WO2025136355A1

WO2025136355A1 - Protrusions into a fluid passage opening

Info

Publication number: WO2025136355A1
Application number: PCT/US2023/084656
Authority: WO
Inventors: Pavel Kornilovich; Susanne Kumpf MUHLY; Katherine Schauer; Christopher Hans BAKKER; Alexander N. Govyadinov; Michael Benjamin HAGER
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2023-12-18
Filing date: 2023-12-18
Publication date: 2025-06-26
Anticipated expiration: 2026-06-18

Abstract

A fluid ejection device may include a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber. A floor of the ejection chamber may include a fluid actuator in an actuator layer adjacent the chamber layer. The fluid ejection device may include a nozzle orifice fluidically connected to the ejection chamber and a protrusion in the chamber layer extending from a shelf of the chamber layer adjacent the fluid passage opening into the fluid passage opening.

Description

PROTRUSIONS INTO A FLUID PASSAGE OPENING

BACKGROUND

[0001] Fluid ejection devices deposit fluid onto a substrate to print in two or three dimensions. Fluid may be ejected from a fluid ejection chamber. Fluid may be 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).

Microfluidic structures for printing marking fluids (e.g., ink) or other liquids including surfactants may be incompatible for use in ejecting aqueous fluids with little to no surfactants.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 is a block diagram of an example fluid ejection device with a protrusion extending into a fluid passage opening.

[0003] FIG. 2 is a block diagram of an example fluid ejection device with a wall of a fluid inlet channel extending into a fluid passage opening.

[0004] FIG. 3 is a block diagram of an example fluid ejection device with a portion of a pillar extending into a fluid passage opening.

[0005] FIG. 4 illustrates a cross-section of an example fluid ejection device.

[0006] FIG. 5 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.

[0007] FIG. 6 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.

[0008] FIG. 7 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. [0009] FIG. 8 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.

[0010] FIG. 9 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.

[0011] FIG. 10 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 of ejection 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.

[0012] FIG. 11 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.

[0013] FIG. 12 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. [0014] FIG. 13 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.

[0015] FIG. 14 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.

[0016] 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 these drawings depict examples in accordance with the disclosure and are therefore, 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

[0017] 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.

[0018] Fluid ejection devices may comprise 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.

[0019] 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.

[0020] 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, for example.

[0021] In some contexts, there may be 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 may cause 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 may travel through a fluid delivery system reliably using capillary forces may depend, among other things, on the ability to keep fluids primed.

[0022] Aqueous fluid may form a meniscus and be pinned within structures having a geometry that does not allow capillary forces to draw aqueous fluid through the structures. In an example, aqueous fluids may be pinned at a fluid passage opening of a fluid ejection device. In an example, the fluid passage opening is a rectangular structure which opens into a chamber layer of a fluid ejection device. Aqueous fluid may be pinned at the fluid passage opening as a fluid path of the aqueous fluid abruptly expands along 180°. The aqueous fluid may form a meniscus at the fluid passage opening and be pinned. The pinned aqueous fluid does not reach the ejection chamber, preventing printing of the aqueous fluid using the ejection chamber. Implementations discussed in the present description propose providing structures (e.g. protrusions) that extend into the fluid passage opening to facilitate priming of ejection chambers using capillary forces. Implementations discussed herein may be used to print aqueous fluids for applications such as cell dispensing.

[0023] To illustrate these principles, the present description refers, without limitation, to the illustrative example of a fluid ejection device. Various microfluidic applications call for the need of a fluid ejection 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. A fluid ejection device may utilize a thermal process for dispensing fluid. Fluid may be ejected from an ejection chamber using a thermal resistor. The thermal resistor may boil a portion of the fluid to create a cavitation wave to eject the fluid out of the ejection chamber. For successful ejection, fluid needs to reach 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 called for that facilitate providing fluids from a reservoir into ejection chambers. 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, as described herein, may be beneficial, such as to avoid pinning.

[0024]

[0025] This disclosure relates to fluid ejection devices. Specifically, this disclosure relates to a fluid ejection device including an ejection chamber for ejecting fluid which is fluidically connected to a fluid inlet channel to provide the fluid to the ejection chamber from a fluid passage opening. The ejection chamber is located within a chamber layer of the fluid ejection device. The fluid ejection device includes a protrusion extending from a shelf adjacent the fluid passage opening into the fluid passage opening. The protrusion may form a cantilever structure as the protrusion extends past the shelf into the fluid passage opening. In some examples, the protrusion extends into the fluid passage opening within the chamber layer and along a plane of the shelf and beyond the chamber layer and the plane of the shelf into the fluid passage opening. In some implementations, the protrusion facilitates priming of the ejection chamber with an aqueous fluid without adding surfactants to the fluid or treating the fluid inlet channel with plasma The protrusion may prevent formation of a meniscus at the fluid passage opening, facilitating priming of the ejection chamber using capillary forces.

[0026] In some examples, the present disclosure relates to a fluid ejection device that comprises a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber; a nozzle orifice fluidically connected to the ejection chamber, and a fluid inlet channel fluidically connected to the ejection chamber, wherein a wall of the fluid inlet channel extends into the fluid passage opening to form a cantilever structure.

[0027] FIG. 1 is a block diagram of an example fluid ejection device 100 with a protrusion

134 extending into a fluid passage opening 112. The fluid passage opening 112 is fluidically connected to a chamber layer 130. The chamber layer 130 includes an ejection chamber 132.

A floor of the ejection chamber 132 includes a fluid actuator in an actuator layer 120 adjacent the chamber layer 130. The fluid ejection device 100 includes a nozzle orifice 142 fluidically connected to the ejection chamber 132. The fluid ejection device 100 includes a protrusion in the chamber layer 130 extending from a shelf 124 of the chamber layer adjacent the fluid passage opening 112 into the fluid passage opening 112.

[0028] The ejection chamber 132 may be referred to as a firing chamber. The ejection chamber 132 may be configured to receive fluid and eject the fluid using the fluid actuator

122 through the nozzle orifice 142. The ejection chamber 132 may be referred to as “primed” when the ejection chamber 132 contains fluid to be ejected. “Priming” the ejection chamber

132 may refer to the process of filling the ejection chamber 132 with fluid to be ejected. The ejection chamber 132 may be sized to receive an amount of fluid such that the fluid actuator 122 ejects a predetermined amount of fluid. The ejection chamber 132 may have any shape.

In an example, the ejection chamber 132 is roughly square-shaped. In an example, the ejection chamber 132 is roughly circular. The ejection chamber 132 may be formed using a lithographic process. In an example, the ejection chamber 132 is formed using SUS or other photoresist material in a layered structure.

[0029] The fluid actuator 122 may be a thermal, mechanical, electrical, and/or electromechanical actuator. In an example, the fluid actuator 122 is a resistor which boils the fluid to eject the fluid through the nozzle orifice 142. In some examples, the fluid actuator 122 is a thermal resistor. A thermal resistor can be used as a heater to heat liquid in the ejection chamber 132 and/or a fluid inlet channel fluidically connecting the ejection chamber 132 and the fluid passage opening 112, 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 122 is a piezoelectric actuator.

[0030] The nozzle orifice 142 may be referred to as a nozzle, ejection opening, orifice, or ejection orifice. The nozzle orifice 142 may shape and/or direct jets or drops of fluid which are directed from the ejection chamber 132. The nozzle orifice 142 may be at a top (ceiling) of the ejection chamber 132 and the fluid actuator 122 may be at a bottom (floor) of the ejection chamber 132. The terms “top,” “bottom,” “floor,” and “ceiling” are used for ease of understanding and do not limit the orientation of the ejection chamber 132. The ejection chamber 132 may be oriented in any direction.

[0031] The shelf 124 may be a portion of the chamber layer 130 and/or the actuator layer

120. In an example, the chamber layer 130 is adjacent the actuator layer 120 and the shelf is a surface of the actuator layer 120 adjacent the chamber layer 130. The shelf 124 may form a

“floor” of the chamber layer 130. The shelf 124 may form a portion of the floor of the chamber layer 130 adjacent the fluid passage opening 112. The shelf 124 may be a surface to which side walls of the ejection chamber 132 are attached. The shelf 124 may be a surface to which side walls of a fluid inlet channel fluidically connecting the ejection chamber 132 to the fluid passage opening 112 are attached.

[0032] In some implementations, a first portion of the protrusion 134 extends within the chamber layer 130 into the fluid passage opening 112 and a second portion of the protrusion

134 extends into a substrate layer of the fluid ejection device 100 through the fluid passage opening 112. The first portion and the second portion of the protrusion 134 may be substantially perpendicular to one another. The first portion of the protrusion 134 may extend within a plane of the chamber layer 130 while the second portion of the protrusion 134 may extend beyond the plane of the chamber layer 130 into the actuator layer 120 and/or the substrate layer. Extending “within the plane of the chamber layer” may refer to the protrusion

134 remaining within the bounds of the chamber layer 130. In an example, in a layered structure including the chamber layer 130, the protrusion 134 may extend within the plane of the chamber layer, not into adjacent layers. In some examples, the second portion of the protrusion 134 may extend a portion of a height of the actuator layer 120 into the fluid passage opening 112. In some examples, the protrusion 134 includes the first portion and extends within the chamber layer into the fluid passage opening 112. The substrate layer may be adjacent the actuator layer 120 and/or attached to the actuator layer 120 by an adhesive layer between the substrate layer and the actuator layer 120. The actuator layer 120 may be between the substrate layer and the chamber layer 130. In some implementations, the first portion of the protrusion extends from a top of the chamber layer 130 to a bottom of the chamber layer

130. The first portion of the protrusion may extend along an entire height of the chamber layer 130.

[0033] In some implementations, the protrusion 134 includes a leading edge extending into the fluid passage opening 112 and a trailing edge facing the ejection chamber 132, 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 132 and the fluid passage opening 112.

The leading edge may be positioned such that fluid from the fluid passage opening 112 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

132. The trailing edge may reduce an effective width of the fluid inlet channel to facilitate priming of the ejection chamber 132.

[0034] In some implementations, the protrusion 134 extends from a first side of the fluid passage opening 112 into the fluid passage opening 112 and the ejection chamber 132 is on a second side of the fluid passage opening 112. The protrusion 134 and the ejection chamber

132 may be on opposite sides of the fluid passage opening 112. The protrusion 134 and the ejection chamber 132 may be on adjacent sides of the fluid passage opening 112.

[0035] In some implementations, the chamber layer 130 includes a first array of ejection chambers on a first side of the fluid passage opening 112 and a second array of ejection chambers on a second side of the fluid passage opening 112 opposite the first side. The protrusion 134 may extend into the fluid passage opening 112 from a third side of the fluid passage opening 112. In an example, arrays of ejection chambers are on opposite sides of the fluid passage opening 112 and protrusions are on other opposite sides of the fluid passage opening 112.

[0036] In some implementations, the protrusion 134 extends across a width of the fluid passage opening 112. The protrusion 134 may extend beyond the chamber layer 130 into the actuator layer 120 and/or a substrate layer as well as across the width of the fluid passage opening 112. A first portion of the protrusion 134 may be on the shelf 124 within the chamber layer 130 and a second portion of the protrusion 134 may extend across the width of the fluid passage opening 112 and beyond the chamber layer 130 into the actuator layer 120 and/or a substrate layer. In some implementations, the protrusion 134 connects (across the fluid passage opening 112) 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.

[0037] In some implementations, the protrusion 134 is formed as a wall of a fluid inlet channel, as a pillar, or as a bridge connecting a wall and/or a pillar.

[0038] In some implementations, the fluid passage opening 112 is fluidically connected to a reservoir containing fluid. The reservoir may be fluidically connected to the ejection chamber

132 through the fluid passage opening 112.

[0039] FIG. 2 is a block diagram of an example fluid ejection device 200 with a wall 234 of a fluid inlet channel 236 extending into a fluid passage opening 212. The fluid passage opening 212 is fluidically connected to a chamber layer 230. The chamber layer 230 includes an ejection chamber 232. The fluid ejection device 200 includes a nozzle orifice 242 fluidically connected to the ejection chamber 232. The fluid inlet channel 236 is fluidically connected to the ejection chamber 232. The fluid inlet channel 236 may fluidically connect the ejection chamber 232 and the fluid passage opening 212. The wall 234 of the fluid inlet channel 236 extends into the fluid passage opening 212 to form a cantilever structure. A first portion of the wall 234 may extend from a bottom to a top of the chamber layer 230 and a second portion of the wall 234 may extend into the fluid passage opening 212. The second portion of the wall 234 may extend, without contacting a bottom of the chamber layer 230, into the fluid passage opening 212 such that the second portion of the wall 234 cantilevers

(extends from a support beyond the support) out into the fluid passage opening 212. The second portion of the wall 234 may extend beyond the chamber layer 230 into an actuator layer and/or a substrate layer of the fluid ejection device 200. [0040] In some implementations, the wall 234 may extend across a width of the fluid passage opening 212. The wall 234 may extend beyond the chamber layer 130 into the actuator layer

120 and/or a substrate layer as well as across the width of the fluid passage opening 212. A first portion of the wall 234 may be on a shelf within the chamber layer 230 and a second portion of the wall 234 may extend across the width of the fluid passage opening 212 and beyond the chamber layer 230 into an actuator layer and/or a substrate layer of the fluid ejection device 200. In some implementations, the wall 234 connects (across the fluid passage opening 212) with a pillar between the fluid passage opening 212 and a second ejection chamber across the fluid passage opening 212.

[0041] In some implementations, the fluid passage opening 212 is fluidically connected to a reservoir containing fluid. The reservoir may be fluidically connected to the ejection chamber

232 through the fluid passage opening 212 and the fluid inlet channel 236.

[0042] FIG. 3 is a block diagram of an example fluid ejection device 300 with a portion of a pillar 334 extending into a fluid passage opening 312. The fluid passage opening 312 is fluidically connected to a chamber layer 330. The portion of the pillar 334 which extends into the fluid passage opening 312 may be referred to as the extending portion of the pillar 334.

The chamber layer 330 includes an ejection chamber 332. The pillar 334 is between the fluid passage opening 312 and the ejection chamber 332 on a shelf 324 of the chamber layer 330.

The extending portion of the pillar extends into the fluid passage opening 312 to form a cantilever structure. A shelf portion of the pillar 334 may extend from a bottom to a top of the chamber layer 330 on the shelf 324 and the extending portion of the pillar 334 may extend into the fluid passage opening 312. The extending portion of the pillar 334 may extend, without contacting a bottom of the chamber layer 330, into the fluid passage opening 312 such that the second portion of the pillar 334 cantilevers out into the fluid passage opening 312. The extending portion of the pillar 334 may extend beyond the chamber layer 330 into an actuator layer and/or a substrate layer of the fluid ejection device 300.

[0043] In some implementations, the pillar 334 may include a leading edge extending into the fluid passage opening 312 and a trailing edge facing the ejection chamber 332. The trailing edge may be configured to reduce an angle of expansion of a fluid inlet channel fluidically connecting the ejection chamber 332 and the fluid passage opening 312. The leading edge may be positioned such that fluid from the fluid passage opening 312 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 332. The trailing edge may reduce an effective width of the fluid inlet channel to facilitate priming of the ejection chamber 332.

[0044] In some implementations, the pillar 334 extends across a width of the fluid passage opening 312. The pillar 334 may extend beyond the chamber layer 330 into an actuator layer and/or a substrate layer of the fluid ejection device 300 as well as across the width of the fluid passage opening 312. A first portion of the pillar 334 may be on a shelf of the chamber layer

330 and a second portion of the protrusion 134 may extend across the width of the fluid passage opening 312 and beyond the chamber layer 330 into the actuator layer and/or the substrate layer. In some implementations, the pillar 334 connects (across the fluid passage opening 312) a second pillar between the fluid passage opening 312 and a second ejection chamber across the fluid passage opening 312.

[0045] In some implementations, the fluid passage opening 312 is fluidically connected to a reservoir containing fluid. The reservoir may be fluidically connected to the ejection chamber

332 through the fluid passage opening 312. [0046] Characteristics attributed to the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3 may be attributed to any of the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3. In addition, characteristics of the fluid ejection device

100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of

FIG. 3 may be combined within a single fluid ejection device.

[0047] FIG. 4 illustrates a cross-section of an example fluid ejection device 400. In some implementations, the fluid ejection device 400 may be similar to, or include components similar to the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3. The fluid ejection device 400 may be an example of the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3.

[0048] The fluid ejection device 400 may include a substrate layer 410, an actuator layer 420, a chamber layer 430, and a nozzle layer 440. The fluid ejection device 400 may be partially or completely formed by depositing layers on a substrate. In an example, the fluid ejection device 400 may be partially or completely formed by depositing layers of material on the substrate layer 410.

[00491 The substrate layer 410 may include a fluid passage opening 412. The fluid passage opening 412 may allow a fluid 402 to travel through the substrate layer 410 and the actuator layer 420 to the chamber layer 430. The substrate layer 410 may include circuitry for controlling fluid ejection. In an example, the substrate layer 410 is silicon. In an example, the substrate layer 410 includes circuitry for controlling fluid actuation by a fluid actuator 422.

The fluid actuator 422 may be in the actuator layer 420. The fluid actuator 422 may span a height of the actuator layer 420 or a portion of the height of the actuator layer 420. The actuator layer 420 may be adjacent the substrate layer 410. The actuator layer 420 may include the fluid passage opening 412 to allow the fluid 402 to pass to the chamber layer 430.

[0050] The chamber layer 430 includes an ejection chamber 432 fluidically connected to a fluid inlet channel 436. The chamber layer 430 is adjacent the actuator layer 420. The ejection chamber 432 may include or be adjacent the fluid actuator 422 such that the fluid actuator

422 can actuate the fluid 402 when the fluid 402 is in the ejection chamber 432. The nozzle layer 440 is adjacent the chamber layer 430. The nozzle layer 440 includes a nozzle 442. The ejection chamber 432 may include or be adjacent the nozzle 442 such that the fluid actuator

422 can actuate the fluid 402 when the fluid 402 is in the ejection chamber 432 to eject the fluid through the nozzle 442.

[0051] The chamber layer 430 may include side walls of the fluid inlet channel 436 (not shown in FIG. 4). The side walls of the fluid inlet channel 436 may be on a shelf 424 of the actuator layer 420. In some implementations, the side walls of the fluid inlet channel 436 may extend from the shelf 424 of the actuator layer 420 to the nozzle layer 440, or along an entire height of the chamber layer 430. The bottom of the fluid inlet channel 436 (when viewed from the nozzle layer) may be the shelf 424 and the top of the fluid inlet channel 436 may be the nozzle layer 440.

[0052] In some implementations, the fluid 402 may form a meniscus 404 at an interface between the fluid passage opening 412 and the chamber layer 430. The fluid 402 may be pinned, or stock, at the meniscus 404 such that the ejection chamber 432 does not prime. The fluid 402 may be pinned due to interactions between the fluid passage opening 412 and the chamber layer 430. In an example, the interface between the fluid passage opening 412 and the chamber layer 430 may have an angle of expansion of one hundred and eighty degrees, causing the convex meniscus 404 to form and the fluid 402 to be pinned at the interface between the fluid passage opening 412 and the chamber layer 430. In an example, the fluid 402 may be pinned due to a change in topography or material at the interface between the fluid passage opening 412 and the chamber layer 430.

[0053] In some implementations, the fluid 402 is not pinned and fills the ejection chamber

432 such that the ejection chamber 432 is primed. The ejection chamber 432 may be primed due to capillary forces drawing the fluid 402 into the ejection chamber 432. The capillary forces may draw the fluid 402 into the ejection chamber 432 due to a protrusion in the chamber layer 430 which extends into the fluid passage opening 412. In an example, the protrusion extends into the fluid passage opening 412 such that the protrusion contacts or pierces the meniscus 404. In an example, the protrusion extends into the fluid passage opening

412 such that the meniscus 404 does not form.

[0054] In some examples, the chamber layer 430 has a height of between 8 and 50 micrometers. In some examples, the fluid passage opening 412 has dimensions of 30-200 micrometers by 30-1000 micro-meters.

[0055] FIG. 5 illustrates a cross-section of an example fluid ejection device 500 including a protrusion 534 extending from a shelf 524 of a chamber layer 530 adjacent a fluid passage opening 512 into the fluid passage opening 512. The fluid ejection device 500 may be similar in many regards to the fluid ejection device 400 of FIG. 4, with the exception that the fluid ejection device 500 includes the protrusion 534 while the fluid ejection device 400 of FIG. 4 does not include a protrusion. The fluid ejection device 500 may be an example of the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3. The protrusion 534 may extend within the chamber layer 530 into the fluid passage opening 512. In some implementations, the protrusion 534 extends within the chamber layer 530 into the fluid passage opening 512 and does not extend into the resistor layer 520 or the substrate layer 510. In some implementations, the protrusion 534 may extend within the chamber layer 530 into the fluid passage opening 512 and beyond the chamber layer 530 into a resistor layer 520 and a substrate layer 510 (as shown). The protrusion 534 may prevent a fluid 502 from being pinned at an interface between the fluid passage opening

512 and the chamber layer 530 such that the fluid 502 passes through a fluid inlet channel

536 into an ejection chamber 532 to prime the ejection chamber 532. Once the ejection chamber 532 is primed, a fluid actuator 522 in the resistor layer 520 between the substrate layer may eject the fluid 502 from the ejection chamber 532 through a nozzle 542 in a nozzle layer 540.

[0056] The protrusion 534 may have any shape. A leading edge of the protrusion 534

(extending into the fluid passage opening 512) may be rounded, flat, sharp, or any other geometry. A trailing edge of the protrusion 534 (towards the ejection chamber 532) may be rounded, flat, sharp, or any other geometry. In an example, the trailing edge of the protrusion

534 is sharp. In some implementations, the protrusion 534 extends from a top to a bottom

(along an entire height) of the chamber layer 530. In some implementations, the protrusion

534 extends a portion of the height of the chamber layer 530 from the shelf 524. In some implementations, the protrusion 534 extends beyond the chamber layer 530 along a portion of a height of the resistor layer 520.

[0057] FIG. 6 illustrates a cross-section of an example fluid ejection device 600 including a protrusion 634 extending from a shelf 624 of the chamber layer 630 across a fluid passage opening 612. The fluid ejection device 600 may be similar in many regards to the fluid ejection device 400 of FIG. 4, with the addition of the protrusion 634. The fluid ejection device 600 may be an example of the fluid ejection device 100 of FIG. 1, the fluid ejection device 200 of Fig. 2, and/or the fluid ejection device 300 of FIG. 3. The protrusion 634 fluid ejection device 600 may be similar in many regards to the fluid ejection device 500 of FIG.

5, except the protrusion 634 extends across the fluid passage opening 612. The protrusion 634 may extend within the chamber layer 630 into the fluid passage opening 612 across the fluid passage opening 612. In some implementations, the protrusion 634 extends within the chamber layer 630 across the fluid passage opening 612 and does not extend into the resistor layer 620 or the substrate layer 610. In some implementations, the protrusion 634 may extend within the chamber layer 630 into the fluid passage opening 612 and beyond the chamber layer 630 into the resistor layer 620 and the substrate layer 610 (as shown). The protrusion

634 may prevent a fluid 602 from being pinned at an interface between the fluid passage opening 612 and the chamber layer 630 such that the fluid 602 passes through a fluid inlet channel 636 into an ejection chamber 632 to prime the ejection chamber 632. Once the ejection chamber 632 is primed, a fluid actuator 622 in the resistor layer 620 between the substrate layer may eject the fluid 602 from the ejection chamber 632 through a nozzle 642 in a nozzle layer 640.

[0058] The protrusion 634 may have any shape. A trailing edge of the protrusion 634

(towards the ejection chamber 632) may be rounded, flat, sharp, or any other geometry. In an example, the trailing edge of the protrusion 634 is sharp. In some implementations, the protrusion 634 extends from a top to a bottom (along an entire height) of the chamber layer

630. In some implementations, the protrusion 634 extends a portion of the height of the chamber layer 630 from the shelf 624. In some implementations, the protrusion 634 extends beyond the chamber layer 630 along a portion of a height of the resistor layer 620.

[0059] FIG. 7 illustrates an example ejection chamber 732 fluidically connected to an example fluid inlet channel 736 with walls 734 of the fluid inlet channel 736 extending into a fluid passage opening 712. The walls 734 of the fluid inlet channel 736 may extend from a shelf 724 adjacent the fluid passage opening 712 into the fluid passage opening 712 to form cantilever structures, or protrusions. In some examples, the walls 734 are similar to or the same as the protrusion 534 in FIG. 5. The walls 734 may be examples of the wall 234 of FIG.

2 and/or the protrusion 134 of FIG. 1. The fluid inlet channel 736 may fluidically connect the ejection chamber 732 and the fluid passage opening 712 to prime the ejection chamber 732,

Once the ejection chamber 732 is primed, a fluid actuator 722 of the ejection chamber 732 may eject fluid out of the ejection chamber 732 through a nozzle.

[0060] The walls 734 of the fluid inlet channel 736 may extend into the fluid passage opening

712 in order to prevent pinning of a fluid at the fluid passage opening 712. The walls 734 may extend into the fluid passage opening 712 to prevent pinning of a meniscus at the fluid passage opening 712. The walls 734 may extend into the fluid passage opening 712 along a plane of the shelf 724. In some examples, the walls 734 extend into the fluid passage opening 712 along the plane of the shelf 724. In some examples, the walls 734 extend into the fluid passage opening 712 along the plane of the shelf 724 and beyond the plane of the shelf 724 into the fluid passage opening 712 (as illustrated in FIG. 5). The walls 734 may facilitate drawing liquid out of the fluid passage opening 712 through the fluid inlet channel 736 into the ejection chamber 732.

[0061] In some implementations, the walls 734 extend one to twenty μmover the shelf 724 into the fluid passage opening 712. In an example, the walls 734 extend about ten μm over the shelf 724. In an example, the walls 734 extend about four μm over the shelf 724. In an example, the walls 734 extend about two μm over the shelf 724.

[0062] FIG. 8 illustrates an array of multiple example ejection chambers 832 fluidically connected to example fluid inlet channels 836 with walls 834 of the fluid inlet channels 836 extending into a fluid passage opening 812. The ejection chambers 832 may be similar to or the same as the ejection chamber 732 of FIG. 7. The fluid inlet channels 836 may share a wall or walls of the walls 834. In an example, adjacent fluid inlet channels of the fluid inlet channels 836 may share a wall of the walls 834. The walls 834 may extend from a shelf 824 into the fluid passage opening 812 to form cantilever structures, or protrusions. The walls 834 may be examples of the wall 234 of FIG. 2 and/or the protrusion 134 of FIG. 1. The walls 834 may extend into the fluid passage opening 812 in order to prevent pinning of a fluid at the fluid passage opening 812. The walls 834 may extend into the fluid passage opening 812 to prevent pinning of a meniscus at the fluid passage opening 812. The walls 834 may extend into the fluid passage opening 812 along a plane of the shelf 824. In some examples, the walls

834 extend into the fluid passage opening 812 along the plane of the shelf 824. In some examples, the walls 834 extend into the fluid passage opening 812 along the plane of the shelf

824 and beyond the plane of the shelf 824 into the fluid passage opening 812 (as illustrated in FIG. 5). The walls 834 may facilitate drawing fluid out of the fluid passage opening 812 through the fluid inlet channels 836 into the ejection chambers 832. The ejection chambers

832 may include fluid actuators 822 for ejecting the fluid.

[0063] In some implementations, the walls 834 extend one to twenty μm over the shelf 824 into the fluid passage opening 812. In an example, the walls 834 extend about ten μm over the shelf 824. In an example, the walls 834 extend about four μm over the shelf 824. In an example, the walls 834 extend about two μm over the shelf 824.

[0064] FIG. 9 illustrates an example ejection chamber 932 fluidically connected to an example fluid inlet channel 936 with a pillar 934 between the ejection chamber 932 and a fluid passage opening 912 extending into the fluid passage opening 912. The pillar 934 may be disposed partially or completely within the fluid inlet channel 936. The pillar 934 may extend from a shelf 924 adjacent the fluid passage opening 912 into the fluid passage opening

912 to form a cantilever structure, or protrusion. The pillar 934 may be an example of the protrusion 534 in FIG. 5. The pillar 934 may be an example of the pillar 334 of FIG. 3 and/or the protrusion 134 of FIG. 1. The fluid inlet channel 936 may fluidically connect the ejection chamber 932 and the fluid passage opening 912 to prime the ejection chamber 932. Once the ejection chamber 932 is primed, a fluid actuator 922 of the ejection chamber 932 may eject fluid out of the ejection chamber 932 through a nozzle. [0065] The pillar 934 of the fluid inlet channel 936 may extend into the fluid passage opening

912 in order to prevent pinning of a fluid at the fluid passage opening 912. The pillar 934 may extend into the fluid passage opening 912 to prevent pinning of a meniscus at the fluid passage opening 912. The pillar 934 may extend into the fluid passage opening 912 along a plane of the shelf 924. In some examples, the pillar 934 extends into the fluid passage opening 912 along the plane of the shelf 924. In some examples, the pillar 934 extends into the fluid passage opening 912 along the plane of the shelf 924 and beyond the plane of the shelf 924 into the fluid passage opening 912 (as illustrated in FIG. 5). The pillar 934 may facilitate drawing liquid out of the fluid passage opening 912 through the fluid inlet channel 936 into the ejection chamber 932. In some examples, the pillar 934 extends from within the ejection chamber 932 into the fluid passage opening 912 to facilitate drawing liquid out of the fluid passage opening 912 through the fluid inlet channel 936 into the ejection chamber 932.

[0066] In some implementations, the pillar 934 may be located within the fluid inlet channel

936. The pillar 934 may be referred to as an “interior pillar” when it is located within the fluid inlet channel 936. The pillar 934 may be located at a distance from side walls of the fluid inlet channel 936 to facilitate priming of the ejection chamber 932. In some examples, the pillar

934 can have a widening portion at an upstream end (leading edge) of the pillar 934. As used herein, “widening portion" refers to a portion of the pillar 934 that increases in width with respect to the direction of fluid flow. The widening portion may increase in width towards the side walls of the fluid inlet channel 936. The widening portion of the pillar 934 can form various acute angles with the side walls of the fluid inlet channel 936 and the top and bottom of the fluid inlet channel 936. 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 936.

[0067] In some examples, the pillar 934 can have a tapering portion at a downstream end

(trailing edge) of the pillar 934. As used herein, “tapering portion” means that the width of the pillar 934 decreases with respect to the fluid flow direction. The tapering portion may decrease in width away from the side walls of the fluid inlet channel 936.

[0068] The pillar 934 can have a variety of shapes which facilitate fluid flow through the fluid inlet channel 936 by capillary action. The pillar 934 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 934 can have an angle of pillar widening in the same plane as the angle of expansion of the fluid inlet channel 936. In some implementations, the angle of pillar widening may be one degree to one hundred and sixty degrees. In an example, the angle of pillar widening may be one degree to one hundred and sixty degrees. In some examples, the angle of pillar widening may be ten degrees to one hundred degrees. In some examples, the angle of pillar widening may be fifteen degrees to ninety degrees. In some examples, the angle of pillar widening may be 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 936. In some implementations, the angle of pillar narrowing may be five degrees to forty-five degrees. In an example, the angle of pillar narrowing may be five degrees to thirty degrees. In an example, the angle of pillar narrowing may be ten degrees to thirty degrees. In an example, the angle of pillar narrowing may be twenty degrees to thirty degrees. In an example, the angle of pillar narrowing may be twenty degrees to forty-five degrees. In some examples, the tapering portion can have a rounded shape.

[0069] In some implementations, the pillar 934 extends one to twenty μm over the shelf 924 into the fluid passage opening 912. In an example, the pillar 934 extends about ten μm over the shelf 924, In an example, the pillar 934 extends about four μm over the shelf 924. In an example, the pillar 934 extends about two μm over the shelf 924.

[0070] FIG. 10 illustrates a first array of example ejection chambers 1032a fluidically connected to a first array of example fluid inlet channels 1036a and a second array of example ejection chambers 1032b fluidically connected to a second array of example fluid inlet channels 1036b with protrusions 1034 extending across a fluid passage opening 1012 to connect first walls 1033a of the first array of fluid inlet channels 1036a with second pillars

1035b between the fluid passage opening 1012 and the second array of ejection chambers

1032b and second walls 1033b of the second array of fluid inlet channels 1036b with first pillars 1035a between the fluid passage opening 1012 and the first array of ejection chambers

1032a.

[0071] The protrusions 1034 may extend across a width of the fluid passage opening 1012.

The protrusions 1034 may extend across the fluid passage opening 1012 in order to prevent pinning of a fluid at the fluid passage opening 1012. The protrusions 1034 may extend into the fluid passage opening 1012 to prevent formation of a meniscus at the fluid passage opening 1012. The protrusions 1034 may extend into the fluid passage opening 1012 along a plane of the first array of ejection chambers 1032a and the second array of ejection chambers

1032b. In some examples, the protrusions 1034 extend into the fluid passage opening 1012 along the plane of the first array of ejection chambers 1032a and the second array of ejection chambers 1032b. In some examples, the protrusions 1034 extend into the fluid passage opening 1012 along the plane of the first array of ejection chambers 1032a and the second array of ejection chambers 1032b and beyond the plane of the first array of ejection chambers

1032a and the second array of ejection chambers 1032b into the fluid passage opening 1012

(as illustrated in FIG. 6). The protrusions 1034 may facilitate drawing liquid out of the fluid passage opening 1012 through the first array of fluid inlet channels 1036a and the second array of fluid inlet channels 1036b into the first array of ejection chambers 1032a and the second array of ejection chambers 1032b.

[0072] FIG. 11 illustrates a first array of example ejection chambers 1132a fluidically connected to a first array of example fluid inlet channels 1136a and a second array of example ejection chambers 1132b fluidically connected to a second array of example fluid inlet channels 1136b with protrusions 1134 extending across a fluid passage opening 1112 to connect first walls 1133a of the first array of fluid inlet channels 1136a with second walls

1133b of the second array of fluid inlet channels 1136b.

[0073] The protrusions 1134 may extend across a width of the fluid passage opening 1112.

The protrusions 1134 may extend across the fluid passage opening 1112 in order to prevent pinning of a fluid at the fluid passage opening 1112. The protrusions 1134 may extend into the fluid passage opening 1112 to prevent formation of a meniscus at the fluid passage opening 1112. The protrusions 1134 may extend into the fluid passage opening 1112 along a plane of the first array of ejection chambers 1132a and the second array of ejection chambers

1132b. In some examples, the protrusions 1134 extend into the fluid passage opening 1112 along the plane of the first array of ejection chambers 1132a and the second array of ejection chambers 1132b. In some examples, the protrusions 1134 extend into the fluid passage opening 1112 along the plane of the first array of ejection chambers 1132a and the second array of ejection chambers 1132b and beyond the plane of the first array of ejection chambers

1132a and the second array of ejection chambers 1132b into the fluid passage opening 1112

(as illustrated in FIG. 6). The protrusions 1134 may facilitate drawing liquid out of the fluid passage opening 1112 through the first array of fluid inlet channels 1136a and the second array of fluid inlet channels 1136b into the first array of ejection chambers 1132a and the second array of ejection chambers 1132b. [0074] FIG. 12 illustrates a first array of example ejection chambers 1232a fluidically connected to a first array of example fluid inlet channels 1236a and a second array of example ejection chambers 1232b fluidically connected to a second array of example fluid inlet channels 1236b with protrusions 1234 extending across a fluid passage opening 1212 to connect first pillars 1235a between the fluid passage opening 1212 and the first array of ejection chambers 1232a with second pillars 1235b between the fluid passage opening 1212 and the second array of ejection chambers 1232b. In some implementations, the protrusions

1234, the first pillars 1235a, and the second pillars 1235b have a same material. In some implementations, the protrusions 1234, the first pillars 1235a, and the second pillars 1235b are monolithic.

[0075] The protrusions 1234 may extend across a width of the fluid passage opening 1212.

The protrusions 1234 may extend across the fluid passage opening 1212 in order to prevent pinning of a fluid at the fluid passage opening 1212. The protrusions 1234 may extend into the fluid passage opening 1212 to prevent pinning of a meniscus at the fluid passage opening

1212. The protrusions 1234 may extend into the fluid passage opening 1212 along a plane of the first array of ejection chambers 1232a and the second array of ejection chambers 1232b.

In some examples, the protrusions 1234 extend into the fluid passage opening 1212 along the plane of the first array of ejection chambers 1232a and the second array of ejection chambers

1232b. In some examples, the protrusions 1234 extend into the fluid passage opening 1212 along the plane of the first array of ejection chambers 1232a and the second array of ejection chambers 1232b and beyond the plane of the first array of ejection chambers 1232a and the second array of ejection chambers 1232b into the fluid passage opening 1212 (as illustrated in FIG. 6). The protrusions 1234 may facilitate drawing liquid out of the fluid passage opening

1212 through the first array of fluid inlet channels 1236a and the second array of fluid inlet channels 1236b into the first array of ejection chambers 1232a and the second array of ejection chambers 1232b.

[0076] FIG. 13 illustrates a first array of example ejection chambers 1332a fluidically connected to a first array of example fluid inlet channels 1336a on a first side of a fluid passage opening 1312 and a second array of example ejection chambers 1332b fluidically connected to a second array of example fluid inlet channels 1336b on a second side of the fluid passage opening 1312 with a protrusion extending into the fluid passage opening 1312 on a third side of the fluid passage opening 1312.

[0077] The protrusion 1334 may extend into the fluid passage opening 1312 in order to prevent pinning of a fluid at the fluid passage opening 1312. The protrusion 1334 may extend into the fluid passage opening 1312 to prevent formation of a meniscus at the fluid passage opening 1312. The protrusion 1334 may extend into the fluid passage opening 1312 along a plane of the shelf 1324. In some implementations, the protrusion 1334 extends from a shelf

1324 adjacent the fluid passage opening 1312 into the fluid passage opening 1312. In some examples, the protrusion 1334 extends into the fluid passage opening 1312 along the plane of the shelf 1324. In some examples, the protrusion 1334 extends into the fluid passage opening

1312 along the plane of the shelf 1324 and beyond the plane of the shelf 1324 into the fluid passage opening 1312 (as illustrated in FIG. 5). The protrusion 1334 may facilitate drawing liquid out of the fluid passage opening 1312 through the first array of fluid inlet channels

1336a into the first array of ejection chambers 1332a and through the second array of fluid inlet channels 1336b into the second array of ejection chambers 1332b. In some examples, the protrusion 1334 being located on the third side of the fluid passage opening 1312 facilitates passage of fluid between adjacent ejection chambers in the first array of ejection chambers 1332a and between adjacent ejection chambers in the second array of ejection chambers 1332b, as there are no protrusions between the adjacent ejection chambers. [0078] In some implementations, the protrusion 1334 extends one to twenty μm over the shelf

1324 into the fluid passage opening 1312. In an example, the protrusion 1334 extends about ten μm over the shelf 1324. In an example, the protrusion 1334 extends about four μm over the shelf 1324. In an example, the protrusion 1334 extends about two μm over the shelf 1324.

[0079] FIG. 14 illustrates a first array of example ejection chambers 1432a on a first side of a fluid passage opening 1412 and a second array of example ejection chambers 1432b on a second side of the fluid passage opening 1412 with a first protrusion 1434a extending into the fluid passage opening 1412 on a third side of the fluid passage opening and a second protrusion 1434b extending into the fluid passage opening 1412 on a fourth side of the fluid passage opening 1412.

[0080] The first protrusion 1434a and the second protrusion 1434b may be the same as or similar to the protrusion 1334ofFIG. 13. The first protrusion 1434a and the second protrusion

1434b may facilitate drawing liquid out of the fluid passage opening 1412 into the first array of ejection chambers 1432a and into the second array of ejection chambers 1432b. In some examples, the first protrusion 1434a and the second protrusion 1434b being located on the third side and the fourth side, respectively, of the fluid passage opening 1412 facilitates passage of fluid between adjacent ejection chambers in the first array of ejection chambers

1432a and between adjacent ejection chambers in the second array of ejection chambers

1432b, as there are no protrusions between the adjacent ejection chambers, improving a speed of priming the first array of example ejection chambers 1432a and the second array of example ejection chambers 1432b.

[0081] In some implementations, the first protrusion 1434a and the second protrusion 1434b extend a same distance into the fluid passage opening 1412. In some implementations, the first protrusion 1434a and the second protrusion 1434b extend different distances into the fluid passage opening 1412. In an example, the first protrusion 1434a and/or the second protrusion 1434b extend one to twenty μm into the fluid passage opening 1312. In an example, the first protrusion 1434a and/or the second protrusion 1434b extend about ten μm into the fluid passage opening 1412. In an example, the first protrusion 1434a and/or the second protrusion 1434b extend about four μm into the fluid passage opening 1412. In an example, the first protrusion 1434a and/or the second protrusion 1434b extend about two μm into the fluid passage opening 1412.

[0082] In some examples, a fluid ejection device comprises a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber, wherein a floor of the ejection chamber includes a fluid actuator in an actuator layer adjacent the chamber layer. The fluid ejection device may include a nozzle orifice fluidically connected to the ejection chamber and a protrusion in the chamber layer extending from a shelf of the chamber layer adjacent the fluid passage opening into the fluid passage opening.

[0083] In some examples, a first portion of the protrusion extends within the chamber layer into the fluid passage opening and a second portion of the protrusion extends into a substrate layer of the fluid ejection device through the fluid passage opening. In some examples, the first portion of the protrusion extends from a top of the chamber layer to a bottom of the chamber layer.

[0084] In some examples, the protrusion includes a leading edge extending into the fluid passage opening and a trailing edge facing the ejection chamber, the trailing edge configured to reduce an angle of expansion of a fluid inlet channel fluidically connecting the ejection chamber and the fluid passage opening.

[0085] In some examples, the protrusion extends from a first side of the fluid passage opening, and the ejection chamber is on a second side of the fluid passage opening. [0086] In some examples, the chamber layer includes a first array of ejection chambers on a first side of the fluid passage opening, a second array of ejection chambers on a second side of the fluid passage opening opposite the first side, wherein the protrusion extends from a third side of the fluid passage opening.

[0087] In some examples, the protrusion extends across a width of the fluid passage opening.

[0088] In some examples, the protrusion connects 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.

[0089] In some examples, a fluid ejection device comprises a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber, a nozzle orifice fluidically connected to the ejection chamber, and a fluid inlet channel fluidically connected to the ejection chamber, wherein a wall of the fluid inlet channel extends into the fluid passage opening to form a cantilever structure.

[0090] In some examples, the wall of the fluid inlet channel extends across a width of the fluid passage opening. In some examples, the wall of the fluid inlet channel connects with a pillar between the fluid passage opening and a second ejection chamber across the fluid passage opening.

[0091] In some examples, a fluid ejection device comprises a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber and a pillar between the ejection chamber and the fluid passage opening, wherein a portion of the pillar extends from a shelf of the chamber layer adjacent the fluid passage opening into the fluid passage opening.

[0092] In some examples, the pillar includes a leading edge extending into the fluid passage opening and a trailing edge facing the ejection chamber, the trailing edge configured to reduce an angle of expansion of a fluid inlet channel fluidically connecting the ejection chamber and the fluid passage opening.

[0093] In some examples, the pillar extends across a width of the fluid passage opening.

[0094] In some examples, the pillar connects with a second pillar between the fluid passage opening and a second ejection chamber across the fluid passage opening.

[0095] The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components.

Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being "operably couplable," to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.

[0096] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. For example, recitations of plural elements can be understood to include of the element discussed.

[0097] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to implementations containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or

"at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or

A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and

B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." Further, unless otherwise noted, the use of the words

“approximate,” “about, “around," “substantially,” etc., mean plus or minus ten percent.

[0098] The foregoing description of illustrative examples has been presented for purposes of illustration and of description. It is not intended to be exhaustive or limiting with respect to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosed examples. It is intended that the scope of the claimed subject matter be defined by the claims appended hereto and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A fluid ejection device comprising: a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber, wherein a floor of the ejection chamber includes a fluid actuator in an actuator layer; a nozzle orifice fluidically connected to the ejection chamber; and a protrusion in the chamber layer extending from a shelf of the chamber layer adjacent the fluid passage opening into the fluid passage opening.

2. The fluid ejection device of claim 1 , wherein a first portion of the protrusion extends within the chamber layer into the fluid passage opening and a second portion of the protrusion extends into a substrate layer of the fluid ejection device through the fluid passage opening.

3. The fluid ejection device of claim 2, wherein the first portion of the protrusion extends from a top of the chamber layer to a bottom of the chamber layer.

4. The fluid ejection device of claim 1 , wherein the protrusion includes a leading edge extending into the fluid passage opening and a trailing edge facing the ejection chamber.

5. The fluid ejection device of claim 1 , wherein the protrusion extends from a first side of the fluid passage opening, and the ejection chamber is on a second side of the fluid passage opening.

6. The fluid ejection device of claim 1 , wherein the chamber layer includes a first array of ejection chambers on a first side of the fluid passage opening, a second array of ejection chambers on a second side of the fluid passage opening opposite the first side, wherein the protrusion extends from a third side of the fluid passage opening.

7. The fluid ejection device of claim 1 , wherein the protrusion extends across a width of the fluid passage opening.

8. The fluid ejection device of claim 1 , wherein the protrusion connects 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.

9. A fluid ejection device comprising: a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber; a nozzle orifice fluidically connected to the ejection chamber; and a fluid inlet channel fluidically connected to the ejection chamber, wherein a wall of the fluid inlet channel extends into the fluid passage opening to form a cantilever structure.

10. The fluid ejection device of claim 9, wherein the wall of the fluid inlet channel extends across a width of the fluid passage opening.

11. The fluid ejection device of claim 9, wherein the wall of the fluid inlet channel connects with a pillar between the fluid passage opening and a second ejection chamber across the fluid passage opening.

12. A fluid ejection device comprising: a fluid passage opening fluidically connected to a chamber layer, the chamber layer including an ejection chamber; and a pillar between the ejection chamber and the fluid passage opening, wherein a portion of the pillar extends from a shelf of the chamber layer adjacent the fluid passage opening into the fluid passage opening.

13. The fluid ejection device of claim 12, wherein the pillar includes a leading edge extending into the fluid passage opening and a trailing edge facing the ejection chamber, the trailing edge configured to reduce an angle of expansion of a fluid inlet channel fluidically connecting the ejection chamber and the fluid passage opening.

14. The fluid ejection device of claim 12, wherein the pillar extends across a width of the fluid passage opening.

15. The fluid ejection device of claim 12, wherein the pillar connects with a second pillar between the fluid passage opening and a second ejection chamber across the fluid passage opening.