WO2025136356A1

WO2025136356A1 - Fluid inlet channel

Info

Publication number: WO2025136356A1
Application number: PCT/US2023/084662
Authority: WO
Inventors: Katherine Schauer; Christopher Hans BAKKER; Pavel Kornilovich; Roberto A. Pugliese, Jr.
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 an ejection chamber including a fluid actuator and an opening. The fluid ejection device may include a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to two to four times a difference between a right angle and a contact angle between a material of the fluid inlet channel and an aqueous fluid.

Description

FLUID INLET CHANNEL

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.

[0003] FIG. 2 is a block diagram of an example dispenser device.

[0004] FIG. 3 illustrates a cross-section of an example fluid ejection device.

[0005] FIG. 4 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel.

[0006] FIG. 5 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel which narrows in width towards the ejection chamber.

[0007] 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.

[0008] 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.

[0009] 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. [0010] FIG. 9 illustrates a cross section of an example ejection chamber fluidically connected to an example fluid inlet channel.

[0011] FIG. 10 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel including a pillar.

[0012] FIG. 11 illustrates an example ejection chamber fluidically connected to an example fluid inlet channel including multiple pillars.

[0013] 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

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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. [0018] 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.

[0019] 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 one example, aqueous fluids may be pinned within a fluid inlet channel fluidically connected to an ejection chamber. The pinned aqueous fluid does not reach the ejection chamber, preventing printing of the aqueous fluid using the ejection chamber. Structures, such as fluid inlet channels, for printing surfactant-laden liquids generally have geometries that cause aqueous fluids to be pinned. Implementations discussed in the present description propose providing fluid inlet channels that facilitate priming of ejection chambers using capillary forces. Implementations discussed herein may be used to print aqueous fluids for applications such as cell dispensing.

[0020] To illustrate these principles, the present description refers, without limitation, to the illustrative example of a digital dispensing device. Various microfluidic applications may 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.

[0021] 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 example, aqueous fluids may be pinned within a fluid inlet channel fluidically connected to an ejection chamber that is not designed to accommodate fluids without surfactants. The pinned aqueous fluid does not reach the ejection chamber, preventing printing of the aqueous fluid using the ejection chamber. Structures, such as fluid inlet channels, for printing surfactant-laden liquids generally have geometries that cause aqueous fluids to be pinned. Implementations discussed in the present disclosure may prevent pinning by providing fluid inlet channels that facilitate priming of ejection chambers using capillary forces. Implementations discussed herein may be used to print aqueous fluids for applications such as cell dispensing.

[0022] This disclosure relates to fluid ejection devices and fluid dispenser devices. Specifically, this disclosure relates to a fluid ejection device or fluid dispenser 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. In some examples, the present disclosure relates to a fluid ejection device comprising an ejection chamber with a fluid actuator and an opening, and a fluid inlet channel fluidically connected to the ejection chamber. The fluid inlet channel may have an angle of expansion less than or equal to two to four times a difference between a right angle and a contact angle between a material of the fluid inlet channel and an aqueous fluid. The fluid inlet channel may have continuous surface materials to facilitate delivery of the fluid to the ejection chamber. The fluid inlet channel may have minimal floor and ceiling topographical changes to facilitate delivery of the fluid to the ejection chamber. In some implementations, the fluid inlet channel facilitates priming of the ejection chamber with an aqueous fluid without adding surfactants to the fluid or treating the fluid inlet channel with plasma. In some implementations, the fluid inlet channel includes at least one pillar which extend from within the fluid inlet channel over an actuator material in the fluid inlet channel and/or into the ejection chamber. In some implementations, the fluid inlet channel facilitates delivery of the fluid into the ejection chamber using capillary forces such that the ejection chamber contains fluid for ejection. In some examples, the present disclosure relates to a dispenser device, the digital dispenser device comprising an array of ejection chambers, each ejection chamber of the array of ejection chambers fluidically connected to a fluid inlet channel of a plurality of fluid inlet channels and further including: a fluid actuator and an opening. The dispenser device also comprises a fluid passage opening fluidically connected to the plurality of fluid inlet channels, wherein each fluid inlet channel of the plurality of fluid inlet channels has an angle of expansion of less than or equal to eighty degrees.

[0023] FIG. 1 is a block diagram of an example fluid ejection device 100. The fluid ejection device 100 includes an ejection chamber 110. The ejection chamber 110 includes a fluid actuator 112 and an ejection opening 114. The ejection chamber 110 may be configured to receive fluid and eject the fluid using the fluid actuator 112 through the ejection opening 114. The ejection chamber 110 may be referred to as “primed” when the ejection chamber 110 contains fluid to be ejected. “Priming” the ejection chamber 110 may refer to the process of filling the ejection chamber 110 with fluid to be ejected. The ejection chamber 110 may be sized to receive an amount of fluid such that the fluid actuator 112 ejects a predetermined amount of fluid. The ejection chamber 110 may have any shape. In an example, the ejection chamber 110 is roughly square-shaped. In an example, the ejection chamber 110 is roughly circular. The ejection chamber 110 may be formed using a lithographic process. In an example, the ejection chamber 110 is formed using SU8 or other photoresist material in a layered structure.

[0024] The fluid actuator 112 may be a thermal, mechanical, electrical, and/or electromechanical actuator. In an example, the fluid actuator 112 is a resistor which boils the fluid to eject the fluid through the ejection opening 114. In an example, the fluid actuator 112 is a piezoelectric actuator. In some examples, the fluid actuator 112 is a thermal resistor. A thermal resistor can be used as a heater to heat liquid in a microfluidic channel (e.g. ejection chamber 110, fluid inlet channel 120), or as a bubble generator to generate vapor bubbles to eject droplets of liquid from an ejection nozzle (e.g., ejection opening 114) or to pump liquid through the microfluidic channel.

[0025] The ejection opening 114 may be referred to as a nozzle, ejection nozzle, orifice, or ejection orifice. The ejection opening 114 may shape and/or direct jets or drops of fluid which are directed from the ejection chamber 110. The ejection opening 114 may be at a top of the ejection chamber 110 and the fluid actuator 112 may be at a bottom of the ejection chamber 110. The terms “top” and “bottom” are used for ease of understanding and do not limit the orientation of the ejection chamber 110. The ejection chamber 110 may be oriented in any direction. [0026] The fluid ejection device 100 includes a fluid inlet channel 120 fluidically connected to the ejection chamber 110. The fluid inlet channel 120 may provide fluid to the ejection chamber 110. The fluid inlet channel 120 may be fluidically connected to a fluid passage opening to provide fluid to the ejection chamber 110. The fluid inlet channel 120 may have an angle of expansion 122. The angle of expansion (oc) may be less than or equal to two times a difference between a right angle (90°) and a contact angle (0) between a material of the fluid inlet channel and a fluid, as in Expression 1.

Expression 1 : oc < 2(90° — 0)

[0027] 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. The range of two to 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 may be due to 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 may 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. The aqueous fluid may be any fluid in which the solvent is water. The aqueous fluid may be any fluid which is over 99% water by weight.

[0028] The angle of expansion 122 is an angle at which the fluid inlet channel 120 expands in width. In some implementations, the fluid inlet channel 120 expands in width towards the ejection chamber 110, according to the angle of expansion 122, to be equal to a width of the ejection chamber 110. In some implementations, the fluid inlet channel 120 expands in width towards the ejection chamber 110, according to the angle of expansion 122, along an entire length of the fluid inlet channel 120 or along a portion of the length of the fluid inlet channel 120. In an example, the fluid inlet channel 120 includes a pinch point, and the angle of expansion 122 is from the pinch point to the ejection chamber 110. The pinch point may be a location within the fluid inlet channel 120 where the fluid inlet channel 120 transitions from narrowing to expanding in width. The pinch point may reduce blowback along the fluid inlet channel 120 during actuation of the fluid actuator 112. The angle of expansion 122 may be the angle at which the fluid inlet channel 120 expands in width from a narrowest point of the fluid inlet channel 120, such as the pinch point, to a width of the ejection chamber 110. In some implementations, the angle of expansion 122 may cause a connecting point, or interface, between the ejection chamber 110 and the fluid inlet channel 120 to have a same width, and/or to lack a sudden expansion between the ejection chamber 110 and the fluid inlet channel 120. The angle of expansion 122 may be measured up to the width of the ejection chamber 110 such that the interface between ejection chamber 110 and the fluid inlet channel 120 does not include a sudden expansion.

[0029] Expression 1 may represent a conservative estimate for a maximum angle of expansion. Fluids may prime the ejection chamber 110 through the fluid inlet channel 120 with an angle of expansion 122 greater than that allowed by Expression 1, dependent upon characteristics of the fluid/surface interaction, including the contact angle between the fluid and surface as well as capillary forces contributed by the top and bottom of the fluid inlet channel, part-to-part variation in a fabrication process, and/or contamination.

[0030] In general, the contact angle of a fluid can be changed (e.g., reduced) by adding surfactants or co-solvents. However, in some applications, surfactants or co-solvents cannot be added to a fluid. In an example, when dispensing biological cells, surfactants or co-solvents cannot be added to a fluid including the biological cells because the surfactants or co-solvents might kill the cells. In this example, the fluid has a contact angle substantially the same as (within 0.1 - 5.0 degrees) the contact angle of pure water.

[0031] The contact angle between the material of the fluid inlet channel 120 and the aqueous fluid may be an angle between a surface of the aqueous fluid and the outline of the contact surface, or an angle between the surface tangent on the liquid-vapor interface and the tangent on the solid-liquid interface at the intersection of those tangents. The contact angle may be referred to as a wetting angle. The contact angle may describe the wettability of the material of the fluid inlet channel 120 by the aqueous fluid. Wettability describes the tendency of a fluid to spread over a material. In an example, water has a contact angle of about 80° on SU8, which means it has low wettability, making the ejection chamber 110 difficult to prime than a surfactant-laden fluid. In this example, the fluid inlet channel 120 may have an angle of expansion less than or equal to 20°, as 2(90°-80°), as in Expression 1, is equal to 20°. In some implementations, Expression 1 assumes a constant height, or distance between a top and bottom of the fluid inlet channel 120. In some implementations, the top and bottom of the fluid inlet channel 120 are parallel for a portion of the fluid inlet channel. In some implementations, the top and bottom of the fluid inlet channel 120 are parallel for the entire length of the fluid inlet channel.

[0032] The fluid inlet channel 120 may be formed using a lithographic process. The fluid inlet channel 120 may be formed from a same material and/or in a same layer as the ejection chamber 110. In an example, the ejection chamber 110 and the fluid inlet channel 120 are formed using SU8 or other photoresist material in a same layer of a layered structure.

[0033] In some implementations, a surface of the fluid inlet channel 120 has a continuous surface material along the length of the fluid inlet channel 120. In this way, a fluid (e.g. aqueous fluid) may have a continuous contact angle with the surface of the fluid inlet channel 120 along the length of the fluid inlet channel 120. In some implementations, each surface of the fluid inlet channel 120 has a continuous surface material along the length of the fluid inlet channel 120. In this way, the fluid may have a continuous contact angle with each surface of the fluid inlet channel 120 along the length of the fluid inlet channel 120. The surfaces of the fluid inlet channel 120 may have the same or different surface materials. In an example, side walls of the fluid inlet channel 120 may have a same surface material and the top and bottom of the fluid inlet channel 120 may have different surface materials that are different from the same surface materials of the side walls of the fluid inlet channel 120. In an example, side walls of the fluid inlet channel 120 and the top of the fluid inlet channel 120 may have a same surface material and the bottom of the fluid inlet channel 120 may have a different surface material. In an example, side walls of the fluid inlet channel 120 and the top of the fluid inlet channel 120 may have a surface material of SU8 and the bottom of the fluid inlet channel 120 may have a different surface material.

[0034] In some implementations, the angle of expansion 122 is between negative five and five degrees such that the fluid inlet channel 120 has a substantially constant width as it approaches the ejection chamber 110. In an example, the angle of expansion 122 is zero degrees, or approximately zero degrees. In some implementations, the angle of expansion 122 is less than or equal to 20 degrees. In an example, the angle of expansion 122 is fifteen degrees. In an example, the angle of expansion is ten degrees. In some implementations, the angle of expansion 122 is between negative five and eighty degrees. In an example, the angle of expansion is between zero and sixty degrees. In an example, the angle of expansion is between five and fifty degrees. In an example, the angle of expansion is between ten and forty -five degrees. In an example, the angle of expansion is between twenty and forty degrees. As discussed herein, a smaller angle of expansion may provide more stable priming than a larger angle of expansion. [0035] In some implementations, the angle of expansion 122 is between twenty and eighty degrees. In an example, the angle of expansion 122 is thirty degrees. In an example, the angle of expansion 122 is forty degrees.

[0036] In some implementations, the fluid inlet channel 120 includes a pillar which extends from within the fluid inlet channel across a threshold and topography of the fluid actuator 112. In some examples, the fluid actuator 112 is a resistor. The angle of expansion 122 may be between a side wall of the pillar and a side wall of the fluid inlet channel 120. The angle of expansion 122 may be on both sides of the pillar. In this way, the pillar may reduce the angle of expansion 122 by effectively creating new, smaller angles of expansion between the side walls of the fluid inlet channel 120 and the different sides of the pillar. In some implementations, the pillar includes a leading edge and a trailing edge. The trailing edge may have a length greater than a length of the leading edge. The trailing edge may extend across the threshold of the fluid actuator 112 or the resistor. The leading edge may contact the aqueous fluid first as the ejection chamber 110 primes, and the trailing edge may contact the aqueous fluid second, relative to the leading edge, as the ejection chamber 110 primes. In some implementations, the pillar has a diamond-shaped cross-section. The diamond-shaped cross-section may be stretched such that the trailing edge has a length greater than a length of the leading edge. The pillar may extend along an entire height, or from the bottom to the top, of the fluid inlet channel 120.

[0037] In some implementations, the pillar may be located within the fluid inlet channel 120. The pillar may be referred to as an “interior pillar” when it is located within the fluid inlet channel 120. The pillar may be located at a distance from side walls of the fluid inlet channel 120 to facilitate priming of the ejection chamber 110. In some examples, the interior pillar can have a widening portion at an upstream end (leading edge) of the pillar. As used herein, “widening portion” refers to a portion of the pillar 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 120. The widening portion of the pillar can form various acute angles with the side walls of the fluid inlet channel 120 and the top and bottom of the fluid inlet channel 120. 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 120.

[0038] In some examples, the pillar can have a tapering portion at a downstream end (trailing edge) of the pillar. As used herein, “tapering portion” means that the width of the pillar 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 120.

[0039] The pillar can have a variety of shapes which facilitate fluid flow through the fluid inlet channel 120 by capillary action. The pillar can have a variety of shapes which do not cause fluid pinning due to an angle of expansion formed between side walls of the fluid inlet channel 120 and the pillar being within the range described in Expression 1 and/or between two to four times a different between a right angle and the contact angle. 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 can have an angle of pillar widening in the same plane as the angle of expansion 122 of the fluid inlet channel 120. 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 122 of the fluid inlet channel 120. 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.

[0040] The angle of expansion 122 may be such that capillary forces draw the aqueous fluid along the fluid inlet channel 120 into the ejection chamber 110. In this way, the ejection chamber 110 primes due to capillary forces. In some implementations, the ejection chamber 110 primes due to capillary forces due to a geometry of the fluid inlet channel 120, including the angle of expansion 122 and the pillar. In some implementations, the ejection chamber 110 primes due to capillary forces due to the geometry of the fluid inlet channel 120 and surface materials of the fluid inlet channel 120.

[0041] In some implementations, the fluid ejection device 100 includes a fluid feed slot, or fluid passage opening to receive fluid from a reservoir. The fluid feed slot may be fluidically connected to the ejection chambers 110 via the fluid inlet channel 120. In this way, fluid is provided from the reservoir through the fluid feed slot and the fluid inlet channel 120 to the ejection chamber 110.

[0042] FIG. 2 is a block diagram of an example dispenser device 200. The dispenser device 200 may be a digital dispenser device which dispenses fluid according to digital signals. The dispenser device 200 includes an array of ejection chambers 210. The digital signals may control when different ejection chambers of the array of ejection chambers 210 eject fluid. Each ejection chamber of the array of ejection chambers 210 includes a fluid actuator and an ejection opening. The array of ejection chambers 210 may be configured to receive fluid and eject the fluid using the fluid actuators 212 through the ejection openings 214. The array of ejection chambers 210 may be primed when the array of ejection chambers 210 contains fluid to be ejected. The array of ejection chambers 210 may each be sized to receive an amount of fluid such that the corresponding fluid actuator of the fluid actuators 212 ejects a predetermined amount of fluid. The array of ejection chambers 210 may have any shape and each ejection chamber of the array of ejection chambers 210 may have any shape. In an example, the array of ejection chambers 210 includes ejection chambers arranged in a row. The array of ejection chambers 210 may be formed using a lithographic process. In an example, the array of ejection chambers 210 is formed using SU8 or other photoresist material in a layered structure.

[0043] The fluid actuators 212 may be thermal, mechanical, electrical, and/or electromechanical actuators. In an example, the fluid actuators 212 are resistors which boil the fluid to eject the fluid through the ejection openings 214. In an example, the fluid actuators 212 are piezoelectric actuators.

[0044] The ejection openings 214 may be referred to as nozzles or ejection nozzles. The ejection openings 214 may shape and/or direct jets or drops of fluid which are directed from the array of ejection chambers 210. The ejection openings 214 may be at a top of the array of ejection chambers 210 and the fluid actuators 212 may be at a bottom of the array of ejection chambers 210. The terms “top” and “bottom” are used for ease of understanding and do not limit the orientation of the array of ejection chambers 210. The array of ejection chambers 210 may be oriented in any direction. In some implementations, each ejection chamber of the array of ejection chambers 210 is oriented in a same direction.

[0045] The dispenser device 200 includes a plurality of fluid inlet channels 220 fluidically connected to the array of ejection chambers 210. Each fluid inlet channel of the plurality of fluid inlet channels 220 may provide fluid to an ejection chamber of the array of ejection chambers 210. The dispenser device 200 may include a fluid passage opening 230 to provide fluid to the plurality of fluid inlet channels 220. The plurality of fluid inlet channels 220 may be fluidically connected to the fluid passage opening 230 to provide fluid to the array of ejection chambers 210. The plurality of fluid inlet channels may have angles of expansion 222. The angles of expansion may be less than or equal to two times a difference between a right angle and a contact angle between a material of the plurality of fluid inlet channels 220 and an aqueous fluid, as in Expression 1. The angles of expansion may be less than or equal to two to four times a difference between a right angle and a contact angle between a material of the plurality of fluid inlet channels 220 and an aqueous fluid. In some implementations, the angles of expansion 222 are the same for the plurality of fluid inlet channels 220. In some implementations, a fluid inlet channel has an angle of expansion different from another angle of expansion of another fluid inlet channel of the plurality of fluid inlet channels 220.

[0046] In some implementations, the array of ejection chambers 210 may include ejection chambers similar to or the same as the ejection chamber 110 of FIG. 1. In some implementations, the fluid actuators 212 may include fluid actuators similar to or the same as the fluid actuator 112 of FIG. 1. In some implementations, the ejection openings 214 may include ejection openings similar to or the same as the ejection opening 114 of FIG. 1. In some implementations, the plurality of fluid inlet channels 220 may include fluid inlet channels similar to or the same as the fluid inlet channel 120 of FIG. 1. In some implementations, the angles of expansion 222 may include angles of expansion similar to or the same as the angle of expansion 122 of FIG. 1. For example, in some implementations, the angles of expansion 222 may be greater than twenty degrees. In some implementations, each fluid inlet channel of the plurality of fluid inlet channels 220 has an angle of expansion of less than or equal to eighty degrees.

[0047] In some implementations, the dispenser device 200 includes a second array of ejection chambers. The array of ejection chambers 210 and the second array of ejection chambers may be disposed on opposite sides of the fluid passage opening 230. The array of ejection chambers 210 and the second array of ejection chambers may include rows of ejection chambers on opposite sides of the fluid passage opening 230.

[0048] In some implementations, the dispenser device 200 includes a fluid feed slot, or fluid passage opening to receive fluid from a reservoir. The fluid feed slot may be fluidically connected to the array of ejection chambers 210 via the plurality of fluid inlet channels 220. In this way, fluid is provided from the reservoir through the fluid feed slot and the plurality of fluid inlet channels 220 to the array of ejection chambers 210.

[0049] FIG. 3 illustrates a cross-section of an example fluid ejection device 300. In some implementations, the fluid ejection device 300 may be similar to, or include components similar to the fluid ejection device 100 of FIG. 1 and/or the dispenser device 200 of FIG. 2.

[0050] The fluid ejection device 300 may include a substrate layer 310, an actuator layer 320, a chamber layer 330, and a nozzle layer 340. The fluid ejection device 300 may be partially formed by depositing layers on a substrate. In an example, the fluid ejection device 300 may be partially formed by depositing layers of material on the substrate layer 310.

[0051] The substrate layer 310 may include a fluid passage opening 312. The fluid passage opening 312 may allow a fluid 302 to travel through the substrate layer 310 and the actuator layer 320 to the chamber layer 330. The substrate layer 310 may include circuitry for controlling fluid ejection. In an example, the substrate layer 310 is silicon. In an example, the substrate layer 310 includes circuitry for controlling fluid actuation by a fluid actuator 322. The fluid actuator 322 may be in the actuator layer 320. The fluid actuator 322 may span a height of the actuator layer 320 or a portion of the height of the actuator layer 320. The actuator layer 320 may be adjacent the substrate layer 310. The actuator layer 320 may include the fluid passage opening 312 to allow the fluid 302 to pass to the chamber layer 330. [0052] The chamber layer 330 includes an ejection chamber 332 fluidically connected to a fluid inlet channel 336. The chamber layer 330 is adjacent the actuator layer 320. The ejection chamber 332 may include or be adjacent the fluid actuator 322 such that the fluid actuator 322 can actuate the fluid 302 when the fluid 302 is in the ejection chamber 332. The nozzle layer 340 is adjacent the chamber layer 330. The nozzle layer 340 includes a nozzle 342. The ejection chamber 332 may include or be adjacent the nozzle 342 such that the fluid actuator 322 can actuate the fluid 302 when the fluid 302 is in the ejection chamber 332 to eject the fluid through the nozzle 342.

[0053] The chamber layer 330 may include side walls of the fluid inlet channel (not shown in FIG. 3). The side walls of the fluid inlet channel 336 may be on a shelf 324 of the actuator layer 320. In some implementations, the side walls of the fluid inlet channel 336 may extend from the shelf 324 of the actuator layer 320 to the nozzle layer 340, or along an entire height of the chamber layer 330. The bottom of the fluid inlet channel 336 (when viewed from the nozzle layer) may be the shelf 324 and the top of the fluid inlet channel 336 may be the nozzle layer 340.

[0054] In some implementations, the fluid 302 may form a meniscus 304 within the chamber layer 330. The fluid 302 may be pinned, or stuck, at the meniscus 304 such that the ejection chamber 332 does not prime. The fluid 302 may be pinned due to interactions between the fluid 302 and fluid inlet channel 336. The interactions between the fluid 302 and the fluid inlet channel 336 may include interactions between the fluid 302 and the actuator layer 320, the nozzle layer 340, and/or the side walls of the fluid inlet channel 336 within the chamber layer 330. In an example, the fluid 302 may be pinned due to an angle of expansion of the fluid inlet channel 336 being too large. In an example, the angle of expansion of the fluid inlet channel 336 is along a width of the fluid inlet channel 336 within the chamber layer 330 and the actuator layer 320 and the nozzle layer 340 are parallel along a length of the fluid inlet channel 336. In an example, the fluid 302 may be pinned due to a change in topography or material in the fluid inlet channel 336 on the shelf 324 of the actuator layer 320 and/or the nozzle layer.

[0055] In some implementations, the fluid 302 is not pinned and fills the ejection chamber 332 such that the ejection chamber 332 is primed. The ejection chamber 332 may be primed due to capillary forces drawing the fluid 302 into the ejection chamber 332. The capillary forces may draw the fluid 302 into the ejection chamber 332 based on a geometry and/or surface material of the fluid inlet channel 336. In an example, the capillary forces may draw the fluid 302 into the ejection chamber 332 based on the fluid inlet channel 336 having an angle of expansion less than or equal to eighty degrees and/or a continuous surface material along a surface of the fluid inlet channel 336. In an example, the capillary forces may draw the fluid 302 into the ejection chamber 332 based on the fluid inlet channel 336 having an angle of expansion less than or equal to twenty degrees and/or a continuous surface material along a surface of the fluid inlet channel 336.

[0056] FIG. 4 illustrates an example ejection chamber 432 fluidically connected to an example fluid inlet channel 436. The ejection chamber 432 includes a fluid actuator 422. The fluid actuator 422 may be a resistor to heat up and boil fluid to eject the fluid out of the ejection chamber 432. In the illustrated example, the direction of fluid ejection is out of the page. A material of the fluid actuator 422 may extend from the ejection chamber 432 into the fluid inlet channel 436. The fluid inlet channel 436 is on a shelf 424 of a fluid ejection device. The fluid inlet channel 436 fluidically connects a fluid passage opening 412 of the fluid ejection device to the ejection chamber 432. In some implementations, the ejection chamber 432 may be the ejection chamber 332 of FIG. 3.

[0057] The fluid inlet channel 436 includes a pinch point 435, where the fluid inlet channel 436 transitions from narrowing in width towards the ejection chamber 432 to expanding in width (or, as in the fluid inlet channel 436, maintaining a constant width) towards the ejection chamber 432. The angle of expansion of the fluid inlet channel 436, from the narrowest point of the fluid inlet channel 436 to the width of the ejection chamber 432, is 180 degrees, as the fluid inlet channel 436 expands abruptly at the interface between the fluid inlet channel 436 and the ejection chamber 432. This abrupt expansion of the fluid inlet channel 436 may cause a fluid to be pinned and form a meniscus 404 at the interface between the fluid inlet channel 436 and the ejection chamber 432.

[0058] Whether or not a fluid is pinned at the interface between the fluid inlet channel 436 and the ejection chamber 432 depends upon interactions between the fluid and the surfaces of the fluid inlet channel 436 and/or the surfaces of the ejection chamber 432. Fluids containing surfactants generally have lower contact angles with materials than aqueous fluids, causing fluids including surfactants to more readily prime the ejection chamber 432. Surfaces that have undergone treatment to lower their surface energy, such as plasma treatment, generally have a lower contact angle with fluids than untreated surfaces, causing the fluids to more readily prime the ejection chamber 432. In an example, the fluid is a marking fluid (e.g., ink) ink and contains surfactants, causing the fluid to not be pinned but instead to prime the ejection chamber 432, such as for a wide range of materials and fluids. In an example, the fluid is an aqueous fluid and surfaces of the fluid inlet channel 436 and/or the ejection chamber 432 are treated with plasma, causing the fluid to not be pinned but instead to prime the ejection chamber 432. In an example, the fluid is an aqueous fluid and the surfaces of the fluid inlet channel 436 are not treated with plasma, causing the fluid to form the meniscus 404 and be pinned at the interface between the fluid inlet channel 436 and the ejection chamber 432. In some implementations, the ejection chamber 432 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 432 may be part of the dispenser device 200 of FIG. 2. [0059] 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 inlet channel 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. In some implementations, the ejection chamber 532 may be the ejection chamber 332 of FIG. 3.

[0060] 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. When the fluid actuator 522 ejects the fluid from the ejection chamber 532, fluid may be ejected out of the ejection chamber 532 through a nozzle (in a direction out of the page) and fluid may be pushed through the fluid inlet channel 536 away from the ejection chamber 532, which backflow of fluid through the fluid inlet channel 536 may be termed “blowback.”

[0061] In some implementations, the ejection chamber 532 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 532 may be part of the dispenser device 200 of FIG. 2.

[0062] 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. In some implementations, the ejection chamber 632 may be the ejection chamber 332 of FIG. 3.

[0063] 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 may be 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 of approximately 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. When the fluid actuator 622 ejects the fluid from the ejection chamber 632, fluid may be ejected out of the ejection chamber 632 through a nozzle (in a direction out of the page) and backflow may pass through the fluid inlet channel 636 away from the ejection chamber 632.

[0064] In some implementations, the ejection chamber 632 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 632 may be part of the dispenser device 200 of FIG. 2.

[0065] 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 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. In some implementations, the ejection chamber 732 may be the ejection chamber 332 of FIG. 3.

[0066] 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 may expand 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 may allow 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.

[0067] 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 the ejection 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 may mitigate blowback from the ejection chamber 732.

[0068] In some implementations, the ejection chamber 732 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 732 may be part of the dispenser device 200 of FIG. 2.

[0069] 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. In some implementations, the ejection chamber 832 may be the ejection chamber 332 of FIG. 3.

[0070] 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 plurality of fluid inlet channels 220 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 may mitigate 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. [0071] In some implementations, the ejection chamber 832 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 832 may be part of the dispenser device 200 of FIG. 2.

[0072] 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. In some implementations, the components of FIG. 9 may be similar or the same as the components of the fluid ejection device 300 of FIG. 3.

[0073] A top surface of the fluid inlet channel 936 may be formed by the nozzle layer 940. A bottom surface of the fluid inlet channel 936 may be 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 shelf of the actuator layer 920. The nozzle layer 940 may have 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 may have 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 may 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.

[0074] The surfaces of the fluid inlet channel 936 may have different surface materials. In an example, the thin film 924 may be a first material which is a continuous bottom surface material of the fluid inlet channel 936, the nozzle layer 940 may be 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 may be a third material which is a continuous sides surface of the fluid inlet channel 936.

[0075] 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, an additional 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 may 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 may cause a fluid to be pinned in the fluid inlet channel 936.

[0076] To facilitate priming of the ejection chamber 932, the fluid inlet channel 936 may have continuous surface materials and/or a constant or narrowing height along the length of the fluid inlet channel 936. The thin film 924 may 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 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 may facilitate priming of the ejection chamber 932, as illustrated in FIG. 10.

[0077] In some implementations, the ejection chamber 932 may be part of the fluid ejection device 100 of FIG. 1. In some implementations, the ejection chamber 932 may be part of the dispenser device 200 of FIG. 2.

[0078] 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. In some implementations, the ejection chamber 1032 may be the ejection chamber 332 of FIG. 3.

[0079] 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 may reduce 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 may be present on different sides of the pillar 1034.

[0080] The pillar 1034 may include a leading edge towards the fluid passage opening 1012 and a trailing edge towards the ejection chamber 1032. The trailing edge may extend 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 may facilitate priming of the ejection chamber 1032. The threshold 1023 may be a point in the fluid inlet channel 1036 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 may facilitate priming of the ejection chamber 1032.

[0081] The pillar 1034 may have a diamond-shaped cross-section, as illustrated in FIG. 10. The diamond-shaped cross-section may prevent 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 may include 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 may affect 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.

[0082] 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 may mitigate blowback from the ejection chamber 1032. The pillar 1034 may reduce blowback by serving as an obstacle within the fluid inlet channel 1036 which resists blowback.

[0083] 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 1132 into 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. In some implementations, the ejection chamber 1132 may be the ejection chamber 332 of FIG. 3.

[0084] 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 may 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.

[0085] The pillars 1134 may each include a leading edge towards the fluid passage opening 1112 and a trailing edge towards the ejection chamber 1132. The trailing edge may extend along the fluid inlet channel 1136 from the pinch point 1135 toward the ejection chamber 1132. In some implementations, the leading edge of at least one of the pillars 1134 extends into the ejection chamber 1132. In some implementations, the leading edge of at least one of the pillars 1134 extends over a threshold of the fluid actuator 1122. The trailing edge of at least one of the pillars 1134 extending over the threshold of the fluid actuator 1122 and/or extending into the ejection chamber 1132 may facilitate priming of the ejection chamber 1132.

[0086] The pillars 1134 may each have a diamond-shaped cross-section, as illustrated in FIG.

11. The diamond-shaped cross-section may prevent pinning of fluids on the pillars 1134 by allowing for a gradual angle of expansion on the trailing edges of the pillars 1134. As discussed herein, the pillars 1134 may each include a widening portion on the leading edges of the pillars 1134 and a tapering portion on the trailing edges of the pillars 1134. An angle of pillar narrowing of the tapering portion on the trailing edges of the pillars 1134 may affect the angle of expansion of the fluid inlet channel 1136 from the pinch point 1135 to the ejection chamber 1132. 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. The pillars 1134 may have a same angle of pillar narrowing or different angles of pillar narrowing.

[0087] The angles of expansion of about twenty-five degrees may cause a fluid to prime the ejection chamber 1132, dependent upon interactions between the fluid and the surface materials of the fluid inlet channel 1136 and/or the pillars 1134. The pinch point 1135 and the pillars 1134 may mitigate blowback from the ejection chamber 1132. The pillars 1134 may reduce blowback by serving as obstacles within the fluid inlet channel 1136 which resist blowback.

[0088] 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 1135 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.

[0089] 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.

[0090] In some examples, a fluid ejection device comprises an ejection chamber including a fluid actuator; and an opening. The fluid ejection device further comprises a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to two to four times a difference between a right angle and a contact angle between a material of the fluid inlet channel and an aqueous fluid.

[0091] In some examples, a surface of the fluid inlet channel has a continuous surface material along a length of the fluid inlet channel. In some examples, in the fluid ejection device, each surface of the fluid inlet channel has a continuous surface material along a length of the fluid inlet channel.

[0092] In some examples, the fluid inlet channel includes a pinch point, and the angle of expansion is from the pinch point to the ejection chamber.

[0093] In some examples, the angle of expansion is between negative five and five degrees, such that the fluid inlet channel has a substantially constant width as it approaches the ejection chamber.

[0094] In some examples, the angle of expansion is less than or equal to twenty degrees. [0095] In some examples, the angle of expansion is between twenty and eighty degrees.

[0096] In some examples, a top and bottom of the fluid inlet channel are parallel for a portion of the fluid inlet channel.

[0097] In some examples, in the fluid ejection device, the fluid inlet channel includes a pillar which extends from within the fluid inlet channel across a threshold of the fluid actuator. In some examples, the pillar includes a leading edge and a trailing edge, wherein the trailing edge has a length greater than a length of the leading edge, and wherein the trailing edge extends across the threshold of the fluid actuator. In some examples, the pillar has a diamondshaped cross-section.

[0098] In some examples, the angle of expansion is such that capillary forces draw the aqueous fluid along the fluid inlet channel into the ejection chamber.

[0099] In some examples, a dispenser device comprises an array of ejection chambers, each ejection chamber of the array of ejection chambers fluidically connected to a fluid inlet channel of a plurality of fluid inlet channels and including a fluid actuator and an opening. The dispenser device may further comprise a fluid passage opening fluidically connected to the plurality of fluid inlet channels, wherein each fluid inlet channel of the plurality of fluid inlet channels has an angle of expansion of less than or equal to eighty degrees.

[0100] In some examples, the angle of expansion of each fluid inlet channel of the plurality of fluid inlet channels is less than twenty degrees.

[0101] In some examples, the dispenser device includes a second array of ejection chambers, wherein the array of ejection chambers and the second array of ejection chambers are disposed on opposite sides of the fluid passage opening.

[0102] The fluid ejection device and dispenser device may be used in dispensing cells suspended in aqueous fluid. In an example, predetermined amounts of aqueous fluid may be dispensed from an ejection chamber, causing a specific number of cells to be dispensed. The cells may be dispensed for biological research.

[0103] 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.

[0104] 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.

[0105] 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 examples 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.

[0106] 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 invention be defined by the claims appended hereto and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A fluid ejection device comprising: an ejection chamber including: a fluid actuator; and an opening; and a fluid inlet channel fluidically connected to the ejection chamber, the fluid inlet channel having an angle of expansion less than or equal to two to four times a difference between a right angle and a contact angle between a material of the fluid inlet channel and an aqueous fluid.

2. The fluid ejection device of claim 1, wherein a surface of the fluid inlet channel has a continuous surface material along a length of the fluid inlet channel.

3. The fluid ejection device of claim 2, wherein each surface of the fluid inlet channel has a continuous surface material along a length of the fluid inlet channel.

4. The fluid ejection device of claim 1, wherein the fluid inlet channel includes a pinch point, and wherein the angle of expansion is from the pinch point to the ejection chamber.

5. The fluid ejection device of claim 1, wherein the angle of expansion is between negative five and five degrees, such that the fluid inlet channel has a substantially constant width as it approaches the ejection chamber.

6. The fluid ejection device of claim 1, wherein the angle of expansion is less than or equal to twenty degrees.

7. The fluid ejection device of claim 1, wherein the angle of expansion is between twenty and eighty degrees.

8. The fluid ejection device of claim 1, wherein a top and bottom of the fluid inlet channel are parallel for a portion of the fluid inlet channel.

9. The fluid ejection device of claim 1, wherein the fluid inlet channel includes a pillar which extends from within the fluid inlet channel across a threshold of the fluid actuator.

10. The fluid ejection device of claim 9, wherein the pillar includes a leading edge and a trailing edge, wherein the trailing edge has a length greater than a length of the leading edge, and wherein the trailing edge extends across the threshold of the fluid actuator.

11. The fluid ejection device of claim 9, wherein the pillar has a diamond-shaped crosssection.

12. The fluid ejection device of claim 1, wherein the angle of expansion is such that capillary forces draw the aqueous fluid along the fluid inlet channel into the ejection chamber.

13. A dispenser device comprising: an array of ejection chambers, each ejection chamber of the array of ejection chambers fluidically connected to a fluid inlet channel of a plurality of fluid inlet channels and including: a fluid actuator; and an opening; and a fluid passage opening fluidically connected to the plurality of fluid inlet channels, wherein each fluid inlet channel of the plurality of fluid inlet channels has an angle of expansion of less than or equal to eighty degrees.

14. The dispenser device of claim 13, wherein the angle of expansion of each fluid inlet channel of the plurality of fluid inlet channels is less than twenty degrees.

15. The dispenser device of claim 13, further comprising: a second array of ejection chambers, wherein the array of ejection chambers and the second array of ejection chambers are disposed on opposite sides of the fluid passage opening.