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: An inkjet printhead includes an inkjet nozzle with a main actuator and a peripheral actuator in a firing chamber. A determination is made as to whether the inkjet nozzle has sat idle, e.g., not firing for a threshold period of time. When the inkjet nozzle has sat idle, both the main actuator and the peripheral actuator are activated to jet at least one ink drop. When the inkjet nozzle has not sat idle, only the main actuator is activated to jet ink drops.

Abstract: A microfluidic bead-packing method includes activating a first micropump to transfer active microbeads through an inlet microchannel from a bead suspension reservoir to an adsorbing channel; packing the microbeads in the adsorbing channel; and activating a second micropump to reverse flow through at least a portion of the inlet microchannel and to transfer a sample fluid through the inlet microchannel from a sample reservoir to the adsorbing channel such that the sample fluid interacts with the packed microbeads.

Abstract: A microfluidic filtering system may include a first microfluidic channel, a first pump to move fluid along the first microfluidic channel in a first direction, a second microfluidic channel, a second pump to move fluid along the second microfluidic channel in a second direction opposite to the first direction and a filter channel extending between and interconnecting the first microfluidic channel and the second microfluidic channel.

Abstract: In one embodiment, a microfluidic mixing device includes a mixing channel, a fluid inlet chamber to pass fluids into the mixing channel, an axis-asymmetric mixing actuator integrated within the channel to cause fluid displacements that mix the fluids as they flow through the channel, and an outlet chamber to receive the mixed fluids.

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: A network of microfluidic channels may include at least three loops interconnected at a junction. Each of the loops may include a fluid channel having a length extending from the junction to a second end; and a fluid actuator along the fluid channel and located at a first distance from junction along the length of the fluid channel and at a second distance less than the first distance from the second end. Activation of the fluid actuator of selected ones of the at least three loops may selectively produce net fluid flow in different directions about the loops. In one implementation, a fluid channel having a fluid actuator may have a bridging portion that extends over another fluid channel.

Abstract: A fluid ejection die includes a substrate including an array of nozzles.

Abstract: In some examples, a fluid nozzle includes an aperture comprising a first lobe that is shaped as an ellipse, and a second lobe that has a non-circular shape and has a different size than a size of the first lobe. The fluid nozzle further includes protrusions between the first and second lobes extending inward and forming a throat between the first and second lobes.

Abstract: In an example implementation, a method of microfluidic filtering includes activating a first fluid pump within a microfluidic channel to cause a forward flow of fluid through the microfluidic channel and through a filter of a filter loop. The filter loop intersects the microfluidic channel at a loop entry and at a loop exit. The method includes activating a second fluid pump to cause a reverse flow of fluid through the filter.

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: 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: In an example implementation, a method of controlling a microfluidic valve includes activating a first inertial pump at a first frequency, and a second inertial pump at a second frequency to create a first fluid flow pattern within a microfluidic valve. The method also includes adjusting at least one of the first frequency and the second frequency to change the first fluid flow pattern to a second fluid flow pattern.

Abstract: An Inkjet nozzle includes an aperture with a noncircular opening substantially defined by a polynomial equation. A droplet generator is also described which includes a firing chamber fluidically coupled to a fluid reservoir a heating resistor and a nozzle. The nozzle includes an aperture forming a passage from the firing chamber to the exterior of the droplet generator through a top hat layer. The nozzle is defined by a closed polynomial and has a mathematically smooth and mathematically continuous shape around aperture's perimeter wall, with two protrusions extending into the center of the aperture.

Abstract: A fluid ejection device including, at least, one recirculation system is disclosed. Such recirculation system contains, at least, one drop generator, recirculation channels that include an inlet channel, an outlet channel and a connection channel and a fluid feedhole that communicates with the drop generator via the inlet channel and the outlet channel of the recirculation channel. The recirculation channels can be asymmetrical with reference to the drop generator.

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: In one embodiment, a method of generating net fluid flow in a microfluidic network includes, with a fluid actuator integrated asymmetrically within a microfluidic channel, generating compressive and tensile fluid displacements that are temporally asymmetric in duration.

Abstract: A fluid ejection die has a substrate through which an array of fluid feed holes is formed. The fluid feed holes are separated by ribs. Each fluid feed hole is to guide fluid to an array of drop generators.

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: 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.