The technology described herein applies to micro-fabricated devices and methods for fabricating same. Particular non-limiting embodiments employ microlithographic fabrication techniques. Particular non-limiting embodiments provide microelectromechanical (MEMs) devices and methods for fabricating same.
A variety of micro-fabricated devices are fabricated to define cavities or voids which can provide a variety of uses to such micro-fabricated devices. For example, MEMs devices can be fabricated to define cavities into which the device can move or deform. In accordance with some micro-fabrication techniques, cavities are fabricated by: depositing a so-called sacrificial layer onto a substrate; coating the sacrificial layer with one or more other device layers while leaving one or more channels which provides access to the sacrificial layer; and then etching away the sacrificial layer with etchant (a typically acidic liquid) which is brought into contact with the sacrificial layer through the channel(s) where the etchant dissolves the sacrificial layer and carries the material of the sacrificial layer (in solution) out of the device via the channels to leave behind a cavity or void in place of the sacrificial layer.
In some applications, there is a desire to seal the channel(s) after the fabrication of a micro-fabricated cavity. Sealing the channel(s) after fabrication of a micro-fabricated cavity may prevent fluids or other contaminants from entering or egressing from the cavity. As a non-limiting example, in some applications and/or devices, it might be desirable to evacuate the cavity, in which case, there is a desire to seal any channel(s) used to fabricate the cavity to maintain the vacuum. Sealing such channel(s) may involve coating the exposed surfaces (e.g. the channel-defining surface(s) of the channel-defining wall(s)) with a coating material that solidifies or is caused to solidify on the channel-defining surface(s) to fill the channel(s), thereby sealing the channel(s).
A drawback with prior art sealing techniques is that some of the sealant material can travel through the channel(s) and into the cavity, where such material ends up inside the cavity after sealing. This contamination of the cavity with sealing material can be undesirable in particular applications.
There is a general desire to provide improved methods for sealing cavities in micro-fabricated devices and to fabricate devices which take advantages of these techniques. There is a general desire to provide improved micro-fabricated devices. There is a general desire to provide methods for sealing cavities in micro-fabricated devices which at least ameliorate the drawbacks with prior art techniques.
One aspect of the invention provides a method for fabricating a micro-fabricated device comprising a cavity-defining surface which defines a cavity. The method comprises: fabricating a channel that provides fluid communication with the cavity, the channel comprising a Tesla valve for permitting fluid flow in a first direction out of the cavity and through the channel while impeding fluid flow through channel into the cavity in a second direction opposed to the first direction; and applying a sealing material to the device to thereby seal the channel, wherein applying the sealing material comprises: introducing the sealing material to the channel; and depositing the sealing material onto one or more channel-defining surfaces. The sealing material is prevented from reaching the cavity at least in part by the action of the Tesla valve.
Applying the sealing material to the device may be performed in a vacuum environment to thereby vacuum seal the cavity by sealing the channel.
Applying the sealing material may comprise applying the sealing material using a conformal coating process. Applying the sealing material may comprise applying the sealing material using a vapor deposition process. Applying the sealing material may comprise applying the sealing material using a conformal vapor deposition process.
Fabricating the channel may comprise: shaping the channel to provide one or more dead-end paths; shaping the channel to provide one or more circuitous path shapes; and/or shaping the channel to provide one or more serpentine (S-shaped) channel shapes.
The method may comprise fabricating the cavity. Fabricating the cavity may comprise: depositing a sacrificial layer on a substrate; depositing a covering layer over the sacrificial layer; and after depositing the covering layer: etching the sacrificial layer; and extracting the etched sacrificial layer through the channel in the first direction to leave the cavity in the volume occupied by the sacrificial layer prior to etching.
The cavity-defining surface may comprise a plurality of electrically conductive surface elements.
The plurality of electrically conductive surface elements may comprise a membrane electrode provided by a membrane element. The membrane electrode may be deformable into the cavity.
The plurality of electrically conductive surface elements may comprise one or more static switch electrodes provided by one or more corresponding switch elements. The one or more static switch electrodes may be located on a portion of the cavity-defining surface generally opposed to the membrane electrode. The membrane electrode may be deformable across the cavity to make electrical contact between the membrane electrode and the one or more switch electrodes.
The one or more static switch electrodes may comprise a plurality of static switch electrodes. The method may comprise locating the plurality of static switch electrodes in such a manner that an amount of deformation of the membrane electrode is positively correlated with a number of the plurality of switch electrodes with which the membrane electrode makes electrical contact.
Electrical contact between the membrane and a particular one of the one or more switch electrodes may complete a corresponding particular circuit. The corresponding particular circuit may comprise a corresponding particular circuit element.
The particular circuit element may comprise a discrete capacitive element. The particular circuit element may comprise at least one of: one or more capacitive elements, one or more inductive elements, one or more resistive elements, one or more solid state transistors, one or more solid state diodes, one or more resonating circuit elements, one or more power sources and one or more electrically activated switches.
The particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes may be connected in parallel with one another.
The membrane may be deformable under an influence of at least one of: external pressure and heat. An amount of deformation of the membrane may be positively correlated with an amount of the external pressure or heat.
The method may comprise fabricating a static touch-mode electrode on a side of the cavity generally opposite the membrane electrode. A touch-mode capacitance provided by the membrane electrode and the touch-mode electrode may be positively correlated with the amount of deformation of the membrane electrode. The touch-mode electrode may be coated with a dielectric layer, the dielectric layer providing a portion of the cavity-defining surface. The touch mode capacitance may be connected in parallel with the particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes.
Another aspect of the invention provides use of a Tesla valve in fabricating a micro-fabricated device comprising a cavity-defining surface which defines a cavity. The us comprises: fabricating a channel that provides fluid communication with the cavity, the channel comprising a Tesla valve for permitting fluid flow in a first direction out of the cavity and through the channel while impeding fluid flow through channel into the cavity in a second direction opposed to the first direction; fabricating the cavity, wherein fabricating the cavity comprises: depositing a sacrificial layer on a substrate; depositing a covering layer over the sacrificial layer; and, after depositing the covering layer: etching the sacrificial layer; and extracting the etched sacrificial layer through the channel in the first direction to leave the cavity in the volume occupied by the sacrificial layer prior to etching. The use comprises, after extracting the etched sacrificial layer through the channel, applying a sealing material to the device to thereby seal the channel, wherein applying the sealing material comprises: introducing the sealing material to the channel; and depositing the sealing material onto one or more channel-defining surfaces. The sealing material is prevented from reaching the cavity at least in part by the action of the Tesla valve.
Applying the sealing material to the device may be performed in a vacuum environment to thereby vacuum seal the cavity by sealing the channel.
Applying the sealing material may comprise applying the sealing material using a conformal coating process. Applying the sealing material m ay comprise applying the sealing material using a vapor deposition process. Applying the sealing material may comprise applying the sealing material using a conformal vapor deposition process.
Fabricating the channel may comprise: shaping the channel to provide one or more dead-end paths; shaping the channel to provide one or more circuitous path shapes; and/or shaping the channel to provide one or more serpentine (S-shaped) channel shapes.
The cavity-defining surface may comprise a plurality of electrically conductive surface elements.
The plurality of electrically conductive surface elements may comprise a membrane electrode provided by a membrane element. The membrane electrode may be deformable into the cavity.
The plurality of electrically conductive surface elements may comprise one or more static switch electrodes provided by one or more corresponding switch elements. The one or more static switch electrodes may be located on a portion of the cavity-defining surface generally opposed to the membrane electrode. The membrane electrode may be deformable across the cavity to make electrical contact between the membrane electrode and the one or more switch electrodes.
The one or more static switch electrodes may comprise a plurality of static switch electrodes. The use may comprise locating the plurality of static switch electrodes in such a manner that an amount of deformation of the membrane electrode is positively correlated with a number of the plurality of switch electrodes with which the membrane electrode makes electrical contact.
Electrical contact between the membrane and a particular one of the one or more switch electrodes may complete a corresponding particular circuit. The corresponding particular circuit may comprise a corresponding particular circuit element.
The particular circuit element may comprise a discrete capacitive element. The particular circuit element may comprise at least one of: one or more capacitive elements, one or more inductive elements, one or more resistive elements, one or more solid state transistors, one or more solid state diodes, one or more resonating circuit elements, one or more power sources and one or more electrically activated switches.
The particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes may be connected in parallel with one another.
The membrane may be deformable under an influence of at least one of: external pressure and heat. An amount of deformation of the membrane may be positively correlated with an amount of the external pressure or heat.
The use may comprise fabricating a static touch-mode electrode on a side of the cavity generally opposite the membrane electrode. A touch-mode capacitance provided by the membrane electrode and the touch-mode electrode may be positively correlated with the amount of deformation of the membrane electrode. The touch-mode electrode may be coated with a dielectric layer, the dielectric layer providing a portion of the cavity-defining surface. The touch mode capacitance may be connected in parallel with the particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes.
Another aspect of the invention provides a microelectromechanical (MEMS) device comprising: a cavity-defining surface which defines a cavity, the cavity-defining surface comprising a plurality of electrically conductive surface elements; a channel that provides fluid communication with the cavity, the channel comprising a Tesla valve for permitting fluid flow in a first direction out of the cavity and through the channel while impeding fluid flow through channel into the cavity in a second direction opposed to the first direction. The channel is sealed during fabrication of the device to prevent ingress of material into the cavity.
The channel may be sealed by sealing material applied to the device.
The channel may be sealed by sealing material applied to the device in a vacuum environment to thereby vacuum seal the cavity by sealing the channel.
The sealing material may be applied using a conformal coating process. The sealing material may be applied using a vapor deposition process. The sealing material may be applied using a conformal vapor deposition process.
The channel may be shaped to provide: one or more dead-end paths; one or more circuitous path shapes; and/or one or more serpentine (S-shaped) channel shapes.
The cavity may be fabricated by extracting an etched sacrificial layer through the channel in the first direction prior to the channel being sealed.
The cavity-defining surface may comprise a plurality of electrically conductive surface elements.
The plurality of electrically conductive surface elements may comprise a membrane electrode provided by a membrane element. The membrane electrode may be deformable into the cavity.
The plurality of electrically conductive surface elements may comprise one or more static switch electrodes provided by one or more corresponding switch elements. The one or more static switch electrodes may be located on a portion of the cavity-defining surface generally opposed to the membrane electrode. The membrane electrode may be deformable across the cavity to make electrical contact between the membrane electrode and the one or more switch electrodes.
The one or more static switch electrodes may comprise a plurality of static switch electrodes. The plurality of static switch electrodes may be located in such a manner that an amount of deformation of the membrane electrode is positively correlated with a number of the plurality of switch electrodes with which the membrane electrode makes electrical contact.
Electrical contact between the membrane and a particular one of the one or more switch electrodes may complete a corresponding particular circuit. The corresponding particular circuit may comprise a corresponding particular circuit element.
The particular circuit element may comprise a discrete capacitive element. The particular circuit element may comprise at least one of: one or more capacitive elements, one or more inductive elements, one or more resistive elements, one or more solid state transistors, one or more solid state diodes, one or more resonating circuit elements, one or more power sources and one or more electrically activated switches.
The particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes may be connected in parallel with one another.
The membrane may be deformable under an influence of at least one of: external pressure and heat. An amount of deformation of the membrane may be positively correlated with an amount of the external pressure or heat.
The device may comprise a static touch-mode electrode on a side of the cavity generally opposite the membrane electrode. A touch-mode capacitance provided by the membrane electrode and the touch-mode electrode may be positively correlated with the amount of deformation of the membrane electrode. The touch-mode electrode may be coated with a dielectric layer, the dielectric layer providing a portion of the cavity-defining surface. The touch mode capacitance may be connected in parallel with the particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes.
Another aspect of the invention provides a microelectromechanical (MEMS) device comprising: a cavity-defining surface which defines a cavity, the cavity-defining surface comprising a plurality of electrically conductive surface elements. The plurality of electrically conductive surface elements comprising: a membrane electrode provided by a membrane element, the membrane electrode deformable into the cavity; and one or more static switch electrodes provided by one or more corresponding switch elements, the one or more static switch electrodes located on a portion of the cavity-defining surface generally opposed to the membrane electrode. The membrane electrode is deformable between a first configuration where the membrane electrode is spaced apart from the one or more switch electrodes and a second configuration wherein the membrane is deformed across the cavity to make electrical contact between the membrane electrode and at least one of the one or more switch electrodes. Electrical contact between the membrane and a particular one of the one or more switch electrodes completes a corresponding particular circuit, the corresponding particular circuit comprising a corresponding particular circuit element.
The one or more static switch electrodes may comprise a plurality of static switch electrodes. The plurality of static switch electrodes may be located in such a manner that an amount of deformation of the membrane electrode is positively correlated with a number of the plurality of switch electrodes with which the membrane electrode makes electrical contact.
The particular circuit element may comprise a discrete capacitive element. The particular circuit element may comprise at least one of: one or more capacitive elements, one or more inductive elements, one or more resistive elements, one or more solid state transistors, one or more solid state diodes, one or more resonating circuit elements, one or more power sources and one or more electrically activated switches.
The particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes may be connected in parallel with one another.
The membrane may be deformable under an influence of at least one of: external pressure and heat. An amount of deformation of the membrane may be positively correlated with an amount of the external pressure or heat.
The device may comprise a static touch-mode electrode on a side of the cavity generally opposite the membrane electrode. A touch-mode capacitance provided by the membrane electrode and the touch-mode electrode may be positively correlated with the amount of deformation of the membrane electrode. The touch-mode electrode may be coated with a dielectric layer, the dielectric layer providing a portion of the cavity-defining surface. The touch mode capacitance may be connected in parallel with the particular circuits completed by the electrical contact between the membrane and the particular ones of the plurality of switch electrodes.
The device may comprise a channel that provides fluid communication with the cavity, the channel comprising a Tesla valve for permitting fluid flow in a first direction out of the cavity and through the channel while impeding fluid flow through channel into the cavity in a second direction opposed to the first direction. The channel may be sealed during fabrication of the device to prevent ingress of material into the cavity.
The channel may be sealed by sealing material applied to the device.
The channel may be sealed by sealing material applied to the device in a vacuum environment to thereby vacuum seal the cavity by sealing the channel.
The sealing material may be applied using a conformal coating process. The sealing material may be applied using a vapor deposition process. The sealing material may be applied using a conformal vapor deposition process.
The channel may be shaped to provide: one or more dead-end paths; one or more circuitous path shapes; and/or one or more serpentine (S-shaped) channel shapes.
The cavity may be fabricated by extracting an etched sacrificial layer through the channel in the first direction prior to the channel being sealed.
Other aspects of the invention provide apparatus having any new and inventive feature, combination of features, or sub-combination of features as described herein.
Other aspects of the invention provide methods having any new and inventive steps, acts, combination of steps and/or acts or sub-combination of steps and/or acts as described herein.
Further aspects and example embodiments are illustrated in the accompanying drawings and/or described in the following description.
The accompanying drawings illustrate non-limiting example embodiments of the invention.
Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense.
Aspects of the invention provides methods for fabricating micro-fabricated devices comprising a cavity-defining surface which defines a cavity. Particular methods comprise: fabricating a channel that provides fluid communication with the cavity, the channel comprising a Tesla valve for permitting fluid flow in a first direction out of the cavity and through the channel while impeding fluid flow through channel into the cavity in a second direction opposed to the first direction; and applying a sealing material to the device (e.g. using a conformal coating which may be applied by a suitable conformal coating technique, such as a conformal vapor deposition technique, where the sealing material has solidifies or is caused to solidify on the channel defining surfaces) to thereby seal the channel. Applying the sealing material may comprise introducing the sealing material to the channel, in such a manner that the sealing material solidifies on the channel-defining surface(s) of the channel-defining wall(s), is caused to solidify on the channel-defining surface(s) or otherwise bonds or sticks to the channel-defining surface(s) and the sealing material is prevented from reaching the cavity at least in part by the action of the Tesla valve.
Other aspects of the invention provide microelectromechanical (MEMS) devices comprising: a cavity-defining surface which defines a cavity. The cavity-defining surface comprises a plurality of electrically conductive surface elements. The plurality of electrically conductive surface elements comprises: a membrane electrode provided by a membrane element, the membrane electrode deformable into the cavity; and one or more static switch electrodes provided by one or more corresponding switch elements, the one or more static switch electrodes located on a portion of the cavity-defining surface generally opposed to the membrane electrode. The membrane electrode is deformable between a first configuration where the membrane electrode is spaced apart from the one or more switch electrodes and a second configuration wherein the membrane is deformed across the cavity to make electrical contact between the membrane electrode and the one or more switch electrodes. Electrical contact between the membrane and a particular one of the one or more switch electrodes completes a corresponding particular circuit comprising a corresponding particular circuit element.
Cavity 16 and cavity-defining surface 14 may generally be fabricated using any suitable technique. In the particular case of the illustrated embodiment and as explained in more detail below, cavity 16 may be fabricated by depositing a sacrificial layer (not shown in
Channels 22 provide fluid communication with cavity 16 to allow introduction and removal of the sacrificial layer as discussed above. In some embodiments, at least one channel 22 comprises one or more valves with no moving parts. An example channel 22 is shown in
While fluids are impeded as they flow through channel 22 in the second direction 28 (i.e. from outside of device 10 toward cavity 16), some materials under some conditions will flow through channel 22 in the second direction 28 to ultimately reach cavity 16. This is the case, for example, where etchant is introduced via channel 22 into contact with the sacrificial layer 110 (described in more detail below), to dissolve the sacrificial layer 110 and to thereby create cavity 16. However, for some materials in some conditions, such as sealing materials 30 deposited onto the surfaces of device 10 in a vapor or gaseous phase (e.g. in conformal vapor deposition techniques), channel 22 (and their Tesla valves) impede the flow of such materials in the second direction 28 sufficiently to prevent the travel of such materials through channel 22 in second direction 28 and to prevent such materials from reaching cavity 16. In some such embodiments, the sealing material 30 solidifies on the channel-defining surface(s) of the channel-defining wall(s) or otherwise bonds or sticks to the channel-defining surface(s) of channel 22 to thereby seal cavity 16.
Device 10 of the illustrated embodiment is sealed with a sealing material which provides a coating layer 30. Coating layer 30 may comprise a conformal coating which may be applied by any suitable technique, such as, by way of non-limiting example, vapor deposition (e.g. conformal chemical or plasma-enhanced vapor deposition) and/or the like. In some embodiments, the coating layer 30 may comprise a suitable dielectric polymer, such as Parylene C, for example, as well as other types of Parylene (N, D, HT, etc.). Advantageously, Parylene C is biocompatible. Other sealing materials that could be applied to provide coating layer 30 include, without limitation, any material that can be deposited by conformal vapor deposition, such as silicon compounds (e.g. polycrystalline silicon, silicon oxides such as SiO2 and/or the like, silicon nitride, etc.), phosphosilicate glass (PSG), tungsten, diamond, carbon, fluorocarbons organofluorines, nitrides and/or the like. Coating layer 30 provides device 10 with protection (e.g. against physical contact and/or moisture) and/or electrical insulation. Coating layer 30 may also seal channels 22, thereby effectively sealing cavity 16. In some embodiments, coating layer 30 may be applied in a vacuum environment to provide cavity 16 with a vacuum seal. During deposition, the sealing material of coating layer 30 may travel into channels 22 and is prevented from reaching cavity 16 by Tesla valves 24, which, as discussed above, impede the flow of fluids in the second direction (from an outside of device 10, through channels 22 and into cavity 16). The sealing material of coating layer 30 is trapped in channels 22 by Tesla valves 24 and deposited onto the channel-defining surface(s) of the walls that define channels 22, until channels 22 and cavity 16 are sealed. Advantageously, Tesla valves 24 in channels 22 prevent the sealing material of coating layer 30 from reaching cavity 16, so that the sealing material does not impact the performance of device 10 (described in more detail below). In particular, the shapes of channels 22 (including their respective Tesla valves) may be designed (e.g. in conjunction with the conditions and materials selected for deposition of coating layer 30) such that the impediment to fluid flow caused by Tesla valves is sufficient to prevent the sealing material of coating layer 30 from reaching cavity 16.
As shown in
In the particular case of device 10 of the
In the case of the illustrated
The electrical contact (or lack of electrical contact) between membrane electrode 34 and switch electrode(s) 36 may provide a switching functionality. In particular, where electrical contact is made between membrane electrode 34 and a particular one of switch electrodes 36, a corresponding circuit may be completed (i.e. an electrical switch may be closed) to permit current flow between membrane electrode 34 and the particular one of switch electrodes 36. In contrast, where there is no electrical contact between membrane electrode 34 and the particular one of switch electrodes 36, current is prevented from flowing therebetween and the circuit is open (i.e. the electrical switch is opened). As shown in
In some particular embodiments, circuit elements 42 comprise capacitive circuit elements. In some embodiments, circuit elements 42 may comprise capacitive elements, inductive elements, resistive elements, transistors (e.g. solid state transistors), diodes (e.g. solid state diodes), resonating circuit elements, power sources, electronically controlled switches and/or the like, combinations of these types of elements and/or the like.
In the particular case of the
In the illustrated embodiment, touch-mode electrode 46 is coated with a touch-mode dielectric layer 48 which permits physical contact (between membrane electrode 34 and touch-mode dielectric layer 48) while preventing electrical (ohmic) contact between membrane electrode 34 and touch-mode electrode 46. Touch-mode dielectric layer 48 permits a “touch-mode” operation. For example, in some such configurations, membrane electrode 34 may be configured (e.g. sized and/or shaped) such that membrane 34 is just barely in contact with touch-mode dielectric layer 48 at a low extreme of expected pressure and is fully in contact with touch-mode dielectric layer 48 at a high extreme of expected pressure. Touch-mode dielectric layer 48 and touch-mode operation are not strictly necessary. In some embodiments, the “touch-mode” capacitance Ctouch_tot may vary merely by bringing variable amounts of surface area of membrane electrode 34 into proximity with touch-mode electrode 48 without actual physical contact or touching. In some embodiments, touch-mode electrode 46 is not necessary.
C
s(p)=Ctouch_tot(p)+CswitchA(p)+CswitchB(p)+Cstructural (1)
where the total capacitance Ctouch_tot(p) provided by the interaction of membrane electrode 34 and touch-mode electrode 46 may be expressed as:
C
touch_tot(p)=Ctouch(p)+Cnon-contact(p) (1A)
where:
It will be appreciated that the capacitance Ctouch_tot(p) is positively correlated with pressure—i.e. Ctouch_tot(p) increases as pressure increases (and the deformation of membrane 12 and membrane electrode 34 (e.g. across cavity 16) increases). This change in capacitance Ctouch_tot(p) may be relatively smoothly varying. In contrast, due to the parallel nature of the connection between capacitive circuit elements 42 (between membrane 34) and node 44, when the deformation of membrane 12 (or membrane electrode 34) brings membrane electrode 34 into electrical contact with one of switch electrodes 36A, 36B (i.e. closing one of switches 50A, 50B), there is a corresponding step in capacitance as CswitchA(p) or CswitchB(p) is added to the total capacitance Cs(p). In this sense, device 10 may be considered to implement and may be referred to herein as a “switch mode” capacitive pressure sensor.
The number of switch electrodes 36 and corresponding circuits 40 and circuit elements 42 in the illustrated embodiment of device 10 is shown as two for brevity and simplicity. However, devices according to particular embodiments, may generally be provided with any suitable number of switch electrodes 36 and corresponding circuits 40 and circuit elements 42, in which case equation (1) can be replaced with:
where:
It will be appreciated that for the functionality of the switch-mode capacitive pressure sensor described above, it is desirable that there not be any contaminants (dielectric or conductive) in cavity 16, as such contaminants cold adversely impact the electrical characteristics (e.g. capacitance) of device 10 or the physical characteristics (e.g. deformation of membrane 12 and/or space in cavity 16 for membrane 12 to deform) of device 10. In particular, there is a desire to coat device 10 with coating layer 30 and/or to seal cavity 16, while preventing the sealing material (e.g. of coating layer 30) from reaching cavity 16. Such functionality may be achieved by providing channels 22 with Tesla valves 24. Such functionality may be achieved by applying coating layer 30 using a conformal coating technique (e.g. conformal vapor deposition) where the material of coating layer solidifies on the channel-defining surface(s) of the channel-defining wall(s), is caused to solidify on the channel-defining surface(s) or otherwise bonds or sticks to the channel-defining surface(s) of channels 22 to seal cavity 16.
In
In
In
In
In
In many respects, device 210 is similar to device 10 and similar features of device 210 are assigned similar reference numerals to those of device 10, except that the features of device 210 are incremented by 200. Except as where otherwise noted, features of device 210 may be similar to those of corresponding features of device 10 and vice versa. Device 210 of the
Cavity 216 and cavity-defining surface 214 may generally be fabricated using any suitable technique. In the particular case of the illustrated embodiment, cavity 216 may be fabricated by depositing a sacrificial layer (not shown in
Channels 222 provide fluid communication with cavity 216 to allow introduction and removal of the sacrificial layer in manners similar to channel 22 of device 10 as discussed above. Channels 222 are shown in more detail in
As shown in
In the particular case of device 210 of the
In some embodiments, switch elements 238 comprise switch leads that connect each switch electrode 236 to a corresponding circuit 240 and each such circuit 240 may comprise one or more corresponding circuit elements 242. In the illustrated embodiment shown in
In the case of the illustrated
The electrical contact (or lack of electrical contact) between membrane electrode 234 and switch electrode(s) 236 may provide a switching functionality. In particular, where electrical contact is made between membrane electrode 234 and a particular one of switch electrodes 236, a corresponding circuit 240 may be completed (i.e. an electrical switch may be closed) to permit current flow between membrane electrode 234 and the particular one of switch electrodes 236. In contrast, where there is no electrical contact between membrane electrode 234 and the particular one of switch electrodes 236, current is prevented from flowing therebetween and the circuit is open (i.e. the electrical switch is opened).
In the particular case of the
where:
where:
It will be appreciated that for the functionality of the switch-mode capacitive pressure sensor 210 described above, it is desirable that there not be any contaminants (dielectric or conductive) in cavity 216, as such contaminants cold adversely impact the electrical characteristics (e.g. capacitance) of device 210 or the physical characteristics (e.g. deformation of membrane 212 and/or space in cavity 216 for membrane 212 to deform) of device 210. In particular, there is a desire to coat device 210 with coating layer 230 and/or to seal cavity 216, while preventing the sealing material (e.g. of coating layer 230) from reaching cavity 216. Such functionality may be achieved by providing channels 222 with Tesla valves 224. Such functionality may be achieved by applying coating layer 230 using a conformal coating technique (e.g. conformal vapor deposition) where the material of coating layer solidifies on the channel-defining surface(s) of the channel-defining wall(s), is caused to solidify on the channel-defining surface(s) or otherwise bonds or sticks to the channel-defining surface(s) of channels 222 to seal cavity 216.
Device 210 may be fabricated on a silicon wafer 302 with an oxide (SiO2) layer 304 as shown in
In
In
In
Then, in
In
In some embodiments, one or more devices 210 may be wire-bonded to PCBs to form a pressure sensor. The performance of such a pressure sensor was experimentally assessed.
Experimental setup 500A (
In
Referring to
Plot 600 shows stepwise capacitive changes of sensor 502 as a function of pressure in both line 601 corresponding to a down cycle and line 603 corresponding to an upcycle. For example, both down cycle line 601 and upcycle line 603 show features of a jump 602 in capacitance value around a pressure of about 20 mmHg. The stepwise capacitive changes are expected due to the switch mode operation of device 210 of sensor 502. Line 605 in
Unless the context clearly requires otherwise, throughout the description and the claims:
Words that indicate directions such as “vertical”, “transverse”, “horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”, “outward”, “vertical”, “transverse”, “left”, “right”, “front”, “back”, “top”, “bottom”, “below”, “above”, “under”, and the like, used in this description and any accompanying claims (where present), depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.
Embodiments of the invention may be implemented using specifically designed hardware, configurable hardware, programmable data processors configured by the provision of software (which may optionally comprise “firmware”) capable of executing on the data processors, special purpose computers or data processors that are specifically programmed, configured, or constructed to perform one or more steps in a method as explained in detail herein and/or combinations of two or more of these. Examples of specifically designed hardware are: logic circuits, application-specific integrated circuits (“ASICs”), large scale integrated circuits (“LSIs”), very large scale integrated circuits (“VLSIs”), and the like. Examples of configurable hardware are: one or more programmable logic devices such as programmable array logic (“PALs”), programmable logic arrays (“PLAs”), and field programmable gate arrays (“FPGAs”)). Examples of programmable data processors are: microprocessors, digital signal processors (“DSPs”), embedded processors, graphics processors, math co-processors, general purpose computers, server computers, cloud computers, mainframe computers, computer workstations, and the like. For example, one or more data processors in a control circuit for a device may implement methods as described herein by executing software instructions in a program memory accessible to the processors.
Processing may be centralized or distributed. Where processing is distributed, information including software and/or data may be kept centrally or distributed. Such information may be exchanged between different functional units by way of a communications network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Internet, wired or wireless data links, electromagnetic signals, or other data communication channel.
For example, while processes or blocks are presented in a given order, alternative examples may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.
In addition, while elements are at times shown as being performed sequentially, they may instead be performed simultaneously or in different sequences. It is therefore intended that the following claims are interpreted to include all such variations as are within their intended scope.
Software and other modules may reside on servers, workstations, personal computers, tablet computers, image data encoders, image data decoders, PDAs, color-grading tools, video projectors, audio-visual receivers, displays (such as televisions), digital cinema projectors, media players, and other devices suitable for the purposes described herein. Those skilled in the relevant art will appreciate that aspects of the system can be practised with other communications, data processing, or computer system configurations, including: Internet appliances, hand-held devices (including personal digital assistants (PDAs)), wearable computers, all manner of cellular or mobile phones, multi-processor systems, microprocessor-based or programmable consumer electronics (e.g., video projectors, audio-visual receivers, displays, such as televisions, and the like), set-top boxes, color-grading tools, network PCs, mini-computers, mainframe computers, and the like.
The invention may also be provided in the form of a program product. The program product may comprise any non-transitory medium which carries a set of computer-readable instructions which, when executed by a data processor, cause the data processor to execute a method of the invention. Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, non-transitory media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, EPROMs, hardwired or preprogrammed chips (e.g., EEPROM semiconductor chips), nanotechnology memory, or the like. The computer-readable signals on the program product may optionally be compressed or encrypted.
In some embodiments, the invention may be implemented in software. For greater clarity, “software” includes any instructions executed on a processor, and may include (but is not limited to) firmware, resident software, microcode, and the like. Both processing hardware and software may be centralized or distributed (or a combination thereof), in whole or in part, as known to those skilled in the art. For example, software and other modules may be accessible via local memory, via a network, via a browser or other application in a distributed computing context, or via other means suitable for the purposes described above.
Where a component (e.g. a software module, processor, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
Where a record, field, entry, and/or other element of a database is referred to above, unless otherwise indicated, such reference should be interpreted as including a plurality of records, fields, entries, and/or other elements, as appropriate. Such reference should also be interpreted as including a portion of one or more records, fields, entries, and/or other elements, as appropriate. For example, a plurality of “physical” records in a database (i.e. records encoded in the database's structure) may be regarded as one “logical” record for the purpose of the description above and the claims below, even if the plurality of physical records includes information which is excluded from the logical record.
Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions, and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments.
Various features are described herein as being present in “some embodiments”. Such features are not mandatory and may not be present in all embodiments. Embodiments of the invention may include zero, any one or any combination of two or more of such features. This is limited only to the extent that certain ones of such features are incompatible with other ones of such features in the sense that it would be impossible for a person of ordinary skill in the art to construct a practical embodiment that combines such incompatible features. Consequently, the description that “some embodiments” possess feature A and “some embodiments” possess feature B should be interpreted as an express indication that the inventors also contemplate embodiments which combine features A and B (unless the description states otherwise or features A and B are fundamentally incompatible).
It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
This application claims the benefit under 35 U.S.C. § 119 of application No. 63/410287, filed 27 Sep. 2023, and entitled SWITCH MODE CAPACITIVE PRESSURE SENSORS which is hereby incorporated herein by reference for all purposes.
Number | Date | Country | |
---|---|---|---|
63410287 | Sep 2022 | US |