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: A microfluidic flow sensor may include a substrate having a microfluidic channel, a bubble generator to introduce a bubble into fluid that is directed through the microfluidic channel and a sensor element along the microfluidic channel and spaced from the bubble generator. The sensor element outputs a signal based upon a sensed passage of the bubble with respect to the sensor element. Portions of the microfluidic channel proximate the sensor element have a first size and wherein the bubble generated by the bubble generator is to have a second size greater than one half the first size.

Abstract: A nucleic acid amplifier may include a sample preparation zone, a fluid ejector, an amplification zone and a capillary break between the amplification zone and the fluid ejector.

Abstract: A microfluidic device may include a first fluid chamber, a second fluid chamber, a first microfluidic passage extending between the first fluid chamber and the second fluid chamber, a second microfluidic passage extending from the second fluid chamber, a first fluid actuator adjacent the first microfluidic passage and proximate the first fluid chamber to inertially pump fluid away from the first fluid chamber and a second fluid actuator adjacent the first microfluidic passage and proximate the second fluid chamber to menially pump fluid towards the first fluid chamber.

Abstract: A microfluidic valve may include a firing chamber having an orifice, a first portion of a liquid conduit connected to the firing chamber at a first port, a second portion of the liquid conduit connected to the firing chamber at a second port and a thermal resistor. The thermal resistor is to form a bubble within the firing chamber to expel liquid from the firing chamber through the orifice such that a first meniscus forms across the first port and a second meniscus forms across the second port to interrupt liquid flow between the first portion and the second portion of the liquid conduit.

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: A fluid ejection apparatus may include a drop generator to eject fluid droplets in a vertical direction and a fluid channel containing the drop generator. The fluid channel may include a vertical inlet through which fluid is to enter the fluid channel and a vertical outlet through which fluid not ejected by the drop generator is to be circulated out of the fluid channel.

Abstract: A microfluidic device may include a valve located between a liquid source and a liquid receiver. The valve may include a channel connecting the liquid source to the liquid receiver, a heater within the channel, and a pinch point in the channel between the heater and the liquid receiver. The microfluidic device may include a controller to activate the heater so as to form a bubble sized so as to be captured by the pinch point in the channel to occlude the channel.

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: A fluid ejection apparatus may include a drop generator to eject fluid droplets in a vertical direction and a fluid channel containing the drop generator. The fluid channel may include a vertical inlet through which fluid is to enter the fluid channel and a vertical outlet through which fluid not ejected by the drop generator is to be circulated out of the fluid channel.

Abstract: The examples provide a fluid ejection apparatus that includes a fluid slot; a passage, a drop generator and a fluid circulation pump. The passage has an inlet connected to the fluid slot and an outlet spaced from the inlet and connected to the fluid slot. The passage as a first portion extending in a first direction from the inlet and a second portion extending from the first portion to the outlet in a second direction, opposite to the first direction. A filter is within the fluid slot across the inlet.

Abstract: A sample-reagent mixture is thermal cycled through a plurality of cycles. Each thermal cycle includes actuating a heater to heat the sample-reagent mixtures; and dispensing a fluid onto the sample-reagent mixture to cool the sample reagent mixture.

Abstract: The examples provide a fluid ejection apparatus that includes a fluid slot; a passage, a drop generator and a fluid circulation pump. The passage has an inlet connected to the fluid slot and an outlet spaced from the inlet and connected to the fluid slot. The passage as a first portion extending in a first direction from the inlet and a second portion extending from the first portion to the outlet in a second direction, opposite to the first direction. A filter is within the fluid slot across the inlet.

Abstract: The examples provide a fluid ejection apparatus that includes a fluid slot; a passage, a drop generator and a fluid circulation pump. The passage has an inlet connected to the fluid slot and an outlet spaced from the inlet and connected to the fluid slot. The passage as a first portion extending in a first direction from the inlet and a second portion extending from the first portion to the outlet in a second direction, opposite to the first direction. A filter is within the fluid slot across the inlet.

Abstract: A fluid ejection apparatus (20, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1220, 1320, 1420, 1490, 1720, 1820) and method eject a droplet of fluid using a drop generator (46, 246, 1546) receiving fluid from a passage (44, 244, 1344, 1444, 1494, 1544, 1744) having an inlet (54, 254, 1554) adjacent a fluid slot (40, 240, 1540) and an outlet (56, 256, 1556) spaced from the inlet (54, 254, 1554) and adjacent the fluid slot (40, 240, 1540). Fluid is drawn through a filter (50, 250, 650, 1550) with a pump (48, 248, 1548) within the passage (44, 244, 1344, 1444, 1494, 1544, 1744) that pumps the fluid towards the inlet (54, 254, 1554) to the drop generator (46, 246, 1546).

Abstract: The examples provide a fluid ejection apparatus that includes a fluid slot; a passage, a drop generator and a fluid circulation pump. The passage has an inlet connected to the fluid slot and an outlet spaced from the inlet and connected to the fluid slot. The passage as a first portion extending in a first direction from the inlet and a second portion extending from the first portion to the outlet in a second direction, opposite to the first direction. A filter is within the fluid slot across the inlet.

Abstract: A printhead die includes end regions, a nozzle surface region, fluid passages, ejection chambers, fluid ejectors, non-ejection chambers, and heating resistors. The nozzle surface region is disposed between the end regions. The fluid passages include corresponding ejection nozzles. The ejection nozzles are disposed on the nozzle surface region. The fluid ejectors correspond to the ejection chambers. Each one of the fluid ejectors selectively ejects printing fluid through a corresponding ejection nozzle. The plurality of heating resistors corresponds to the non-ejection chambers. The heating resistors selectively provide heat to the end regions while not ejecting printing fluid through the ejection nozzles.

Abstract: A fluid ejection apparatus (20, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1220, 1320, 1420, 1490, 1720, 1820) and method eject a droplet of fluid using a drop generator (46, 246, 1546) receiving fluid from a passage (44, 244, 1344, 1444, 1494, 1544, 1744) having an inlet (54, 254, 1554) adjacent a fluid slot (40, 240, 1540) and an outlet (56, 256, 1556) spaced from the inlet (54, 254, 1554) and adjacent the fluid slot (40, 240, 1540). Fluid is drawn through a filter (50, 250, 650, 1550) with a pump (48, 248, 1548) within the passage (44, 244, 1344, 1444, 1494, 1544, 1744) that pumps the fluid towards the inlet (54, 254, 1554) to the drop generator (46, 246, 1546).

Abstract: A printhead die includes end regions, a nozzle surface region, fluid passages, ejection chambers, fluid ejectors, non-ejection chambers, and heating resistors. The nozzle surface region is disposed between the end regions. The fluid passages include corresponding ejection nozzles. The ejection nozzles are disposed on the nozzle surface region. The fluid ejectors correspond to the ejection chambers. Each one of the fluid ejectors selectively ejects printing fluid through a corresponding ejection nozzle. The plurality of heating resistors corresponds to the non-ejection chambers. The heating resistors selectively provide heat to the end regions while not ejecting printing fluid through the ejection nozzles.