Nicotine Liquid Formulation Incorporating Sugar Esters For An Electronic Vaporization Device and Methods of Making Same

An electronic vaporization device liquid and method for making the same. The electronic vaporization device liquid may include nicotine, sugar esters, and a biological suitable carrier solution. Sugar esters may be added to a biological suitable carrier solution to create a first mixture. The first mixture may be mixed at a temperature range until the sugar esters are dissolved. The first mixture may be cooled to room temperature.

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Description
RELATED CASES

This application claims the benefit of U.S. Provisional Application No. 62/964,812 filed on 23 Jan. 2020, the contents of which are all incorporated by reference.

BACKGROUND

Some formulations of best-selling e-cigarette liquid (e-liquid) may generally consist of Benzoic Acid to adjust the liquid pH and the protonation state of nicotine, while at the same time reducing the harshness of nicotine. Due to the nature of the flavors of the primary ingredients in such formulations, additional flavorants are typically always required in the e-liquid to make the product pleasant and well-accepted by the smoker's palate.

BRIEF SUMMARY OF DISCLOSURE

In one example implementation, a method of making an electronic vaporization device liquid, may include but is not limited to adding sugar esters to a biological suitable carrier solution to create a first mixture. The first mixture may be mixed at a temperature range until the sugar esters are dissolved. The first mixture may be cooled to room temperature.

One or more of the following example features may be included. One or more additional solvents may be added to the first mixture and the one or more additional solvents may be mixed in the first mixture until homogenous to create a second mixture. A nicotine freebase may be added to the first mixture. The nicotine freebase may have a concentration between 0.1%-5%. Mixing may include one of sonication and stirring. The temperature range may be between 20° C.-100° C. The sugar esters may include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters. The biological suitable carrier solution may include at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol. The biological suitable carrier solution may include a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG. The sugar esters may have a concentration of 0.1%-5%.

In another example implementation, an electronic vaporization device liquid may include but is not limited to nicotine, sugar esters, and a biological suitable carrier solution.

One or more of the following example features may be included. The sugar esters may include glucose esters. The sugar esters may include sucrose esters. The sugar esters may include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters. The biological suitable carrier solution may include at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol. The biological suitable carrier solution may include a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG. The nicotine may be a nicotine freebase with a concentration between 0.1%-5%. The sugar esters may have a concentration between 0.1%-5%.

In another example implementation, an electronic vaporization device liquid may include but is not limited to sugar esters, and a biological suitable carrier solution.

One or more of the following example features may be included. The sugar esters may include sucrose esters. The sugar esters may include glucose esters. The sugar esters may include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters. The biological suitable carrier solution may include at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol. The biological suitable carrier solution may include a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG. The electronic vaporization device liquid may include a nicotine freebase with a concentration between 0.1%-5%. The sugar esters may have a concentration between 0.1%-5%.

The details of one or more example implementations are set forth in the accompanying drawings and the description below. Other possible example features and/or possible example advantages will become apparent from the description, the drawings, and the claims. Some implementations may not have those possible example features and/or possible example advantages, and such possible example features and/or possible example advantages may not necessarily be required of some implementations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example flowchart of a process to make an e-liquid according to one or more example implementations of the disclosure;

FIG. 2 is an example diagrammatic view of glucose tetraester, glucose tetrapropionate, and glucose tetravalerate according to one or more example implementations of the disclosure; and

FIG. 3 is an example diagrammatic view of a sucrose tetraesters according to one or more example implementations of the disclosure.

Like reference symbols in the various drawings may indicate like elements.

DETAILED DESCRIPTION

Electronic cigarettes (e-cigarettes) may be used as an HPHC-reduced alternative to smoking tobacco. In an e-cigarette, a mechanism reduces a liquid (“e-cigarette fluid,” “e-fluid,” “e-liquid,” or “vaping fluid”) into a smoke-like mixture of air and tiny droplets (an aerosol) which material is then inhaled by the user. Any active constituents in the vaping fluid may then be absorbed by the lungs like real cigarette smoke. Because e-cigarettes do not produce smoke, other terms have been developed to describe using the devices (e.g., “vaping.”) The most common type of e-cigarette has a heating element causing the vaporization of the e-fluid to create an aerosol. Other types of e-cigarettes may use mechanical production of the aerosol (e.g., a piezoelectric diaphragm vibrating at ultrasonic speeds to directly form an aerosol from the e-fluid, similar to a misting humidifier).

Some formulations of e-liquids or vaping fluid may generally consist of benzoic acid or some other organic acids to adjust the liquid pH and the protonation state of nicotine, while at the same time reducing the harshness of nicotine. A generic e-liquid may have nicotine, propylene glycol, glycerin, flavorants. It may include organic acids (for example benzoic acid, lactic acid, etc.). Organic acids are typically added into the solvents, mixed until fully dissolved. Nicotine is then added into the mixture, followed by the flavorants and mixed until fully dissolved. Additional solvents may be added in the end to achieve the target nicotine concentration. A typical generic nicotine salt formulation may consist of nicotine and organic acids fully dissolved in typical e-cigarette solvents (e.g., PG and VG). A non-salt generic nicotine formulation may consist of nicotine and typical e-cigarette solvents (e.g., PG and VG). Freebase is the conjugated base or deprotonated form of nicotine, which is also the natural chemical state of pure nicotine. Some nicotine salt formulations for aerosol devices may be used for the e-liquid, but such unflavored nicotine salt formulations generally provide users an artificial/chemical taste, not perceived pleasant or well accepted by users. Due to the nature of the flavors of the primary ingredients in such formulations, additional flavorants are typically always required in the e-liquid to make the product pleasant and well-accepted by the smoker's palate. Example flavorants may include, e.g., Vanilla Extracts, Tobacco Absolutes, Orange Oil, Menthol, Ethyl Maltol, Linalool, and artificial flavorants may include, e.g., Vanillin (synthesized instead of isolated from vanilla beans), Ethyl Acetate, Furfural, Leaf Alcohol. Per definition, artificial flavorants are the flavoring compounds not directly isolated from nature. This has led to hundreds of added flavors in the e-liquid, many of which contain chemical substances that have not been fully understood regarding their inhalation toxicity and thermal stability. Also, artificially flavored e-liquids have been criticized being the primary cause of the so-called teen vaping epidemic.

Other nicotine liquid formulations for e-cigarettes that are not nicotine salt based may be used, but most of these liquid formulations contain only nicotine freebase. The freebase formulations generally fail to provide sufficient satisfaction for nicotine cravings at a low level of nicotine, and will be too harsh to inhale when the concentration of nicotine is high.

Therefore, as will be discussed below, in some implementations, the present disclosure may include a unique liquid formulation that may be used with an electronic vaporization device (e.g., e-cigarette) to deliver natural tobacco flavor and satisfaction of nicotine cravings simultaneously without artificial flavoring ingredients. In some implementations, the formulation may also provide sufficient satisfaction at nicotine levels no higher than, e.g., 1.7% (the current approved EU limit), however, it will be appreciated that varying levels of nicotine may still be used without departing from the scope of the present disclosure.

As discussed above and referring also at least to the example implementations of FIGS. 1-3, a method of making an electronic vaporization device liquid, may include but is not limited to adding 100 sugar esters to a biological suitable carrier solution to create a first mixture. The first mixture may be mixed 102 at a temperature range until the sugar esters are dissolved. The first mixture may be cooled 104 to room temperature.

As also discussed above and referring also at least to the example implementations of FIGS. 1-3, an electronic vaporization device liquid may include but is not limited to nicotine, sugar esters, and a biological suitable carrier solution. In some implementations, an electronic vaporization device liquid may include but is not limited to sugar esters, and a biological suitable carrier solution.

As will be discussed below, unlike other e-liquid formulations, the example formulations do not add acid to the e-liquid production process in order to neutralize nicotine freebase. Rather, upon heating in the e-cigarette, the sugar esters may undergo thermal degradation to produce sugar and acids in the vapor. The acids may then interact with the nicotine in the vapor to protonate nicotine. Additionally, sugar esters naturally exist in tobacco plant and further contribute to tobacco aroma while burning. Thus, in some implementations, the formulations of e-liquids or vaping fluid of the present disclosure do not use benzoic acid or any other organic acids. Instead, in some implementations, it may use sugar esters to achieve the nicotine protonation results, while providing natural tobacco aroma and flavor at the same time. This may allow minimal to no flavorants, in particular artificial flavorants, to be used in the e-liquid. In some implementations, the sugar esters may include sucrose esters, and in some implementations, the sugar esters may include glucose esters. In some implementations, the sugar esters may include one or multiple glucose esters and/or sucrose esters. In some implementations, the esters may be mono-, bi-, tri-, or tetraesters. That is, in some implementations, the sugar esters may include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters etc., or any mixture/combination of the esters mentioned. In some implementations, example tetraesters of glucose or sucrose may include glucose tetrapropionate 200B (shown in FIG. 2), glucose tetravalerate 200C (shown in FIG. 2), glucose tetramethylvalerate, glucose tetralactate, sucrose tetraproprionate, sucrose tetravalerate, sucrose tetramethylvalerate, and sucrose tetralactate. In some implementations, the sugar esters may either be extracted from tobacco or synthesized.

In some implementations, the sugar esters may be glucose tetraesters and/or sucrose tetraesters of lower carboxylic acids, all of which may be naturally existing in tobacco at a higher level than lower carboxylic acids. The example and non-limiting chemical structures of glucose tetraesters 200 and sucrose tetraesters 300 are shown in the example implementations of FIG. 2 and FIG. 3 respectively for example purposes only, where R=C3-C8 Carboxylates and R′=Acetate.

In some example implementations, it has been discovered that the sugar tetraesters of lower carboxylic acids readily release free carboxylic acids on thermolysis. Therefore, when an e-liquid gets vaporized in an electronic vaporization device (or similar device), the released free carboxylic acids may move the nicotine chemical equilibrium to its protonated state, subsequently providing the so-called “head buzz” to the users in order to fulfill their cravings for nicotine. Also through the thermolysis process, the increased reducing sugars may add balance to the vapor flavor, neutralizing the nicotine throat hit, and make the vapor sensory experience more similar to flue-cured tobacco. In some implementations, as sugar esters may be the identified primary tobacco aroma precursors in natural tobacco, the present disclosure may also provide the smoker a “closer to cigarette tobacco flavor” without the need for artificial flavors. In some implementations, glucose or sucrose or other reduced sugar compounds may be added to an existing nicotine salt formulation for the purpose of adding natural tobacco flavor. In some implementations, the disclosed formulation may be a nicotine freebase formulation with added sugar esters. Adding sugar esters to a nicotine salt formulation (whether is benzoate salt or a salt formed with other acids) is more like enhancing the nicotine salt formulation in natural tobacco aroma, balancing the nicotine buzz and throat hit from the original nicotine salt formulation. Though a non-salt based nicotine formulation is defined as nicotine formulations without acids, it is equivalent to a nicotine freebase formulation under the current market situation. In some implementations, the sugar ester nicotine formulation as described may be a non-salt nicotine formulation. Making a sugar esters nicotine-free formulation will not provide any nicotine head buzz but will still release tobacco-like aroma.]

In some implementations, as noted above, the present disclosure may include an e-liquid formulation that may contain nicotine, sugar esters, and a biological suitable carrier solution. In some implementations, the biological suitable carrier solution may include at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol, or combinations thereof. It will be appreciated that the e-liquid formulation of the present disclosure need not contain nicotine. For instance, a zero nicotine e-liquid formulation may also be used when users only wish to experience the tobacco aroma but not the nicotine uptake. As such, the use of nicotine should be taken as example only and not to otherwise limit the scope of the present disclosure.

In some implementations, the e-liquid formulation may contain a nicotine freebase. In some implementations, the nicotine freebase may have a concentration between 0.1%-5%. In some implementations, a preferred range may be 0.8%-3%, as well as 0.8%-1.7% as this may be the trending range in all countries and regions. In some implementations, as also noted above, the e-liquid formulation may contain sugar esters, and in some implementations, the sugar esters may have a concentration of 0.1%-5%. In some implementations, a preferred range may be 0.36%-2.4% (matching 0.8-3% nicotine range above), as well as 0.36%-1.3% (matching 0.8-1.7% nicotine range above).

In some implementations, sugar esters may be added 100 to a biological suitable carrier solution to create a first mixture, and in some implementations, the first mixture may be mixed 102 at a temperature range until the sugar esters are dissolved. For instance, in some implementations, the sugar esters may be added to, e.g., 100% PG, and then stirred at a moderate temperature (e.g., between 20° C.-100° C.) until dissolved. In some implementations, mixing may include one of sonication and stirring (e.g., stirring with magnetic stirrer, stirring with electric lab mixer, etc.). For example, sonication may be used to facilitate dissolution of the sugar esters; however, it will be appreciated that any known technique capable of dissolving the sugar esters into the carrier solution (e.g., PG) may be used without departing from the scope of the present disclosure.

In some implementations, the first mixture may be cooled 104 to room temperature. For instance, the first mixture with the sugar esters dissolved into the PG may be cooled to room temperature (e.g., between 15° C.-40° C.). It will be appreciated that the first mixture may be cooled to less than or greater than room temperature without departing from the scope of the present disclosure. For example, a controlled room temperature of 20° C.-25° C. may be used.

In some implementations, one or more additional solvents may be added 106 to the first mixture, and a nicotine freebase may be added 108 to the first mixture, and in some implementations, the one or more additional solvents and/or the nicotine freebase may be mixed 110 in the first mixture until homogenous to create a second mixture. For example, nicotine (when used) and other solvents (e.g., other biological suitable carrier solutions such as VG) may then be added to the sugar ester PG solution and mixed until homogeneous (e.g., all ingredients are dissolved in the mixture and the mixture is uniform throughout. Quantitatively, all ingredients concentration should measure the same at any sampling point in the mixture).

In some implementations, the biological suitable carrier solution may include a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG. In some implementations, the preferred compositions of PG/VG may include, e.g., 60% PG and 40% VG, 55% PG and 45% VG, 50% PG and 50% VG, 45% PG and 55% VG, 40% PG and 60% VG. However, it will be appreciated that other combinations of PG/VG, as well as other types of biological suitable carrier solutions, may also be used without departing from the scope of the disclosure. The final mixture may then be filled into a cartridge or pod which may then be used in combination with an electronic vaporization device at an operation temperature between, e.g., 150°-300° C. The vapor generated from the device may be inhaled by smokers/vapors when desired. In some implementations, the formulation described in the present disclosure may be, e.g., filled in a disposable e-cigarette, filled in a pod that may be sealed and installed by a vapor onto a multi-use e-cigarette, manually filled into any open-system, e.g., a MOD or a tank vaporizer by the user, used as a blending solvent for heat not burn material.

As such, in some implementations, the present disclosure may, e.g., (1) provide e-cigarette natural tobacco aroma that is most similar to cigarettes; (2) eliminate or at least reduce the need of artificial flavors to make e-cigarettes more palatable, thus reducing the suspected source of the so-called teen vaping epidemic; (3) have a composition more similar to natural tobacco and may include a thermolysis process in vaporization that provides vaping with a more similar experience to smoking; and/or (4) as a result of item 3 above, the more similarly satisfying experience may allow the e-liquid formulation to contain low nicotine concentration in compliance with the regions with nicotine level regulation without sacrificing the user experience.

In some implementations, it may be preferred that the sugar tetraester to nicotine molar ratio is 0.75 to 1 (e.g., 0.75 mole sugar tetraester added to 1 mole nicotine) so that when the tetraester undergoes thermolysis, it may release 4 acids, thus the acid to nicotine ratio may be 3:1, which is the preferred acid:nicotine ratio. More specifically, in some implementations, it may be preferred that the molar ratio between the total ester groups and the nicotine is 3:1, e.g., for sugar triester which has 3 esters that can potentially release 3 acids in the vapor, would be used at 1:1 molar ratio to nicotine, so that the molar ratio of its ester groups to nicotine would be 3:1.

In some implementations, the sugar esters that would make a successful nicotine e-liquid formulation may undergo the targeted thermolysis reaction at the e-cigarette typical operation temperature range (e.g., 160° C.-350° C.) to release acid in the vapor in order to protonate nicotine, and at the same time the reducing sugars from the thermolysis may provide tobacco-like aroma. For example, totally esterified sugar esters (e.g., glucose pentaisovalerate or sucrose octaesters do not easily release their acids upon heating.

The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the language “at least one of A, B, and C” (and the like) should be interpreted as covering only A, only B, only C, or any combination of the three, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps (not necessarily in a particular order), operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps (not necessarily in a particular order), operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents (e.g., of all means or step plus function elements) that may be in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications, variations, substitutions, and any combinations thereof will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The implementation(s) were chosen and described in order to explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various implementation(s) with various modifications and/or any combinations of implementation(s) as are suited to the particular use contemplated.

Having thus described the disclosure of the present application in detail and by reference to implementation(s) thereof, it will be apparent that modifications, variations, and any combinations of implementation(s) (including any modifications, variations, substitutions, and combinations thereof) are possible without departing from the scope of the disclosure defined in the appended claims.

Claims

1. An electronic vaporization device liquid comprising:

nicotine;
sugar esters; and
a biological suitable carrier solution.

2. The electronic vaporization device liquid of claim 1 wherein the sugar esters include glucose esters.

3. The electronic vaporization device liquid of claim 1 wherein the sugar esters include sucrose esters.

4. The electronic vaporization device liquid of claim 1 wherein the sugar esters include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters.

5. The electronic vaporization device liquid of claim 1 wherein the biological suitable carrier solution includes at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol.

6. The electronic vaporization device liquid of claim 1 wherein the biological suitable carrier solution includes a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG.

7. The electronic vaporization device liquid of claim 1 wherein the nicotine is a nicotine freebase with a concentration between 0.1%-5%.

8. The electronic vaporization device liquid of claim 1 wherein the sugar esters have a concentration between 0.1%-5%.

9. An electronic vaporization device liquid comprising:

sugar esters; and
a biological suitable carrier solution.

10. The electronic vaporization device liquid of claim 9 wherein the sugar esters include sucrose esters.

11. The electronic vaporization device liquid of claim 9 wherein the sugar esters include glucose esters.

12. The electronic vaporization device liquid of claim 9 wherein the sugar esters include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters.

13. The electronic vaporization device liquid of claim 9 wherein the biological suitable carrier solution includes at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol.

14. The electronic vaporization device liquid of claim 9 wherein the biological suitable carrier solution includes a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG.

15. The electronic vaporization device liquid of claim 9 further comprising a nicotine freebase with a concentration between 0.1%-5%.

16. The electronic vaporization device liquid of claim 9 wherein the sugar esters have a concentration between 0.1%-5%.

17. A method of making an electronic vaporization device liquid comprising:

adding sugar esters to a biological suitable carrier solution to create a first mixture;
mixing the first mixture at temperature range until the sugar esters are dissolved; and
cooling the first mixture to room temperature.

18. The method of claim 17 further comprising:

adding one or more additional solvents to the first mixture; and
mixing the one or more additional solvents in the first mixture until homogenous to create a second mixture.

19. The method of claim 18 further comprising adding a nicotine freebase.

20. The method of claim 17 wherein mixing includes one of sonication and stirring.

21. The method of claim 17 wherein the temperature range is 20° C.-100° C.

22. The method of claim 17 wherein the sugar esters include at least one of glucose monoesters, glucose biesters, glucose triesters, glucose tetraesters, sucrose monoesters, sucrose biesters, sucrose triesters, and sucrose tetraesters.

23. The method of claim 17 wherein the biological suitable carrier solution includes at least one of propylene glycol (PG), vegetable glycerin (VG), water, alcohol, and 1,3-propanediol.

24. The method of claim 17 wherein the biological suitable carrier solution includes a composition including one of 100% propylene glycol (PG), 90% PG and 10% vegetable glycerin (VG), 80% PG and 20% VG, 70% PG and 30% VG, 60% PG and 40% VG, 50% PG and 50% VG, 40% PG and 60% VG, 30% PG and 70% VG, 20% PG and 80% VG, 10% PG and 90% VG, and 100% VG.

25. The method of claim 19 wherein the nicotine freebase has a concentration between 0.1%-5%.

26. The method of claim 17 wherein the sugar esters have a concentration between 0.1%-5%.

Patent History
Publication number: 20210227873
Type: Application
Filed: Jan 22, 2021
Publication Date: Jul 29, 2021
Inventor: Chenyue Xing (San Mateo, CA)
Application Number: 17/156,297
Classifications
International Classification: A24B 15/167 (20060101); A24B 15/40 (20060101);