Patent Application
20200209188
This disclosure relates generally to humidity sensing devices. More particularly, the present disclosure relates to humidity sensing devices comprising black phosphorus nanoflakes, to methods for sensing humidity with such devices, to transistors comprising black phosphorus nanoflakes, and to methods for switching the gate of such transistors.
Black phosphorus (BP) is the most thermodynamically stable allotrope of phosphorus, and has an orthorhombic layered structure and highly anisotropic properties. Due to its high charge carrier mobility, tunable direct bandgap, large on/off ratios (>105), and anisotropic properties, BP has potential for use in electronics and optoelectronics. The potential uses for BP in further applications such as energy generation, storage systems, and electrocatalysis have also been demonstrated. However, the material has yet to be demonstrated to be appropriate for long-term applications, in view of the observed ambient instability of atomically thin BP flakes.
Humidity control is important in a variety of different applications, including industrial processes, environmental applications, electronic and biotechnology applications, agriculture, libraries and household applications. Semiconductor manufacturing and certain medical applications, including respiratory equipment, sterilizers, incubators, pharmaceutical processing, and the manufacture of biological products all require controlled humidity. Chemical gas purification, film desiccation, paper and textile production and food processing also may require controlled humidity.
Recently, an increasing demand has developed for low-cost humidity sensors with accuracy, reproducibility, and long-term stability. However, good humidity sensors are generally expensive. Many inexpensive sensors do not perform well at either extreme of relative humidity (RH).
Accordingly, there remains a need for a cost-effective humidity sensor that is accurate, reliable, and stable.
One aspect of the disclosure is a device for sensing moisture, the device including
Another aspect of the disclosure is a transistor that includes
Another aspect of the disclosure is a humidity sensor that includes
Another aspect of the disclosure is a method for sensing moisture in an environment, the method including
Another aspect of the disclosure is a method for switching a transistor, the method including
The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Thus, before the disclosed processes and devices are described, it is to be understood that the aspects described herein are not limited to specific embodiments, apparati, or configurations, and as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and, unless specifically defined herein, is not intended to be limiting.
The terms “a,” “an,” “the” and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
All methods described herein can be performed in any suitable order of steps unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.
As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of or consist of its particular stated element, step, ingredient or component. As used herein, the transition term “comprise” or “comprises” means includes, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase “consisting of” excludes any element, step, ingredient or component not specified. The transition phrase “consisting essentially of” limits the scope of the embodiment to the specified elements, steps, ingredients or components and to those that do not materially affect the embodiment.
Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. When further clarity is required, the term “about” has the meaning reasonably ascribed to it by a person skilled in the art when used in conjunction with a stated numerical value or range, i.e. denoting somewhat more or somewhat less than the stated value or range, to within a range of ±20% of the stated value; ±19% of the stated value; ±18% of the stated value; ±17% of the stated value; ±16% of the stated value; ±15% of the stated value; ±14% of the stated value; ±13% of the stated value; ±12% of the stated value; ±11% of the stated value; ±10% of the stated value; ±9% of the stated value; ±8% of the stated value; ±7% of the stated value; ±6% of the stated value; ±5% of the stated value; ±4% of the stated value; ±3% of the stated value; ±2% of the stated value; or ±1% of the stated value.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
Some embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Furthermore, numerous references have been made to patents and printed publications throughout this specification. Each of the cited references and printed publications are individually incorporated herein by reference in their entirety.
In closing, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention may be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.
In various aspects and embodiments, the disclosure relates to devices comprising at least one atomic layer of black phosphorus nanoflakes disposed on a substrate. The disclosure demonstrates sensing devices comprising at least one atomic layer of black phosphorus nanoflakes disposed on a substrate to be selective for water and highly sensitive, with negligible drift over time.
One aspect of the disclosure described herein is a device for sensing humidity comprising at least one atomic layer of black phosphorus nanoflakes (BP NF) disposed on a substrate. One example of such a device is shown in schematic view in
In some embodiments of the devices and methods as otherwise described herein, devices comprising BP NFs exhibit excellent sensitivity and selectivity for humidity sensing with quick recovery characteristics. In some embodiments, the at least one atomic layer of BP NFs may comprise stacks of BP NFs, i.e., a film of stacked BP NFs with a thickness within the range of 10 nm to 1000 μm, e.g., 25 nm to 1000 μm, or 50 nm to 1000 μm, or 75 nm to 1000 μm, or 100 nm to 900 μm, or 150 nm to 800 μm, or 200 nm to 700 μm, or 250 nm to 600 μm, or 500 nm to 500 μm, or 750 nm to 400 μm, or 1 μm to 300 μm, or 2 μm to 250 μm, or 3 μm to 200 μm, or 4 μm to 175 μm, or 5 μm to 150 μm.
In some embodiments of the devices and methods as otherwise described herein, the at least one atomic layer of BP NFs is in fluid communication with the exterior of the device.
While not being bound by theory, the impedance spectroscopy and electrical characterization of the Examples suggest that the sensing mechanism of the BP film sensors is based on the modulation in the leakage ionic current due to protonation of water molecules and phosphorus oxoacids in the presence of humidity. The degradation rate of the BP flakes in humid environments is estimated by consecutive atomic force microscopy (AFM) topography mappings and is found to be slow enough to allow for the use of BP NF devices in practical applications, with an effective lifetime of several years.
The person of ordinary skill in the art will appreciate that BP NF may be made by liquid exfoliation through ultra-sonication followed by vacuum filtration. In some embodiments of the devices and methods as otherwise described herein, the liquid exfoliation solvent for BP NF may be an aprotic, polar solvent, e.g., DMF, DMSO, and the like. In some embodiments, vacuum filtration may be performed using filter paper or a membrane filter, e.g., a PTFE membrane filter to form a layer of BP NF on a substrate. Following vacuum filtration, BP NF films may be rinsed and dried under vacuum, as described with respect to
In some embodiments of the devices and methods as otherwise described herein, devices comprising BP NF are highly selective for moisture content in the environment, and are insensitive to other analytes such as alcohols, ketones, benzenes, etc. The person of ordinary skill in the art will appreciate the need to avoid cross-sensitivity and false-positive issues in practical moisture detection applications.
In some embodiments of the devices and methods as otherwise described herein, the substrate of the device may be flexible. In some embodiments, the substrate of the device may comprise filter paper or a membrane filter, e.g., a polytetrafluoroethylene (PTFE) membrane filter. This flexibility may allow the sensing devices to be flexible. The person of ordinary skill in the art will appreciate that flexible sensing devices may be used in wearable applications, such as wearable medical devices, environmental monitoring systems, military defense, homeland security, food processing units, etc.
In some embodiments of the devices and methods as otherwise described herein, the device may further comprise at least two electrodes, e.g., two electrodes, or three electrodes, or four electrodes, etc. In some embodiments, the at least two electrodes may be two-probe electrical contacts. The at least two electrodes are disposed in electrical contact with the at least one atomic layer of BP NF. One example of such a device is shown in schematic view in
In some embodiments of the devices and methods as otherwise described herein, the at least two electrodes include a first electrode and a second electrode. In certain embodiments, the distance between the first electrode and the second electrode is less than 2 cm, e.g., less than 1.75 cm, or less than 1.5 cm, or less than 1 cm, or less than 900 μm, or less than 800 μm, or less than 700 μm, or less than 600 μm, or less than 500 μm, or less than 400 μm, or less than 300 μm, or less than 200 μm, or less than 100 μm, or less than 75 μm, or less than 50 μm, or less than 25 μm, or less than 15 μm, or less than 10 μm, or less than 8 μm, or less than 6 μm, or less than 5 μm, or less than 4 μm, or less than 3 μm, or less than 2 μm, or less than 1 μm.
In some embodiments of the devices and methods as otherwise described herein, the at least two electrodes include a first electrode and a second electrode, and the device further comprises a voltage source configured to apply a voltage across the first electrode and the second electrode sufficient to cause a drain current to flow through the at least one atomic layer of BP NF, wherein the drain current has a magnitude. One example of such a device is shown in schematic view in
In some embodiments of the devices and methods as otherwise described herein, the drain current has a magnitude within the range of about 10−18 A to about 1 A, e.g., about 10−16 A to about 10−2 A, or about 10−14 A to about 10−4 A, or about 10−12 A to about 10−6 A, or about 10−10 A to about 10−6 A.
In some embodiments of the devices and methods as otherwise described herein, the device further comprises electronics configured to detect the magnitude of the drain current. One example of such a device is shown in schematic view in
In some embodiments of the devices and methods as otherwise described herein, the electronics are further configured to correlate the magnitude of the drain current with a moisture level in an environment when the device is in fluid communication with the environment. The person of ordinary skill in the art will appreciate that the electronics may comprise any component or combination of components that are capable of correlating the magnitude of the drain current with a moisture level, for example, a processor configured to correlate the magnitude of the drain current with a moisture level (e.g., using a calibration curve), or an electrical circuit configured to correlate the magnitude of the drain current with a moisture level (e.g., using a calibration curve). In some embodiments, the electronics may include a moisture level indicator, e.g., one or more LED lights that correspond to a certain moisture level, an analog moisture level meter, a digital display, etc.
In operation, the sensing device may have a drain current, i.e., the current flowing between two electrodes upon the application of a voltage bias between them. The drain current may increase by at least three orders of magnitude as the relative humidity increases from 10% to 85%, at a temperature of, e.g., about 10° C., or about 15° C., or about 20° C., or about 25° C., or about 30° C., or about 35° C., or about 40° C., or about 45° C., or about 50° C.
In one example of a device of the present disclosure, a device for sensing moisture comprises a substrate, a surface comprising at least one atomic layer of BP NF disposed on the substrate, the at least one atomic layer of BP NF being in fluid communication with the exterior of the device, a first electrode disposed in electrical contact with the at least one atomic layer of BP NF, a second electrode disposed in electrical contact with the at least one atomic layer of BP NF, a voltage source configured to apply a voltage across the first electrode and the second electrode sufficient to cause a drain current to flow through the at least one atomic layer of black phosphorus nanoflakes, the drain current having a magnitude, and electronics configured to detect the magnitude of the drain current. The device may be specific to sensing humidity, exhibiting a selective response against water vapor. The BP NF used in the device may, e.g, be produced by liquid exfoliation through ultra-sonication. The BP NF film may be, e.g., between 10 nm and 1000 μm or more thick. Certain such examples may have, e.g., an estimated height reduction rate of about 2.7 nm/week for BP NF films in saturated relative humidity at 25° C. The person of ordinary skill in the art will appreciate that in certain such embodiments, it would take several years before the the device undergoes even a noticeable change in the thickness of the film of BP NF.
Another aspect of the disclosure described herein is a transistor comprising a substrate, a surface comprising a film of stacked black phosphorous nanoflakes disposed on the substrate, and a gate.
The person of ordinary skill in the art will appreciate, however, that in certain embodiments, the “gate” function of the transistor is the action of humidity on the film of black phosphorus nanoflakes, such that the film of black phosphorus nanoflakes allows more current to flow as the humidity is increased (i.e., due to a decrease in resistance in the film as humidity decreases). Accordingly, in other aspects of the disclosure, a transistor includes
The transistor may be specific to sensing humidity, exhibiting a selective response against water vapor. The BP NF film used in the transistor may be, e.g., produced by liquid exfoliation through ultra-sonication. The transistor substrate may be flexible. In some embodiments, the substrate may comprise filter paper or a membrane filter, e.g., a polytetrafluoroethylene (PTFE) membrane filter.
In some embodiments of the devices and methods as otherwise described herein, the film of stacked BP NF is in fluid communication with the exterior of the device.
In some embodiments of the devices and methods as otherwise described herein, the transistor may further comprise at least two electrodes, e.g., two electrodes, or three electrodes, or four electrodes, etc. In some embodiments, the at least two electrodes may be two-probe electrical contacts. In some embodiments, the at least two electrodes are disposed in electrical contact with the at least one atomic layer of BP NF. A variety of suitable electrode materials are known in the art. In some embodiments, the at least two electrodes may be Gallium-Indium eutectic. In some embodiments, the at least two electrodes may comprise one or more of any suitable metal, e.g., gold, copper, tungsten, zinc, lead, silver, platinum, and palladium.
In some embodiments of the devices and methods as otherwise described herein, the at least two electrodes include a first electrode and a second electrode. In certain embodiments, the distance between the two electrodes is less than 2 cm, e.g., less than 1.75 cm, or less than 1.5 cm, or less than 1 cm, or less than 900 μm, or less than 800 μm, or less than 700 μm, or less than 600 μm, or less than 500 μm, or less than 400 μm, or less than 300 μm, or less than 200 μm, or less than 100 μm, or less than 75 μm, or less than 50 μm, or less than 25 μm, or less than 15 μm, or less than 10 μm, or less than 8 μm, or less than 6 μm, or less than 5 μm, or less than 4 μm, or less than pm, or less than 2 μm, or less than 1 μm.
The transistors and humidity sensors described herein may be configured such that a change in relative humidity causes a relatively large change in resistance. For example, in certain embodiments, a change in relative humidity of 20%, for example, from 40 to 60% (e.g., at 20° C., or in other embodiments at any temperature in the range of 10° C.-60° C.) causes an increase in resistance between a first electrode and a second electrode of at least five times, at least five times, or even at least ten times.
Another aspect of the disclosure described herein is a humidity sensor comprising a sensor chamber having an opening, and a device for sensing moisture as otherwise described herein, wherein the device is disposed within the chamber, and the chamber is in fluid communication with the opening.
One aspect of the disclosure described herein is a method for sensing moisture in an environment, the method comprising providing a device for sensing moisture as otherwise described herein, applying a voltage across the first electrode and the second electrode sufficient to cause a drain current to flow through the at least one atomic layer of BP NF, the drain current having a magnitude, and detecting the magnitude of the drain current. In some embodiments, the voltage applied is within the range of about 0.01 V to about 4 V, e.g., about 0.01 V to about 3.5 V, or about 0.01 to about 3 V, or about 0.01 V to about 2.5 V, or about 0.01 V to about 2 V, or about 0.01 V to about 1.75 V, or about 0.01 V to about 1.5 V, or about 0.01 V to about 1.25 V, or about 0.01 V to about 1 V, or about 0.05 V to about 0.9 V, or about 0.075 V to about 8 V, or about 0.1 V to about 7 V, or about 0.1 V to about 0.6 V, or about 0.1 V to about 0.5 V, or about 0.2 V to about 0.4 V. In some embodiments of the devices and methods as otherwise described herein, the drain current has a magnitude within the range of about 10−18 A to about 1 A, e.g., about 10−16 A to about 10−2 A, or about 10−14 A to about 10−4 A, or about 10−12 A to about 10−6 A, or about 10−10 A to about 10−6 A.
Methods as described herein can further include determining a moisture level in the environment based on the magnitude of the drain current. The person of ordinary skill in the art will appreciate that any suitable set of electronics can do this, e.g., a general purpose processor programmed to determine the moisture level, or a processor or other circuit specially configured to determine the moisture level.
Another aspect of the disclosure described herein is a method for switching a transistor gate, the method comprising providing a transistor in fluid communication with an environment with a moisture level, the transistor as otherwise described herein, applying a voltage across the first electrode and the second electrode sufficient to cause a drain current to flow through the film of stacked BP NF, the drain current having a magnitude, and altering the level of moisture sufficiently to alter the magnitude of the drain current.
The Examples that follow are illustrative of specific embodiments of the invention, and various uses thereof. They are set forth for explanatory purposes only, and are not to be taken as limiting the invention.
Black phosphorus (BP) nanoflake (NF) films were prepared by liquid exfoliation. 15 mg of bulk BP was ground and immersed in 20 mL of an appropriate aprotic, polar solvent (DMF or DMSO). The samples were sonicated for 12 hours to provide a suspension shown in
Wet films prepared according to Example 1 were immersed in IPA, sonicated to separate flakes from the film, and then re-filtered on a mixed cellulose membrane filter. The films were cooled in liquid nitrogen to enhance fragility, and then broken to access an intact cross-sectional view.
Scanning electron microscopy (SEM) images of the stacked BP NF on the membrane filter show densely packed and uniformly distributed BP NF (See,
Raman spectra of the BP NF films were acquired with a HORIBA LabRAM HR Evolution confocal Raman microscope. The instrument was configured with a 532 nm laser source, 1200 g/mm grating, a Horiba Synapse OE CCD detector, and either a 50× or 100× objective. Laser powers at the sample were between 1-15 mW. Integration times and averaging parameters were chosen to maximize signal-to-noise while minimizing any sample degradation.
Raman spectra (See,
Wet films prepared according to Example 1 were dried under vacuum and cut into pieces of the desired size. Two-probe electrical contacts were established using Gallium-Indium (Ga—In) eutectic (See,
Sensing experiments were carried out in either dynamic (pulse injection) or static (closed chamber) setups. The injection unit of a gas chromatography system (HP 6890) was used to inject a known volume (0.2 to 5 μL) of the analytes with a 400 to 5000 split ratio. In static experiments, a constant humidity was initially generated in a custom-made environmental chamber equipped with a reference humidity/temperature sensor (Si7005, Silicon Labs). The sensor was then loaded, the chamber was sealed, and the responses of the BP NF film and reference sensor were simultaneously recorded.
The water vapor sensing characteristics of BP films were compared to those of polycrystalline monolayer graphene (grown in an atmospheric pressure CVD process), and molybdenum disulfide (MoS2) grown by chemical vapor deposition, as well as graphene and MoS2 films of stacked flakes made by liquid exfoliation according to Example 1 (See,
for these sensors with respect to reciprocal recovery time (1/T) upon injection of 0.5 to 12.5 nl of water vapor. The results for films of stacked MoS2 NF were not included in
Because RH strongly correlates with temperature, the temperature-dependent response of the humidity sensors was carefully characterized.
The performance of BP films with respect to the pressure of humid air was also tested.
A set of experiments to gain insight into the operational principles of the BP films was performed. In general, the sensing mechanism in humidity sensors is associated with either: (i) modulation in the electronic conduction due to a charge transfer between the analytes and the sensor surface (doping effect), (ii) modulation in the ionic conduction upon formation of a capillary condensed electrolytic media, or (iii) modulation in the capacitance of the sensor due to structural modification or change in the dielectric properties of the sensing material. In homogenous sensing media such as individual flake devices, the first case is naturally the governing mechanism, while any scenario could govern the operation of heterogeneous and porous sensors such as films of stacked flakes or composite structures. With this perspective, the sensing performance of the BP NF devices was compared to that of mechanically exfoliated individual flakes.
Cyclic current-voltage (I-V) experiments in different RH levels were performed, demonstrating a scan-rate dependency (
To better understand the effects of resistive and capacitive contributions on the overall response of the BP film sensors, impedance spectroscopy (IS) experiments were performed by sweeping the frequency from 100 Hz to 10 MHz. As shown in
BP flakes were shown to efficiently absorb the ambient moisture and form a layer of liquid on the surface of the flakes, which can potentially be ionic conductive. The hydrophilicity of BP flakes is also an ideal characteristic for humidity detection, as it facilitates the formation a uniform layer of moisture media for ion hopping. Additionally, BP flakes were shown to react with humid air and form phosphorus oxides, which can produce acids in exposure to water molecules. In principle, the acids can ionically dissolve in the moist media and enhance the concentration of mobile H+ ions. Thus, water auto ionization and ionic solvation of the phosphorus oxoacids in the moist absorbed layer deliver the required ions for the charge transfer process.
A set of experiments to find the degradation rate of the sensors in high humidity environments was performed. The morphology of the flakes in a saturated humidity (100% RH) environment at room temperature was measured at different time intervals (
The stability of the sensing response in BP film sensors was also explored over extended periods.
Additionally, the drift of the sensors under continuous operation was tested. In drift tests, saturated solution of potassium chloride (KCl) and magnesium chloride (MgCl2) were loaded into the chamber, which yielded the constant relative humidity (RH) of 83% and 35% in room temperature, respectively. As shown in
The baseline and maximum value of the drain current in operation of a BP film sensor was examined at different applied voltages. The base current increases linearly, but the maximum current deviates from a linear trend in large voltages above 0.5 V (See,
The above Examples demonstrate the application of films of stacked BP NF for highly sensitive and selective humidity detection as well as pressure measurement of humid. Results revealed that the degradation rate of BP flakes in saturated humidity is reasonably slow, allowing BP thin films and composites to be used in many scenarios in which the devices may be exposed to harsh ambient conditions, including energy storage, catalysis, chemical and bio-sensing applications, with years of effective lifetime.
It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be incorporated within the spirit and purview of this application and scope of the appended claims.
This application claims the benefit of priority of U.S. Provisional Patent Application no. 62/203,440, filed Aug. 11, 2015, which is hereby incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/046521 | 8/11/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62203440 | Aug 2015 | US |
