Abstract: An example printhead includes a circulation channel having an inlet for receiving a fluid and an outlet for expelling the fluid, a first nozzle fluidically coupled to the circulation channel, the first nozzle being operable at a first absolute pressure, and a second nozzle fluidically coupled to the circulation channel, the second nozzle being operable at a second absolute pressure, the absolute second pressure being lower than the first absolute pressure. The absolute pressure in the circulation channel decreases as the fluid flows from the inlet to the outlet, and the first nozzle is positioned closer to the inlet of the circulation channel than the second nozzle.

Abstract: A thermal inkjet printing device includes a fluidic die having a thermal sensor and a processor coupled to the fluidic die. The processor is to receive temperature data from the thermal sensor and determine a flow rate of liquid printing agent through the fluidic die based on the temperature data and an operating parameter for the fluidic die.

Abstract: An example recirculation fluid ejection device includes a first unit droplet generator including a first actuator and a first nozzle between a first and a second fluid feed hole, the first fluid feed hole located on a first channel and the second fluid feed hole and a first pump located on a second channel. The example device includes a second unit droplet generator including a second actuator and a second nozzle between a third and a fourth fluid feed hole, the third feed hole located on a third channel and the fourth fluid feed hole and a second pump located on a fourth channel. The first and the second actuators eject fluid at substantially the same backpressure. A first pressure measurable at an inlet of the first channel and the third channel are different from a second pressure measurable at an outlet of the second channel and the fourth channel.

Abstract: An example printhead includes a set of circulation channels for flowing a fluid therethrough, the set of nozzles including higher-pressure channels and lower-pressure channels; a first nozzle array having a first nozzle; a second nozzle array having a second nozzle, the first nozzle and the second nozzle forming a row region; a first inter-channel passage fluidically coupling the first nozzle to a first pair of adjacent circulation channels, the first pair including a higher-pressure channel on a first side of a lower-pressure channel; and a second inter-channel passage fluidically coupling the second nozzle to a second pair of adjacent circulation channels, the second pair including a higher-pressure channel on a second side of a lower-pressure channel, the second side being opposite the first side.

Abstract: An example printhead includes a circulation channel having an inlet for receiving a fluid and an outlet for expelling the fluid, a first nozzle fluidically coupled to the circulation channel, the first nozzle being operable at a first absolute pressure, and a second nozzle fluidically coupled to the circulation channel, the second nozzle being operable at a second absolute pressure, the absolute second pressure being lower than the first absolute pressure. The absolute pressure in the circulation channel decreases as the fluid flows from the inlet to the outlet, and the first nozzle is positioned closer to the inlet of the circulation channel than the second nozzle.

Abstract: In one example in accordance with the present disclosure, a fluid analysis system is described. The fluid analysis system includes a fluidic die. The fluidic die includes a fluid chamber to hold a volume of fluid to be analyzed and an impedance sensor disposed within the fluid chamber. The impedance sensor measures an impedance of the fluid in the fluid chamber. The fluid analysis system also includes an evaluator device electrically coupled to the impedance sensor. The evaluator device determines at least one property of the fluid based on the impedance.

Abstract: In an example implementation, a method of reducing inkjet aerosol in a fluid drop ejection system includes imaging fluid drops from an ejection event as the drops travel from an ejection nozzle toward a substrate, determining the momentum of each fluid drop from the imaging, comparing the momentum of each fluid drop with a threshold momentum, and determining that a fluid drop will become aerosol when its momentum does not exceed the threshold momentum.

Abstract: A method of distinguishing between fluids may include providing a current to an electrode disposed within a fluidic passageway of a fluidic die, the current to be forced into a fluid within the fluidic die, sensing an impedance at the electrode, and determining a particle vehicle separation level of the fluid based on the sensed impedance between a first instance and a second instance.

Abstract: In one example in accordance with the present disclosure, a fluidic system is described. The fluidic system includes a fluidic die. The fluidic die includes a substrate in which a number of fluid chambers are formed. Each fluid chamber includes a fluid actuator disposed within the fluid chamber. A number of actuator sensors are disposed on the substrate to output at least one value indicative of a sensed characteristic of fluid actuators. A number of substrate temperature sensors are also disposed on the substrate to sense a temperature for the substrate. An actuator evaluation device of the fluidic system determines a state of the fluid actuator based at least in part on the at least one value and at least one correction value associated with the temperature sensed by the number of substrate temperature sensors.

Abstract: In one example in accordance with the present disclosure, a fluid analysis system is described. The fluid analysis system includes a fluidic die. The fluidic die includes a fluid chamber to hold a volume of fluid to be analyzed and an impedance sensor disposed within the fluid chamber. The impedance sensor measures an impedance of the fluid in the fluid chamber. The fluid analysis system also includes an evaluator device electrically coupled to the impedance sensor. The evaluator device determines at least one property of the fluid based on the impedance.

Abstract: A method of distinguishing between fluids may include providing a current to an electrode disposed within a fluidic passageway of a fluidic die, the current to be forced into a fluid within the fluidic die, sensing an impedance at the electrode, and determining a particle vehicle separation level of the fluid based on the sensed impedance between a first instance and a second instance.

Abstract: In one example in accordance with the present disclosure, a fluidic system is described. The fluidic system includes a fluidic die. The fluidic die includes a substrate in which a number of fluid chambers are formed. Each fluid chamber includes a fluid actuator disposed within the fluid chamber. A number of actuator sensors are disposed on the substrate to output at least one value indicative of a sensed characteristic of fluid actuators. A number of substrate temperature sensors are also disposed on the substrate to sense a temperature for the substrate. An actuator evaluation device of the fluidic system determines a state of the fluid actuator based at least in part on the at least one value and at least one correction value associated with the temperature sensed by the number of substrate temperature sensors.

Abstract: In an example implementation, a method of reducing inkjet aerosol in a fluid drop ejection system includes imaging fluid drops from an ejection event as the drops travel from an ejection nozzle toward a substrate, determining the momentum of each fluid drop from the imaging, comparing the momentum of each fluid drop with a threshold momentum, and determining that a fluid drop will become aerosol when its momentum does not exceed the threshold momentum.

Abstract: A fluid particle concentration detection device may include at least one electrode disposed within a fluidic passageway of a fluidic die, and control circuitry to activate the electrode within the fluidic die. An impedance sensed at the electrode corresponds to a particle concentration within the fluid.

Abstract: An inkjet nozzle includes an aperture with a noncircular opening having a first segment substantially defined by a first polynomial equation and a second segment substantially defined by a second equation.

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: 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: 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: According to an example, in a method for enhancing temperature distribution uniformity across a printer die, in which the printer die includes a plurality of drop generators arranged in a plurality of columns, a warming map that identifies the drop generators of the plurality of drop generators that are to be supplied with warming pulses to enhance temperature distribution uniformity across the printer die may be accessed. The warming map may identify a non-uniform distribution of the drop generators across a column of the plurality of columns. In addition, the warming map may be implemented to supply the drop generators identified in the warming map as the drop generators that are to receive the warming pulses.

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.