Center anchored MEMS based active cooling system

Abstract

This invention relates to a center-anchored MEMS-based active cooling system, and more particularly to a cooling system comprising: a support structure; a cooling element having a first cantilever region, a second cantilever region, a central region between the first and second cantilever regions, and a periphery, the cooling element being supported by the support structure at the central region, at least a portion of the periphery being unfixed, the cooling element being configured to undergo vibratory motion upon actuation to drive fluid toward a heat-generating structure; and an orifice plate having at least one orifice therein, the cooling element being configured to undergo vibratory motion of the first and second cantilever regions upon actuation to drive the fluid through the at least one orifice, the orifice plate being situated in a fluid path between the cooling element and the heat-generating structure.

Description

[0001] This application is a divisional application of the PCT patent application "Center-anchored MEMS-based active cooling system" (application number: 202080026619.3, applicant: Fluor Systems, Inc.), which entered the Chinese national phase on September 30, 2021.

[0002] Cross-references to related applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 945,001, filed December 6, 2019, entitled “CENTRALLY PINNED COOLING ELEMENTS IN A MEMS-BASED COOLING SYSTEM,” which is incorporated herein by reference for all purposes. Background Technology

[0004] As the speed and computing power of computing devices increase, the heat generated by these devices also increases. Various mechanisms have been proposed to address this heat generation. Active devices such as fans can be used to drive air through large computing devices such as laptops or desktop computers. Passive cooling devices such as vapor chambers can be used for smaller mobile computing devices such as smartphones, virtual reality devices, and tablets. However, both active and passive devices may not adequately cool both mobile devices like smartphones and larger devices such as laptops or desktop computers. Therefore, additional cooling solutions are needed for computing devices. Attached Figure Description

[0005] Various embodiments of the invention are disclosed in the following detailed description and accompanying drawings.

[0006] Figures 1A to 1C An embodiment of an active cooling system including a centrally anchored cooling element is described.

[0007] Figures 2A to 2B An embodiment of a cooling element that can be used in an active cooling system including a centrally anchored cooling element is described.

[0008] Figures 3A to 3B An embodiment of a cooling element that can be used in an active cooling system including a centrally anchored cooling element is described.

[0009] Figures 4A to 4E An embodiment of an active cooling system including a centrally anchored cooling element is described.

[0010] Figure 5 An embodiment of an active cooling system comprising a centrally anchored cooling element and a folded top chamber is depicted.

[0011] Figures 6A to 6C An embodiment of an active cooling system comprising multiple cooling elements is described.

[0012] Figures 7A to 7C An embodiment of an active cooling system comprising multiple centrally anchored cooling elements is described.

[0013] Figures 8A to 8E An embodiment of an active cooling system including a centrally anchored cooling element and a flexible structure is described.

[0014] Figures 9A to 9B An embodiment of an active cooling system comprising a centrally anchored cooling element driven by a phase difference is described.

[0015] Figures 10A to 10C An embodiment of an active cooling system including a centrally anchored cooling element is described.

[0016] Figures 11A to 11D An embodiment of a cooling system comprising stacked, centrally anchored cooling elements is described.

[0017] Figure 12 An embodiment of a cooling system comprising stacked, centrally anchored cooling elements is described.

[0018] Figure 13 A top view depicting an embodiment of a cooling system comprising multiple cooling units is shown.

[0019] Figures 14A to 14B An embodiment of a piezoelectric cooling element is described.

[0020] Figure 15 This is a flowchart depicting an embodiment of a technology for driving an active cooling element.

[0021] Figure 16 This is a flowchart depicting an embodiment of a technology for driving an active cooling element. Detailed Implementation

[0022] This invention can be implemented in various ways, including as: a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer-readable storage medium; and / or a processor, such as a processor configured to execute instructions stored in and / or provided by a memory coupled to the processor. In this specification, these embodiments or any other forms in which the invention may take are referred to as techniques. Generally, within the scope of this invention, the order of the steps of the disclosed process may be changed. Unless otherwise stated, components such as processors or memory described as configured to perform tasks may be implemented as general-purpose components temporarily configured to perform tasks at a given time or as specific components manufactured to perform tasks. As used herein, the term "processor" refers to one or more devices, circuits, and / or processing cores configured to process data such as computer program instructions.

[0023] The following provides a detailed description of one or more embodiments of the present invention, along with accompanying drawings illustrating the principles of the invention. The invention has been described in conjunction with such embodiments, but is not limited to any particular embodiment. The scope of the invention is defined only by the claims, and the invention covers many alternatives, modifications, and equivalents. To provide a full understanding of the invention, numerous specific details are set forth in the following description. These details are provided for illustrative purposes, and the invention may be practiced according to the claims without requiring some or all of these specific details. For clarity, technical materials known in the art related to the invention have not been described in detail so as not to unnecessarily obscure the invention.

[0024] As semiconductor devices become increasingly powerful, the heat generated during operation also increases. For example, processors in mobile devices such as smartphones, tablets, laptops, and virtual reality devices can operate at high clock speeds, but this generates a significant amount of heat. Due to the amount of heat generated, the processor may only run at full speed for a relatively short period. After that time, throttling occurs (e.g., the processor's clock speed slows down). While throttling reduces heat generation, it also negatively impacts processor speed and, consequently, the performance of the devices using that processor. This problem is expected to worsen as technology advances towards 5G and beyond.

[0025] Larger devices, such as laptops or desktop computers, include electric fans with rotating blades. These fans are powered in response to rising temperatures in internal components. The fan drives air through the larger device to cool the internal components. However, such fans are often too large for mobile devices like smartphones or thinner devices like tablets. Fans may also have limited effectiveness due to the air boundary layer present at the surface of the components, providing limited airspeed for airflow across the hot surfaces that need cooling, and may generate excessive noise. Passive cooling solutions may include components such as vapor chambers and heat pipes or vapor chambers to transfer heat to a heat exchanger. While vapor chambers mitigate temperature rise at hot spots to some extent, the heat generated in current and future devices may not be adequately handled. Similarly, heat pipes or vapor chambers may not provide sufficient heat transfer to remove excess heat generated. Therefore, alternative cooling solutions are needed for both smaller mobile devices and larger devices.

[0026] A cooling system is described. The cooling system includes a support structure and a cooling element having a central region and a periphery. The cooling element is supported by the support structure at the central region. At least a portion of the periphery of the cooling element is unfixed. The cooling element is configured to undergo vibratory motion when actuated to drive fluid toward a heating structure. In some embodiments, the cooling element has a first side close to the heating structure and a second side away from the heating structure. The vibratory motion drives fluid from the second side to the first side of the cooling element. The cooling system may also include a top plate having at least one vent hole therein. The cooling element is located between the top plate and the heating structure. A top chamber is formed between the cooling element and the top plate. In some embodiments, the top chamber has a length from the center to the periphery of the cooling element corresponding to an odd number multiplied by the wavelength divided by 4. The wavelength is the acoustic wavelength of the frequency of the vibratory motion. The frequency of the vibratory motion also corresponds to the structural resonance of the cooling element and the acoustic resonance of the top chamber having that wavelength. In some embodiments, the top chamber is a folded top chamber.

[0027] In some embodiments, the cooling system includes an orifice plate having at least one orifice therein. The orifice plate is disposed between a cooling element and a heating structure. The cooling element is actuated to drive fluid through the orifice(s). In some embodiments, the orifice(s) are located at least 100 micrometers from a periphery, and a portion of the periphery is no more than 1 millimeter from the periphery. In some embodiments, the orifice plate includes a raised ridge on that portion closer to the periphery of the cooling element than the orifice(s). In some embodiments, the orifice plate includes multiple grooves therein. The multiple grooves include multiple orifices therein.

[0028] In some embodiments, the vibrational motion of the cooling element is out-of-phase vibrational motion. In some embodiments, a portion of a single cooling element within a cooling unit is actuated out of phase. In some embodiments, multiple cooling elements may operate out of phase. For example, multiple cooling elements within a single cooling unit are actuated out of phase. In some embodiments, cooling elements in different units are actuated out of phase. For example, cooling elements in adjacent units may be actuated 180 degrees out of phase.

[0029] The cooling system may include a resilient structure coupled to a cooling element. For example, the resilient structure may connect multiple cooling elements in a unit and / or multiple portions of a single cooling element. The cooling element may be a piezoelectric cooling element with a length not exceeding 8 mm. In some embodiments, the cooling element has a length not exceeding 10 mm. Vibrational motion may drive fluid toward the heating structure at a speed of at least 30 m / s. In some embodiments, the vibrational motion drives the fluid such that the fluid is incident on the surface of the heating structure substantially parallel to the normal to the surface of the heating structure, and is then deflected to move along the surface of the heating structure, thereby extracting heat from the heating structure, with the orifice plate at a distance of at least 200 micrometers from the surface of the heating structure.

[0030] The cooling system may include multiple cooling units. Each of the cooling units may be similar to those described above. In some embodiments, the cooling units share multiple perforated plates and / or multiple top plates. For example, a single top plate may be used for a cooling unit. Such a top plate includes multiple vent holes for each cooling unit. Similarly, the perforated plate may include a set of orifices for each cooling unit.

[0031] A method for cooling a heating structure is described. The method includes driving a cooling element to induce vibrational motion at a certain frequency. The cooling element has a central region and a periphery. The cooling element is supported by a support structure in the central region. At least a portion of the periphery is unfixed. Thus, a cooling element is actuated to induce vibrational motion, thereby driving fluid toward the heating structure. In some embodiments, driving the cooling element includes driving the cooling element at a frequency corresponding to the structural resonance of the cooling element. Furthermore, the cooling element is located between a top plate and the heating structure. The top plate has at least one vent therein. The cooling element and the top plate form a top chamber between the cooling element and the top plate. The top chamber has a length. The frequency of the vibrational motion corresponds to an acoustic resonance whose wavelength corresponds to the length multiplied by 4 and divided by an odd number.

[0032] Figures 1A to 1C This is a diagram depicting an exemplary embodiment of an active cooling system 100, which can be used with a heat-generating structure 102 and includes a centrally anchored cooling element 120. For clarity, only certain components are shown. Figures 1A to 1CNot drawn to scale. Although shown as symmetrical, the cooling system 100 is not necessarily symmetrical.

[0033] Cooling system 100 includes a top plate 110 having vents 112 therein, a cooling element 120, an orifice plate 130 having openings 132 therein, a support structure (or “anchor”) 160, and chambers 140 and 150 (collectively referred to as chambers 140 / 150) formed therein. Cooling element 120 is supported by anchor 160 at its central region. When actuated, the region of cooling element 120 closer to and including the periphery of the cooling element (e.g., tip 121) vibrates. In some embodiments, tip 121 of cooling element 120 includes the portion of the periphery furthest from anchor 160 and experiences the greatest deflection during actuation of cooling element 120. For clarity, in Figure 1A Only one tip 121 of the cooling element 120 is marked in the text.

[0034] Figure 1A The cooling system 100 is depicted in a neutral position. Therefore, the cooling element 120 is shown as substantially flat. In operation, the cooling element 120 is driven... Figure 1B and Figure 1C The system vibrates between the indicated locations. This vibrational motion draws fluid (e.g., air) into the vent 112 at high speed and / or high flow rate, through chambers 140 and 150, and out through orifice 132. For example, the velocity at which the fluid impacts the heating structure 102 may be at least 30 m / s. In some embodiments, the fluid is driven toward the heating structure 102 by the cooling element 120 at a velocity of at least 45 m / s. In some embodiments, the fluid is driven toward the heating structure 102 by the cooling element 120 at a velocity of at least 60 m / s. Other velocities are also possible in some embodiments. The cooling system 100 is also configured such that little or no fluid is drawn back into chambers 140 / 150 through orifice 132 by the vibrational motion of the cooling element 120.

[0035] It is desirable that the heat-generating structure 102 be cooled by the cooling system 100. In some embodiments, the heat-generating structure 102 generates heat. For example, the heat-generating structure may be an integrated circuit. In some embodiments, it is desirable that the heat-generating structure 102 be cooled, but it does not generate heat itself. The heat-generating structure 102 may conduct heat (e.g., from a nearby object that generates heat). For example, the heat-generating structure 102 may be a vapor chamber. Therefore, the heat-generating structure 102 may include: (multiple) semiconductor components, including individual integrated circuit components such as processors, (multiple) other integrated circuits and / or (multiple) chip packages; (multiple) sensors; (multiple) optical devices; one or more batteries; (multiple) other components of electronic devices such as computing devices; vapor chambers; heat pipes; (multiple) other electronic components and / or (multiple) other devices that require cooling.

[0036] Devices wishing to use cooling system 100 may also have limited space to house the cooling system. For example, cooling system 100 may be used in computing devices. Such computing devices may include, but are not limited to, smartphones, tablets, laptops, writing tablets, 2-in-1 laptops, handheld gaming systems, digital cameras, virtual reality headsets, augmented reality headsets, mixed reality headsets, and other thin and light devices. Cooling system 100 may be a microelectromechanical system (MEMS) cooling system capable of residing within mobile computing devices and / or other devices with limited space in at least one dimension. For example, the total height of cooling system 100 (from the top of heating structure 102 to the top of top plate 110) may be less than 2 mm. In some embodiments, the total height of cooling system 100 may not exceed 1.5 mm. In some embodiments, the total height may not exceed 250 micrometers. In some embodiments, the total height may not exceed 1.1 mm. In some embodiments, the total height may not exceed 1 micrometer. Similarly, the distance y between the bottom of orifice plate 130 and the top of heating structure 102 may be very small. In some embodiments, y is at least 200 micrometers and not more than 1 mm. In some embodiments, y is at least 200 micrometers and no more than 300 micrometers. Therefore, the cooling system 100 can be used in computing devices and / or other devices with limited space in at least one dimension. However, nothing prevents the use of the cooling system 100 in devices with less space constraints and / or for purposes other than cooling. Although one cooling system 100 (e.g., a cooling unit) is shown, multiple cooling systems 100 can be used in conjunction with the heat-generating structure 102. For example, a one-dimensional or two-dimensional array of cooling units can be utilized.

[0037] The cooling system 100 is in fluid communication with the heat-generating structure 102. The fluid may be a gas or a liquid. For example, the fluid may be air. In some embodiments, the fluid includes fluid from outside the device where the cooling system 100 resides (e.g., provided through an external vent in the device). In some embodiments, the fluid circulates within the device where the cooling system resides (e.g., in a closed device).

[0038] The cooling element 120 can be considered to divide the interior of the active cooling system 100 into a top chamber 140 and a bottom chamber 150. The top chamber 140 is formed by the cooling element 120, sides, and a top plate 110. The bottom chamber 150 is formed by a perforated plate 130, sides, the cooling element 120, and an anchor 160. The top chamber 140 and the bottom chamber 150 are connected at the periphery of the cooling element 120 and together form chambers 140 / 150 (e.g., the internal chambers of the cooling system 100).

[0039] The size and configuration of the top chamber 140 may vary depending on the unit (cooling system 100) size, the frequency of movement and operation of the cooling element 120. The top chamber 140 has a height h1. The height of the top chamber 140 may be selected to provide sufficient pressure to drive fluid to the bottom chamber 150 and through the orifice 132 at a desired flow rate and / or velocity. The top chamber 140 is also high enough that the cooling element 120 does not contact the top plate 110 when actuated. In some embodiments, the height of the top chamber 140 is at least 50 micrometers and no more than 500 micrometers. In some embodiments, the top chamber 140 has a height of at least 200 micrometers and no more than 300 micrometers.

[0040] The bottom chamber 150 has a height h2. In some embodiments, the height of the bottom chamber 150 is sufficient to accommodate the movement of the cooling element 120. Therefore, during normal operation, no part of the cooling element 120 contacts the orifice plate 130. The bottom chamber 150 is typically smaller than the top chamber 140 and helps to reduce fluid backflow into the orifice 132. In some embodiments, the height of the bottom chamber 150 is the maximum deflection of the cooling element 120 plus at least 5 micrometers and no more than 10 micrometers. In some embodiments, the deflection of the cooling element 120 (e.g., the deflection of the tip 121) z has an amplitude of at least 10 micrometers and no more than 100 micrometers. In some such embodiments, the amplitude of the deflection of the cooling element 120 is at least 10 micrometers and no more than 60 micrometers. However, the amplitude of the deflection of the cooling element 120 depends on factors such as the desired flow rate through the cooling system 100 and the construction of the cooling system 100. Therefore, the height of the bottom chamber 150 is typically dependent on the flow rate through the cooling system 100 and other components of the cooling system 100.

[0041] The top plate 110 includes a vent 112 through which fluid can be drawn into the cooling system 100. The top vent 112 may have a size selected based on the desired sound pressure level in the chamber 140. For example, in some embodiments, the width w of the vent 112 is at least 500 micrometers and no more than 1000 micrometers. In some embodiments, the width of the vent 112 is at least 250 micrometers and no more than 2000 micrometers. In the illustrated embodiment, the vent 112 is a small hole centrally located in the top plate 110. In other embodiments, the vent 112 may be located elsewhere. For example, the vent 112 may be closer to one of the edges of the top plate 110. The vent 112 may have a circular, rectangular, or other shaped coverage area. Although a single vent 112 is shown, multiple vents may also be used. For example, the vents may be offset toward the edge of the top chamber 140 or located on one or more sides of the top chamber 140.

[0042] Anchor (support structure) 160 supports the cooling element 120 at its central portion. Therefore, at least a portion of the periphery of the cooling element 120 is not fixed and is free to vibrate. In some embodiments, anchor 160 extends along the central axis of the cooling element 120 (e.g., perpendicular to...). Figures 1A to 1C (See page in [link]). In such embodiments, the vibrating portion of the cooling element 120 (e.g., including the tip 121) moves in a cantilever manner. Therefore, a portion of the cooling element 120 can move in a manner similar to a butterfly's wing. The cantilevered portion of the cooling element 120 vibrates in phase in some embodiments and out of phase in others. In some embodiments, the anchor 160 does not extend along the axis of the cooling element 120. In such embodiments, all portions of the periphery of the cooling element 120 vibrate freely (e.g., similar to a jellyfish). In the illustrated embodiment, the anchor 160 supports the cooling element 120 from the bottom. In other embodiments, the anchor 160 may support the cooling element 120 in another manner. For example, the anchor 160 may support the cooling element 120 from the top (e.g., the cooling element 120 is suspended from the anchor 160). In some embodiments, the width 'a' of the anchor 160 is at least 0.5 mm and no more than 4 mm. In some embodiments, the width of the anchor 160 is at least 2 mm and no more than 2.5 mm. The anchor 160 may occupy at least 10% and no more than 50% of the cooling element 120.

[0043] The cooling element 120 has a first side away from the heat-generating structure 102 and a second side close to the heat-generating structure 102. Figures 1A to 1C In the illustrated embodiment, the first side of the cooling element 120 is the top of the cooling element 120 (closer to the top plate 110), and the second side is the bottom of the cooling element 120 (closer to the perforated plate 130). The cooling element 120 is actuated to undergo vibratory motion, such as... Figures 1A to 1C As shown. The vibrational motion of the cooling element 120 drives fluid from a first side of the cooling element 120 away from the heating structure 102 (e.g., from the top chamber 140) to a second side of the cooling element 120 closer to the heating structure 102 (e.g., to the bottom chamber 150). The vibrational motion of the cooling element 120 also draws fluid into the top chamber 140 through the vent 112; forces fluid from the top chamber 140 to the bottom chamber 150; and drives fluid from the bottom chamber 150 through the orifice 132 of the orifice plate 130.

[0044] The cooling element 120 has a length L, which depends on the desired frequency of vibration of the cooling element 120. In some embodiments, the length of the cooling element 120 is at least 4 mm and no more than 10 mm. In some such embodiments, the cooling element 120 has a length of at least 6 mm and no more than 8 mm. The depth of the cooling element 120 (e.g., perpendicular to...) Figures 1A to 1CThe plane shown can vary from one-quarter to twice the length of L. For example, the cooling element 120 may have a depth equal to its length. The thickness t of the cooling element 120 may vary based on the construction of the cooling element 120 and / or the frequency at which the cooling element 120 is desired to be actuated. In some embodiments, for a cooling element 120 with a length of 8 mm and driven at a frequency of at least 20 kHz and no more than 25 kHz, the cooling element thickness is at least 200 micrometers and no more than 350 micrometers. The length C of the chamber 140 / 150 is close to the length L of the cooling element 120. For example, in some embodiments, the distance d between the edge of the cooling element 120 and the wall of the chamber 140 / 50 is at least 100 micrometers and no more than 500 micrometers. In some embodiments, d is at least 200 micrometers and no more than 300 micrometers.

[0045] Cooling element 120 can be driven at a frequency equal to or close to both the acoustic resonance frequency of the pressure wave in the fluid in top chamber 140 and the structural resonance frequency of cooling element 120. The portion of cooling element 120 undergoing vibrational motion is driven at or near the resonance (structural resonance) of cooling element 120. The frequency of the structural resonance vibration is called the structural resonance frequency. Using the structural resonance frequency when driving cooling element 120 reduces the power consumption of cooling system 100. Cooling element 120 and top chamber 140 can also be configured such that the structural resonance frequency corresponds to the resonance (acoustic resonance) of the pressure wave in the fluid driven through top chamber 140. The frequency of this pressure wave is called the acoustic resonance frequency. At acoustic resonance, pressure nodes appear near vent 112, and pressure antinodes appear near the periphery of cooling system 100 (e.g., near the tip 121 of cooling element 120 and near the junction between top chamber 140 and bottom chamber 150). The distance between these two regions is C / 2. Therefore, C / 2 = nλ / 4, where λ is the acoustic wavelength of the fluid and n is an odd number (e.g., n = 1, 3, 5, etc.). For the lowest order mode, C = λ / 2. Because the length of chamber 140 (e.g., C) is close to the length of cooling element 120, in some embodiments, L / 2 = nλ / 4 is also approximately correct, where λ is the acoustic wavelength of the fluid and n is an odd number. Therefore, the frequency v at which cooling element 120 is driven is equal to or close to the structural resonant frequency of cooling element 120. Frequency v is also equal to or close to the acoustic resonant frequency of at least the top chamber 140. The acoustic resonant frequency of the top chamber 140 generally varies less drastically with parameters such as temperature and size compared to the structural resonant frequency of cooling element 120. Therefore, in some embodiments, cooling element 120 may be driven at (or closer to) the structural resonant frequency rather than the acoustic resonant frequency.

[0046] The orifice plate 130 has orifices 132 therein. Although a specific number and distribution of orifices 132 are shown, other numbers and / or other distributions may also be used. A single orifice plate 130 is used for a single cooling system 100. In other embodiments, multiple cooling systems 100 may share an orifice plate. For example, multiple units 100 may be provided together in a desired configuration. In such embodiments, units 100 may be of the same size and configuration or of different sizes and / or configurations(s). The orifices 132 are shown as having axes orthogonal to the surface orientation of the heating structure 102. In other embodiments, the axes of one or more orifices 132 may form another angle. For example, the angle of the axis may be selected from substantially zero degrees and non-zero acute angles. The orifices 132 also have sidewalls that are substantially parallel to the normal to the surface of the orifice plate 130. In some embodiments, the orifices may have sidewalls that form a non-zero angle with the normal to the surface of the orifice plate 130. For example, the orifice 132 may be conical.

[0047] The size, distribution, and location of orifice 132 are selected to control the flow rate of fluid driven to the surface of heating structure 102. The location and configuration of orifice 132 can be configured to increase / maximize fluid flow from bottom chamber 150 through orifice 132 to the injection channel (the area between the bottom of orifice plate 130 and the top of heating structure 102). The location and configuration of orifice 132 can be selected to reduce / minimize suction flow (e.g., backflow) from injection channel through orifice 132. For example, it is desirable that the orifice be located far enough from tip 121 that the suction in the upward stroke of cooling element 120 (tip 121 moving away from orifice plate 13) is reduced, which would draw fluid into bottom chamber 150 through orifice 132. It is also desirable that the orifice be located close enough to tip 121 that the suction in the upward stroke of cooling element 120 also allows higher pressure from top chamber 140 to push fluid from top chamber 140 into bottom chamber 150. In some embodiments, during the upward stroke, the ratio (“net flow ratio”) of the flow rate from the top chamber 140 into the bottom chamber 150 to the flow rate from the injection channel through the orifice 132 is greater than 2:1. In some embodiments, the net flow ratio is at least 85:15. In some embodiments, the net flow ratio is at least 90:10. To provide the desired pressure, flow rate, suction, and net flow ratio, it is desirable that the orifice 132 is at least r1 away from the tip 121 and no more than r2 away from the tip 121 of the cooling element 120. In some embodiments, r1 is at least 100 micrometers (e.g., r1 ≥ 100 μm), and r2 is no more than 1 millimeter (e.g., r2 ≤ 1000 μm). In some embodiments, the orifice 132 is at least 200 micrometers away from the tip 121 of the cooling element 120 (e.g., r1 ≥ 200 μm). In some such embodiments, the orifice 132 is at least 300 micrometers (e.g., r1 ≥ 300 μm) from the tip 121 of the cooling element 120. In some embodiments, the orifice 132 has a width o of at least 100 micrometers and no more than 500 micrometers. In some embodiments, the orifice 132 has a width of at least 200 micrometers and no more than 300 micrometers. In some embodiments, the orifice spacing s is at least 100 micrometers and no more than 1 millimeter. In some such embodiments, the orifice spacing is at least 400 micrometers and no more than 600 micrometers. In some embodiments, it is also desirable for the orifice 132 to occupy a specific percentage of the area of ​​the orifice plate 130. For example, the orifice 132 may cover at least 5% and no more than 15% of the coverage area of ​​the orifice plate 130 in order to obtain a desired flow rate of fluid through the orifice 132. In some embodiments, the orifice 132 covers at least 8% and no more than 12% of the coverage area of ​​the orifice plate 130.

[0048] In some embodiments, the cooling element 120 is actuated using a piezoelectric element. Therefore, the cooling element 120 may be a piezoelectric cooling element. The cooling element 120 may be driven by a piezoelectric element mounted on or integrated into the cooling element 120. In some embodiments, the cooling element 120 is driven in another manner, including but not limited to providing a piezoelectric element on another structure within the cooling system 100. The cooling element 120 and similar cooling elements are hereinafter referred to as piezoelectric cooling elements, although it is possible to drive the cooling element using mechanisms other than a piezoelectric element. In some embodiments, the cooling element 120 includes a piezoelectric layer on a substrate. The substrate may be a stainless steel, nickel alloy, and / or Hastelloy substrate. In some embodiments, the piezoelectric layer includes a plurality of sublayers formed as a thin film on the substrate. In other embodiments, the piezoelectric layer may be an intrinsic layer attached to the substrate. Such a piezoelectric cooling element 120 also includes electrodes for activating the piezoelectric element. In some embodiments, the substrate serves as the electrode. In other embodiments, a bottom electrode may be disposed between the substrate and the piezoelectric layer. Other layers may be included in the piezoelectric cooling element, including but not limited to seed layers, capping layers, passivation layers, or other layers. Therefore, the cooling element 120 can be actuated using a piezoelectric element.

[0049] In some embodiments, the cooling system 100 includes a chimney (not shown) or other conduit. Such conduit provides a path for heated fluid to flow away from the heat-generating structure 102. In some embodiments, the conduit returns the fluid to the side of the top plate 110 away from the heat-generating structure 102. In some embodiments, the conduit may alternatively direct the fluid away from the heat-generating structure 102 in a direction parallel to or perpendicular to the heat-generating structure 102, but in the opposite direction (e.g., towards the bottom of the page). For devices using external fluids in the cooling system 100, the conduit may direct the heated fluid to a vent. In embodiments where the device is enclosed, the conduit may provide a circuitous path back to an area near the vent 112 and away from the heat-generating structure 102. Such a path allows the fluid to dissipate heat before being reused to cool the heat-generating structure 102. In other embodiments, the conduit may be omitted or otherwise constructed. This allows the fluid to carry away heat from the heat-generating structure 102.

[0050] The operation of cooling system 100 is in Figures 1A to 1C The description is within the context of specific pressures, clearance sizes, and flow timings. However, the operation of the cooling system 100 is not dependent on this interpretation. References Figure 1B The cooling element 120 has been actuated, causing its tip 121 to move away from the top plate 110. Therefore, it can be considered that... Figure 1BThe image depicts the end of the downward stroke of the cooling element 120. Due to the vibratory motion of the cooling element 120, the size of the gap 152 in the bottom chamber 150 has decreased and is shown as gap 152B. Conversely, the size of the gap 142 in the top chamber 140 has increased and is shown as gap 142B. During the downward stroke, when the cooling element 120 is in the neutral position, a lower (e.g., minimum) pressure is generated at the periphery. As the downward stroke continues, the size of the bottom chamber 150 decreases and the size of the top chamber 140 increases, as shown... Figure 1B As shown. Therefore, the fluid is driven out of the orifice 132 in a direction perpendicular or nearly perpendicular to the surface of the orifice plate 130 and / or the top surface of the heating structure 102. The fluid is driven from the orifice 132 toward the heating structure 102 at a high speed, for example, exceeding 35 m / s. In some embodiments, the fluid then travels along the surface of the heating structure 102 and toward the periphery of the heating structure 102, where the pressure is lower than near the orifice 132. Also during the downward travel, the size of the top chamber 140 increases, and a lower pressure exists in the top chamber 140. As a result, the fluid is drawn into the top chamber 140 through the vent 112. The fluid's entry into the vent 112, its passage through the orifice 132, and its movement along the surface of the heating structure 102... Figure 1B The arrow in the middle is not marked.

[0051] The cooling element 120 is also actuated, causing the tip 121 to move away from the heat-generating structure 102 and toward the top plate 110. Therefore, it can be considered that... Figure 1C The image depicts the end of the upward stroke of the cooling element 120. Due to the movement of the cooling element 120, the size of gap 142 has decreased and is shown as gap 142C. The size of gap 152 has increased and is shown as gap 152C. During the upward stroke, when the cooling element 120 is in the neutral position, a higher (e.g., maximum) pressure is generated at the periphery. As the upward stroke continues, the size of the bottom chamber 150 increases, and the size of the top chamber 140 decreases, as... Figure 1C As shown. Therefore, fluid is driven from the top chamber 140 (e.g., the periphery of chambers 140 / 150) to the bottom chamber 150. Thus, as the tip 121 of the cooling element 120 moves upward, the top chamber 140 acts as a nozzle for the fluid to enter, accelerating and being driven towards the bottom chamber 150. The movement of the fluid into the bottom chamber 150 is... Figure 1CThe arrows not marked in the diagram are shown. The location and configuration of the cooling element 120 and the orifice 132 are chosen to reduce suction, and thus reduce fluid backflow from the injection channel (between the heating structure 102 and the orifice plate 130) into the orifice 132 during the upward stroke. Therefore, the cooling system 100 is able to drive fluid from the top chamber 140 to the bottom chamber 150 without excessive backflow of heated fluid from the injection channel into the bottom chamber 10.

[0052] repeat Figure 1B and Figure 1C The movement between the indicated positions. Therefore, the cooling element 120 undergoes... Figures 1A to 1C The vibrational motion indicated in the diagram draws fluid from the distal side of the top plate 110 into the top chamber 140 through the vent 112; transfers the fluid from the top chamber 140 to the bottom chamber 150; and propels the fluid through the orifice 132 toward the heating structure 102. As discussed above, the cooling element 120 is driven to vibrate at or near its structural resonant frequency. Furthermore, the structural resonant frequency of the cooling element 120 is configured to coincide with the acoustic resonance of chambers 140 / 150. The structural and acoustic resonant frequencies are generally selected within the ultrasonic range. For example, the vibrational motion of the cooling element 120 may be at frequencies from 15 kHz to 30 kHz. In some embodiments, the cooling element 120 vibrates at one or more frequencies of at least 20 kHz and not exceeding 30 kHz. The structural resonant frequency of the cooling element 120 is within 10% of the acoustic resonant frequency of the cooling system 100. In some embodiments, the structural resonant frequency of the cooling element 120 is within 5% of the acoustic resonant frequency of the cooling system 100. In some embodiments, the structural resonant frequency of the cooling element 120 is within 3% of the acoustic resonant frequency of the cooling system 100. Therefore, efficiency and flow rate can be improved. However, other frequencies can be used.

[0053] Fluid driven toward the heating structure 102 can move substantially orthogonally (perpendicularly) to the top surface of the heating structure 102. In some embodiments, the fluid movement can have a non-zero acute angle relative to the normal to the top surface of the heating structure 102. In either case, the fluid can be thinned and / or or perforations can be formed in the fluid boundary layer at the heating structure 102. As a result, heat transfer from the heating structure 102 can be improved. The fluid deflects away from the heating structure 102 and travels along the surface of the heating structure 102. In some embodiments, the fluid moves in a direction substantially parallel to the top of the heating structure 102. Therefore, heat from the heating structure 102 can be extracted by the fluid. The fluid can exit the region between the orifice plate 130 and the heating structure 102 at the edge of the cooling system 100. A chimney or other conduit (not shown) at the edge of the cooling system 100 allows the fluid to be carried away from the heating structure 102. In other embodiments, the heated fluid can be further transferred from the heating structure 102 in another manner. The fluid can exchange heat transferred from the heating structure 102 to another structure or the surrounding environment. Therefore, the fluid on the distal side of the top plate 110 can remain relatively cool, thereby allowing additional heat extraction. In some embodiments, the fluid circulates and returns to the distal side of the top plate 110 after cooling. In other embodiments, the heated fluid is carried away and replaced by fresh fluid on the distal side of the cooling element 120. As a result, the heating structure 102 can be cooled.

[0054] Using the cooling system 100, fluid drawn in through vent 112 and driven through orifice 132 can efficiently dissipate heat from the heating structure 102. Because the fluid impacts the heating structure at a sufficient velocity (e.g., at least 30 m / s) and, in some embodiments, is substantially orthogonal to the heating structure, the fluid boundary layer at the heating structure can be thinned and / or partially removed. Therefore, heat transfer between the heating structure 102 and the moving fluid is improved. Because the heating structure is cooled more efficiently, the corresponding integrated circuit can operate at higher speeds and / or power for longer periods. For example, if the heating structure corresponds to a high-speed processor, such a processor can operate for longer periods before throttling. Therefore, the performance of devices utilizing the cooling system 100 can be improved. Furthermore, the cooling system 100 can be a MEMS device. Therefore, the cooling system 100 is suitable for smaller devices and / or mobile devices with limited available space, such as smartphones, other mobile phones, virtual reality headsets, writing tablets, 2-in-1 computers, wearable devices, and handheld game consoles. Therefore, the performance of such devices can be improved. Because the cooling element 120 can vibrate at frequencies of 15 kHz or higher, the user may not hear any noise associated with the actuation of the cooling element. If driven at or near the structural and / or acoustic resonance frequency, the power used in operating the cooling system can be significantly reduced. During vibration, the cooling element 120 does not physically contact the top plate 110 or the orifice plate 130. Therefore, the resonance of the cooling element 120 can be more easily maintained. More specifically, physical contact between the cooling element 120 and other structures disrupts the resonance conditions of the cooling element 120. Disrupting these conditions can drive the cooling element 120 out of resonance. Therefore, additional power is required to maintain the actuation of the cooling element 120. Furthermore, the fluid flow rate driven by the cooling element 120 can be reduced. These problems are avoided by using the pressure differential and fluid flow rate discussed above. The benefits of improved quiet cooling can be achieved with limited additional power. Therefore, the performance of the device incorporating the cooling system 100 is improved. In addition, the cooling system 100 can be used in other applications that require high fluid flow and / or speed (e.g., with or without a heat-generating structure 102).

[0055] Figures 2A to 2B Plan views depicting embodiments of cooling systems 200A and 200B, which are similar to active cooling systems such as cooling system 100. Figure 2A and Figure 2BNot drawn to scale. For simplicity, only portions of cooling elements 220A and 220B and anchors 260A and 260B are shown. Cooling elements 220A and 220B are similar to cooling element 120. Therefore, the size and / or material for cooling elements 220A and / or 220B may be similar to the size and / or material for cooling element 120. Anchors (support structures) 260A and 260B are similar to anchor 160 and are indicated by dashed lines.

[0056] For cooling elements 220A and 220B, anchors 260A and 260B are centrally positioned and extend along the central axes of cooling elements 220A and 220B, respectively. Therefore, cantilever portions actuated to vibrate are located on the right and left sides of anchors 260A and 260B. In some embodiments, cooling elements(s) 220A and / or 220B are a continuous structure, with both portions actuated (e.g., the cantilever portions on the outer sides of anchors 260A and 260B). In some embodiments, cooling elements(s) 220A and / or 220B include separate cantilever portions, each of which is attached to and actuated by anchors 260A and 260B, respectively. The cantilever portions of cooling elements 220A and 220B can thus be configured to vibrate in a manner similar to butterfly wings. Figure 2A and Figure 2B In this context, L represents the length of the cooling element, similar to... Figures 1A to 1C The length described in the text. Also in... Figure 2A and Figure 2B In the figure, the depth P of cooling elements 220A and 220B is indicated.

[0057] exist Figures 2A to 2B The piezoelectric element 223 is also shown in dashed lines. The piezoelectric element 223 is used to actuate cooling elements 220A and 220B. Although described in the context of a piezoelectric element, another mechanism for actuating cooling elements 220A and 220B can be used. Such another mechanism can be located at the position of the piezoelectric element 223, or it can be located elsewhere. In cooling element 220A, the piezoelectric element 223 can be attached to the cantilever portion, or it can be integrated into the cooling element 220A. Furthermore, although the piezoelectric element 223 is... Figure 2A and Figure 2B It is shown as having a specific shape and size, but other constructions can also be used.

[0058] exist Figure 2AIn the illustrated embodiment, anchor 260A extends the entire depth of cooling element 220A. Therefore, a portion of the periphery of cooling element 220A is pinned. The unsecured portion of the periphery of cooling element 220A is part of a cantilever section that experiences vibrational movement. In other embodiments, the anchor does not need to extend the entire length of the central axis. In such embodiments, the entire periphery of the cooling element is unsecured. However, such a cooling element still has a cantilever section configured to vibrate in the manner described herein. For example, in Figure 2B In this configuration, anchor 260B does not extend to the periphery of cooling element 220B. Therefore, the periphery of cooling element 220B is not secured. However, anchor 260B still extends along the central axis of cooling element 220B. Cooling element 220B is still actuated, causing the cantilever portion to vibrate (e.g., similar to butterfly wings).

[0059] Although the cooling element 220A is depicted as rectangular, the cooling element may have another shape. In some embodiments, the corners of the cooling element 220A may be rounded. Figure 2B The cooling element 220B has a rounded cantilever section. Other shapes are possible. Figure 2B In the illustrated embodiment, anchor 260B is hollow and includes a small hole 263. In some embodiments, cooling element 220B has a plurality of small holes in the region of anchor 260B. In some embodiments, cooling element 220B includes multiple portions such that a plurality of small holes exist in the region of anchor 260B. As a result, fluid can be drawn through cooling element 220B and through anchor 260B. Therefore, cooling element 220B can be used in place of a top plate, such as top plate 110. In such embodiments, the small holes and small holes 263 in cooling element 220B can function similarly to vent 112.

[0060] Figures 3A to 3B Plan views depicting embodiments of cooling systems 300A and 300B, which are similar to active cooling systems such as cooling system 100. Figure 3A and Figure 3B Not drawn to scale. For simplicity, only cooling elements 320A and 320B, and anchors 360A and 360B are shown separately. Cooling elements 320A and 320B are similar to cooling element 120. Therefore, the size and / or material used for cooling elements 320A and / or 320B may be similar to the size and / or material used for cooling element 120. Anchors 360A and 360B are similar to anchor 160 and are indicated by dashed lines.

[0061] For cooling elements 320A and 320B, anchors 360A and 360B are respectively confined to the central regions of cooling elements 320A and 320B. Therefore, the regions surrounding anchors 360A and 360B experience vibratory motion. Cooling elements 320A and 320B can thus be configured to vibrate in a manner similar to the opening / closing of a jellyfish or an umbrella. In some embodiments, the entire periphery of cooling elements 320A and 320B vibrates in phase (e.g., moves upward or downward together). In other embodiments, portions of the periphery of cooling elements 320A and 320B vibrate out of phase. Figure 3A and Figure 3B In this context, L is the length (e.g., diameter) of the cooling element, similar to... Figures 1A to 1C The length is depicted in the diagram. Although cooling elements 320A and 320B are depicted as circular, the cooling elements may have another shape. Furthermore, the piezoelectric element ( Figures 3A to 3B (not shown in the image) and / or other mechanisms may be used to drive the vibratory motion of cooling elements 320A and 320B.

[0062] exist Figure 3B In the illustrated embodiment, anchor 360B is hollow and has a small hole 363. In some embodiments, cooling element 320B has a plurality of small holes in the region of anchor 360B. In some embodiments, cooling element 320B comprises multiple portions such that a plurality of small holes exist in the region of anchor 360B. As a result, fluid can be drawn through cooling element 320B and through anchor 360B. Fluid can exit through small holes 363. Therefore, cooling element 320B can be used in place of a top plate, such as top plate 110. In such embodiments, the small holes and small holes 363 in cooling element 320B can function similarly to vent 112.

[0063] Cooling systems such as cooling system 100 can utilize multiple cooling elements 220A, 220B, 320A, 320B and / or similar cooling elements. Such cooling systems can also share the benefits of cooling system 100. Cooling systems using multiple cooling elements 220A, 220B, 320A, 320B and / or similar cooling elements can more efficiently drive fluid towards the heat-generating structure at high speeds. Therefore, heat transfer between the heat-generating structure and the moving fluid is improved. Because the heat-generating structure is cooled more efficiently, the corresponding equipment can exhibit improved operation, such as operating at higher speeds and / or power for longer periods. Cooling systems employing multiple cooling elements 220A, 220B, 320A, 320B and / or similar cooling elements are suitable for smaller equipment and / or mobile equipment with limited available space. Therefore, the performance of such equipment can be improved. Because the cooling elements(s) 220A, 220B, 320A, 320B and / or similar cooling elements can vibrate at frequencies of 15 kHz or higher, the user may not hear any noise associated with the actuation of the cooling elements. For the cooling elements(s) 220A, 220B, 320A, 320B and / or similar cooling elements, if driven at or near the acoustic and / or structural resonant frequency, the power used in operating the cooling system can be significantly reduced. The cooling elements(s) 220A, 220B, 320A, 320B and / or similar cooling elements do not need to physically contact the plate during use, thus allowing for easier maintenance of resonance. The benefits of improved quiet cooling can be achieved with limited additional power. Therefore, the performance of devices incorporating the cooling elements(s) 220A, 220B, 320A, 320B and / or similar cooling elements can be improved.

[0064] Figures 4A to 4E Embodiments of active cooling systems 400A, 400B, 400C, 400D and 400E, including centrally anchored cooling elements, are described. Figures 4A to 4E The drawings are not to scale and only neutral configurations are shown. For simplicity, only portions of cooling systems 400A, 400B, 400C, 400D, and 400E are shown. In particular, cooling systems 400A, 400B, 400C, 400D, and 400E are similar to cooling system 100. Therefore, similar components have similar markings. For example, cooling systems 400A, 400B, 400C, 400D, and 400E are used in conjunction with a heating structure 402, which is similar to heating structure 102.

[0065] Cooling system 400A includes a top plate 410 with vent 412, a cooling element 420A, an orifice plate 430A with orifice 432A, a top chamber 440 with gap 442, a bottom chamber 450 with gap 452, and an anchor (i.e., support structure) 460, which are respectively similar to a top plate 110 with vent 112, a cooling element 120, an orifice plate 130 with orifice 132, a top chamber 140 with gap 142, a bottom chamber 150 with gap 152, and an anchor (i.e., support structure) 160. Therefore, cooling element 420A is centrally supported by anchor 460, allowing at least a portion of the periphery of cooling element 420A to vibrate freely. In some embodiments, anchor 460 extends along the axis of cooling element 420A (e.g., in a manner similar to anchor 260A and / or 260B). In other embodiments, anchor 460 is located only near the central portion of cooling element 420A (e.g., similar to anchor 360A and / or 360B).

[0066] The orifice plate 430A also includes a groove 434A surrounding an orifice 432A. In some embodiments, the groove 434A is at least 25 micrometers and no more than 150 micrometers deep. The groove 434A is configured such that the orifice 432A is located at the bottom of the groove 434A. The sidewalls of the groove 434A are shown as perpendicular to the top surface of the orifice plate 430A. In some embodiments, the sidewalls of the groove 434A form different angles with the top surface of the orifice plate 430A. In some embodiments, the groove 434A extends across the orifice plate 430A (e.g., parallel to the top surface of the orifice plate 430A) such that up to 50% of the surface of the orifice plate 430A aligned with the cooling element 420A is part of the groove 434A. Furthermore, the orifice 432A has a conical cross-section. Therefore, the sidewalls of the orifice 432A are not perpendicular to the surface of the orifice plate 430A. Conversely, the sidewalls of orifice 432A are angled, making the portion of orifice 432A closer to cooling element 420A wider than the portion of orifice 432A closer to heat-generating structure 402.

[0067] Cooling system 400A operates in a manner similar to cooling system 100 and shares the benefits(s) of cooling system 100. Furthermore, the use of groove 434A allows for better control of gap 452. In some embodiments, it is desirable that gap 452 not exceed 5 micrometers to obtain a channel closest to orifice plate 430A (e.g., at the bottom of the downward stroke of cooling element 420A). Therefore, backflow of fluid through orifice 432A into the bottom chamber 450 can be further reduced. The use of angled orifice 432A improves the formation of fluid droplets exiting orifice 432A. Therefore, the performance of cooling system 400A can be further improved.

[0068] Figure 4BThe cooling system 400B includes a top plate 410 with vent 412, a cooling element 420A, an orifice plate 430B with orifice 432B, a top chamber 440 with gap 442, a bottom chamber 450 with gap 452, and an anchor (i.e., support structure) 460, which are respectively similar to the top plate 110 with vent 112, the cooling element 120, the orifice plate 130 with orifice 132, the top chamber 140 with gap 142, the bottom chamber 150 with gap 152, and the anchor (i.e., support structure) 160. Therefore, the cooling element 420B is centrally supported by the anchor 460, allowing at least a portion of the periphery of the cooling element 420B to vibrate freely. In some embodiments, the anchor 460 extends along the axis of the cooling element 420B (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 460 is located only near the central portion of cooling element 420B (e.g., similar to anchor 360A and / or 360B).

[0069] The orifice plate 430B also includes a raised ridge 434B near the orifice 432B. In some embodiments, the raised ridge 434B is at least 25 micrometers and no more than 150 micrometers high. In some embodiments, the raised ridge 434B is formed by adding material to the orifice plate 430B. In other embodiments, the raised ridge 434B can be formed by extending a groove similar to a groove 434A across the bottom of the orifice plate 430B. The raised ridge 434B is shown perpendicular to the top surface of the orifice plate 430B. In some embodiments, the raised ridge 434B forms a different angle with the top surface of the orifice plate 430B. The raised ridge 434B is configured such that the orifice 432B is located lower than the top surface of the raised ridge 434B. In the illustrated embodiment, the cross-section of the orifice 432B is cylindrical. In other words, the sidewalls of the orifice 432B are perpendicular to the surface of the orifice plate 430B. However, other shapes are possible.

[0070] Cooling system 400B operates in a manner similar to cooling system 100 and shares the benefits of cooling system 100(s). Furthermore, the use of the ridge 434B allows for better control of the gap 452. Therefore, backflow of fluid through orifice 432B into the bottom chamber 450 can be reduced. In some embodiments, it is desirable that the gap 452 not exceed 5 micrometers to obtain a passage closest to orifice plate 430B (e.g., at the bottom of the downward stroke of cooling element 420B). Thus, the performance of cooling system 400B can be further improved.

[0071] Figure 4CThe cooling system 400C includes a top plate 410 with vents 412, a cooling element 420C, an orifice plate 430C with orifices 432C, a top chamber 440 with gaps 442, a bottom chamber 450 with gaps 452, and an anchor (i.e., support structure) 460, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140 with gaps 142, a bottom chamber 150 with gaps 152, and an anchor (i.e., support structure) 160. Therefore, the cooling element 420C is centrally supported by the anchor 460, allowing at least a portion of the periphery of the cooling element 420C to vibrate freely. In some embodiments, the anchor 460 extends along the axis of the cooling element 420C (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 460 is located only near the central portion of cooling element 420C (e.g., similar to anchors 360A and / or 360B).

[0072] Orifice plate 430C is similar to orifice plate 430A because it includes groove 434C. In the illustrated embodiment, orifice 432C is similar to orifice 432B and therefore has a cylindrical cross-section. In other words, the sidewalls of orifice 432C are perpendicular to the surface of orifice plate 430C. However, other shapes are possible.

[0073] Cooling element 420C includes a top ridge 422C. Orifice plate 430C includes a groove 434C configured such that the top ridge 422C is within the groove 434C when actuated. For example, the top ridge 422C may be at least 10 micrometers and no more than 75 micrometers high. Similarly, the groove 434C may have a depth of at least 25 micrometers and no more than 150 micrometers. In some embodiments, orifice plate 430C may include a ridge instead of a groove 434C. In such an embodiment, the top ridge 422C may extend to anchor 460.

[0074] Cooling system 400C operates in a manner similar to cooling system 100 and shares several of the benefits of cooling system 100. Furthermore, the combination of the top ridge 422C and the groove 434C allows for better control of the gap 452, and thus better control of the backflow. Therefore, the performance of cooling system 400C can be further improved.

[0075] Figure 4DThe cooling system 400D includes a top plate 410 with vent 412, a cooling element 420D, an orifice plate 430D with orifice 432D, a top chamber 440 with gap 442, a bottom chamber 450 with gap 452, and an anchor (i.e., support structure) 460, which are respectively similar to the top plate 110 with vent 112, the cooling element 120, the orifice plate 130 with orifice 132, the top chamber 140 with gap 142, the bottom chamber 150 with gap 152, and the anchor (i.e., support structure) 160. Therefore, the cooling element 420D is centrally supported by the anchor 460, allowing at least a portion of the periphery of the cooling element 420D to vibrate freely. In some embodiments, the anchor 460 extends along the axis of the cooling element 420D (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 460 is located only near the central portion of cooling element 420D (e.g., similar to anchors 360A and / or 360B). Cooling element 420D includes a top ridge 422D. In some embodiments, the top ridge 422D is at least 10 micrometers and no more than 75 micrometers high.

[0076] Cooling system 400D operates in a manner similar to cooling system 100 and shares several of the benefits of cooling system 100. Furthermore, the use of the top ridge 422D allows for better control of the gap 452, and thus better control of the return flow. Therefore, the performance of cooling system 400D can be further improved.

[0077] Figure 4E A plan view of the orifice plate 430E of the cooling system 400E is depicted. The cooling system 400E is similar to the cooling system 100. Therefore, the orifice plate 430E, including orifice 432E, is similar to the orifice plate 130, including orifice 132. The remainder of the cooling system 400E is similar to the corresponding structures in cooling systems(s) 100, 400A, 400B, 400C, and / or 400D. For example, although in Figure 4E Not shown, but the orifice plate 430E may include grooves or ridges similar to (a plurality of) grooves 434A and / or 434C or ridges 434B.

[0078] The orifice plate 430E includes orifices 432E having elliptical coverage areas. For example, in some embodiments, the secondary (short) axis of orifice 432E is at least 100 micrometers and no more than 300 micrometers. In some embodiments, the primary (long) axis of orifice 432E is at least 200 micrometers and no more than 400 micrometers. Other lengths are possible. Furthermore, in some embodiments, not all orifices 432E have the same shape and / or size. Although in Figure 4ENot specified, but orifice 432E can be conical (e.g., similar to orifice 432A) or have another shape. Because orifice 432E is not circular, orifice 432E can be stacked differently in a given area. For example, orifice 432E may be offset in the x-direction, and the edges of columns of orifice 432E may overlap. Therefore, orifice plate 430A can include a higher density of orifice 432E compared to the case where orifice 432E is circular. Therefore, the shape, position, and distribution of orifices can be customized.

[0079] Cooling system 400E operates in a manner similar to cooling system 100 and shares the benefits of cooling system 100(s). Furthermore, the shape, location, and distribution of the orifices can be designed. The desired flow rate through orifice 432E can be achieved. Therefore, the performance of cooling system 400E can be further improved. In addition, cooling systems 400A, 400B, 400C, 400D, and / or 400E can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without heat-generating structure 402).

[0080] Figure 5 An embodiment of an active cooling system 500, including a centrally anchored cooling element and a folded top chamber, is depicted. Figure 5Not drawn to scale, and only neutral construction is shown. For simplicity, only a portion of the cooling system 500 is shown. The cooling system 500 is similar to the cooling system 100. The cooling system 500 includes top plates 510A and 510B (collectively referred to as top plate 510) with vents 512 and 514, a cooling element 520, an orifice plate 530 with orifices 532, top chambers 540A and 540B (collectively referred to as top chamber 540) with gaps 542, a bottom chamber 550 with gaps 552, and an anchor (i.e., support structure) 560, which are respectively similar to the top plate 110 with vents 112, the cooling element 120, the orifice plate 130 with orifices 132, the top chamber 140 with gaps 142, the bottom chamber 150 with gaps 152, and the anchor (i.e., support structure) 160. Therefore, the cooling element 520 is centrally supported by the anchor 560, allowing at least a portion of the periphery of the cooling element 520 to vibrate freely. In some embodiments, the anchor 560 extends along the axis of the cooling element 520 (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, the anchor 560 is located only near the central portion of the cooling element 520 (e.g., similar to anchors 360A and / or 360B). Furthermore, the orifice plate 530, orifice 532, and / or cooling element 520 may be constructed in a manner similar to one or more of the orifice plates 430A, 430B, 430C, 430D, and / or 430E, orifices 432A, 432B, 432C, 432D, and / or 432E, and / or one or more cooling elements 420A, 420B, 420C, and / or 420D.

[0081] The top chamber 540 is similar to the top chamber 140, but is a folded chamber comprising two parts (top chamber 540A and top chamber 540B). The top chamber 540 and the cooling element 520 can still be configured such that the acoustic resonant frequency of the top chamber 540 is equal to or close to the structural resonant frequency of the cooling element 520. However, the length of the top chamber 540 includes portions of top chamber 540A and top chamber 540B. Specifically, fluid enters the top chamber 540 through vent 514, traverses a portion of top chamber 540B to reach vent 512, passes through vent 512, traverses a portion of top chamber 540A to reach the periphery of the cooling element 520, is transferred to the bottom chamber 550, and is expelled from the orifice 532. This path is... Figure 5 The arrows not marked in the figure depict this. Therefore, between the fluid entering the top chamber 540 at the vent 514 and being transferred to the bottom chamber 550 near the periphery of the cooling element 520, the fluid travels a distance of approximately C (the entire width of chambers 540 / 550). This is twice the distance traveled in the top chamber 140 of the cooling system 100 depicted in Figure 1.

[0082] It is desirable that the cooling element 520 be driven at a frequency corresponding to its structural resonance (e.g., equal to or close to the structural resonance frequency). It is also desirable that this frequency corresponds to (e.g., equal to or close to) the acoustic resonance frequency of the cooling system 500 / top chamber 540. Furthermore, in acoustic resonance, pressure nodes appear at the vent 514, and pressure antinodes are formed at the periphery of the cooling element 520. Therefore, C = effective length of the top chamber 540 = nλ / 4, where λ is the acoustic wavelength of the fluid, and n is an odd number (e.g., n = 1, 3, 5, etc.). Thus, for approximately the same acoustic resonance frequency, the cooling element 520 and the cooling system 500 can be manufactured to half the length. The frequency v at which the cooling element 520 is driven is not only the structural resonance frequency of the cooling element 520, but also equal to or close to the acoustic resonance frequency, at least for the top chamber 540. In some embodiments, the cooling element 520 is driven at a frequency corresponding to the lowest order acoustic mode (C = λ / 4). In some embodiments, the cooling element 520 is driven at a frequency corresponding to the next acoustic mode (C = 3λ / 4).

[0083] Cooling system 500 operates in a manner similar to cooling system 100 and shares many of the benefits of cooling system 100. Furthermore, cooling system 500 utilizes a folded top chamber 540. As a result, for approximately the same drive (and resonant) frequency, cooling system 500, chambers 540 / 550, and cooling element 520 can be manufactured to be narrower than cooling system 100. Therefore, cooling system 500 can also have a smaller coverage area than cooling system 100. Cooling system 500 can also be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without heat-generating structure 502).

[0084] Figures 6A to 6C An embodiment of an active cooling system 600 comprising multiple cooling elements 620 and 610 is described. Figures 6A to 6C It was not drawn to scale. Figure 6A It depicts a neutral structure. Figure 6B The end of the downward stroke of the cooling element 620 and the end of the upward stroke of the cooling element 610 are depicted. Figure 6CThe end of the upward stroke of cooling element 620 and the end of the downward stroke of cooling element 610 are depicted. For simplicity, only a portion of cooling system 600 is shown. Cooling system 600 is similar to cooling system 100. Cooling system 600 includes cooling element 620, orifice plate 630 including orifice 632, top chamber 640, bottom chamber 650, and anchor (i.e., support structure) 660, which are respectively similar to cooling element 120, orifice plate 130 including orifice 132, top chamber 140, bottom chamber 150, and anchor (i.e., support structure) 160. Thus, cooling element 620 is centrally supported by anchor 660, allowing at least a portion of the periphery of cooling element 620 to vibrate freely. In some embodiments, anchor 660 extends along the axis of cooling element 620 (e.g., in a manner similar to anchor 260A and / or 260B). In other embodiments, anchor 660 is located only near the central portion of cooling element 620 (e.g., similar to anchors 360A and / or 360B). Furthermore, orifice plate 630, orifice 632, and / or cooling element 620 may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0085] In the cooling system 600, the top plate is replaced by a cooling element 610. The cooling element 610 therefore has a vent 612 and is supported or anchored at its periphery. Therefore, the maximum deflection of the cooling element 610 may occur near the center (e.g., near the vent 612). Although a single centrally located vent 612 is shown, multiple vents and / or (multiple) vents located elsewhere (including on the sidewalls) can be used. Cooling elements 610 and 620 are also driven out of phase. In some embodiments, the vibrational movements of cooling elements 610 and 620 are out of phase by 180 degrees or nearly 180 degrees. Therefore, when cooling element 620 experiences a downward stroke, cooling element 610 experiences an upward stroke, and vice versa. This is in Figure 6B and Figure 6C Described in the text.

[0086] It is also desirable that cooling elements 610 and 620 be driven at their structural resonant frequencies. Therefore, the structural resonant frequencies of cooling elements 610 and 620 are chosen to be close. In some embodiments, it is desirable that the resonant frequencies of cooling elements 610 and 620 are within 100 Hz of each other. In some embodiments, feedback is used to keep cooling elements 610 and 620 at or near resonance. For example, the current used to drive cooling elements 610 and 620 may be periodically measured, and the drive frequencies of cooling elements 610 and 620 may be adjusted to maintain resonance. In some embodiments, cooling elements(s) 610 and / or 620 are driven within several hundred Hz of one or more resonant frequencies to optimize performance. However, other frequencies are possible. The drive frequencies of cooling elements 610 and 620 may also be adjusted to keep the cooling elements out of phase by 180 degrees or close to 180 degrees. Furthermore, it is desirable that the structural resonant frequencies of cooling elements 610 and 620 and their drive frequencies are equal to or close to the acoustic resonant frequency of the top chamber 640 of the cooling system 600.

[0087] During operation, cooling element 610 undergoes an upward stroke, while cooling element 620 undergoes a downward stroke, such as... Figure 6B As indicated in the diagram. Therefore, the cooling element 620 drives fluid to flow out of the orifice 632 at high speed, as discussed with respect to the cooling system 100. Furthermore, fluid is drawn into the top chamber 640 via the vent 612. This fluid movement is caused by… Figure 6B The unmarked arrows indicate that as the cooling element 620 undergoes its upward and downward strokes, fluid is driven from the top chamber 640 to the bottom chamber 650. This fluid movement is caused by... Figure 6C The arrows not marked are shown. The orifice plate 630, orifice 632, and / or cooling element 620 are also configured to reduce or eliminate suction that would cause fluid to flow back through orifice 632 into the bottom chamber 650. Therefore, cooling system 600 operates in a similar manner to cooling system 100. Thus, the benefits of cooling system 100 can be realized. Furthermore, cooling system 600 can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without the heat-generating structure 602).

[0088] Figures 7A to 7C An embodiment of an active cooling system 700 comprising multiple centrally anchored cooling elements 720 and 770 is depicted. Figures 7A to 7C It was not drawn to scale. Figure 7A It depicts a neutral structure. Figure 7B The end of the downward stroke of the cooling element 720 and the end of the upward stroke of the cooling element 770 are depicted. Figure 7CThe end of the upward stroke of cooling element 720 and the end of the downward stroke of cooling element 770 are depicted. For simplicity, only a portion of cooling system 700 is shown. Cooling system 700 is similar to cooling system 100. Cooling system 700 includes a top plate 710 with vent 712, cooling element 720, perforated plate 730 with orifice 732, top chamber 740, bottom chamber 750, and anchor (i.e., support structure) 760, which are respectively similar to top plate 110 with vent 112, cooling element 120, perforated plate 130 with orifice 132, top chamber 140, bottom chamber 150, and anchor (i.e., support structure) 160. Thus, cooling element 720 is centrally supported by anchor 760, allowing at least a portion of the periphery of cooling element 720 to vibrate freely. In some embodiments, anchor 760 extends along the axis of cooling element 720 (e.g., in a manner similar to anchor 260A and / or 260B). In other embodiments, the anchor 760 does not extend along the axis of the cooling element 720 (e.g., in a manner similar to anchors 360A and / or 360B). Furthermore, the orifice plate 730, orifice 732, and / or cooling element 720 may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0089] The cooling system 700 also includes a cooling element 770, a support structure (e.g., an anchor) 772, and an upper chamber 780. The cooling element 770 is centrally supported by the anchor 772, allowing at least a portion of the periphery of the cooling element 770 to vibrate freely. In some embodiments, the anchor 772 extends along the axis of the cooling element 770 (e.g., in a manner similar to anchors 260A and / or 260B). In some embodiments, the anchor 772 does not extend along the axis of the cooling element 770 (e.g., in a manner similar to anchors 360A and / or 360B).

[0090] In some embodiments, cooling elements 720 and 770 are driven out of phase. In some embodiments, the vibrational motions of cooling elements 720 and 770 are out of phase by 180 degrees or nearly 180 degrees. Thus, when cooling element 720 experiences a downward stroke, cooling element 770 experiences an upward stroke, and vice versa. It is also desirable that cooling elements 720 and 770 are driven at their structural resonant frequencies. Therefore, the structural resonant frequencies of cooling elements 720 and 770 are chosen to be close. In some embodiments, it is desirable that the resonant frequencies of cooling elements 720 and 770 are within 100 Hz of each other. In some embodiments, feedback is used to keep the cooling elements(s) at or near resonance. For example, the current used to drive cooling elements 720 and 770 may be periodically measured, and the drive frequencies of cooling elements 720 and 770 may be adjusted to maintain resonance. In some embodiments, cooling elements(s) 720 and / or 770 are driven within several hundred Hz of one or more resonant frequencies to optimize performance. However, other frequencies are possible. The driving frequencies of cooling elements 720 and 770 can also be adjusted to maintain the cooling elements out of phase by 180 degrees or close to 180 degrees. In addition, it is desirable that the structural resonant frequencies of cooling elements 720 and 770 and their driving frequencies are equal to or close to the acoustic resonant frequency of cooling system 700.

[0091] During operation, cooling element 770 undergoes an upward stroke, while cooling element 720 undergoes a downward stroke, such as... Figure 7B As indicated in the diagram. Therefore, the cooling element 720 drives fluid out of the orifice 732 at high speed, as described with respect to the cooling system 100. Similarly, during the upward stroke of the cooling element 770, fluid is driven from the upper chamber 780 to the top chamber 740. In the illustrated embodiment, the anchor 772 and the orifice (not shown) in the cooling element 770 allow fluid to flow from the upper chamber 780 through the anchor 772 into the chamber 740. This fluid movement is caused by… Figure 7B Unmarked arrows indicate this. In other embodiments where no orifices are present in anchor 772 and cooling element 770, fluid flows from upper chamber 780 to top chamber 740 at the periphery of cooling system 700. Fluid is driven from top chamber 740 to bottom chamber 750 as cooling element 720 undergoes an upward stroke and cooling element 770 undergoes a downward stroke. Fluid is also drawn into upper chamber 780 through vent 712. Fluid movement is... Figure 7C The arrows not marked in the text indicate this. The orifice plate 730, orifice 732, and / or cooling element 720 are also configured to reduce or eliminate suction that would cause fluid to flow back through orifice 732 into bottom chamber 750.

[0092] Therefore, cooling system 700 operates in a similar manner to cooling system 100. Thus, the benefits of cooling system 100 can be realized. Furthermore, the use of multiple cooling elements 720 and 770 allows cooling system 700 to operate even under higher back pressures in the injection channel (the area between the heating structure 702 and the orifice plate 730). Therefore, the range of applications utilizing cooling system 700 can be increased. Additionally, cooling system 700 can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without the heating structure 702).

[0093] Figures 8A to 8E Embodiments of active cooling systems 800A, 800B, and 800C, including centrally anchored cooling elements and elastic structures 890D and 890E, are depicted. Figures 8A to 8E It was not drawn to scale. Figure 8A A cooling system 800A utilizing a cooling element 820A and an elastic structure 890A is depicted. Cooling system 800A is similar to cooling system 100. Cooling system 800 includes a top plate 810 with vents 812, a cooling element 820, an orifice plate 830 including orifices 832, a top chamber 840, a bottom chamber 850, and an anchor (i.e., support structure) 860, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 including orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Therefore, the cooling element 820A is centrally supported by the anchor 860, allowing at least a portion of the periphery of the cooling element 820A to vibrate freely. In some embodiments, the anchor 860 extends along the axis of the cooling element 820A (e.g., in a manner similar to anchors 260A and / or 260B). Furthermore, the orifice plate 830, orifice 832 and / or cooling element 820A may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0094] Figure 8A The piezoelectric element 823 of the cooling element 820A and the elastic structure 890A are also shown. The elastic structure 890A resides between the cooling element 820A and the top plate 810. The elastic structure 890A is used to couple the vibrational motion of opposite segments of the cooling element 820A. For example, if the vibrations are in phase (both segments experience upward travel or both segments experience downward travel), the elastic structure 890A helps to keep these portions of the cooling element 820A in phase. For embodiments in which the anchor 860 is only close to the central portion of the cooling element 820A (e.g., similar to anchors 360A and / or 360B), the elastic structure 890A can be constructed differently.

[0095] Therefore, cooling system 800A operates in a similar manner to cooling system 100. Thus, the benefits of cooling system 100 can be realized. Furthermore, the use of elastic structure 890A allows the vibration of a portion of cooling element 820A to be maintained in the desired phase. Therefore, the performance of cooling system 800A can be further improved.

[0096] Figure 8B A plan view of a portion of a cooling system 800B utilizing a cooling element 820B and an elastic structure 890B is depicted. Cooling system 800B is similar to cooling systems 100 and 800A. For simplicity, only the cooling element 820B, elastic structure 890B, and anchor 860 are shown. The elastic structure 890B resides on the side of the cooling element 820B. The elastic structure 890B is used to couple the vibrational motion of opposite segments of the cooling element 820B. For example, if the vibrations are in phase (both segments experience upward travel or both segments experience downward travel), the elastic structure 890B helps to keep these portions of the cooling element 820B in phase. For embodiments where the anchor 860 is only located near the central portion of the cooling element 820B (e.g., similar to anchors 360A and / or 360B), the elastic structure 890B can be constructed differently.

[0097] Cooling system 800B operates in a similar manner to cooling system 100. Therefore, the benefits of cooling system 100 can be realized. Furthermore, the use of the elastic structure 890B allows the vibration of a portion of the cooling element 820B to be maintained in the desired phase. Therefore, the performance of cooling system 800B can be further improved.

[0098] Figure 8CA neutral configuration of a cooling system 800C comprising multiple cooling elements 820C and 870 is depicted. Cooling system 800C is similar to cooling systems 100 and 700. Cooling system 800C includes a top plate 810 with vents 812, cooling elements 820C, an orifice plate 830 with orifices 832, a top chamber 840, a bottom chamber 850, and an anchor (i.e., support structure) 860, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Cooling system 800C also includes additional cooling elements 870, an anchor (support structure) 872, and an upper chamber 880, which are respectively similar to cooling elements 770, anchor 772, and upper chamber 780. Therefore, cooling elements 820C and 870 are centrally supported by anchors 860 and 872, respectively, allowing at least a portion of the periphery of cooling elements 820C and 870 to vibrate freely. In some embodiments, anchors 860 and 872 extend along the axes of cooling elements 820C and 870 (e.g., in a manner similar to anchors 260A and / or 260B). Furthermore, the orifice plate 830, orifice 832, and / or cooling element 820C may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0099] Figure 8C The diagram also shows an elastic structure 890C. The elastic structure 890C resides between cooling elements 820C and 870. The elastic structure 890C is used to couple the vibrational motions of the cooling elements 820C and 870. For example, if they are vibrating out of phase, the elastic structure 890C helps maintain the phase of the vibrations of these cooling elements 820C and 870. Figure 8D and Figure 8E Embodiments of flexible structures 890D and 890E that can be used in cooling system 800C are depicted.

[0100] Therefore, cooling system 800C operates in a similar manner to cooling systems 100 and / or 700. Thus, the benefits of cooling systems(s) 100 and / or 700 can be realized. Furthermore, the use of elastic structures 890C, 890D, and / or 890E allows the vibrations of cooling elements 820C and 870 to be maintained in the desired phase. Therefore, the performance of cooling system 800C can be further improved. Additionally, cooling systems 800A, 800B, and / or 800C can be used in other applications requiring high fluid flow rates and / or speeds (e.g., with or without a heat-generating structure 802).

[0101] Figures 9A to 9B An embodiment of an active cooling system 900 including a centrally anchored cooling element 920 is described. Figures 9A to 9B It was not drawn to scale. Figure 9A and Figure 9B The end of the stroke of cooling element 920 is depicted. The neutral structure is... Figure 9A and Figure 9B The dashed lines in the diagram represent the components. For simplicity, only a portion of the cooling system 900 is shown.

[0102] Cooling system 900 is similar to cooling system 100. Cooling system 900 includes a top plate 910 with vents 912, a cooling element 920, an orifice plate 930 with orifices 932, a top chamber 940, a bottom chamber 950, and an anchor (i.e., support structure) 960, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Thus, cooling element 920 is centrally supported by anchor 960, allowing at least a portion of the periphery of cooling element 920 to vibrate freely. In some embodiments, anchor 960 extends along the axis of cooling element 920 (e.g., in a manner similar to anchors 260A and / or 260B). Furthermore, the orifice plate 930, orifice 932, and / or cooling element 920 may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0103] exist Figures 9A to 9B In the illustrated embodiment, the cooling element 920 is driven out of phase. More specifically, sections of the cooling element 920 on opposite sides of the anchor 960 (and therefore on opposite sides of the central region of the cooling element 920 supported by the anchor 960) are driven to vibrate out of phase. In some embodiments, the sections of the cooling element 920 on opposite sides of the anchor 960 are driven out of phase by an angle equal to or close to 180 degrees. Thus, one section of the cooling element 920 vibrates toward the top plate 910, while another section of the cooling element 920 vibrates toward the orifice plate 930 / heating structure 902. The movement of the section of the cooling element 920 toward the top plate 910 (upward stroke) drives fluid in the top cavity 940 to the bottom cavity 950 on that side of the anchor 960. The movement of the section of the cooling element 920 toward the orifice plate 930 drives fluid through the orifice 932 toward the heating structure 902. Therefore, fluid traveling at high speed (e.g., the speed described with respect to cooling system 100) is alternately driven out from orifices 932 on opposite sides of anchor 960.

[0104] Therefore, cooling system 900 operates in a similar manner to cooling system 100. Thus, the benefits of cooling system 100 can be realized. Furthermore, the out-of-phase vibration of cooling element 920 allows the position of the center of mass of cooling element 900 to remain more stable. Although torque is applied to cooling element 920, the force generated due to the movement of the center of mass is reduced or eliminated. As a result, vibration caused by the movement of cooling element 920 is reduced. Furthermore, by using out-of-phase vibration motion on both sides of cooling element 920, the efficiency of cooling system 900 can be improved. Therefore, the performance of cooling system 900 can be further improved. In addition, cooling system 900 can be used in other applications requiring high fluid flow rate and / or velocity (e.g., with or without heat-generating structure 902).

[0105] Figures 10A to 10C Embodiments of active cooling systems 1000A, 1000B, and 1000C, each comprising multiple cooling units 1001A, 1001B, and 1001C, are depicted. Each cooling unit 1001A, 1001B, and 1001C has a centrally anchored cooling element 1020A, 1020B, and 1020C, respectively. Figures 10A to 10C It was not drawn to scale. Figures 10A to 10C The same geometry is depicted, but units 1001A, 1001B, and 1001C are driven with different phases. Therefore, although indicated as different systems, cooling systems 1000A, 1000B, and 1000C can be the same physical system driven by different input signals. For simplicity, only portions of cooling systems 1000A, 1000B, and 1000C are shown.

[0106] refer to Figure 10AEach unit 1001A of the cooling system 1000A is similar to that of the cooling system 100. The cooling system 1000A includes a top plate 1010 with vents 1012, a cooling element 1020A, an orifice plate 1030 with orifices 1032, a top chamber 1040, a bottom chamber 1050, and an anchor (i.e., support structure) 1060, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Therefore, the cooling element 1020A is centrally supported by the anchor 1060, allowing at least a portion of the periphery of the cooling element 1020A to vibrate freely. In some embodiments, the anchor 1060 extends along the axis of the cooling element 1020A (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 1060 is located only near the central portion of cooling element 1020A (e.g., similar to anchors 360A and / or 360B). Furthermore, orifice plate 1030, orifice 1032, and / or cooling element 1020A may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0107] Each cooling element 1020A is driven to vibrate in phase. Therefore, the portions of cooling elements 1020A not supported by the anchor 1060 vibrate together toward the top plate 1010 or together toward the perforated plate 1030. However, the cooling elements 1020A in adjacent units 1001A vibrate out of phase. Therefore, if one cooling element 1020A is undergoing a downward stroke, the adjacent cooling element 1020A is undergoing an upward stroke.

[0108] The cooling unit 1001A of the cooling system 1000A operates in a similar manner to the cooling system 100. Therefore, the benefits of the cooling system 100 can be realized for each cooling unit 1001A. Using multiple units increases the cooling capacity of the cooling system 1000A. Furthermore, the out-of-phase vibration of the cooling elements 1020A in adjacent units reduces vibrations in the cooling system 1000A caused by the movement of the cooling elements 1020A. Therefore, the performance of the cooling system 1000A can be further improved. In addition, the cooling system 1000A can be used in other applications requiring high fluid flow rates and / or speeds (e.g., with or without heat-generating structures).

[0109] Figure 10BA cooling system 1000B is depicted, wherein each unit 1001B is similar to cooling systems 100 and 900. Cooling system 1000B includes a top plate 1010 with vents 1012, a cooling element 1020B, an orifice plate 1030 with orifices 1032, a top chamber 1040, a bottom chamber 1050, and an anchor (i.e., support structure) 1060, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Thus, the cooling element 1020B is centrally supported by the anchor 1060, allowing at least a portion of the periphery of the cooling element 1020B to vibrate freely. In some embodiments, the anchor 1060 extends along the axis of the cooling element 1020B (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 1060 is located only near the central portion of cooling element 1020B (e.g., similar to anchor 360A and / or 360B). Furthermore, orifice plate 1030, orifice 1032, and / or cooling element 1020B may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0110] Cooling elements 1020B are driven to vibrate in phase. Therefore, some portions of the cooling elements 1020B not supported by the anchor 1060 vibrate together toward the top plate 1010, while other portions vibrate toward the perforated plate 1030. Furthermore, in the illustrated embodiment, the cooling elements 1020B in adjacent units 1001B vibrate out of phase. In other embodiments, the cooling elements 1020B in adjacent units 1001B may vibrate in phase (e.g., the right-hand portions of the cooling elements 1020B in all units 1001B vibrate together toward the top plate 1010).

[0111] The cooling unit 1001B of the cooling system 1000B operates in a similar manner to cooling systems 900 and 100. Therefore, the benefits of cooling systems 100 and 900 can be realized for each cooling unit 1001B. The cooling capacity of the cooling system 1000B can be increased by using multiple cooling units 1001B. Furthermore, the out-of-phase vibration of the cooling element 1020B in a single unit 1001B allows for reduction of vibrations in the cooling system 1000B caused by the movement of the cooling element 1020B. Therefore, the performance of the cooling system 1000B can be further improved. In addition, the cooling system 1000B can be used in other applications requiring high fluid flow rates and / or speeds (e.g., with or without heat-generating structures).

[0112] refer to Figure 10CThe image depicts a cooling system 1000C, wherein each unit 1001C is similar to the cooling system 100. The cooling system 1000C includes a top plate 1010 with vents 1012, a cooling element 1020C, an orifice plate 1030 with orifices 1032, a top chamber 1040, a bottom chamber 1050, and an anchor (i.e., support structure) 1060, which are respectively similar to a top plate 110 with vents 112, a cooling element 120, an orifice plate 130 with orifices 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. Thus, the cooling element 1020C is centrally supported by the anchor 1060, allowing at least a portion of the periphery of the cooling element 1020C to vibrate freely. In some embodiments, the anchor 1060 extends along the axis of the cooling element 1020C (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchor 1060 is located only near the central portion of cooling element 1020C (e.g., similar to anchors 360A and / or 360B). Furthermore, orifice plate 1030, orifice 1032, and / or cooling element 1020C may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0113] Cooling elements 1020C are driven to vibrate in phase. Therefore, the portions of cooling elements 1020C not supported by anchor 1060 vibrate together toward the top plate 1010 or together toward the perforated plate 1030. Furthermore, cooling elements 1020C in adjacent units 1001C vibrate in phase. Therefore, cooling elements 1020C in all units 10001C experience both downward and upward strokes together.

[0114] Therefore, the cooling unit 1001C of the cooling system 1000C operates in a similar manner to the cooling system 100. Thus, the benefits of the cooling system 100 can be realized for each cooling unit 1001C. Using multiple cooling units 1001C can further increase the cooling capacity of the cooling system 1000. Therefore, the performance of the cooling system 1000A can be further improved. However, the in-phase vibration of the cooling elements 1020C in adjacent units can allow for increased vibration in the cooling system 1000C due to the movement of the cooling elements 1020A. The cooling system 1000C can also be used in other applications requiring high fluid flow rates and / or speeds (e.g., with or without heat-generating structures).

[0115] Figures 11A to 11D Embodiments of active cooling systems 1100 and 1100D, comprising multiple cooling elements 1110 and 1120, are described. Figures 11A to 11D It was not drawn to scale. Figures 11A to 11D The same geometry was depicted, but the cooling elements were driven in a different way.

[0116] Figure 11A A neutral configuration of a cooling system 1100 with multiple centrally anchored cooling elements 1110 and 1120 is depicted. Cooling system 1100 is similar to cooling system 700, but has staggered cooling elements 1110 and 1120. Cooling system 1100 includes cooling elements 1120 and 1110, an orifice plate 1130 including an orifice 1132, a top chamber 1140, a bottom chamber 1150, and an anchor (i.e., support structure) 1160, which are respectively similar to cooling elements 120 (and cooling elements 720 and 770), an orifice plate 130 including an orifice 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160. A top ridge 1114, similar to top ridges 422E and 422D, is also shown. In some embodiments, top ridge 1114 may be omitted. Therefore, each cooling element 1120 and 1110 is centrally supported by an anchor 1160, allowing at least a portion of the periphery of the cooling elements 1120 and 1110 to vibrate freely. In some embodiments, the anchor 1160 extends along the axis of the cooling elements 1110 and / or 1120 (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, the anchor 1160 is located only near the central portion of the cooling elements 1110 and / or 1120 (e.g., similar to anchors 360A and / or 360B). Furthermore, the orifice plate 1130, the orifice 1132, and / or the cooling elements 1110 and 1120 may be constructed in a similar manner to one or more of the other orifice plates and / or cooling elements depicted herein.

[0117] Figures 11B to 11C A cooling system 1100 is depicted when each cooling element 1110 and 1120 is driven to vibrate in phase. Therefore, the unsupported portions of each cooling element 1120 vibrate together away from the orifice plate or together toward the orifice plate 1130. Similarly, the unsupported portions of the cooling element 1110 vibrate together away from the orifice plate or together toward the orifice plate 1130. However, adjacent cooling elements 1110 and 1120 vibrate out of phase. Therefore, if one cooling element 1120 is experiencing a downward stroke, the adjacent cooling element 1110 is experiencing an upward stroke, and vice versa. Alternatively, a cooling system 1100D is depicted when each cooling element 1110 and 1120 are driven out of phase. Therefore, some portions of the unsupported cooling elements 1110 and 1120 vibrate together away from the orifice plate, while the other portions of the cooling elements 1110 and 1120 vibrate toward the orifice plate 1130 respectively. Therefore, depending on how the cooling elements 1110 and 1120 are actuated, in-phase or out-of-phase vibrations can be used.

[0118] Cooling systems 1100 / 1100D operate in a similar manner to cooling system 100. Therefore, the benefits of cooling system 100 can be realized. Using multiple cooling elements increases the cooling capacity of cooling systems 1100 / 1100D. Furthermore, stacking cooling elements 1110 and 1120 allows for supporting higher back pressures. Therefore, the performance of cooling systems 1100 / 1100D can be further improved. Additionally, cooling systems 1100 and / or 1100D can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without heat-generating structures).

[0119] Figure 12 An embodiment of an active cooling system 200 comprising multiple cooling elements 1210, 1220 and 1280 is described. Figure 12 Not drawn to scale. Cooling system 1200 is similar to cooling systems 700 and 1100. Cooling system 1200 includes cooling elements 1220 and 1210, an orifice plate 1230 including orifice 1232, a top chamber 1240, a bottom chamber 1250, and an anchor (i.e., support structure) 1260, which are similar to cooling elements 120 (and cooling elements 710 and 770), an orifice plate 130 including orifice 132, a top chamber 140, a bottom chamber 150, and an anchor (i.e., support structure) 160, respectively. A top ridge 1214 similar to ridges 422E and 422D is also shown. In some embodiments, top ridge 1214 may be omitted.

[0120] Cooling elements 1220 and 1210 are each centrally supported by anchors 1260, allowing at least a portion of the periphery of cooling elements 1220 and / or 1210 to vibrate freely. In some embodiments, anchors 1260 extend along the axes of cooling elements 1210 and 1220 (e.g., in a manner similar to anchors 260A and / or 260B). In other embodiments, anchors 1260 are located only near the central portion of cooling elements 1210 and / or 1220 (e.g., similar to anchors 360A and / or 360B). Furthermore, orifice plate 1230, orifice 1232, and / or cooling elements 1210, 1220, and 1280 may be constructed in a manner similar to one or more of the other orifice plates and / or cooling elements depicted herein.

[0121] In addition, the cooling system 1200 has an additional layer of cooling element 1280 and upper chamber 1270. Cooling element 1280 functions in a manner similar to cooling elements 1210 and / or 1220. Furthermore, cooling elements 1210, 1220 and 1280 can be driven in-phase or out-of-phase.

[0122] Therefore, cooling system 1200 operates in a similar manner to cooling system 100. Thus, the benefits of cooling system 100 can be realized. Using multiple cooling elements increases the cooling capacity of cooling system 1200. Furthermore, stacking cooling elements 1210, 1220, and 1280 allows for supporting higher back pressures. Therefore, the performance of cooling system 1200 can be further improved. Additionally, cooling system 1200 can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without heat-generating structures).

[0123] Figure 13 A top view depicting an embodiment of a cooling system 1300 including multiple cooling units 1301 is shown. Figure 13 Not drawn to scale. Cooling unit 1301 is similar to one or more of the cooling systems described herein, such as cooling systems 100, 400A, 400B, 400C, 400D, 400E, 500, 600, 700, 800A, 800B, 800C, 900, 1000A, 1000B, 1000C, 1100, 1100D, and / or 1200. As indicated in cooling system 1300, cooling unit 1301 can be arranged in a two-dimensional array of desired size and configuration. Therefore, the configuration of cooling unit 1301 can be adapted to a desired application. Furthermore, cooling system 1300 can be used in other applications requiring high fluid flow rates and / or velocities (e.g., with or without heat-generating structures).

[0124] Figures 14A to 14B Embodiments of cooling elements 1400A and 1400B are described respectively. Figure 14A and Figure 14B Not drawn to scale. Cooling elements 1400A and 1400B are piezoelectric cooling elements that may be used as or included in the cooling elements described herein. Reference Figure 14A The cooling element 1400A includes a piezoelectric layer 1404 on a substrate 1402. In some embodiments, the substrate 1402 comprises stainless steel, nickel, and / or Hastelloy. In some embodiments, the piezoelectric layer 1404 comprises a plurality of sublayers. In some embodiments, the piezoelectric layer 1404 is fabricated on the substrate 1402 using a deposition technique. In some embodiments, the piezoelectric layer 1404 comprises or is attached to an intrinsic layer of the substrate 1402. The piezoelectric cooling element 1400A also includes a top electrode 1406. In some embodiments, a bottom electrode may be formed from a stainless steel substrate 1402. In other embodiments, a bottom electrode (not shown) may be disposed between the substrate 1402 and the piezoelectric layer 1404. Other layers (not shown) may be included in the piezoelectric cooling element 1400, including but not limited to seed layers, capping layers, passivation layers, or other layers. The thickness and width of the cooling element 1400A may be within the range described for other cooling elements discussed herein.

[0125] Figure 14B A piezoelectric cooling element 1400B, similar to cooling element 1400A, is depicted. The piezoelectric cooling element 1400B includes a piezoelectric layer 1404B on a substrate 1402B. In some embodiments, the substrate 1402B comprises stainless steel, nickel, and / or Hastelloy. In some embodiments, each piezoelectric layer 1404B includes a plurality of sublayers. In some embodiments, each piezoelectric layer 1404B is fabricated on the substrate 1402B using a deposition technique. In some embodiments, each piezoelectric layer 1404B includes or is attached to an intrinsic layer of the substrate 1402B. The piezoelectric cooling element 1400B also includes a top electrode 1406B for each piezoelectric layer 1404B. Thus, each portion of the piezoelectric cooling element 1400B can be individually actuated. In some embodiments, a bottom electrode may be formed from the substrate 1402B. In other embodiments, a bottom electrode (not shown) may be disposed between the substrate 1402B and the piezoelectric layer 1404B. Other layers (not shown) may be included in the piezoelectric cooling element 1400B, including but not limited to a seed layer, capping layer, passivation layer, or other layers. The thickness and width of the cooling element 1400B may be within the range described for other cooling elements discussed herein.

[0126] Figure 15 This is a flowchart depicting an exemplary embodiment of a method 1500 for operating a cooling system. Method 1500 may include steps not depicted for simplicity. Method 1500 is described in the context of a piezoelectric cooling system 100. However, method 1500 can be used in other cooling systems, including but not limited to the systems and units described herein.

[0127] In 1502, one or more of the cooling elements(s) in the cooling system are actuated to vibrate. In 1502, the cooling elements(s) are driven using an electrical signal having a desired frequency. In some embodiments, in 1502, the cooling elements are driven at a frequency equal to or close to the structural and / or acoustic resonance frequency. The driving frequency may be 15 kHz or higher. If multiple cooling elements are driven in 1502, the cooling elements may be driven out of phase. In some embodiments, the cooling elements are driven substantially 180 degrees out of phase. Furthermore, in some embodiments, the individual cooling elements are driven out of phase. For example, different portions of the cooling elements may be driven to vibrate in opposite directions.

[0128] At 1504, feedback from the piezoelectric cooling elements(s) is used to regulate the drive current. In some embodiments, regulation is used to maintain the frequency at or near the acoustic and / or structural resonant frequency of the cooling elements(s) and / or the cooling system(s). The resonant frequency of a particular cooling element may drift, for example, due to temperature variations. The regulation performed at 1504 allows for taking into account the drift in the resonant frequency.

[0129] For example, at 1502, the piezoelectric cooling element 120 may be driven at one or more of its structural resonant frequencies. This resonant frequency may also be equal to or close to the acoustic resonant frequency of the top chamber 140. At 1504, feedback is used to keep the cooling element 120 in resonance and, in some embodiments driving multiple cooling elements, to maintain a 180-degree out-of-phase configuration. Therefore, the efficiency of the cooling element 120 can be maintained as the driving fluid flows through the cooling system 100 and to the heating structure 102. In some embodiments, 1504 includes sampling and regulating the current through the cooling element 120 to maintain resonance and low input power.

[0130] In another example, at 1502, piezoelectric cooling elements 720 and 770 can be driven at one or more of their structural resonant frequencies. These structural resonant frequencies can also be equal to or close to the acoustic resonant frequency of the top chamber 740. Because multiple cooling elements 720 and 770 are driven, there may be small differences in the resonant frequencies and therefore the driving frequencies. Therefore, cooling elements 720 and 770 can be driven at slightly different frequencies. Furthermore, cooling elements 720 and 770 are actuated to vibrate out of phase (e.g., 180 degrees out of phase).

[0131] At 1504, feedback is used to keep cooling elements 720 and 770 in resonance, and in some embodiments, to maintain a 180-degree out-of-phase relationship. For example, the drive current can be sampled and adjusted to reduce the power input of the deflection or fluid flow rate by the same amount. The power reduction occurs at resonance. Using feedback, cooling elements 720 and 770 can be kept in resonance or near resonance. Therefore, the efficiency of cooling elements 720 and 770 can be maintained as the drive fluid flows through the cooling system 700 and to the heat-generating structure 702.

[0132] Therefore, cooling elements such as (multiple) cooling elements 120, 720 and / or 770 can operate as described above. Method 1500 thus provides a method for using the piezoelectric cooling system described herein. Therefore, the piezoelectric cooling system can cool semiconductor devices more efficiently and quietly with lower power.

[0133] Figure 16 This is a flowchart depicting an exemplary embodiment of a method 1600 for operating a cooling system. Method 1600 may include steps not depicted for simplicity. Method 1600 is described in the context of a piezoelectric cooling system 100. However, method 1600 can be used in other cooling systems, including but not limited to the systems and units described herein. Method 1600 begins after a drive current(s) has been provided to actuate one or more cooling elements. Therefore, the cooling elements(s) are driven using electrical signals(s) having a desired frequency. In some embodiments, the cooling elements are driven at a frequency equal to or close to the structural and acoustic resonance frequencies.

[0134] In step 1602, the current(s) used in driving (multiple) cooling elements(s) is measured. In step 1604, the driving frequency of the current(s) is adjusted. For example, in step 1604, the driving current frequency can be increased. Furthermore, the current can be adjusted to maintain the same flow rate or deflection amplitude after a frequency change. In step 1606, the new current used to drive (multiple) cooling elements is measured.

[0135] At 1608, determine whether the drive current has decreased in response to the change in drive frequency. If not, at 1610, adjust the frequency of the drive current in the opposite direction. If the drive current has decreased, at 1612, adjust the current in the same direction.

[0136] In 1614, processes 1606, 1608, 1610, and / or 1612 are repeated iteratively until the measured current indicates that the driving frequency of the cooling element(s) is within the tolerance of the structural and / or acoustic resonant frequency. Therefore, these processes are repeated until the measured current is within the tolerance of the minimum driving current. In 1616, this current is used to drive the cooling element(s).

[0137] For example, the piezoelectric cooling element 120 can be driven at a frequency equal to or close to its structural resonant frequency. Over time, the structural and / or acoustic resonant frequencies of the cooling system 100 may drift. Therefore, at 1602, the current used to drive the cooling element 120 is measured. At 1604, the frequency of the drive signal is adjusted. The magnitude of the current used in the drive signal is also adjusted to provide the desired flow rate and / or deflection of the cooling element. At 1606, the current used to drive the cooling element 120 at a new frequency with the desired amplitude is measured. At 1608, it is determined whether the drive current has decreased. If the new drive frequency is further away from the (drifted) structural / acoustic resonant frequency than the previous drive frequency, the drive current increases. If the new drive frequency is closer to the (drifted) structural / acoustic resonant frequency, the drive current decreases. Therefore, based on the determination in 1606, the frequency of the drive signal is adjusted in the same direction at 1612, or in the opposite direction at 1610. In 1614 and 1616, the measurements (1606), difference determination (1608), and adjustment (1610 or 1612) are repeated iteratively until the cooling element 120 is driven to the desired tolerance of the structural and / or acoustic resonance frequency.

[0138] Therefore, a cooling element such as element 120 can operate as described above. Method 1600 thus provides a method for using the piezoelectric cooling system described herein. Therefore, the piezoelectric cooling system can cool semiconductor devices more efficiently and quietly with lower power.

[0139] This paper has described various constructs, methods, and features. Some or all of the constructs, methods, and / or features may be combined in ways not explicitly described herein.

[0140] Although the foregoing embodiments have been described in detail to a certain extent for the purpose of clarity, the invention is not limited to the details provided. Many alternative ways of implementing the invention exist. The disclosed embodiments are illustrative and not restrictive.

Claims

1. A cooling system, comprising: a support structure; a cooling element having a first cantilevered region, a second cantilevered region, a central region between the first and second cantilevered regions, and a perimeter, the cooling element being supported at the central region by the support structure, at least a portion of the perimeter being unsecured, the cooling element being configured to undergo a vibrational motion when actuated; and an orifice plate having at least one orifice therein, the cooling element being configured to undergo the vibrational motion of the first and second cantilevered regions when actuated to drive fluid toward the orifice plate and through the at least one orifice, the orifice plate being in a fluid path between the cooling element and a heat-generating structure.

2. The cooling system of claim 1, wherein, the cooling element having a first side proximate the heat-generating structure and a second side distal the heat-generating structure, the vibrational motion driving the fluid from the second side of the cooling element to the first side of the cooling element.

3. The cooling system of claim 1, wherein, the cooling system further comprising: a top plate having at least one through-hole therein, the cooling element being between the top plate and the orifice plate, a top chamber being formed between the cooling element and the top plate, the vibrational motion of the cooling element being configured to draw fluid through the at least one through-hole.

4. The cooling system of claim 3, wherein, the top chamber having a length corresponding to an odd multiple of a wavelength divided by 4, the wavelength being an acoustic wavelength for a frequency of the vibrational motion, the frequency of the vibrational motion corresponding to a structural resonance for the cooling element and an acoustic resonance for the top chamber having the wavelength.

5. The cooling system of claim 4, wherein, the top chamber being a folded top chamber.

6. The cooling system of claim 1, wherein, the cooling system having a height of no more than 2 millimeters.

7. The cooling system of claim 1, wherein, the orifice plate including at least one of a ridge and at least one groove in the orifice plate, the at least one groove including the at least one orifice therein, the ridge being closer to the perimeter of the cooling element than the at least one orifice.

8. The cooling system of claim 1, wherein, the vibrational motion being out-of-phase vibrational motion.

9. The cooling system of claim 1, wherein, the cooling system further comprising: a resilient structure coupled to the cooling element.

10. The cooling system of claim 1, wherein, the cooling element being a piezoelectric cooling element having a length of no more than 10 millimeters, and wherein the vibrational motion drives the fluid toward the heat-generating structure at a velocity of at least 30 meters per second.

11. A cooling system, comprising: a plurality of cooling units, each of the plurality of cooling units including a support structure and a cooling element, the cooling element having a first cantilevered region, a second cantilevered region, a central region between the first and second cantilevered regions, and a perimeter, the cooling element being supported at the central region by the support structure, at least a portion of the perimeter being unsecured, the cooling element being configured to undergo a vibrational motion when actuated; and an orifice plate having at least one orifice therein, the cooling element being configured to undergo the vibrational motion of the first and second cantilevered regions when actuated to drive fluid toward the orifice plate and through the at least one orifice, the orifice plate being in a fluid path between the cooling element and a heat-generating structure. an orifice plate having a plurality of orifices therein, a portion of the plurality of orifices corresponding to each of the plurality of cooling units, the cooling element configured to undergo vibrational motion of the first cantilever region and the second cantilever region when actuated to drive fluid toward the orifice plate and through the portion of the plurality of orifices, the orifice plate in a fluid path between the cooling element and a heat generating structure.

12. The cooling system of claim 11, wherein, The cooling system further comprises: a top plate having at least one through hole therein for each of the plurality of cooling units, the cooling element between the top plate and the orifice plate, a top chamber formed between the cooling element and the top plate for each of the plurality of cooling units, the vibrational motion of the cooling element configured to draw fluid through the at least one through hole, the top chamber having a length configured to provide an acoustic resonance corresponding to an odd number times a wavelength divided by four, the wavelength an acoustic wavelength for a frequency of the vibrational motion, the frequency of the vibrational motion at a structural resonance for the cooling element.

13. The cooling system of claim 11, wherein, In each of the plurality of cooling units, the portion of the plurality of orifices is located at least 100 microns from the perimeter of the cooling element and no more than 1 millimeter from the perimeter of the cooling element.

14. The cooling system of claim 11, wherein, For adjacent cooling units of the plurality of cooling units, the vibrational motion is out of phase vibrational motion.

15. A method of cooling a heat generating structure, comprising: driving a cooling element to induce vibrational motion at a frequency, the cooling element having a first cantilever region, a second cantilever region, a central region between the first cantilever region and the second cantilever region, and a perimeter, the cooling element supported at the central region by a support structure, at least a portion of the perimeter being unsecured, the cooling element configured to undergo vibrational motion when actuated, an orifice plate having at least one orifice therein and in a fluid path between the cooling element and the heat generating structure, the cooling element configured to undergo vibrational motion of the first cantilever region and the second cantilever region when actuated to drive the fluid toward the orifice plate and through the at least one orifice.

16. The method of claim 15, wherein, The driving further comprises: driving the cooling element at a frequency for the vibrational motion, the frequency corresponding to a structural resonance for the cooling element, the cooling element between a top plate and the heat generating structure, the top plate having at least one through hole therein, the cooling element and the top plate forming a top chamber between the cooling element and the top plate, the vibrational motion of the cooling element configured to draw fluid through the at least one through hole, the top chamber having a length configured, the frequency also corresponding to an acoustic resonance, the acoustic resonance having a wavelength corresponding to the length times four divided by an odd number.

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