Abstract: By directly connecting, ballast to an emitter electrode of an ion generator (e.g., a corona-discharge device), a rapid and self-corrective reduction in emitter-to-collector voltage may be provided responsive to an increase in current characteristic of incipient sparking discharge. Voltage levels in the emitter-to-collector gap can be rapidly reduced based on voltage drop across the ballast that, while negligible under nominal ion current conditions, transiently increases in the event of a sparking discharge. As a result, the portion of supply voltage (typically multi-KV supply voltage) across the emitter-to-collector gap is transiently reduced to levels below a current breakdown voltage and, indeed, field intensity proximate to the emitter is transiently reduced below levels otherwise necessary to sustain ion generation.

Abstract: Surfaces for electromagnetic shielding, retaining electrostatic charge and indeed collecting ion current in EHD fluid mover designs may be formed as or on surfaces of other components and/or structures in an electronic device. In this way, dimensions may be reduced and packing densities increased. In some cases, electrostatically operative portions of an EHD fluid mover are formed as or on surfaces of an enclosure, an EMI shield, a circuit board and/or a heat pipe or spreader. Depending on the role of these electrostatically operative portions, dielectric, resistive and/or ozone robust or catalytic coatings or conditioning may be applied.

Abstract: Cleaning and/or conditioning electrode surfaces can provide significant performance and operational benefits in EHD devices. In particular, conditioning of emitter electrode surfaces with silver (Ag), silver compositions or silver preparations applied in situ at successive times throughout the operating lifetime of an EHD air mover has been found to significantly reduce ozone production. Structures and techniques are described for in situ conditioning electrode surfaces and, in particular, emitter electrode surfaces of an EHD device such as an air mover or precipitator, with a conditioning material that includes silver.

Abstract: Disclosed herein are apparatuses and methods related to an electrohydrodynamic (EHD) fluid mover that includes emitter and collector electrodes energizable to motivate fluid flow therebetween. Ozone reducing catalyst bearing heat transfer surfaces may be disposed downstream of the emitter electrode in a flow path of the motivated fluid flow. A controller may be configured to, at respective times throughout the operating life of the EHD fluid mover, selectively employ at least one ozone reduction enhancement response selected from a set of responses. One response includes triggering a conditioning mechanism to apply an additional, but at least partially consumable, ozone reducing catalyst to a surface of the emitter electrode.

Abstract: An electrohydrodynamic fluid accelerator includes an emitter electrode and leading surfaces of a collector electrode that are substantially exposed to ion bombardment. Heat transfer surfaces downstream of the emitter electrode along a fluid flow path include a first portion not substantially exposed to the ion bombardment that is conditioned with a first ozone reducing material. The leading surfaces of the collector electrode are not conditioned with the first ozone reducing material, but may include a different surface conditioning. The downstream heat transfer surfaces and the leading surfaces can be separately formed and joined to form the unitary structure or can be integrally formed. The electrohydrodynamic fluid accelerator can be used in a thermal management assembly of an electronic device with a heat dissipating device thermally coupled to the conditioned heat transfer surfaces.

Abstract: Small form-factor ion flow fluid movers that provide electrostatically operative surfaces in a flow channel adjacent to an emitter electrode, but upstream of a collector electrode or electrodes, can shape operative electric fields and influence ion flows in ways that accentuate downstream flow while minimizing upstream ion migration. In some cases, dielectric surfaces (or even electrically isolated conductive surfaces) along a flow channel adjacent to an emitter electrode can be configured to collect and retain an initial population of generated ions and thereafter electrostatically repel further ions. Depending on the configuration of such dielectric or electrically isolated conductive surfaces, these repelling electrostatic forces may dissuade ion migration or flow from sensitive but closely proximate components and/or may shape fields to enhance ion flows in a desired downstream direction.

Abstract: An electrohydrodynamic fluid accelerator apparatus includes a corona electrode having an axial shape and configured to receive a first voltage. The electrohydrodynamic fluid accelerator apparatus includes a collector electrode disposed coaxially around the at least one corona electrode and configured to receive a second voltage. Application of the first and second voltages on the corona electrode and the collector electrode, respectively, causes fluid proximate to the corona electrode to ionize and travel in a first direction between the corona electrode and the collector electrode, thereby causing other fluid molecules to travel in a second direction to generate a fluid stream. In at least one embodiment of the invention, the ionized fluid proximate to the emitter electrode travels in a radial direction from the corona electrode to the collector electrode, causing the other fluid molecules to travel in an axial direction to thereby generate the fluid stream.

Abstract: Conditioning an electrode is performed with a cleaning device for removing detrimental material from forming electrode surfaces of an electrohydrodynamic device or other ion flow generating device. A conditioning material is deposited on the electrode to at least partially mitigate erosion, corrosion, oxidations, dendrite formation on the electrode or ozone production. The conditioning material can be deposited by a wearable portion of one or more cleaning blocks or wipers. The cleaning blocks may have a composition selected to be hard enough to remove detrimental material under a selected pressure, while soft enough to be wearable to deposit a conditioning layer on the electrode surface. The conditioning material can be applied as a solid or liquid. The applied conditioning material can include at least one of silver, palladium, platinum, manganese, nickel, zirconium, titanium, tungsten, aluminum, oxides or alloys thereof, carbon, and organometallic materials that decompose under plasma conditions.

Abstract: Performance of an electrohydrodynamic fluid accelerator device may be improved and adverse events such as sparking or arcing may be reduced based, amongst other things, on electrode geometries and/or positional interrelationships of the electrodes. For example, in a class of EHD devices that employ a longitudinally elongated corona discharge electrode (often, but not necessarily, a wire), a plurality of generally planar, collector electrodes may be positioned so as to present respective leading surfaces toward the corona discharge electrode. The generally planar collector electrodes may be oriented so that their major surfaces are generally orthogonal to the longitudinal extent of the corona discharge electrode. In such EHD devices, a high intensity electric field can be established in the “gap” between the corona discharge electrode and leading surfaces of the collector electrodes.

Abstract: In thermal management systems that employ EHD devices to motivate flow of air between ventilated boundary portions of an enclosure, it can be desirable to have some heat transfer surfaces participate in electrohydrodynamic acceleration of fluid flow while providing additional heat transfer surfaces that may not. In some embodiments, both collector electrodes and additional heat transfer surfaces are thermally coupled into a heat transfer path. Collector electrodes then contribute both to flow of cooling air and to heat transfer to the air flow so motivated. The collector electrodes and additional heat transfer surfaces may be parts of a unitary, or thermally coupled, structure that is introduced into a flow path at multiple positions therealong. In some embodiments, the collector electrodes and additional heat transfer surfaces may be proximate each other along the flow path. In some embodiments, the collector electrodes and additional heat transfer surfaces may be separate structures.

Abstract: Reversible flow may be provided in certain EHD device configurations that selectively energize corona discharge electrodes arranged to motivate flows in generally opposing directions. In some embodiments, a first set of one or more corona discharge electrodes is positioned, relative to a first array of collector electrode surfaces, to when energized, motivate flow in a first direction, while second set of one or more corona discharge electrodes is positioned, relative to a second array of collector electrode surfaces, to when energized, motivate flow in a second direction that opposes the first. In some embodiments, the first and second arrays of collector electrode surfaces are opposing surfaces of individual collector electrodes. In some embodiments, the first and second arrays of collector electrode surfaces are opposing surfaces of respective collector electrodes.

Abstract: An apparatus for tandem cleaning of an emitter electrode and collector electrode in electrohydrodynamic fluid accelerator and precipitator devices via movement of a cleaning mechanism including respective cleaning surfaces positioned to frictionally engage the emitter electrode and collector electrode. The cleaning mechanism causes the respective cleaning surfaces to travel along a longitudinal extent of the emitter electrode and, in tandem, over a major dimension of the collector electrode to remove detrimental material from respective electrode surfaces. Alternatively, the electrodes can be transited in tandem in frictional engagement with a fixed cleaning mechanism in the same or opposite directions. A conditioning material is optionally deposited on an electrode to at least partially mitigate ozone, erosion, corrosion, oxidation, or dendrite formation on the electrodes. The conditioning material can include an ozone reducer.

Abstract: By selecting different materials for each layer, a multi-layered electrode structure can be made with superior performance characteristics. For example, a multilayered electrode can include a high tensile strength tungsten core, a conductive intermediate palladium, palladium-nickel, or other platinum group metal layer for generating a corona discharge, and a hardened layer comprising rhodium or other platinum group metal or alloy of the same to resist frictional abrasion during removal of silica dendrites that accumulate on the electrode surface during operation.

Abstract: Cleaning and/or conditioning electrode surfaces can provide significant performance and operational benefits in EHD devices. In particular, conditioning of emitter electrode surfaces with silver (Ag), silver compositions or silver preparations applied in situ at successive times throughout the operating lifetime of an EHD air mover has been found to significantly reduce ozone production. Structures and techniques are described for in situ conditioning electrode surfaces and, in particular, emitter electrode surfaces of an EHD device such as an air mover or precipitator, with a conditioning material that includes silver.

Abstract: An electrohydrodynamic (EHD) air mover is positionable within the enclosure to, when energized, motivate air flow through the enclosure along a flow path between the inlet and outlet ventilation boundaries. Ductwork within the enclosure has cross-sections substantially matched to a cross-section of the EHD air mover. A fan curve-type, pressure-air flow characteristic measured for the EHD air mover in open air substantially overstates mechanical impedance of the EHD air mover to air flow along the flow path between the inlet and outlet ventilation boundaries in that, when the EHD air mover is operably positioned within the enclosure appurtenant to the ductwork, no more than about 50% of the mechanical impedance of the EHD air mover indicated by the measured fan curve-type, pressure-air flow characteristic actually contributes to total mechanical impedance to air flow through the enclosure along the flow path between the inlet and outlet ventilation boundaries.

Abstract: Small form-factor ion flow fluid movers that provide electrostatically operative surfaces in a flow channel adjacent to an emitter electrode, but upstream of a collector electrode or electrodes, can shape operative electric fields and influence ion flows in ways that accentuate downstream flow while minimizing upstream ion migration. In some cases, dielectric surfaces (or even electrically isolated conductive surfaces) along a flow channel adjacent to an emitter electrode can be configured to collect and retain an initial population of generated ions and thereafter electrostatically repel further ions. Depending on the configuration of such dielectric or electrically isolated conductive surfaces, these repelling electrostatic forces may dissuade ion migration or flow from sensitive but closely proximate components and/or may shape fields to enhance ion flows in a desired downstream direction.

Abstract: Flow paths, duct work, ventilation boundaries, and/or placement of EHD and mechanical air mover within a electronic device enclosure can all affect the efficacy of a thermal management solution that seeks to provide silent air cooling over a significant thermal operating envelope with staged introduction of electrohydrodynamic (EHD) and mechanical air mover devices. For electronic devices in which it is desirable to employ passive, unforced convective cooling over a portion of the thermal operating envelope, practical designs for consumer electronics form factors may be quite sensitive to flow path, duct work and ventilation boundary design as well as to the placement of EHD and mechanical air mover components relative thereto and to each other. A range of inventive solutions that have been developed to address some or all of these design challenges.

Abstract: An electronic system enclosure houses a plurality of electronic components together presenting one or more surfaces coated with ozone reducing material. An EHD air mover positioned remote from an outlet ventilation boundary of the enclosure motivates air flow through the enclosure along a flow path past the one or more surfaces coated with ozone destructive material over heat transfer surfaces and out through an outlet ventilation boundary of the enclosure.

Abstract: Techniques are described for integration of EHD-type air movers with electronic systems, and in particular, for limiting infiltration of ions and/or charged particulates into an internal air plenum. In some designs, it may be desirable to allow or even encourage EHD motivated air flow (whether drawn or forced) through the internal air plenum while providing a barrier to transit of ions and/or charged particulates that may be generated during EHD operation. Such a barrier may employ electrostatic forces to impede transit of ions and/or charged particulate across a vent positioned to allow air flow from or into the internal air plenum. In some cases, an electrostatic barrier may include a fluid permeable mesh or grill that spans a substantial cross-section of the vent.

Abstract: An electronic system including an enclosure and an internal air plenum within the enclosure. At least one component of the electronic system within the enclosure evolves heat and has a surface exposed to the internal air plenum. The enclosure has inlet and outlet ventilation boundaries together with an EHD air mover disposed therein to motivate airflow along a flow path between the inlet and outlet ventilation boundaries, wherein the flow path is substantially excluded from the internal air plenum by a barrier.