.

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 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 first 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: A fluid ejection device includes a fluid slot, two laterally adjacent fluid ejection chambers each having a drop ejecting element therein, a fluid circulation path communicated with the fluid slot and each of the two laterally adjacent fluid ejection chambers, and a fluid circulating element within the fluid circulation path, with the fluid circulating element laterally adjacent at least one of the two laterally adjacent fluid ejection chambers, and the two laterally adjacent fluid ejection chambers to substantially simultaneously eject drops of fluid therefrom such that the drops of fluid are to coalesce during flight.

Abstract: An example device includes a microfluidic channel and a movable element retained in the microfluidic channel to move from a first position to a second position by fluid flow through the microfluidic channel. The device includes a sensor to take a sensor reading to determine fluid flow through the microfluidic channel. The device includes a microfluidic pump to return the movable element from the second position to the first position. The device includes a controller to actuate the microfluidic pump and to determine a flow rate of the fluid flow through the microfluidic channel based on the sensor reading.

Abstract: A fluid ejection device may include a series of spaced two-sided walls forming three channels therebetween. Each of the three channels may contain a drop ejector. The device may further include a fluid circulating element to circulate fluid across the drop ejector within each of the channels.

Abstract: A fluid ejection device includes a fluid slot, a first fluid ejection chamber communicated with the fluid slot and including a first drop ejecting element, a second fluid ejection chamber including a second drop ejecting element, and a fluid circulation path including a first portion communicated with the fluid slot and the second fluid ejection chamber, and a second portion communicated with the first fluid ejection chamber and the second fluid ejection chamber, with the fluid circulation path including a fluid circulating element within the first portion.

Abstract: A fluid ejection device includes a fluid slot, a fluid ejection chamber communicated with the fluid slot, a drop ejecting element within the fluid ejection chamber, a fluid circulation channel communicated at one end with the fluid slot and communicated at another end with the fluid ejection chamber, a fluid circulating element within the fluid circulation channel, and a channel wall separating the fluid ejection chamber and the fluid circulation channel. The fluid circulation channel includes a channel loop, and a width of the channel wall is based on a width of the channel loop and a width of the fluid ejection chamber.

Abstract: A fluid ejection device includes a fluid slot, at least one fluid ejection chamber communicated with the fluid slot, a drop ejecting element within the at least one fluid ejection chamber, a fluid circulation channel communicated with the fluid slot and the at least one fluid ejection chamber, and a fluid circulating element communicated with the fluid circulation channel. The fluid circulating element is to provide on-demand circulation of fluid from the fluid slot through the fluid circulation channel and the at least one fluid ejection chamber.

Abstract: In an example implementation, a method of cell lysis includes moving cell fluid from a first reservoir through a microfluidic channel toward a second reservoir, activating a lysing element multiple times as a cell from the cell fluid passes through the microfluidic channel, and moving lysate fluid that results from the activating through the microfluidic channel and into the second reservoir.

Abstract: The present disclosure is drawn to microfluidic devices. In one example, a microfluidic device can include a driver chip and a fluid chamber located over the driver chip. First and second microfluidic loops can have fluid driving ends and fluid outlet ends connected to the fluid chamber. The first and second microfluidic loops can include a portion thereof located outside a boundary of the driver chip. A first fluid actuator can be on the driver chip associated with the fluid driving end of the first microfluidic loop to circulate fluid through the first microfluidic loop. A second fluid actuator can be on the driver chip associated with the fluid driving end of the second microfluidic loop to circulate fluid through the second microfluidic loop.