Fluid dispenser device including a regulator to direct gas transverse a nozzle

Abstract

A dispenser device may include a fluid ejection device including an ejection chamber including a fluid actuator, an ejection nozzle, a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to eighty degrees, and a regulator to direct a compressed gas transverse the ejection nozzle from a compressed gas source. A method can include providing fluid to the dispenser device, directing compressed gas transverse the ejection nozzle from a compressed gas source to cause the fluid to pass through the fluid inlet channel into the ejection chamber, and dispensing the fluid from the ejection chamber of the dispenser device.

Description

FLUID DISPENSER DEVICE INCLUDING A REGULATOR TO DIRECT GAS TRANSVERSE A NOZZLECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to PCT Patent Application No.: PCT / US2023 / 084656, filed December 18, 2023 and PCT Patent Application No. PCT / US2023 / 084662, filed December 18, 2023, which applications are incorporated herein in their entirety.BACKGROUND

[0002] Fluid ejection devices deposit fluid onto a substrate to print in two or three dimensions. Fluid is ejected from a fluid ejection chamber. Fluid is provided to the fluid ejection chamber for ejection. Some fluid dispensing applications call for ejecting aqueous fluids without the use of any other chemical compounds (such as surfactants). Fluids with high surface tension such as aqueous fluids without chemical compounds that reduce surface tension (i.e., surfactants) may have a surface tension that impedes passage of the fluids through microfluidic passages into the fluid ejection chamber, preventing ejection from the fluid ejection chamber. While surfactants and other substances reduce surface tension and facilitate passage of fluids through microfluidic passages, substances such as surfactants cannot be used in all fluids, or for all dispensing applications.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. l is a block diagram of an example dispenser device.

[0004] FIG. 2 illustrates a cross-section of an example dispenser device.

[0005] FIG. 3 A is a perspective view of an example dispenser device.

[0006] FIG. 3B is a perspective view of the dispenser device of FIG. 3 A with an actuator engaged to position a compressed gas nozzle to direct gas transverse ejection nozzles of a microfluidic structure.

[0007] FIG. 4 illustrates a compressed gas nozzle adjacent a microfluidic structure to provide a flow of gas transverse nozzles of the microfluidic structure.

[0008] FIG. 5 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel which narrows in width towards the ejection chamber.

[0009] FIG. 6 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel which does not expand in width towards the ejection chamber.

[0010] FIG. 7 illustrates an example ejection chamber which expands in width, the ejection chamber fluidically connected to an example fluid inlet channel which expands in width from a pinch point towards the ejection chamber.

[0011] FIG. 8 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel which expands in width from a pinch point towards the ejection chamber.

[0012] FIG. 9 illustrates a cross section of an example ejection chamber fluidically connected to an example fluid inlet channel.

[0013] FIG. 10 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel including a pillar.

[0014] FIG. 11 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel including multiple pillars.

[0015] FIG. 12 is a block diagram of an example fluid ejection device with a protrusion extending into a fluid passage opening.

[0016] FIG. 13 is a block diagram of an example fluid ejection device with a wall of a fluid inlet channel extending into a fluid passage opening.

[0017] FIG. 14 is a block diagram of an example fluid ejection device with a portion of a pillar extending into a fluid passage opening.

[0018] FIG. 15 illustrates a cross-section of an example fluid ejection device.

[0019] FIG. 16 illustrates a cross-section of an example fluid ejection device including a protrusion extending from a shelf of a chamber layer adjacent a fluid passage opening into the fluid passage opening.

[0020] FIG. 17 illustrates a cross-section of an example fluid ejection device including a protrusion extending from a shelf of the chamber layer across a fluid passage opening.

[0021] FIG. 18 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel with walls of the fluid inlet channel extending into a fluid passage opening.

[0022] FIG. 19 illustrates an array of example ejection chambers fluidically connected to an array of example fluid inlet channels with walls of the fluid inlet channels extending into a fluid passage opening.

[0023] FIG. 20 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel with a pillar between the ejection chamber and a fluid passage opening extending into the fluid passage opening.

[0024] FIG. 21 illustrates a first array of example ejection chambers fluidically connected to a first array of example fluid inlet channels and a second array of example ejection chambers fluidically connected to a second array of example fluid inlet channels with protrusions extending across a fluid passage opening to connect first walls of the first array of fluid inlet channels with second pillars between the fluid passage opening and the second array ofejection chambers and second walls of the second array of fluid inlet channels with first pillars between the fluid passage opening and the first array of ejection chambers.

[0025] FIG. 22 illustrates a first array of example ejection chambers fluidically connected to a first array of example fluid inlet channels and a second array of example ejection chambers fluidically connected to a second array of example fluid inlet channels with protrusions extending across a fluid passage opening to connect first walls of the first array of fluid inlet channels with second walls of the second array of fluid inlet channels.

[0026] FIG. 23 illustrates a first array of example ejection chambers fluidically connected to a first array of example fluid inlet channels and a second array of example ejection chambers fluidically connected to a second array of example fluid inlet channels with protrusions extending across a fluid passage opening to connect first pillars between the fluid passage opening and the first array of ejection chambers with second pillars between the fluid passage opening and the second array of ejection chambers.

[0027] FIG. 24 illustrates a first array of example ejection chambers fluidically connected to a first array of example fluid inlet channels on a first side of a fluid passage opening and a second array of example ejection chambers fluidically connected to a second array of example fluid inlet channels on a second side of the fluid passage opening with a protrusion extending into the fluid passage opening on a third side of the fluid passage opening.

[0028] FIG. 25 illustrates a first array of example ejection chambers on a first side of a fluid passage opening and a second array of example ejection chambers on a second side of the fluid passage opening with a first protrusion extending into the fluid passage opening on a third side of the fluid passage opening and a second protrusion extending into the fluid passage opening on a fourth side of the fluid passage opening.

[0029] The foregoing and other features of the present disclosure will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that while these drawings depict several examples in accordance with the disclosure, they are, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.DETAILED DESCRIPTION

[0030] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative examples described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made part of this disclosure.

[0031] Fluid ejection devices include various components and structures for enabling the flow, storage, processing, and ejection of volumes of fluid. For example, in the context of fluid ejection for printing applications, volumes of marking fluids, such as for forming markings on a substrate (in the context of 2D printing) or building objects on a build plate (in the context of 3D printing), marking fluids may be delivered to an ejection chamber from a storage reservoir through a series of delivery components in varying volumes. In some examples, the volumes may be delivered by applying an external pressure to the fluidic passages through which fluids travel. In other examples, capillary forces may be relied upon to engender fluid flow.

[0032] Ejection of fluid from a fluid ejection chamber may be performed using any number of technologies, including, but not limited to, thermal and piezoelectric actuation. Thermal actuation refers to the use of a mechanism to rapidly heat fluids in the chamber, such as by using a resistor to boil a portion of the fluid and create a cavitation wave. The resulting bubble formation will eject a controlled fluidic droplet via an orifice (e.g., nozzle) of the fluid ejection chamber. Analogously, in the case of a piezoelectric actuator, current may be pulsed through a piezoelectric membrane, which, in turn will impart pressure on the fluid in the ejection chamber and eject a controlled fluidic droplet via an orifice. It is noted, however, that there are other methods of fluid ejection, and the foregoing is merely provided by way of illustration. It is also noted that ejection from an ejection chamber may refer to both ejection via an orifice and also ejection via a chamber outlet, such as on to a different fluidic passage or chamber.

[0033] In any case, the ability of a fluid ejection device to reliably eject fluidic droplets may be dependent on a fluid carrier, which refers to a component of a fluid mixture that is used to facilitate delivery of components and particles (e.g., pigments in the case of printing, intravenous drugs suspended in aqueous fluids in the case of IVs for healthcare, cells in the case of digital dispense, etc.). Some fluid carriers may be more challenging to eject with reliability.

[0034] In some contexts, there is a desire to cause fluid flow using capillary forces, such as instead of, or in addition to, applying a positive or a negative pressure to a fluid line from an external source (e.g., a pump or a vacuum) to cause fluid to flow. Analogously to the preceding discussion of fluid ejection, a number of factors, including the materials making up a fluid passage, fluid contact angles of a fluid carrier, characteristics of structures (e.g., shape), environmental temperature and barometric levels, etc., contribute to the ability to cause fluid to travel reliably through fluidic passages. Indeed, microfluidic structures maycause a fluid to be pinned before reaching the ejection chamber, preventing dispensing of the fluid. And as shall be discussed in greater detail hereinafter, whether or not a fluid travels through a fluid delivery system reliably using capillary forces depends, among other things, on the ability to keep ejection chambers primed (i.e., supplied with fluid to be ejected). The term “primed,” as used herein, means that the entire surface of the ejection chamber is filled up with or supplied with fluid. “Priming” can facilitate ejection of the fluid from the ejection chamber, such that the ejection chamber is “primed” for firing.

[0035] Fluid can form a meniscus and be pinned (i.e., stuck, prevented from progressing) within structures due to a geometry of the structures. The term “pinned,” as used herein, means that fluid is prevented from efficiently progressing through microfluidic passages. When a fluid is “pinned” within a fluid inlet channel to an ejection chamber, the fluid is unable to reach the ejection chamber. All fluids can be pinned within microfluidic structures dependent upon a geometry of the microfluidic structures, but fluids with higher surface tension are more readily pinned. For example, surfactant-free fluids (e.g., aqueous fluids containing cells for cell-dispensing applications) have higher surface tension and are more readily pinned within structures (e.g., microfluidic channels) than non-aqueous fluids such as fluids containing surfactants. Thus, fluids with higher surface tension can be pinned within structures that do not cause other fluids with lower surface tension to become pinned. In one example, a fluid with a higher surface tension such as an aqueous fluid is pinned within a fluid inlet channel fluidically connected to an ejection chamber. The pinned fluid does not reach the ejection chamber, preventing printing of the fluid using the ejection chamber.

[0036] Structures, such as fluid inlet channels, for printing surfactant-laden liquids generally have geometries that cause aqueous fluids to be pinned. Surfactant-free fluids, such as aqueous fluids, may be used in applications where surfactants are avoided. For example, celldispensing applications call for surfactant-free fluids, as surfactants can damage cellstructures. In order to avoid damage to cell structures, cells are suspended in surfactant-free fluids for dispensing of cells. Implementations discussed in the present description propose providing fluid inlet channels and / or protrusions extending from fluid inlet channels that facilitate priming of ejection chambers using capillary forces, allowing for use of some surfactant-free fluids, such as aqueous fluids, in dispensing applications. Implementations discussed in the present description provide for a regulator to direct compressed gas transverse ejection nozzles of ejection chambers to reduce pressure outside the ejection nozzles to further facilitate priming of the ejection chambers, allowing for use of additional surfactant-free fluids, such as aqueous fluids, in dispensing applications.

[0037] To illustrate these principles, the present description refers, without limitation, to the illustrative example of a digital dispensing device. Various microfluidic applications can be performed by a digital dispensing device. Microfluidic applications, such as dispensing cells suspended in aqueous fluid, call for careful control of amounts of fluid at scales where capillary forces dominate the movement of the fluid. As noted, a dispenser device may utilize a thermal process for dispensing fluid. For successful ejection, fluid needs to reach the thermal resistor inside the ejection chamber. However, microfluidic structures may cause a fluid to be pinned before reaching the ejection chamber, preventing dispensing of the fluid. In order for stable, consistent dispensing of fluids, microfluidic structures are needed that facilitate drawing fluids into ejection chambers and over thermal resistors. In an example, for controlled dispensing of cells suspended in an aqueous fluid, such as for 3D printing of biological material, microfluidic structures that facilitate drawing fluids into ejection chambers and over thermal resistors, as described herein, may be beneficial, such as to avoid pinning. Microfluidic structures that facilitate drawing fluids into ejection chambers include fluid inlet channels leading to the ejection chambers having an angle of expansion of less than or equal to eighty degrees. Additional microfluidic structures that facilitate drawing fluidsinto the ejection chambers include protrusions extending from the fluid inlet channels into a fluid passage opening fluidically connected to the fluid inlet channels.

[0038] This disclosure relates to fluid ejection devices and fluid dispensing devices. Specifically, this disclosure relates to a fluid dispenser device including a regulator to direct compressed gas transverse ejection nozzles of ejection chambers to reduce pressure outside the ejection nozzles to facilitate flow of liquid through microfluidic passages. The reduction in pressure outside the ejection nozzles can overcome pinning, or facilitate movement of a liquid through the microfluidic passages to facilitate movement of the liquid into firing chambers (i.e., priming). The reduction in pressure may be due to the “Venturi effect,” where a faster-moving gas or liquid has a lower pressure than a slower-moving gas or liquid, causing a reduction in pressure in passages or conduits exposed to regions of fast-moving gas or liquid.

[0039] As discussed herein, liquid (e.g., aqueous liquid) can get stuck (pinned) in the microfluidic passages due to liquid properties and interactions between the liquid and surfaces of the microfluidic passages (e.g., capillary forces, surface tension, etc.). Characteristics of the microfluidic passages such as a geometry of the microfluidic passages (e.g., angle of expansion) and structures extending into the microfluidic passages can facilitate movement of liquids through the microfluidic passages, but may not always result in liquid reaching the firing chambers. To facilitate movement of the liquid through the microfluidic passages, a regulator can directed compressed gas to flow transverse ejection nozzles of microfluidic structures to reduce pressure outside the ejection nozzles and pull the fluid toward the ejection nozzles and into ejection chambers. The reduction in press outside the ejection nozzles causes pressures pushing the fluid toward the ejection nozzles to overcome pressures pushing the fluid away from the ejection nozzles, resulting in a net force toward the ejection nozzles and toward the ejection chambers.

[0040] FIG. 1 is a block diagram of an example dispenser device 101. The dispenser device 101 includes a fluid ejection device 100 and a regulator 130.

[0041] The fluid ejection device 100 ejects fluid to enable the dispenser device 101 to dispense fluid. The fluid ejection device 100 includes a fluid inlet channel 120 and an ejection chamber 110. The fluid inlet channel 120 is fluidically connected to the ejection chamber 110 to supply fluid to the ejection chamber. The fluid inlet channel 120 may be fluidically connected to a reservoir or fluid passage opening (i.e., opening that fluidically connects the fluid inlet channel 120 to the reservoir). The fluid inlet channel 120 is a microfluidic channel such that microfluidic fluid properties dominate interaction of fluids with the fluid inlet channel 120. The fluid inlet channel 120 has an angle of expansion 122 to facilitate passage of fluid through the fluid inlet channel 120 into the ejection chamber 110, as discussed herein. The angle of expansion 122 defines an angle at which the fluid inlet channel 120 expands to connect to the ejection chamber 110. The angle of expansion 122 can be measured between opposite walls of the fluid inlet channel 120. In some implementations, the fluid inlet channel 120 does not expand along its entire length, and the angle of expansion 122 is measured from a narrowest point of the fluid inlet channel 120. In some implementations, the fluid inlet channel 120 includes a pillar and the angle of expansion 122 is measured between the walls of the fluid inlet channel 120 and the walls of the pillar. In these implementations, the fluid inlet channel 120 includes two effective angles of expansion, where a first angle of expansion is between a first wall of the fluid inlet channel 120 and a first wall of the pillar, and a second angle of expansion is between a second wall of the fluid inlet channel 120 and a second wall of the pillar, as illustrated in FIG. 10. In some implementations, the fluid inlet channel 120 includes multiple pillars, causing the fluid inlet channel 120 to include more than two angles of expansion, as illustrated in FIG. 11. In some implementations, the angle of expansion 122is less than or equal to eighty degrees. In some implementations, the angle of expansion 122 is less than forty or twenty degrees.

[0042] The angle of expansion 122 being less than or equal to eighty degrees renders the dispenser device 101 more efficient, as fluid passes more quickly through the fluid inlet channel 120 into the ejection chamber 110. Faster passage of fluid through the fluid inlet channel 120 to the ejection chamber 110 can allow the dispenser device 101 to dispense fluid more quickly and more efficiently. In an example, the angle of expansion 122 being less than or equal to eighty degrees allows the dispenser device 101 to dispense more drops per minute, with fewer priming failures calling for manual intervention, than similar dispenser devices with fluid inlet channels have angles of expansion greater than eighty degrees. Other mechanisms discussed herein for facilitating priming (e.g., protrusions into a fluid passage opening, gas flows) may also increase an efficiency of the dispenser device 101 and / or separately increase an efficiency of the dispenser device 101. Additional mechanisms for facilitating priming may improve the efficiency of the dispenser device 101 in dispensing particular fluids.

[0043] In an example, a fluid having a lowest surface tension primes efficiently without the use of mechanisms to facilitate priming and the efficiency of the dispenser device 101 in dispensing the fluid having the lowest surface tension is not affected by the use of mechanisms to facilitate priming, a fluid having a low surface tension primes efficiently only with the use of a protrusion into a fluid passage opening, a fluid having a high surface tension primes efficiently only with the use of a protrusion into a fluid passage opening and an angle of expansion of less than or eighty degrees, and a fluid having a highest surface tension only primes efficiently with the use of a protrusion into a fluid passage opening, an angle of expansion of less than or eighty degrees, and a gas flow transverse an ejection nozzle 114 of the dispenser device 101.

[0044] The ejection chamber 110 ejects fluid from an interior of the ejection chamber 110. The ejection chamber 110 includes a fluid actuator 112 and the ejection nozzle 114. The fluid actuator 112 causes fluid to be ejected from the ejection chamber 110 through the ejection nozzle 114. In an example, the fluid actuator 112 is a thermal resistor that causes cavitation bubbles in the fluid to cause the fluid to be ejected through the ejection nozzle 114.

[0045] The ejection chamber 110 fills with fluid for the fluid ejection device 100 to eject the fluid. The fluid may pass through the fluid inlet channel 120 via capillary forces to fill the ejection chamber 110. To facilitate passage of the fluid into the fluid inlet channel 120 and / or through the fluid inlet channel 120 into the ejection chamber 110, the regulator 130 directs compressed gas 132 transverse the ejection nozzle 114. The regulator 130 directs the gas 132 transverse the ejection nozzle 114 to cause the gas 132 to flow transverse the ejection nozzle 114 to cause a reduction in pressure outside the ejection nozzle 114 to draw the fluid toward the ejection nozzle 114 through the fluid inlet channel 120. The reduction in pressure outside the ejection nozzle 114 (i.e., at an opening of the ejection nozzle 114 opposite the ejection chamber 110) due to the flow of the gas 132 is termed the “Venturi effect.” The reduction in pressure disrupts an equilibrium of pressures on the fluid, causing a pressure pushing the fluid toward the ejection chamber 110 to be greater than a pressure pushing the fluid away from the ejection chamber 110.

[0046] In an example, with the dispenser device 101 at sea level, a pressure inside the fluid inlet channel 120 (pushing the fluid toward the ejection chamber 110 is one atmosphere and a pressure outside the ejection nozzle 114 (pushing the fluid away from the ejection chamber 110) is one atmosphere until the flow of the gas 132 reduces the pressure outside the ejection nozzle 114 to 0.99 atmospheres and causing the fluid to experience a net pressure of 0.01 atmospheres toward the ejection chamber 110. Reduction in pressure to disrupt a pressure equilibrium to cause movement is commonly referred to as “sucking.” Thus, the flow of thegas 132 operates to suck the fluid through the fluid inlet channel 120 into the ejection chamber110.

[0047] The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 to reduce pressure outside the ejection nozzle 114 (i.e., suck the fluid through the fluid inlet channel 120) to overcome pinning at an interface between a fluid passage opening and the fluid inlet channel 120 as illustrated in FIG. 15. The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 to reduce pressure outside the ejection nozzle 114 (i.e., suck the fluid through the fluid inlet channel 120) to overcome pinning within the fluid inlet channel 120. The reduction in pressure can disrupt or prevent formation of a meniscus that can stop passage of fluid into or through the fluid inlet channel (i.e., pinning).

[0048] The regulator 130 directs the compressed gas 132 transverse the ejection nozzle 114 from a compressed gas source. The regulator 130 controls a pressure from the compressed gas source that is directed transverse the ejection nozzle 114 (e.g., from a compressed gas nozzle). The regulator 130 can include a valve to allow the gas 132 to pass from the compressed gas source to flow transverse the ejection nozzle 114. The valve can be electromagnetically actuated in response to electrical signals. In some implementations, the regulator 130 includes a first valve to control a pressure of gas to be directed transverse the ejection nozzle 114 and the dispenser device 101 includes a second valve to release the gas at the pressure transverse the ejection nozzle 114.

[0049] In some implementations, the compressed gas source is part of, or coupled to, the dispenser device 101. In some implementations, the compressed gas source is separate from the dispenser device 101. In some implementations, the compressed gas source is an air compressor. In an example, the air compressor is coupled to the dispenser device 101. In an example, the air compressor is separate from the dispenser device 101 and delivers the gas 132 to the regulator 130 via tubing. In some implementations, the compressed gas source is acompressed gas tank. In an example, the compressed gas source is a CO2 cartridge. In an example, the compressed gas source is a nitrogen gas tank.. The gas 132 can be any gas. In an example, the gas 132 is air that has been compressed to provide gas flow transverse the ejection nozzle 114. In an example, the gas 132 is nitrogen.

[0050] In some implementations, the dispenser device 101 includes a plurality of ejection chambers each including a fluid actuator and an ejection nozzle, and the regulator 130 directs the gas 132 transverse the ejection nozzle of each chamber of the plurality of ejection chambers. In some implementations, the dispenser device 101 includes a plurality of fluid ejection devices including the plurality of ejection chambers. In some implementations, the fluid ejection device 110 includes the plurality of ejection chambers. In an example, the plurality of ejection chambers are positioned such that the gas 132 can flow transverse the plurality of ejection nozzles of the plurality of ejection chambers from a single source. In an example, the dispenser device 101 includes a manifold to direct the gas 132 transverse the plurality of ejection nozzles of the plurality of ejection chambers.

[0051] In some implementations, the fluid ejection device 100 includes a fluid passage opening fluidically connected to the fluid inlet channel and a protrusion extending from the fluid inlet channel 120 into the fluid passage opening, as discussed herein. In some implementations, the fluid ejection device 100 includes a fluid passage opening fluidically connected to the fluid inlet channel 120 and a protrusion extending from the fluid inlet channel 120 into the fluid passage opening, as discussed herein. Examples of protrusions extending into fluid passage openings are illustrated in FIGS. 16-25. The reduction in pressure outside the ejection nozzle 114 provided by the regulator 130 can cause the fluid to contact, or increase contact, with the protrusion to facilitate movement of the fluid out of the fluid passage opening and through the fluid inlet channel 120 into the ejection chamber 110.

[0052] In some implementations, the regulator 130 directs a predetermined amount of the compressed gas 132 transverse the ejection nozzle 114 to facilitate movement of the fluid through the fluid inlet channel 120 into the ejection chamber 110. The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 at different pressures, within the capacity of the compressed gas source. In an example, the regulator 130 directs the gas 132 transverse the ejection nozzle 114 at 10-100 psi. In an example, the regulator 130 directs the gas 132 transverse the ejection nozzle 114 at 40 psi. In an example, the regulator 130 directs the gas 132 transverse the ejection nozzle 114 at 65 psi. The regulator 130 may direct the gas 132 at a pressure corresponding to a target reduction in pressure. The target reduction in pressure can corresponding to a resultant force for causing movement of the fluid into the ejection chamber 110. In an example, the regulator 130 directs the gas 132 at a lower pressure for a fluid that primes successfully with a lower reduction in pressure and directs the gas 132 at a higher pressure for a fluid that primes successfully with a higher reduction in pressure. As the pressure outside the ejection nozzle 114 decreases as a speed of the gas 132 increases, ahigher pressure of gas 132 directed by the regulator 130 transverse the ejection nozzle 114 results in a greater reduction in pressure outside the ejection nozzle 114 and a greater resultant force on the fluid toward the ejection chamber 110.

[0053] The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 to overcome stoppage (i.e., pinning) of fluids in various locations in the fluid ejection device 100. The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 to overcome pinning at an interface between a fluid passage opening and the fluid inlet channel 120 as illustrated in FIG. 15. The regulator 130 can direct the gas 132 transverse the ejection nozzle 114 to overcome pinning within the fluid inlet channel 120. In some implementations, the regulator 130 directs the gas 132 transverse the ejection nozzle 114 at different pressures to overcome pinning in different locations in the fluid ejection device 100. In an example, theregulator 130 directs the gas 132 transverse the ejection nozzle 114 at a first pressure to overcome pinning at the interface between the fluid passage opening and the fluid inlet channel 120 and directs the gas 132 transverse the ejection nozzle 114 at a second pressure to overcome pinning within the fluid inlet channel 120, dependent upon where pinning occurs in the fluid ejection device 100.

[0054] The regulator 130 can direct a sequence of pulses of the compressed gas 132 transverse the ejection nozzle 114. The sequence of pulses of the compressed gas 132 are configured to facilitate movement of the fluid through the fluid inlet channel 120 into the fluid ejection device 100. The pulses in the sequence of pulses can have different pressures and / or different durations. In an example, the regulator 130 directs the gas 132 transverse the ejection nozzle 114 at a lower pressure and shorter duration to overcome pinning at the interface between the fluid passage opening and the fluid inlet channel 120 and then directs the gas 132 transverse the ejection nozzle 114 at a higher pressure and longer duration to overcome pinning within the fluid inlet channel 120.

[0055] The dispenser device 101 can include a compressed gas nozzle coupled to the regulator 130, the compressed gas nozzle directed transverse the ejection nozzle 114. The compressed gas nozzle can shape the flow of the gas 132 transverse the ejection nozzle 114. The compressed gas nozzle can cause the flow of the gas 132 to extend a predetermined distance and / or to cause a target reduction in pressure over the predetermined distance. In an example, the compressed gas nozzle is conical to increase a velocity of the gas 132.

[0056] In some implementations, the dispenser device 101 includes a mechanical actuator to move the compressed gas nozzle into position such that the compressed gas nozzle is directed transverse the ejection nozzle 114. The mechanical actuator may orient the compressed gas nozzle to direct the gas 132 transverse the ejection nozzle 114. The mechanical actuator may move the compressed gas nozzle to be adjacent the ejection nozzle 114. In an example, themechanical actuator moves the compressed gas nozzle along a row of ejection nozzles of the dispenser device 101 to direct the gas 132 transverse the row of ejection nozzles. The mechanical actuator can be an electromagnetic actuator or a pneumatic actuator. In an example, the mechanical actuator is a pneumatic actuator that is driven by the gas 132 to move the compressed gas nozzle into position. In an example, the mechanical actuator is a solenoid that is driven by electricity to move the compressed gas nozzle into position.

[0057] In some implementations, the dispenser device 101 includes an attachment site to couple the compressed gas source to the regulator 130. The attachment site can include a coupling for a gas hose in order to allow a compressed gas source that is external to the dispenser device 101 to be used. The attachment site is coupled to the regulator 130 for the regulator 130 to control flow of the gas 132 from the external compressed gas source. The external compressed gas source can be an air compressor, a compressed gas tank, or other compressed gas source. In an example, the external compressed gas source is an air compressor. In an example, the external compressed gas source is compressed gas from a set of pipes extending through a facility, sometimes referred to as “facility air,” where the set of pipes are provided with compressed gas from an air compressor or gas tank.

[0058] FIG. 2 illustrates a cross-section of an example dispenser device 201. The dispenser device 201 may be similar in structure and / or function to the dispenser device 101 of FIG. 1. The dispenser device 201 includes an ejection chamber 210 including a fluid actuator 212 and an ejection nozzle 214. A fluid inlet channel 220 fluidically connects the ejection chamber 210 to a fluid passage opening 218. A protrusion 216 extends from the fluid inlet channel 220 into the fluid passage opening 218 to facilitate movement of a fluid 202 through the fluid passage opening 218 into the fluid inlet channel 220 toward the ejection chamber 210.

[0059] A flow of a gas 232 is transverse to the ejection nozzle 214 to reduce a pressure outside the ejection nozzle 214 to cause pressure on the fluid 202 toward the ejection chamber 210 toovercome reduced pressure on the fluid 202 away from the ejection chamber 210, resulting in movement of the fluid 202 toward the ejection chamber 210. The flow of the gas 232 is directed transverse the ejection nozzle 214 by a regulator from a compressed gas source not shown in FIG. 2. In some implementations, the reduction in pressure caused by the flow of the gas 232 facilitates movement of the fluid 202 to contact the protrusion 216 and / or the fluid inlet channel 220, at which point a geometry (e.g., angle of expansion) of the fluid inlet channel 220 facilitates movement of the fluid 202 into the ejection chamber 210. A reduction in pressure sufficient to cause the fluid 202 to move through the fluid passage opening 218 and the fluid inlet channel 220 into the ejection chamber 210 depends upon characteristics of the fluid 202. In an example, the fluid 202 has a low surface tension and a low reduction in pressure caused by a low flow of the gas 232 is sufficient to cause the fluid 202 to prime the ejection chamber 210. In an example, the fluid 202 has a high surface tension and a high reduction in pressure caused by a high flow of the gas 232 is sufficient to cause the fluid 202 to prime the ejection chamber 210.

[0060] FIG. 3 A is a perspective view of an example dispenser device 301. The dispenser device 301 may be similar in structure and / or function to the dispenser device 101 of FIG. 1 and the dispenser device 201 of FIG. 2. The dispenser device 301 includes a microfluidic structure 340, otherwise referred to as a “cassette.” The microfluidic structure 340 includes a fluid ejection device including a plurality of fluid inlet channels and ejection chambers. The plurality of fluid inlet channels and ejection chambers can include structures such as those illustrated in FIGS. 5-11 and 18-25. The microfluidic structure 340 receives fluid for ejection using the plurality of ejection chambers. The fluid ejection device includes a reservoir that is fluidically connected to the plurality of fluid inlet channels and ejection chambers. Fluid passes through microfluidic channels from the reservoir to the ejection chambers of the fluid ejection device. In some implementations, the microfluidic structure includes a plurality offluid ejection devices each including a reservoir fluidically connected to a plurality of fluid inlet channels and ejection chambers.

[0061] The dispenser device 301 includes a regulator 330 coupled to a compressed gas source 331. The regulator 330 directs gas from the compressed gas source 331 transverse ejection nozzles of the microfluidic structure 340. The dispenser device 301 includes an actuator 334 to move a compressed gas nozzle 360 (not shown in FIG. 3A) into position to provide a flow of gas transverse the nozzles of the microfluidic structure 340. The flow of gas reduces a pressure outside the nozzles of the microfluidic structure 340 to facilitate passage of fluid into ejection chambers of the microfluidic structure 340. In FIG. 3 A, the actuator 334 has not been activated to move the compressed gas nozzle 360 into position.

[0062] The dispenser device 301 includes an electronic interface 350 that provides electrical signals to the microfluidic structure 340. The electronic interface 350 provides electrical signals to the microfluidic structure 340 to cause ejection of fluid from the microfluidic structure 340. The electronic interface 350 provides electrical signals to the microfluidic structure 340 to power and control fluid actuators of the microfluidic structure 340 to cause the microfluidic structure 340 to dispense fluid.

[0063] FIG. 3B is a perspective view of the dispenser device 301 of FIG. 3 A with the actuator 334 engaged to position the compressed gas nozzle 360 to direct the gas 332 transverse ejection nozzles of the microfluidic structure 340. In some implementations, the actuator 334 is a pneumatic actuator that is powered by gas from the compressed gas source 331. In some implementations, the actuator 334 is an electromagnetic actuator (e.g., solenoid) that is powered by electricity. The compressed gas nozzle 360 may be positioned away from the nozzles of the microfluidic structure 340 when the actuator 334 is not activated to allow for movement of the microfluidic structure 340 and then moved into position by the actuator 334 to facilitate priming of ejection chambers of the microfluidic structure 340.

[0064] The regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340 after fluid has been added to the reservoir of the microfluidic structure 340. The regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340 at a predetermined time after fluid is added to the reservoir of the microfluidic structure 340. In some implementations, the regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340 in response to a failure of liquid to reach the ejection chambers of the fluid ejection device (i.e., a priming failure). In some implementations, the priming failure is detected by detecting a failure to eject fluid. In some implementations, the priming failure is detected using priming sensors that indicate whether ejection chambers are primed (i.e., filled with fluid). The regulator 330 can direct the gas 332 transverse the nozzles of the microfluidic structure 340 based on priming feedback. In an example, the regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340, fluid ejection is attempted, and the regulator 330 again directs the gas 332 transverse the nozzles of the microfluidic structure 340 if the fluid ejection failed. In this example, the regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340 until the fluid ejection is successful. In an example, the regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340, priming sensors indicate whether priming is successful, and the regulator 330 again directs the gas 332 transverse the nozzles of the microfluidic structure 340if the priming failed. In this example, the regulator 330 directs the gas 332 transverse the nozzles of the microfluidic structure 340 until the priming is successful.

[0065] An example method for priming the ejection chambers of the microfluidic structure 340 of the dispenser device 301 includes providing fluid to the dispenser device 301. In some implementations, providing fluid to the dispenser device 301 includes providing fluid to a reservoir of a fluid ejection device of the dispenser device 301, the fluid ejection device including an ejection chamber including a fluid actuator and an ejection nozzle, a fluid inletchannel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to eighty degrees. The reservoir of the fluid ejection device is fluidically connected to the fluid inlet channel via a fluid passage opening in the fluid ejection device.

[0066] The method includes directing, by the regulator 330, the compressed gas 332 transverse the ejection nozzle from the compressed gas source 331 to cause the fluid to pass through the fluid inlet channel into the ejection chamber and dispensing the fluid from the ejection chamber of the dispenser device 301. As shown in FIG. 3B, the dispenser device 301 can include the compressed gas source 331. The compressed gas source 331 can be an air compressor or a compressed gas tank. Directing the compressed gas 332 transverse the ejection nozzle can include providing an electrical signal to the regulator 330 coupled to the compressed gas source 331. The regulator 330 can include a valve that is electromechanically actuated to direct the compressed gas 332 from the compressed gas source 331 transverse the ejection nozzle. In some implementations, the regulator 330 includes a first valve to control a pressure of gas to be directed transverse the ejection nozzle 114 and the dispenser device 301 includes a second valve to release the gas at the pressure transverse the ejection nozzle 114. The method can include controlling (e.g., using electrical signals) the first valve to control an amount of pressure for the gas 332 and controlling the second valve to release the gas 332 with the controlled amount of pressure.

[0067] As discussed herein, the method can include verifying that the ejection chamber was primed by either attempting to dispense the fluid or by using a sensor coupled to the ejection chamber (e.g., a priming sensor). In an example, the method includes verifying that the fluid passed through the fluid inlet channel into the ejection chamber by either attempting to dispense the fluid or using a sensor coupled to the ejection chamber. In some implementations, the dispenser device 310 can include a plurality of ejection chambers eachincluding a fluid actuator and an ejection nozzle. The method can include directing the compressed gas 332 transverse the ejection nozzle of each ejection chamber of the plurality of ejection chambers.

[0068] In some implementations, the electronic interface 350 triggers activation of the actuator 334 and / or the regulator 330. The electronic interface 350 may trigger activation of the actuator 334 and / or the regulator 330 based on a presence of fluid in a reservoir of the microfluidic structure 340 to facilitate priming of ejection chambers of the microfluidic structure 340. Activating the regulator 330 can include providing an electrical signal to electromagnetically actuate a valve of the regulator 330. In some implementations, the electronic interface 350 triggers activation of the regulator 330 and a release valve, where the regulator 330 controls an amount of pressure of the gas 332 and the release valve releases the gas 332 at the controlled pressure to the compressed gas nozzle 360.

[0069] In an example, a user provides (e.g., dispenses, pipettes) fluid to the microfluidic structure 340 and the electronic interface 350 triggers activation of the actuator 334 and / or the regulator 330 to facilitate movement of the fluid into the ejection chambers of the microfluidic structure 340. In this example, the electronic interface 350 triggers activation of the actuator 334 and / or the regulator 330 after a predetermined interval of time after the fluid is provided to ensure the fluid travels through the microfluidic structure 340 to either prime the ejection chambers or prevent formation of a meniscus (e.g., at the interface between the fluid passage opening and the fluid inlet channel). In some implementations, the electronic interface 350 triggers activation of the actuator 334 and / or the regulator 330 in response to the electronic interface 350 coming into electrical contact with the microfluidic structure 340. In some implementations, the electronic interface 350 triggers activation of the actuator 334 and / or the regulator 330 in response to the electronic interface 350 receiving a signal from apriming sensor of the microfluidic structure that a firing chamber has failed to prime (i.e., does not include liquid).

[0070] FIG. 4 illustrates a compressed gas nozzle 460 adjacent a microfluidic structure 440 to provide a flow of gas transverse nozzles of the microfluidic structure 440. The microfluidic structure 440 includes a first dispense head 441a, a second dispense head 441b, a third dispense head 441c, a fourth dispense head 44 Id, a fifth dispense head 44 le, a sixth dispense head 44 If, a seventh dispense head 441g, and an eighth dispense head 44 Ih, referred to collectively as dispense heads 441. Each of the dispense heads 441 includes a fluid ejection device including a plurality of ejection chambers with corresponding nozzles and fluidically connected to a corresponding fluid inlet channel, where each fluid inlet channel has an angle of expansion of less than or equal to eighty degrees. The compressed gas nozzle 460 is positioned adjacent the dispense heads 441 to direct compressed gas transverse the dispense heads 441 and thus transverse the ejection nozzles of the dispense heads 441. While the dispense heads 441 are illustrated as including eight dispense heads, the dispense heads 441 can include any number of dispense heads. In an example, the dispense heads 441 include one dispense head. In an example, the dispense heads 441 include four dispense heads. In an example, the dispense heads 441 include twelve dispense heads.

[0071] The flow of the compressed gas transverse the nozzles of the dispense heads 441 varies based on distance from the compressed gas nozzle 460. The first dispense head 441a is 0mm from the compressed gas nozzle 460, the second dispense head 441b is 9mm from the compressed gas nozzle 460, the third dispense head 441c is 18mm from the compressed gas nozzle 460, the fourth dispense head 44 Id is 27mm from the compressed gas nozzle 460, the fifth dispense head 441e is 36mm from the compressed gas nozzle 460, the sixth dispense head 441f is 45mm from the compressed gas nozzle 460, the seventh dispense head 441g is 54mm from the compressed gas nozzle 460, and the eighth dispense head 441h is 9mm fromthe compressed gas nozzle 460. The gas flow slows as a distance from the compressed gas nozzle 460 increases due to friction between the gas flow and the microfluidic structure 440 and turbulence. Thus, the first dispense head 441a experiences a faster flow of gas and a higher resulting reduction in pressure than the second dispense head 441b which experiences a faster flow of gas and a higher resulting reduction in pressure than the third dispense head 441c, with each successive dispense head experiencing a slower flow of gas and a lower resulting reduction in pressure as the distance from the compressed gas nozzle 460 increases.

[0072] Table 1 includes example testing data for the dispense heads 441 of the microfluidic structure 440, showing how distance from the compressed gas nozzle 460 reduces an effectiveness of the gas flow in facilitating priming of ejection chambers of the dispense heads 441. In Table 1, the first dispense head 441a is referred to as “DH1,” with the remaining dispense heads 441 referred to in similar manner. In Table 1, the psi (pounds per square inch) values correspond to a psi directed by a regulator to the compressed gas nozzle 460 from a compressed gas source.Table 1

[0073] The testing results in Table 1 correspond to use of a fluid which results in a prime success rate of less than 100% in the microfluidic structure absent reduction in pressure outside the ejection nozzles of the dispense heads 441. The dispense heads 441 of the microfluidic structure 440 each include structures as described in FIGS. 1 and 2, including fluid inlet channels having an angle of expansion of less than or equal to eighty degrees. As shown in Table 1, different pressures of compressed gas result in priming in different dispenseheads, where dispense heads farther from the compressed gas nozzle 460 were not primed as effectively as dispense heads nearer to the compressed gas nozzle 460. For example, Table 1 shows that with compressed gas delivered at 40 psi to the compressed gas nozzle 460, the first dispense head 441 through the sixth dispense head 441f successfully primed, while the seventh dispense head 441g and the eighth dispense head 441h did not successfully prime. Table 1 shows that with compressed gas delivered at 63 psi to the compressed gas nozzle 460, all of the dispense heads 441 successfully primed.

[0074] In some implementations, multiple compressed gas nozzles are provided to deliver gas flow transverse the ejection nozzles of the dispense heads 441. In an example, a first compressed gas nozzle is provided on one end of the microfluidic structure 440 (i.e., where the compressed gas nozzle 460 is located) and a second compressed gas nozzle is provided on an opposite end of the microfluidic structure 440, and the first and second compressed gas nozzles deliver gas flow at different times to successfully prime ejection chambers of the dispense heads 441. In an example, the microfluidic structure 440 includes a manifold to deliver gas flow from a single source (e.g., the compressed gas nozzle 460) directly adjacent each of the dispense heads 441.

[0075] A combination of fluidic structure characteristics and sufficiently high pressures delivered to the compressed gas nozzle 460 may result in successful priming with a fluid, where the fluidic structure characteristics and high pressures individually may not result in priming with the fluid. The fluidic structure characteristics include a fluid inlet channel having an angle of expansion of less than or equal to eighty degrees. As noted above, Table 1 shows results for a combination of the fluid inlet channels of the microfluidic structure 440 having an angle of expansion of less than or equal to eighty degrees and a reduction in pressure provided by the gas directed transverse the ejection nozzles of the dispense heads 441. However, the same gas flows (provided at the same pressures) do not result in successfulpriming in microfluidic structures having fluid inlet channels having an angle of expansion greater than eighty degrees. The combination of the angle of expansion less than or equal to eighty degrees and the reduction in pressure provided by the gas flow facilitates successful priming in the microfluidic structure.

[0076] Table 2 includes example testing data for dispense heads of a microfluidic structure including fluid inlet channels having an angle of expansion greater than eighty degrees. Table 2 shows, as discussed above, how the same pressures as applied in Table 1 do not result in priming in microfluidic structures including fluid inlet channels having an angle of expansion greater than eighty degrees.Table 2

[0077] While Table 2 shows that none of the dispense heads of the microfluidic structure including fluid inlet channels having an angle of expansion greater than eighty degrees were successfully primed (i.e., ejection chambers were not successfully primed), higher pressures resulting in faster gas flows causing greater reductions in pressure may facilitate successful priming.

[0078] FIG. 5 illustrates an example ejection chamber 532 fluidically connected to an example fluid inlet channel 536 which narrows in width towards the ejection chamber 532. The ejection chamber 532 includes a fluid actuator 522. The fluid actuator 522 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 532. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 522 may extend from the ejection chamber 532 into the fluid inlet channel 536. The fluid inletchannel 536 is on a shelf 524 of a fluid ejection device. The fluid inlet channel 536 fluidically connects a fluid passage opening 512 of the fluid ejection device to the ejection chamber 532.

[0079] The fluid inlet channel 536 has a negative angle of expansion, as the fluid inlet channel narrows in width towards the ejection chamber 532. The negative angle of expansion may cause a fluid to prime the ejection chamber 532. The negative angle of expansion may not prevent blowback from the ejection chamber into the fluid inlet channel 536 as effectively as a fluid inlet channel that narrows along a portion of the fluid inlet channel. When the fluid actuator 522 ejects the fluid from the ejection chamber 532, fluid is ejected out of the ejection chamber 532 through a nozzle (in a direction out of the page) and fluid is pushed through the fluid inlet channel 536 away from the ejection chamber 532, which backflow of fluid through the fluid inlet channel 536 is referred to as “blowback.”

[0080] FIG. 6 illustrates an example ejection chamber 632 fluidically connected to an example fluid inlet channel 636 which does not expand in width towards the ejection chamber 632. The ejection chamber 632 includes a fluid actuator 622. The fluid actuator 622 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 632. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 622 may extend from the ejection chamber 632 into the fluid inlet channel 636. The fluid inlet channel 636 is on a shelf 624 of a fluid ejection device. The fluid inlet channel 636 fluidically connects a fluid passage opening 612 of the fluid ejection device to the ejection chamber 632.

[0081] The fluid inlet channel 636 has an angle of expansion of approximately zero from the narrowest portion of the fluid inlet channel 636 to the width of the ejection chamber 632. The angle of expansion of approximately zero is zero, plus or minus five degrees (0±5°). The angle of expansion of approximately zero causes the fluid inlet channel 636 to have a constant width the same as a width of the ejection chamber 632 from the narrowest point of the fluid inlet channel 636 to the width of the ejection chamber 632. The angle of expansion ofapproximately zero may cause a fluid to prime the ejection chamber 632. The angle of expansion of approximately zero may not prevent blowback from the ejection chamber into the fluid inlet channel 636 as effectively as a fluid inlet channel that narrows along a portion of the fluid inlet channel.

[0082] FIG. 7 illustrates an example ejection chamber 732 which expands in width, the ejection chamber 732 fluidically connected to an example fluid inlet channel 736 which expands in width from a pinch point 735 towards the ejection chamber 732. The pinch point 735 is where the fluid inlet channel 736 transitions from narrowing in width towards the ejection chamber 732 to expanding in width towards the ejection chamber 732. The ejection chamber 732 includes a fluid actuator 722. The fluid actuator 722 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 732. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 722 may extend from the ejection chamber 732 into the fluid inlet channel 736. The fluid inlet channel 736 is on a shelf 724 of a fluid ejection device. The fluid inlet channel 736 fluidically connects a fluid passage opening 712 of the fluid ejection device to the ejection chamber 732.

[0083] The fluid inlet channel 736 has an angle of expansion of about fifteen degrees from the pinch point 735 of the fluid inlet channel 736 to the full width of the ejection chamber 732. In some implementations the ejection chamber 732 expands in width along approximately half of a length of the ejection chamber 732 to the full width of the ejection chamber 732. The expansion in width of the ejection chamber 732 allows for a smaller angle of expansion of the fluid inlet channel 736, as the fluid inlet channel 736 expands from the pinch point 735 to a portion of the full width of the ejection chamber 732.

[0084] The angle of expansion of about fifteen degrees may cause a fluid to prime the ejection chamber 732. In an example, the fluid inlet channel 736 and the ejection chamber 732 have side walls of SU8 such that an aqueous fluid would, according to Expression 1, prime theejection chamber 732 through the fluid inlet channel 736, as fifteen degrees is less than the twenty degrees for water and SU8 under Expression 1. The pinch point 735 mitigates blowback from the ejection chamber 732.Expression 1 : oc < 2(90° — 0)

[0085] In Expression 1, oc represents the angle of expansion 122 and 9 represents the contact angle between the material of the fluid inlet channel 120 and the fluid. The fluid may be an aqueous fluid. In some implementations, the angle of expansion 122 (oc) may be less than or equal to two to four (2-4) times the difference between the right angle (90°) and the contact angle (9) between a material of the fluid inlet channel and the fluid, dependent upon differences in capillary forces from the top and bottom of the fluid inlet channel 120, part-to- part variation in a fabrication process, and / or contamination. In an example, when the top and bottom of the fluid inlet channel 120 are close enough to contribute capillary forces to prime the ejection chamber, stable priming can be achieved when the angle of expansion 122 is less than or equal to three or four times the difference between the right angle (90°) and the contact angle (9) between a material of the fluid inlet channel and the fluid. In some implementations, the aqueous fluid is any fluid in which the solvent is water.

[0086] FIG. 8 illustrates an example ejection chamber 832 fluidically connected to an example fluid inlet channel 836 which expands in width from a pinch point 835 towards the ejection chamber 832. The ejection chamber 832 includes a fluid actuator 822. The fluid actuator 822 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 832. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 822 may extend from the ejection chamber 832 into the fluid inlet channel 836. The fluid inlet channel 836 is on a shelf 824 of a fluid ejection device. The fluid inlet channel 836 fluidically connects a fluid passage opening 812 of the fluid ejection device to the ejection chamber 832.

[0087] The fluid inlet channel 836 has an angle of expansion of about forty degrees from the pinch point 835 of the fluid inlet channel 836 to the width of the ejection chamber 832. The angle of expansion of about forty degrees may cause a fluid to prime the ejection chamber 832. The angle of expansion of about forty degrees may not follow the inequality set forth in Expression 1. However, as discussed herein, Expression 1 represents a conservative estimate for a maximum angle of expansion, with safety margins for stable priming. The angle of expansion of about forty degrees may be less stable than an angle of expansion following the inequality in Expression 1. As discussed herein, the angle of expansion of about forty degrees may cause the fluid to prime the ejection chamber 832 as the angle of expansion of about forty degrees is less than or equal to two to four times a difference between the right angle and the contact angle between the material of the fluid inlet channel 836 and the aqueous fluid. In an example, if the contact angle is eighty degrees, four times the difference between the right angle of ninety degrees and eighty degrees is forty degrees. The pinch point 835 mitigates blowback from the ejection chamber 832. As the ejection chamber 832 does not narrow in width as the ejection chamber 732 of FIG. 7, the ejection chamber 832 may have a larger area than the ejection chamber 732 of FIG. 7.

[0088] FIG. 9 illustrates a cross section of an example ejection chamber 932 fluidically connected to an example fluid inlet channel 936. The ejection chamber 932 may include and / or be adjacent and fluidically connected to a nozzle 942 in a nozzle layer 940. The ejection chamber 932 may include and / or be adjacent a fluid actuator 922 in an actuator layer 920 of a fluid ejection device including the ejection chamber 932. The actuator layer 920 may be adjacent a substrate layer 910 of the fluid ejection device.

[0089] A top surface of the fluid inlet channel 936 is formed by the nozzle layer 940. A bottom surface of the fluid inlet channel 936 is formed by a thin film 924 in the actuator layer 920. The thin film 924 may overlay the fluid actuator 922. The thin film 924 may form a shelfof the actuator layer 920. The nozzle layer 940 has a continuous material along the length of the fluid inlet channel 936, causing the top surface of the fluid inlet channel 936 to have a continuous surface material. The thin film 924 has a continuous material along the length of the fluid inlet channel 936, causing the bottom surface of the fluid inlet channel 936 to have a continuous surface material. Side walls of the fluid inlet channel 936 have a continuous material along the length of the fluid inlet channel, causing the side surfaces of the fluid inlet channel 936 to have a continuous surface material. Each surface of the fluid inlet channel 936 may have a continuous surface material.

[0090] The surfaces of the fluid inlet channel 936 may have different surface materials. In an example, the thin film 924 is a first material which is a continuous bottom surface material of the fluid inlet channel 936, the nozzle layer 940 is a second material which is a continuous top surface material of the fluid inlet channel 936, and the side walls of the fluid inlet channel 936 are a third material which is a continuous sides surface of the fluid inlet channel 936.

[0091] The nozzle layer 940 and the thin film 924 may be substantially parallel along the length of the fluid inlet channel 936. The ceiling (formed by the nozzle layer 940) and the floor (formed by the thin film 924) of the fluid inlet channel 936 may have minimal topographical changes. The ceiling and floor of the fluid inlet channel 936 may be continuous surfaces, uninterrupted by shelfs, edges, turns, or other topographical changes. The fluid inlet channel 936 may have a constant height along the length of the fluid inlet channel 936. The constant height of the fluid inlet channel 936 may facilitate priming of the ejection chamber 932. Expansion in the height of the fluid inlet channel 936 may prevent priming and cause a fluid to be pinned in the fluid inlet channel 936. In an example, an additional layer of material on the thin film 924 which ends in the fluid inlet channel 936, resulting in a shelf (e.g., 90- degree edge) from the additional layer to the thin film 924 (an angle of expansion of ninety degrees) may cause a fluid to be pinned in the fluid inlet channel 936. In an example, anadditional layer on the thin film 924 of four pm with an angle of expansion of approximately ninety degrees from the additional layer to the thin film 924 can cause a fluid to be pinned in the fluid inlet channel 936. In an example, an additional layer on the thin film 924 of half a micron with an angle of expansion of approximately ninety degrees from the additional layer to the thin film 924 can cause a fluid to be pinned in the fluid inlet channel 936.

[0092] To facilitate priming of the ejection chamber 932, the fluid inlet channel 936 has continuous surface materials and / or a constant or narrowing height along the length of the fluid inlet channel 936. The thin film 924 can be raised above the fluid actuator 922, causing the height of the fluid inlet channel 936 to be reduced where the fluid actuator 922 extends beyond the ejection chamber 932 into the fluid inlet channel 936. In some examples, the thin film 924 includes a bevel where the thin film 924 is raised over the fluid actuator 922. The point on the thin film 924 in the fluid inlet channel 936 where the thin film 924 extends over the fluid actuator 922 may be referred to as a “threshold” of the fluid actuator 922. In some examples, a structure extending from within the fluid inlet channel 936 over the threshold of the fluid actuator 922 can facilitate priming of the ejection chamber 932, as illustrated in FIG. 10.

[0093] FIG. 10 illustrates an example ejection chamber 1032 fluidically connected to an example fluid inlet channel 1036 including a pillar 1034. The ejection chamber 1032 includes a fluid actuator 1022. The fluid actuator 1022 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 1032. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 1022 may extend from the ejection chamber 1032 into the fluid inlet channel 1036. The fluid inlet channel 1036 is on a shelf 1024 of a fluid ejection device. The fluid inlet channel 1036 fluidically connects a fluid passage opening 1012 of the fluid ejection device to the ejection chamber 1032.

[0094] The fluid inlet channel 1036 has an angle of expansion of about thirty degrees from the pinch point 1035 of the fluid inlet channel 1036 to the width of the ejection chamber 1032 on either side of the pillar 1034. The pillar 1034 may serve to reduce the angle of expansion by providing additional surfaces between the side walls of the fluid inlet channel 1036 such that portions of the fluid inlet channel formed on opposite sides of the pillar 1034 have a smaller angle of expansion than measured between the side walls of the fluid inlet channel 1036. The pillar 1034 reduces the effective width of the fluid inlet channel 1036, increasing capillary forces drawing the fluid through the fluid inlet channel 1036 and into the ejection chamber 1032 and facilitating priming of the ejection chamber 1032. In an example, the fluid inlet channel 1036 has an angle of expansion of about forty degrees as measured between side walls of the fluid inlet channel 1036 and angles of expansion of about thirty degrees as measured between the side walls of the fluid inlet channel and the pillar 1034. As fluid contacts the side walls of the fluid inlet channel 1036 and the pillar 1034, priming of the ejection chamber 1032 is facilitated by the angles of expansion as measured between the side walls of the fluid inlet channel and the pillar 1034. The pillar 1034 is illustrated as having equal angles of expansion on either side of the pillar 1034, but different angles of expansion can be present on different sides of the pillar 1034.

[0095] The pillar 1034 includes a leading edge towards the fluid passage opening 1012 and a trailing edge towards the ejection chamber 1032. The trailing edge extends along the fluid inlet channel 1036 from the pinch point 1035 toward the ejection chamber 1032. In some implementations, the leading edge of the pillar 1034 extends into the ejection chamber 1032. In some implementations, the leading edge of the pillar 1034 extends over a threshold 1023 of the fluid actuator 1022. The trailing edge of the pillar 1034 extending over the threshold 1023 of the fluid actuator 1022 and / or extending into the ejection chamber 1032 facilitates priming of the ejection chamber 1032. The threshold 1023 is a point in the fluid inlet channel1036 to which the fluid actuator 1022 extends, resulting in a slight change in topography in the floor of the fluid inlet channel 1036. The trailing edge of the pillar 1034 extending over the threshold 1023 and corresponding topographical change in the fluid inlet channel 1036 facilitates priming of the ejection chamber 1032.

[0096] The pillar 1034 may have a diamond-shaped cross-section, as illustrated in FIG. 10. The diamond-shaped cross-section prevents pinning of fluids on the pillar 1034 by allowing for a gradual angle of expansion on the trailing edge of the pillar 1034. As discussed herein, the pillar 1034 includes a widening portion on the leading edge of the pillar 1034 and a tapering portion on the trailing edge of the pillar 1034. An angle of pillar narrowing of the tapering portion on the trailing edge of the pillar 1034 affects the angle of expansion of the fluid inlet channel 1036 from the pinch point 1035 to the ejection chamber 1032. In some implementations, the angle of pillar narrowing is five to thirty degrees. In an example, the angle of pillar narrowing is ten degrees. In an example, the angle of pillar narrowing is fifteen degrees. In an example, the angle of pillar narrowing is twenty degrees.

[0097] The angle of expansion of about thirty degrees may cause a fluid to prime the ejection chamber 1032, dependent upon interactions between the fluid and the surface materials of the fluid inlet channel 1036 and / or the pillar 1034. The pinch point 1035 and the pillar 1034 mitigate blowback from the ejection chamber 1032. The pillar 1034 reduces blowback by serving as an obstacle within the fluid inlet channel 1036 which resists blowback.

[0098] FIG. 11 illustrates an example ejection chamber 1132 fluidically connected to an example fluid inlet channel 1036 including a first pillar 1134a and a second pillar 1134b, referred to collectively herein as pillars 1134. The ejection chamber 1132 includes a fluid actuator 1122. The fluid actuator 1122 may be a resistor to heat up fluid to eject the fluid out of the ejection chamber 1132. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 1122 may extend from the ejection chamber 1132into the fluid inlet channel 1136. The fluid inlet channel 1136 is on a shelf 1124 of a fluid ejection device. The fluid inlet channel 1136 fluidically connects a fluid passage opening 1112 of the fluid ejection device to the ejection chamber 1132.

[0099] The fluid inlet channel 1136 has an angle of expansion of about twenty-five degrees from the pinch point 1135 of the fluid inlet channel 1136 to the width of the ejection chamber 1132 between a left side wall of the fluid inlet channel 1136 and a left side of the first pillar 1134a, between a right side of the first pillar 1134a and a left side of the second pillar 1134b, and between a right side of the second pillar 1134b and a right side wall of the fluid inlet channel 1136. The pillars 1134 serve to reduce the angle of expansion by providing additional surfaces between the side walls of the fluid inlet channel 1136 such that portions of the fluid inlet channel 1136 formed between the pillars 1134 and between the pillars 1134 and the side walls of the fluid inlet channel 1136 have a smaller angle of expansion than measured between the side walls of the fluid inlet channel 1136. In an example, the fluid inlet channel 1136 has an angle of expansion of about forty degrees as measured between side walls of the fluid inlet channel 1136 and angles of expansion of about twenty-five degrees as measured between the side walls of the fluid inlet channel 1136 and the pillars 1134 and between the pillars 1134. As fluid contacts the side walls of the fluid inlet channel 1136 and the pillars 1134, priming of the ejection chamber 1132 is facilitated by the angles of expansion as measured between the side walls of the fluid inlet channel and the pillars 1134 and between the pillars 1134. The pillars 1134 are illustrated as having equal angles of expansion on opposite sides of the pillars 1134 and between the pillars, but different angles of expansion may be present on different sides of the pillars 1134 and / or between the pillars 1134. While the pillars 1134 are illustrated as being located at a same location along the length of the fluid inlet channel, the pillars 1134 may be at different locations along the length of the fluid inlet channel. While two pillars are illustrated, any number of pillars may be present in the fluid inlet channel 1136.

[0100] The pillars 1134 each include a leading edge towards the fluid passage opening 1112 and a trailing edge towards the ejection chamber 1132, as described herein.

[0101] In some examples, the ejection chamber 1132 has a width of about 53 pm and a length of about 52 pm. In some examples, the fluid inlet channel 1136 has a width of about 70 pm at its widest point (inlet). In some examples, the fluid inlet channel 1136 has a width of about 40 pm at its narrowest point (the pinch point 1135). In some examples, the pillars 1134 have a width of about 7 pm at their widest point. In some examples, the pillars 1134 have a length of about 26.5 pm.

[0102] In some examples, the fluid inlet channel 120 can have a channel height from 2 pm to 100 pm, or from 5 pm to 80 pm, or from 10 pm to 50 pm, or from 10 pm to 30 pm, or from 10 pm to 20 pm, or from 20 pm to 50 pm, or from 20 pm to 80 pm. In some examples, the fluid inlet channel 120 can have a width from 5 pm to 200 pm, or from 10 pm to 150 pm, or from 10 pm to 100 pm, or from 10 pm to 80 pm, or from 15 pm to 60 pm, or from 20 pm to 45 pm, or from 20 pm to 100 pm.

[0103] FIG. 12 is a block diagram of an example fluid ejection device 1200 with a protrusion 1234 extending into a fluid passage opening 1212. The fluid passage opening 1212 is fluidically connected to a chamber layer 1230. The chamber layer 1230 is a layer of the fluid ejection device 1200 (e.g., layer formed using lithography) that includes an ejection chamber 1232. A floor of the ejection chamber 1232 includes a fluid actuator in an actuator layer 1220 adjacent the chamber layer 1230. The fluid ejection device 1200 includes a nozzle orifice 1242 fluidically connected to the ejection chamber 1232. The fluid ejection device 1200 includes a protrusion in the chamber layer 1230 extending from a shelf 1224 of the chamber layer adjacent the fluid passage opening 1212 into the fluid passage opening 1212. The shelf 1224 is a surface of the chamber layer 1230 adjacent the fluid passage opening 1212. In someimplementations, the shelf 1224 is a surface of the chamber layer 1230 that extends parallel to the fluid actuator 1222 in the actuator layer 1220.

[0104] The ejection chamber 1232 may be referred to as a firing chamber. The ejection chamber 1232 may be configured to receive fluid and eject the fluid using the fluid actuator 1222 through the nozzle orifice 1242. The ejection chamber 1232 may be referred to as “primed” when the ejection chamber 1232 contains fluid to be ejected. “Priming” the ejection chamber 1232 may refer to the process of filling the ejection chamber 1232 with fluid to be ejected. The ejection chamber 1232 may be sized to receive an amount of fluid such that the fluid actuator 1222 ejects a predetermined amount of fluid. The ejection chamber 1232 may have any shape. In an example, the ejection chamber 1232 is roughly square-shaped. In an example, the ejection chamber 1232 is roughly circular. The ejection chamber 1232 may be formed using a lithographic process. In an example, the ejection chamber 1232 is formed using SU8 or other photoresist material in a layered structure.

[0105] The fluid actuator 1222 may be a thermal, mechanical, electrical, and / or electromechanical actuator. In an example, the fluid actuator 1222 is a resistor which boils the fluid to eject the fluid through the nozzle orifice 1242. In some examples, the fluid actuator 1222 is a thermal resistor. A thermal resistor can be used as a heater to heat liquid in the ejection chamber 1232 and / or a fluid inlet channel fluidically connecting the ejection chamber 1232 and the fluid passage opening 1212, or as a bubble generator to generate vapor bubbles to eject droplets of liquid from an ejection nozzle or to pump liquid through the fluid inlet channel. In an example, the fluid actuator 1222 is a piezoelectric actuator.

[0106] The nozzle orifice 1242 may be referred to as a nozzle, ejection opening, orifice, or ejection orifice. The nozzle orifice 1242 may shape and / or direct jets or drops of fluid which are directed from the ejection chamber 1232. The nozzle orifice 1242 may be at a top (ceiling) of the ejection chamber 1232 and the fluid actuator 1222 may be at a bottom (floor) of theejection chamber 1232. The terms “top,” “bottom,” “floor,” and “ceiling” are used for ease of understanding and do not limit the orientation of the ejection chamber 1232. The ejection chamber 1232 may be oriented in any direction.

[0107] The shelf 1224 may be a portion of the chamber layer 1230 and / or the actuator layer 1220. In an example, the chamber layer 1230 is adjacent the actuator layer 1220 and the shelf is a surface of the actuator layer 1220 adjacent the chamber layer 1230. The shelf 1224 may form a “floor” of the chamber layer 1230. The shelf 1224 may form a portion of the floor of the chamber layer 1230 adjacent the fluid passage opening 1212. The shelf 1224 may be a surface to which side walls of the ejection chamber 1232 are attached. The shelf 1224 may be a surface to which side walls of a fluid inlet channel fluidically connecting the ejection chamber 1232 to the fluid passage opening 1212 are attached.

[0108] In some implementations, a first portion of the protrusion 1234 extends within the chamber layer 1230 into the fluid passage opening 1212 and a second portion of the protrusion 1234 extends into a substrate layer of the fluid ejection device 1200 through the fluid passage opening 1212. The first portion and the second portion of the protrusion 1234 may be substantially perpendicular to one another. The first portion of the protrusion 1234 may extend within a plane of the chamber layer 1230 while the second portion of the protrusion 1234 may extend beyond the plane of the chamber layer 1230 into the actuator layer 1220 and / or the substrate layer. Extending “within the plane of the chamber layer” may refer to the protrusion 1234 remaining within the bounds of the chamber layer 1230. In an example, in a layered structure including the chamber layer 1230, the protrusion 1234 may extend within the plane of the chamber layer, not into adjacent layers. In some examples, the second portion of the protrusion 1234 may extend a portion of a height of the actuator layer 1220 into the fluid passage opening 1212. In some examples, the protrusion 1234 includes the first portion and extends within the chamber layer into the fluid passage opening 1212. The substrate layermay be adjacent the actuator layer 1220 and / or attached to the actuator layer 1220 by an adhesive layer between the substrate layer and the actuator layer 1220. The actuator layer 1220 may be between the substrate layer and the chamber layer 1230. In some implementations, the first portion of the protrusion extends from a top of the chamber layer 1230 to a bottom of the chamber layer 1230. The first portion of the protrusion may extend along an entire height of the chamber layer 1230.

[0109] In some implementations, the protrusion 1234 includes a leading edge extending into the fluid passage opening 1212 and a trailing edge facing the ejection chamber 1232, the trailing edge configured to reduce an angle of expansion of a fluid inlet channel. The fluid inlet channel may fluidically connect the ejection chamber 1232 and the fluid passage opening 1212. The leading edge may be positioned such that fluid from the fluid passage opening 1212 contacts the leading edge before contacting the trailing edge. The trailing edge may reduce the angle of expansion of the fluid inlet channel to facilitate priming of the ejection chamber 1232. The trailing edge may reduce an effective width of the fluid inlet channel to facilitate priming of the ejection chamber 1232.

[0110] In some implementations, the protrusion 1234 extends from a first side of the fluid passage opening 1212 into the fluid passage opening 1212 and the ejection chamber 1232 is on a second side of the fluid passage opening 1212. The protrusion 1234 and the ejection chamber 1232 may be on opposite sides of the fluid passage opening 1212. The protrusion 1234 and the ejection chamber 1232 may be on adjacent sides of the fluid passage opening 1212.[OHl] In some implementations, the chamber layer 1230 includes a first array of ejection chambers on a first side of the fluid passage opening 1212 and a second array of ejection chambers on a second side of the fluid passage opening 1212 opposite the first side. The protrusion 1234 may extend into the fluid passage opening 1212 from a third side of the fluidpassage opening 1212. In an example, arrays of ejection chambers are on opposite sides of the fluid passage opening 1212 and protrusions are on other opposite sides of the fluid passage opening 1212.

[0112] In some implementations, the protrusion 1234 extends across a width of the fluid passage opening 1212. The protrusion 1234 may extend beyond the chamber layer 1230 into the actuator layer 1220 and / or a substrate layer as well as across the width of the fluid passage opening 1212. A first portion of the protrusion 1234 may be on the shelf 1224 within the chamber layer 1230 and a second portion of the protrusion 1234 may extend across the width of the fluid passage opening 1212 and beyond the chamber layer 1230 into the actuator layer 1220 and / or a substrate layer. In some implementations, the protrusion 1234 connects (across the fluid passage opening 1212) a first wall of a first fluid inlet channel of a first ejection chamber to a second wall of a second fluid inlet channel of a second ejection chamber.

[0113] In some implementations, the protrusion 1234 is formed as a wall of a fluid inlet channel, as a pillar, or as a bridge connecting a wall and / or a pillar.

[0114] In some implementations, the fluid passage opening 1212 is fluidically connected to a reservoir containing fluid. The reservoir may be fluidically connected to the ejection chamber 1232 through the fluid passage opening 1212.

[0115] FIG. 13 is a block diagram of an example fluid ejection device 1300 with a wall 1334 of a fluid inlet channel 1336 extending into a fluid passage opening 1312. The fluid passage opening 1312 is fluidically connected to a chamber layer 1330. The chamber layer 1330 includes an ejection chamber 1332. The fluid ejection device 1300 includes a nozzle orifice 1342 fluidically connected to the ejection chamber 1332. The fluid inlet channel 1336 is fluidically connected to the ejection chamber 1332. The fluid inlet channel 1336 may fluidically connect the ejection chamber 1332 and the fluid passage opening 1312. The wall1334 of the fluid inlet channel 1336 extends into the fluid passage opening 1312 to form a cantilever structure. A first portion of the wall 1334 may extend from a bottom to a top of the chamber layer 1330 and a second portion of the wall 1334 may extend into the fluid passage opening 1312. The second portion of the wall 1334 may extend, without contacting a bottom of the chamber layer 1330, into the fluid passage opening 1312 such that the second portion of the wall 1334 cantilevers (extends from a support beyond the support) out into the fluid passage opening 1312. The second portion of the wall 1334 may extend beyond the chamber layer 1330 into an actuator layer and / or a substrate layer of the fluid ejection device 1300.

[0116] In some implementations, the wall 1334 may extend across a width of the fluid passage opening 1312. The wall 1334 may extend beyond the chamber layer 1330 into the actuator layer and / or a substrate layer as well as across the width of the fluid passage opening 1312. A first portion of the wall 1334 may be on a shelf within the chamber layer 1330 and a second portion of the wall 1334 may extend across the width of the fluid passage opening 1312 and beyond the chamber layer 1330 into an actuator layer and / or a substrate layer of the fluid ejection device 1300. In some implementations, the wall 1334 connects (across the fluid passage opening 1312) with a pillar between the fluid passage opening 1312 and a second ejection chamber across the fluid passage opening 1312.

[0117] In some implementations, the fluid passage opening 1312 is fluidically connected to a reservoir containing fluid. The reservoir may be fluidically connected to the ejection chamber 1332 through the fluid passage opening 1312 and the fluid inlet channel 1336.

[0118] FIG. 14 is a block diagram of an example fluid ejection device 1400 with a portion of a pillar 1434 extending into a fluid passage opening 1412. The fluid passage opening 1412 is fluidically connected to a chamber layer 1430. The portion of the pillar 1434 which extends into the fluid passage opening 1412 may be referred to as the extending portion of the pillar 1434. The chamber layer 1430 includes an ejection chamber 1432. The pillar 1434 is betweenthe fluid passage opening 1412 and the ejection chamber 1432 on a shelf 1424 of the chamber layer 1430. The extending portion of the pillar extends into the fluid passage opening 1412 to form a cantilever structure. A shelf portion of the pillar 1434 may extend from a bottom to a top of the chamber layer 1430 on the shelf 1424 and the extending portion of the pillar 1434 may extend into the fluid passage opening 1412. The extending portion of the pillar 1434 may extend, without contacting a bottom of the chamber layer 1430, into the fluid passage opening 1412 such that the second portion of the pillar 1434 cantilevers out into the fluid passage opening 1412. The extending portion of the pillar 1434 may extend beyond the chamber layer 1430 into an actuator layer and / or a substrate layer of the fluid ejection device 1400.

[0119] In some implementations, the pillar 1434 may include a leading edge extending into the fluid passage opening 1412 and a trailing edge facing the ejection chamber 1432. The trailing edge may be configured to reduce an angle of expansion of a fluid inlet channel fluidically connecting the ejection chamber 1432 and the fluid passage opening 1412. The leading edge may be positioned such that fluid from the fluid passage opening 1412 contacts the leading edge before contacting the trailing edge. The trailing edge may reduce the angle of expansion of the fluid inlet channel to facilitate priming of the ejection chamber 1432. The trailing edge may reduce an effective width of the fluid inlet channel to facilitate priming of the ejection chamber 1432.

[0120] In some implementations, the pillar 1434 extends across a width of the fluid passage opening 1412. The pillar 1434 may extend beyond the chamber layer 1430 into an actuator layer and / or a substrate layer of the fluid ejection device 1400 as well as across the width of the fluid passage opening 1412. A first portion of the pillar 1434 may be on a shelf of the chamber layer 1430 and a second portion of the protrusion 134 may extend across the width of the fluid passage opening 1412 and beyond the chamber layer 1430 into the actuator layer and / or the substrate layer. In some implementations, the pillar 1434 connects (across the fluidpassage opening 1412) a second pillar between the fluid passage opening 1412 and a second ejection chamber across the fluid passage opening 1412.

[0121] In some implementations, the fluid passage opening 1412 is fluidically connected to a reservoir containing fluid. The reservoir is fluidically connected to the ejection chamber 1432 through the fluid passage opening 1412.

[0122] Characteristics attributed to the fluid ejection device 1200 of FIG. 12, the fluid ejection device 1300 of FIG. 13, and / or the fluid ejection device 1400 of FIG. 14 can be attributed to any of the fluid ejection device 1200 of FIG. 12, the fluid ejection device 1300 of FIG. 13, and / or the fluid ejection device 1400 of FIG. 14. In addition, characteristics of the fluid ejection device 1200 of FIG. 12, the fluid ejection device 1300 of Fig. 13, and / or the fluid ejection device 1400 of FIG. 14 can be combined within a single fluid ejection device.

[0123] FIG. 15 illustrates a cross-section of an example fluid ejection device 1500. The fluid ejection device 1500 includes a substrate layer 1510, an actuator layer 1520, a chamber layer 1530, and a nozzle layer 1540. The fluid ejection device 1500 may be partially or completely formed by depositing layers on a substrate. In an example, the fluid ejection device 1500 may be partially or completely formed by depositing layers of material on the substrate layer 1510.

[0124] The substrate layer 1510 includes a fluid passage opening 1512. The fluid passage opening 1512 allows a fluid 1502 to travel through the substrate layer 1510 and the actuator layer 1520 to the chamber layer 1530. The substrate layer 1510 includes circuitry for controlling fluid ejection. In an example, the substrate layer 1510 is silicon. In an example, the substrate layer 1510 includes circuitry for controlling fluid actuation by a fluid actuator 1522. The fluid actuator 1522 may be in the actuator layer 1520. The fluid actuator 1522 may span a height of the actuator layer 1520 or a portion of the height of the actuator layer 1520. The actuator layer 1520 may be adjacent the substrate layer 1510. The actuator layer 1520includes the fluid passage opening 1512 to allow the fluid 1502 to pass to the chamber layer1530.

[0125] The chamber layer 1530 includes an ejection chamber 1532 fluidically connected to a fluid inlet channel 1536. The chamber layer 1530 is adjacent the actuator layer 1520. The ejection chamber 1532 may include or be adjacent the fluid actuator 1522 such that the fluid actuator 1522 can actuate the fluid 1502 when the fluid 1502 is in the ejection chamber 1532. The nozzle layer 1540 is adjacent the chamber layer 1530. The nozzle layer 1540 includes a nozzle 1542. The ejection chamber 1532 may include or be adjacent the nozzle 1542 such that the fluid actuator 1522 can actuate the fluid 1502 when the fluid 1502 is in the ejection chamber 1532 to eject the fluid through the nozzle 1542.

[0126] The chamber layer 1530 includes side walls of the fluid inlet channel 1536 (not shown in FIG. 15). The side walls of the fluid inlet channel 1536 are on a shelf 1524 of the actuator layer 1520. In some implementations, the side walls of the fluid inlet channel 1536 extend from the shelf 1524 of the actuator layer 1520 to the nozzle layer 1540, or along an entire height of the chamber layer 1530. The bottom of the fluid inlet channel 1536 (when viewed from the nozzle layer) is the shelf 1524 and the top of the fluid inlet channel 1536 is the nozzle layer 1540.

[0127] The fluid 1502 may form a meniscus 1504 at an interface between the fluid passage opening 1512 and the chamber layer 1530. The fluid 1502 may be pinned, or stuck, at the meniscus 1504 such that the ejection chamber 1532 does not prime. The fluid 1502 can be pinned due to interactions between the fluid passage opening 1512 and the chamber layer 1530. In an example, the interface between the fluid passage opening 1512 and the chamber layer 1530 has an angle of expansion of one hundred and eighty degrees, causing the convex meniscus 1504 to form and the fluid 1502 to be pinned at the interface between the fluid passage opening 1512 and the chamber layer 1530. In an example, the fluid 1502 is pinneddue to a change in topography or material at the interface between the fluid passage opening1512 and the chamber layer 1530.

[0128] In some implementations, the fluid 1502 is not pinned and fills the ejection chamber 1532 such that the ejection chamber 1532 is primed. The ejection chamber 1532 may be primed due to capillary forces drawing the fluid 1502 into the ejection chamber 1532. The capillary forces may draw the fluid 1502 into the ejection chamber 1532 due to a protrusion in the chamber layer 1530 which extends into the fluid passage opening 1512. In an example, the protrusion extends into the fluid passage opening 1512 such that the protrusion contacts or pierces the meniscus 1504. In an example, the protrusion extends into the fluid passage opening 1512 such that the meniscus 1504 does not form.

[0129] In some examples, the chamber layer 1530 has a height of between 8 and 50 micrometers. In some examples, the fluid passage opening 1512 has dimensions of 30-200 micrometers by 30-1000 micro-meters.

[0130] FIG. 16 illustrates a cross-section of an example fluid ejection device 1600 including a protrusion 1634 extending from a shelf 1624 of a chamber layer 1630 adjacent a fluid passage opening 1612 into the fluid passage opening 1612. The fluid ejection device 1600 may be similar in many regards to the fluid ejection device 1500 of FIG. 15, with the exception that the fluid ejection device 1600 includes the protrusion 1634 while the fluid ejection device 1500 of FIG. 15 does not include a protrusion. The fluid ejection device 1600 may be an example of the fluid ejection device 1200 of FIG. 12, the fluid ejection device 1300 of FIG. 13, and / or the fluid ejection device 1400 of FIG. 14. The protrusion 1634 may extend within the chamber layer 1630 into the fluid passage opening 1612. In some implementations, the protrusion 1634 extends within the chamber layer 1630 into the fluid passage opening 1612 and does not extend into the actuator layer 1620 or the substrate layer 1610. In some implementations, the protrusion 1634 extends within the chamber layer 1630into the fluid passage opening 1612 and beyond the chamber layer 1630 into an actuator layer 1620 and a substrate layer 1610 (as shown). The protrusion 1634 may prevent a fluid 1602 from being pinned at an interface between the fluid passage opening 1612 and the chamber layer 1630 such that the fluid 1602 passes through a fluid inlet channel 1636 into an ejection chamber 1632 to prime the ejection chamber 1632. Once the ejection chamber 1632 is primed, a fluid actuator 1622 in the actuator layer 1620 between the substrate layer ejects the fluid 1602 from the ejection chamber 1632 through a nozzle 1642 in a nozzle layer 1640.

[0131] The protrusion 1634 may have any shape. A leading edge of the protrusion 1634 (extending into the fluid passage opening 1612) may be rounded, flat, sharp, or any other geometry. A trailing edge of the protrusion 1634 (towards the ejection chamber 1632) may be rounded, flat, sharp, or any other geometry. In an example, the trailing edge of the protrusion 1634 is sharp. In some implementations, the protrusion 1634 extends from a top to a bottom (along an entire height) of the chamber layer 1630. In some implementations, the protrusion 1634 extends a portion of the height of the chamber layer 1630 from the shelf 1624. In some implementations, the protrusion 1634 extends beyond the chamber layer 1630 along a portion of a height of the actuator layer 1620.

[0132] FIG. 17 illustrates a cross-section of an example fluid ejection device 1700 including a protrusion 1734 extending from a shelf 1724 of the chamber layer 1730 across a fluid passage opening 1712. The fluid ejection device 1700 may be similar in many regards to the fluid ejection device 1500 of FIG. 15, with the addition of the protrusion 1734. The fluid ejection device 1700 may be an example of the fluid ejection device 1200 of FIG. 12, the fluid ejection device 1300 of Fig. 13, and / or the fluid ejection device 1400 of FIG. 14. The protrusion 1734 fluid ejection device 1700 may be similar in many regards to the fluid ejection device 1600 of FIG. 16, except the protrusion 1734 extends across the fluid passage opening 1712. The protrusion 1734 extends within the chamber layer 1730 into the fluidpassage opening 1712 across the fluid passage opening 1712. In some implementations, the protrusion 1734 extends within the chamber layer 1730 across the fluid passage opening 1712 and does not extend into the actuator layer 1720 or the substrate layer 1710. In some implementations, the protrusion 1734 extends within the chamber layer 1730 into the fluid passage opening 1712 and beyond the chamber layer 1730 into the actuator layer 1720 and the substrate layer 1710 (as shown). The protrusion 1734 may prevent a fluid 1702 from being pinned at an interface between the fluid passage opening 1712 and the chamber layer 1730 such that the fluid 1702 passes through a fluid inlet channel 1736 into an ejection chamber 1732 to prime the ejection chamber 1732. Once the ejection chamber 1732 is primed, a fluid actuator 1722 in the actuator layer 1720 between the substrate layer ejects the fluid 1702 from the ejection chamber 1732 through a nozzle 1742 in a nozzle layer 1740.

[0133] The protrusion 1734 may have any shape. A trailing edge of the protrusion 1734 (towards the ejection chamber 1732) may be rounded, flat, sharp, or any other geometry. In an example, the trailing edge of the protrusion 1734 is sharp. In some implementations, the protrusion 1734 extends from a top to a bottom (along an entire height) of the chamber layer 1730. In some implementations, the protrusion 1734 extends a portion of the height of the chamber layer 1730 from the shelf 1724. In some implementations, the protrusion 1734 extends beyond the chamber layer 1730 along a portion of a height of the actuator layer 1720.

[0134] FIG. 18 illustrates an example ejection chamber 1832 fluidically connected to an example fluid inlet channel 1836 with walls 1834 of the fluid inlet channel 1836 extending into a fluid passage opening 1812. The walls 1834 of the fluid inlet channel 1836 may extend from a shelf 1824 adjacent the fluid passage opening 1812 into the fluid passage opening 1812 to form cantilever structures, or protrusions. The fluid inlet channel 1836 may fluidically connect the ejection chamber 1832 and the fluid passage opening 1812 to prime the ejectionchamber 1832. Once the ejection chamber 1832 is primed, a fluid actuator 1822 of the ejection chamber 1832 ejects fluid out of the ejection chamber 1832 through a nozzle.

[0135] The walls 1834 of the fluid inlet channel 1836 extend into the fluid passage opening 1812 in order to prevent pinning of a fluid at the fluid passage opening 1812. The walls 1834 extend into the fluid passage opening 1812 to prevent pinning of a meniscus at the fluid passage opening 1812. The walls 1834 extend into the fluid passage opening 1812 along a plane of the shelf 1824. In some examples, the walls 1834 extend into the fluid passage opening 1812 along the plane of the shelf 1824. In some examples, the walls 1834 extend into the fluid passage opening 1812 along the plane of the shelf 1824 and beyond the plane of the shelf 1824 into the fluid passage opening 1812 (as illustrated in FIG. 5). The walls 1834 facilitate drawing liquid out of the fluid passage opening 1812 through the fluid inlet channel 1836 into the ejection chamber 1832.

[0136] In some implementations, the walls 1834 extend one to twenty pmover the shelf 1824 into the fluid passage opening 1812. In an example, the walls 1834 extend about ten pm over the shelf 1824. In an example, the walls 1834 extend about four pm over the shelf 1824. In an example, the walls 1834 extend about two pm over the shelf 1824.

[0137] FIG. 19 illustrates an array of multiple example ejection chambers 1932 fluidically connected to example fluid inlet channels 1936 with walls 1934 of the fluid inlet channels 1936 extending into a fluid passage opening 1912. The ejection chambers 1932 may be similar to or the same as the ejection chamber 1832 of FIG. 18. The fluid inlet channels 1936 may share a wall or walls of the walls 1934. In an example, adjacent fluid inlet channels of the fluid inlet channels 1936 share a wall of the walls 1934. The walls 1934 extend from a shelf 1924 into the fluid passage opening 1912 to form cantilever structures, or protrusions. The walls 1934 extend into the fluid passage opening 1912 in order to prevent pinning of a fluid at the fluid passage opening 1912. The walls 1934 extend into the fluid passage opening1912 to prevent pinning of a meniscus at the fluid passage opening 1912. The walls 1934 may extend into the fluid passage opening 1912 along a plane of the shelf 1924. In some examples, the walls 1934 extend into the fluid passage opening 1912 along the plane of the shelf 1924. In some examples, the walls 1934 extend into the fluid passage opening 1912 along the plane of the shelf 1924 and beyond the plane of the shelf 1924 into the fluid passage opening 1912 (as illustrated in FIG. 5). The walls 1934 facilitate drawing fluid out of the fluid passage opening 1912 through the fluid inlet channels 1936 into the ejection chambers 1932. The ejection chambers 1932 include fluid actuators 1922 for ejecting the fluid.

[0138] In some implementations, the walls 1934 extend one to twenty pm over the shelf 1924 into the fluid passage opening 1912. In an example, the walls 1934 extend about ten pm over the shelf 1924. In an example, the walls 1934 extend about four pm over the shelf 1924. In an example, the walls 1934 extend about two pm over the shelf 1924.

[0139] FIG. 20 illustrates an example ejection chamber 2032 fluidically connected to an example fluid inlet channel 2036 with a pillar 2034 between the ejection chamber 2032 and a fluid passage opening 2012 extending into the fluid passage opening 2012. The pillar 2034 can be disposed partially or completely within the fluid inlet channel 2036. The pillar 2034 extends from a shelf 2024 adjacent the fluid passage opening 2012 into the fluid passage opening 2012 to form a cantilever structure, or protrusion. The pillar 2034 may be an example of the protrusion 1634 in FIG. 16. The pillar 2034 may be an example of the pillar 1434 of FIG. 14 and / or the protrusion 1234 of FIG. 12. The fluid inlet channel 2036 fluidically connects the ejection chamber 2032 and the fluid passage opening 2012 to prime the ejection chamber 2032. Once the ejection chamber 2032 is primed, a fluid actuator 2022 of the ejection chamber 2032 ejects fluid out of the ejection chamber 2032 through a nozzle.

[0140] The pillar 2034 of the fluid inlet channel 2036 extends into the fluid passage opening2012 in order to prevent pinning of a fluid at the fluid passage opening 2012. The pillar 2034extends into the fluid passage opening 2012 to prevent pinning of a meniscus at the fluid passage opening 2012. The pillar 2034 extends into the fluid passage opening 2012 along a plane of the shelf 2024. In some examples, the pillar 2034 extends into the fluid passage opening 2012 along the plane of the shelf 2024. In some examples, the pillar 2034 extends into the fluid passage opening 2012 along the plane of the shelf 2024 and beyond the plane of the shelf 2024 into the fluid passage opening 2012 (as illustrated in FIG. 5). The pillar 2034 facilitates drawing liquid out of the fluid passage opening 2012 through the fluid inlet channel 2036 into the ejection chamber 2032. In some examples, the pillar 2034 extends from within the ejection chamber 2032 into the fluid passage opening 2012 to facilitate drawing liquid out of the fluid passage opening 2012 through the fluid inlet channel 2036 into the ejection chamber 2032.

[0141] In some implementations, the pillar 2034 is located within the fluid inlet channel 2036. The pillar 2034 can be referred to as an “interior pillar” when it is located within the fluid inlet channel 2036. The pillar 2034 may be located at a distance from side walls of the fluid inlet channel 2036 to facilitate priming of the ejection chamber 2032. In some examples, the pillar 2034 can have a widening portion at an upstream end (leading edge) of the pillar 2034. As used herein, “widening portion” refers to a portion of the pillar 2034 that increases in width with respect to the direction of fluid flow. The widening portion increases in width towards the side walls of the fluid inlet channel 2036. The widening portion of the pillar 2034 can form various acute angles with the side walls of the fluid inlet channel 2036 and the top and bottom of the fluid inlet channel 2036. These acute angles can attract fluid because of adhesion forces between the fluid and the walls and / or the top and bottom of the fluid inlet channel 2036.

[0142] In some examples, the pillar 2034 can have a tapering portion at a downstream end(trailing edge) of the pillar 2034. As used herein, “tapering portion” means that the width ofthe pillar 2034 decreases with respect to the fluid flow direction. The tapering portion decreases in width away from the side walls of the fluid inlet channel 2036.

[0143] The pillar 2034 can have a variety of shapes which facilitate fluid flow through the fluid inlet channel 2036 by capillary action. The pillar 2034 can have a variety of shapes which do not cause fluid pinning due. In some examples, the widening portion can have a wedge shape, with an angled upstream edge (leading edge). The wedge-shaped upstream edge (leading edge) of the pillar 2034 can have an angle of pillar widening in the same plane as the angle of expansion of the fluid inlet channel 2036. In some implementations, the angle of pillar widening is one degree to one hundred and sixty degrees. In an example, the angle of pillar widening is one degree to one hundred and sixty degrees. In some examples, the angle of pillar widening is ten degrees to one hundred degrees. In some examples, the angle of pillar widening is fifteen degrees to ninety degrees. In some examples, the angle of pillar widening is twenty degrees to sixty degrees. The widening portion can also have other shapes, such as a polygonal shape or a rounded shape. The tapering portion can end at an angled downstream edge (trailing edge) having an angle of pillar narrowing in the same plane as the angle of expansion of the fluid inlet channel 2036. In some implementations, the angle of pillar narrowing is five degrees to forty-five degrees. In an example, the angle of pillar narrowing is five degrees to thirty degrees. In an example, the angle of pillar narrowing is ten degrees to thirty degrees. In an example, the angle of pillar narrowing is twenty degrees to thirty degrees. In an example, the angle of pillar narrowing is twenty degrees to forty-five degrees. In some examples, the tapering portion can have a rounded shape.

[0144] In some implementations, the pillar 2034 extends one to twenty pm over the shelf 2024 into the fluid passage opening 2012. In an example, the pillar 2034 extends about ten pm over the shelf 2024. In an example, the pillar 2034 extends about four pm over the shelf 2024. In an example, the pillar 2034 extends about two pm over the shelf 2024.

[0145] FIG. 21 illustrates a first array of example ejection chambers 2132a fluidically connected to a first array of example fluid inlet channels 2136a and a second array of example ejection chambers 2132b fluidically connected to a second array of example fluid inlet channels 2136b with protrusions 2134 extending across a fluid passage opening 2112 to connect first walls 2133a of the first array of fluid inlet channels 2136a with second pillars 2135b between the fluid passage opening 2112 and the second array of ejection chambers 2132b and second walls 2133b of the second array of fluid inlet channels 2136b with first pillars 2135a between the fluid passage opening 2112 and the first array of ejection chambers 2132a.

[0146] In some implementations, the protrusions 2134 extend across a width of the fluid passage opening 2112. The protrusions 2134 extend across the fluid passage opening 2112 in order to prevent pinning of a fluid at the fluid passage opening 2112. The protrusions 2134 extend into the fluid passage opening 2112 to prevent formation of a meniscus at the fluid passage opening 2112. The protrusions 2134 extend into the fluid passage opening 2112 along a plane of the first array of ejection chambers 2132a and the second array of ejection chambers 2132b. In some examples, the protrusions 2134 extend into the fluid passage opening 2112 along the plane of the first array of ejection chambers 2132a and the second array of ejection chambers 2132b. In some examples, the protrusions 2134 extend into the fluid passage opening 2112 along the plane of the first array of ejection chambers 2132a and the second array of ejection chambers 2132b and beyond the plane of the first array of ejection chambers 2132a and the second array of ejection chambers 2132b into the fluid passage opening 2112 (as illustrated in FIG. 6). The protrusions 2134 facilitate drawing liquid out of the fluid passage opening 2112 through the first array of fluid inlet channels 2136a and the second array of fluid inlet channels 2136b into the first array of ejection chambers 2132a and the second array of ejection chambers 2132b.

[0147] FIG. 22 illustrates a first array of example ejection chambers 2232a fluidically connected to a first array of example fluid inlet channels 2236a and a second array of example ejection chambers 2232b fluidically connected to a second array of example fluid inlet channels 2236b with protrusions 2234 extending across a fluid passage opening 2212 to connect first walls 2233a of the first array of fluid inlet channels 2236a with second walls 2233b of the second array of fluid inlet channels 2236b.

[0148] The protrusions 2234 extend across a width of the fluid passage opening 2212. The protrusions 2234 extend across the fluid passage opening 2212 in order to prevent pinning of a fluid at the fluid passage opening 2212. The protrusions 2234 extend into the fluid passage opening 2212 to prevent formation of a meniscus at the fluid passage opening 2212. The protrusions 2234 extend into the fluid passage opening 2212 along a plane of the first array of ejection chambers 2232a and the second array of ejection chambers 2232b. In some examples, the protrusions 2234 extend into the fluid passage opening 2212 along the plane of the first array of ejection chambers 2232a and the second array of ejection chambers 2232b. In some examples, the protrusions 2234 extend into the fluid passage opening 2212 along the plane of the first array of ejection chambers 2232a and the second array of ejection chambers 2232b and beyond the plane of the first array of ejection chambers 2232a and the second array of ejection chambers 2232b into the fluid passage opening 2212 (as illustrated in FIG. 6). The protrusions 2234 facilitate drawing liquid out of the fluid passage opening 2212 through the first array of fluid inlet channels 2236a and the second array of fluid inlet channels 2236b into the first array of ejection chambers 2232a and the second array of ejection chambers 2232b.

[0149] FIG. 23 illustrates a first array of example ejection chambers 2332a fluidically connected to a first array of example fluid inlet channels 2336a and a second array of example ejection chambers 2332b fluidically connected to a second array of example fluid inletchannels 2336b with protrusions 2334 extending across a fluid passage opening 2312 to connect first pillars 2335a between the fluid passage opening 2312 and the first array of ejection chambers 2332a with second pillars 2335b between the fluid passage opening 2312 and the second array of ejection chambers 2332b. In some implementations, the protrusions 2334, the first pillars 2335a, and the second pillars 2335b have a same material. In some implementations, the protrusions 2334, the first pillars 2335a, and the second pillars 2335b are monolithic.

[0150] The protrusions 2334 extend across a width of the fluid passage opening 2312. The protrusions 2334 extend across the fluid passage opening 2312 in order to prevent pinning of a fluid at the fluid passage opening 2312. The protrusions 2334 extend into the fluid passage opening 2312 to prevent pinning of a meniscus at the fluid passage opening 2312. The protrusions 2334 extend into the fluid passage opening 2312 along a plane of the first array of ejection chambers 2332a and the second array of ejection chambers 2332b. In some examples, the protrusions 2334 extend into the fluid passage opening 2312 along the plane of the first array of ejection chambers 2332a and the second array of ejection chambers 2332b. In some examples, the protrusions 2334 extend into the fluid passage opening 2312 along the plane of the first array of ejection chambers 2332a and the second array of ejection chambers 2332b and beyond the plane of the first array of ejection chambers 2332a and the second array of ejection chambers 2332b into the fluid passage opening 2312 (as illustrated in FIG. 6). The protrusions 2334 facilitate drawing liquid out of the fluid passage opening 2312 through the first array of fluid inlet channels 2336a and the second array of fluid inlet channels 2336b into the first array of ejection chambers 2332a and the second array of ejection chambers 2332b.

[0151] FIG. 24 illustrates a first array of example ejection chambers 2432a fluidically connected to a first array of example fluid inlet channels 2436a on a first side of a fluidpassage opening 2412 and a second array of example ejection chambers 2432b fluidically connected to a second array of example fluid inlet channels 2436b on a second side of the fluid passage opening 2412 with a protrusion extending into the fluid passage opening 2412 on a third side of the fluid passage opening 2412.

[0152] The protrusion 2434 extends into the fluid passage opening 2412 in order to prevent pinning of a fluid at the fluid passage opening 2412. The protrusion 2434 extends into the fluid passage opening 2412 to prevent formation of a meniscus at the fluid passage opening 2412. The protrusion 2434 extends into the fluid passage opening 2412 along a plane of the shelf 2424. In some implementations, the protrusion 2434 extends from a shelf 2424 adjacent the fluid passage opening 2412 into the fluid passage opening 2412. In some examples, the protrusion 2434 extends into the fluid passage opening 2412 along the plane of the shelf 2424. In some examples, the protrusion 2434 extends into the fluid passage opening 2412 along the plane of the shelf 2424 and beyond the plane of the shelf 2424 into the fluid passage opening 2412 (as illustrated in FIG. 5). The protrusion 2434 facilitates drawing liquid out of the fluid passage opening 2412 through the first array of fluid inlet channels 2436a into the first array of ejection chambers 2432a and through the second array of fluid inlet channels 2436b into the second array of ejection chambers 2432b. In some examples, the protrusion 2434 being located on the third side of the fluid passage opening 2412 facilitates passage of fluid between adjacent ejection chambers in the first array of ejection chambers 2432a and between adjacent ejection chambers in the second array of ejection chambers 2432b, as there are no protrusions between the adjacent ejection chambers.

[0153] In some implementations, the protrusion 2434 extends one to twenty pm over the shelf 2424 into the fluid passage opening 2412. In an example, the protrusion 2434 extends about ten pm over the shelf 2424. In an example, the protrusion 2434 extends about four pm over the shelf 2424. In an example, the protrusion 2434 extends about two pm over the shelf 2424.

[0154] FIG. 25 illustrates a first array of example ejection chambers 2532a on a first side of a fluid passage opening 2512 and a second array of example ejection chambers 2532b on a second side of the fluid passage opening 2512 with a first protrusion 2534a extending into the fluid passage opening 2512 on a third side of the fluid passage opening and a second protrusion 2534b extending into the fluid passage opening 2512 on a fourth side of the fluid passage opening 2512.

[0155] The first protrusion 2534a and the second protrusion 2534b may be the same as or similar to the protrusion 2434 of FIG. 24. The first protrusion 2534a and the second protrusion 2534b facilitate drawing liquid out of the fluid passage opening 2512 into the first array of ejection chambers 2532a and into the second array of ejection chambers 2532b. In some examples, the first protrusion 2534a and the second protrusion 2534b being located on the third side and the fourth side, respectively, of the fluid passage opening 2512 facilitates passage of fluid between adjacent ejection chambers in the first array of ejection chambers 2532a and between adjacent ejection chambers in the second array of ejection chambers 2532b, as there are no protrusions between the adjacent ejection chambers, improving a speed of priming the first array of example ejection chambers 2532a and the second array of example ejection chambers 2532b.

[0156] In some implementations, the first protrusion 2534a and the second protrusion 2534b extend a same distance into the fluid passage opening 2512. In some implementations, the first protrusion 2534a and the second protrusion 2534b extend different distances into the fluid passage opening 2512. In an example, the first protrusion 2534a and / or the second protrusion 2534b extend one to twenty pm into the fluid passage opening 1312. In an example, the first protrusion 2534a and / or the second protrusion 2534b extend about ten pm into the fluid passage opening 2512. In an example, the first protrusion 2534a and / or the second protrusion 2534b extend about four pm into the fluid passage opening 2512. In anexample, the first protrusion 2534a and / or the second protrusion 2534b extend about two pm into the fluid passage opening 2512.

[0157] As discussed herein, the protrusions described in FIGS. 16-25 can be included in a dispenser device, such as the dispenser devices described in FIGS. 1-3.

Claims

WHAT IS CLAIMED IS:

1. A dispenser device comprising: a fluid ejection device comprising: an ejection chamber including: a fluid actuator; an ejection nozzle; a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to eighty degrees; and a regulator to direct a compressed gas transverse the ejection nozzle from a compressed gas source.

2. The dispenser device of claim 1, further comprising the compressed gas source.

3. The dispenser device of claim 1 or claim 2, wherein the compressed gas source comprises an air compressor.

4. The dispenser device of claim 1 or claim 2, wherein the compressed gas source comprises a compressed gas tank.

5. The dispenser device of claim 1, wherein the dispenser device includes a plurality of ejection chambers each including a fluid actuator and an ejection nozzle, and wherein the regulator is to direct the compressed gas transverse the ejection nozzle of each ejection chamber of the plurality of ejection chambers.

6. The dispenser device of claim 1, wherein the fluid ejection device includes: a fluid passage opening fluidically connected to the fluid inlet channel; and a protrusion extending from the fluid inlet channel into the fluid passage opening.

7. The dispenser device of claim 1, wherein the regulator directs a predetermined amount of the compressed gas transverse the ejection nozzle to facilitate movement of a fluid through the fluid inlet channel into the ejection chamber.

8. The dispenser device of claim 1, wherein the regulator directs a sequence of pulses of the compressed gas transverse the ejection nozzle.

9. The dispenser device of claim 1, further comprising a compressed gas nozzle coupled to the regulator, wherein the compressed gas nozzle is directed transverse the ejection nozzle.

10. The dispenser device of claim 9, further comprising a mechanical actuator to move the compressed gas nozzle into position such that the compressed gas nozzle is directed transverse the ejection nozzle.

11. The dispenser device of claim 1, further comprising an attachment site to couple the compressed gas source to the regulator.

12. A method comprising: providing fluid to a dispenser device comprising: a fluid ejection device comprising: an ejection chamber including: a fluid actuator; an ejection nozzle; a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to eighty degrees; directing compressed gas transverse the ejection nozzle from a compressed gas source to cause the fluid to pass through the fluid inlet channel into the ejection chamber; and dispensing the fluid from the ejection chamber of the dispenser device.

13. The method of claim 12, comprising verifying that the fluid passed through the fluid inlet channel into the ejection chamber by either attempting to dispense the fluid or using a sensor coupled to the ejection chamber.

14. The method of claim 12, wherein the dispenser device includes a plurality of ejection chambers each including a fluid actuator and an ejection nozzle, and wherein the method further comprises directing the compressed gas transverse the ejection nozzle of each ejection chamber of the plurality of ejection chambers.

15. The dispenser device of claim 1, wherein directing the compressed gas transverse the ejection nozzle includes providing an electrical signal to a regulator coupled to the compressed gas source.

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