RESPONSIVE SENSORS

FIELD OF THE DISCLOSURE

[0001] Polymeric coatings or layers can be used in a touch/force sensor, for example, a triboelectric sensor. The coating can be located above an electrode wherein charges can be generated when a human finger touches the coating as a result of the principle of contact electrification, also known as tribo electrification.

SUMMARY

[0002] Aspects of the disclosure relate to a coating including a polymer matrix including a polymer including a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane. The polycarbonate includes benzophenone moieties, the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and the isofluoropropyl polyhedral oligomeric silsesquioxane self aggregates to form aggregates at or near an outermost surface of the coating.

[0003] Aspects of the disclosure further relate to a touch/force responsive sensor including: a substrate; an electrode; and a coating adjacent to the electrode. The coating includes a polymer matrix including a polymer including a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane. The polycarbonate includes benzophenone moieties, the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating.

[0004] Additional aspects of the disclosure relate to a method of applying a coating to an electrode including: dissolving a polymer including polycarbonate and benzophenone moieties into a solvent to form a first solution; mixing isofluoropropyl polyhedral oligomeric silsesquioxane into the first solution; allowing the isofluoropropyl polyhedral oligomeric silsesquioxane to dissolve to form a second solution, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties; spin coating the second solution onto the electrode to form the coating, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating; and exposing the coating to an ultraviolet light source, wherein after exposure, the isofluoropropyl polyhedral oligomeric silsesquioxane is locked into place.

BRIEF DESCRIPTION OF THE FIGURES

[0005] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various aspects discussed in the present document.

[0006] FIG. 1 shows a method for creating a coating for a touch/force sensor.

[0007] FIG. 2 shows a single electrode sensor, a dual electrode sensor, and common voltage outputs of the sensors.

[0008] FIG. 3 shows a touch/force sensor operation.

[0009] FIG. 4 shows a polymeric coating layer, the polymeric coating layer with the addition of a second polymer, and a graph comparing the single polymers versus the combination of the polymers.

[0010] FIG. 5 shows a touch/force device containing multiple contact pads and sensors and the output voltage of the sensor.

[0011] FIG. 6 is a graph of output voltage in volts versus a second polymer concentration in weight percent of the coating.

[0012] FIG. 7 is a graph of output voltage in volts versus electrical load in mega ohms.

[0013] FIG. 8 is a graph of output voltage in volts versus coating layer thickness in micrometers.

[0014] FIG. 9 is a graph comparing output voltage in volts versus time in seconds for three different polymeric coatings.

[0015] FIG. 10 is a graph comparing output voltage in volts for four different polymeric coatings.

[0016] FIG. 11 is Raman spectra comparing three different polymeric coatings.

[0017] FIG. 12 shows optical surface profiles and three dimensional (3D) surface models of four different polymeric coatings. [0018] FIG. 13 shows optical images of the four different polymeric coatings of FIG.

12

DETAILED DESCRIPTION

[0019] The present disclosure can be understood more readily by reference to the following detailed description of the disclosure and the Examples included therein. In various aspects, the present disclosure pertains to a coating including a polymer matrix including a polymer including a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane. The polycarbonate includes benzophenone moieties, the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and the isofluoropropyl polyhedral oligomeric silsesquioxane self aggregates to form aggregates at or near an outermost surface of the coating.

[0020] Before the present compounds, compositions, articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, 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 is not intended to be limiting.

[0021] Various combinations of elements of this disclosure are encompassed by this disclosure, e.g., combinations of elements from dependent claims that depend upon the same independent claim.

[0022] Moreover, it is to be understood that unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of aspects described in the specification.

[0023] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. Definitions

[0024] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term“comprising” can include the aspects“consisting of’ and“consisting essentially of.” Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined herein.

[0025] As used in the specification and the appended claims, the singular forms“a,”

“an” and“the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to“a photoactive polycarbonate” includes mixtures of two or more photoactive polycarbonate polymers.

[0026] As used herein, the term“combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0027] Ranges can be expressed herein as from one value (first value) to another value (second value). When such a range is expressed, the range includes in some aspects one or both of the first value and the second 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. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as“about” that particular value in addition to the value itself. For example, if the value“10” is disclosed, then“about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0028] As used herein, the terms“about” and“at or about” mean that the amount or value in question can be the designated value, approximately the designated value, or about the same as the designated value. It is generally understood, as used herein, that it is the nominal value indicated ±10% variation unless otherwise indicated or inferred. The term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is“about” or“approximate” whether or not expressly stated to be such. It is understood that where “about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0029] Disclosed are the components to be used to prepare the compositions of the disclosure as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively

contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the disclosure. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific aspect or combination of aspects of the methods of the disclosure.

[0030] References in the specification and concluding claims to parts by weight of a particular element or component in a composition or article, denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound. [0031] A weight percent of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0032] As used herein, the terms“number average molecular weight” or“Mn” can be used interchangeably, and refer to the statistical average molecular weight of all the polymer chains in the sample and is defined by the formula:

where Mi is the molecular weight of a chain and Ni is the number of chains of that molecular weight. Mn can be determined for polymers, e.g., polycarbonate polymers, by methods well known to a person having ordinary skill in the art using molecular weight standards, e.g. polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

[0033] As used herein, the terms“weight average molecular weight” or“Mw” can be used interchangeably, and are defined by the formula:

where Mi is the molecular weight of a chain and Ni is the number of chains of that molecular weight. Compared to Mn, Mw takes into account the molecular weight of a given chain in determining contributions to the molecular weight average. Thus, the greater the molecular weight of a given chain, the more the chain contributes to the Mw. Mw can be determined for polymers, e.g., polycarbonate polymers, by methods well known to a person having ordinary skill in the art using molecular weight standards, e.g., polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

[0034] As used herein,“polycarbonate” refers to an oligomer or polymer including residues of one or more dihydroxy compounds, e.g., dihydroxy aromatic compounds, joined by carbonate linkages; it also encompasses homopolycarbonates, copolycarbonates, and (co)polyester carbonates.

[0035] The terms“residues” and“structural units”, used in reference to the constituents of the polymers, are synonymous throughout the specification.

[0036] As used herein the terms“weight percent,”“wt%,” and“wt. %,” which can be used interchangeably, indicate the percent by weight of a given component based on the total weight of the composition, unless otherwise specified. That is, unless otherwise specified, all wt% values are based on the total weight of the composition. It should be understood that the sum of wt% values for all components in a disclosed composition or formulation are equal to 100

[0037] Unless otherwise stated to the contrary herein, all test standards are the most recent standard in effect at the time of filing this application.

[0038] Each of the materials disclosed herein are either commercially available and/or the methods for the production thereof are known to those of skill in the art.

[0039] It is understood that the compositions disclosed herein have certain functions.

Disclosed herein are certain structural requirements for performing the disclosed functions and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

Coatings and Sensors Including the Coatings

[0040] Force and tactile sensing has been demonstrated in touch/force sensors, for example, triboelectric sensors. Triboelectric sensors are advantageous to other touch/force sensors due to their simple architecture, self-powering capabilities, ease of manufacture, and potentially lower cost, when compared with incumbent capacitive, resistive, piezoelectric, and optical sensors. Charges are generated in the triboelectric layer upon contact with a material having an opposite electro affinity. For instance, charges are generated when a human finger touches the triboelectric layer as a result of the principle of contact

electrification, also known as tribo electrification. Devices having a single or dual electrode configuration have been proposed as the common structures for touch/force sensors. A coating layer of a material can be deposited adjacent to the electrode. The coating layer can exhibit electronegative characteristics thus, improving a voltage output when coming in contact with an electropositive material.

[0041] Common materials for the coating layer include poly(dimethylsiloxane)

(PDMS), polytetrafluoroethylene (PTFE), polyfmethyl methacrylate) (PMMA), polyimide (PI), polyamide (PA), nylon, and polyvinylidene fluoride or polyvinylidene difluoride, (PVDF) and its copolymers, such as PVDF-TrFE and PVDF-TrFE-CFE. Techniques commonly used for fabricating triboelectric active layers include laser ablation, hot embossing, injection molding, wet and dry etching processes. PDMS is generally understood to be the most widely employed polymer material for the fabrication of triboelectric sensor devices owing to a number of peculiar advantages: simple nanofabrication, processability advantages with different replica processes, biocompatibility, and high transparency. [0042] However, despite these materials exhibiting good triboelectric properties

(especially those being highly electronegative), surface nanostructuring is required to improve their voltage output. An addition drawback to these materials is that for materials such as PDMS or PMMA, very thick layers are required, which significantly impacts the optical properties (transparency in particular) as well as cost. For example, the required thickness of PDMS is quite high (/. e. , >200 pm) to get a reasonable power output for triboelectric sensor. As a result, the surface of the PDMS layer very often impedes immediate use without additional processing. Such additional processing can include further functionalization either by the addition of different nanostructures (nanoparticles, nanowires, nanolayers, etc.) or by selectively creating surface roughness using different plasma etching processes. This additional processing adds to the overall cost and time of manufacturing. Therefore, there is a need and an on-going industry wide concern for new polymeric coating layers for touch/force sensors.

[0043] It has been discovered that a coating layer can include a polymer matrix, wherein the polymer matrix includes a photoactive polycarbonate (XPC) containing benzophenone moieties and isofluoropropyl polyhedral oligomeric silsesquioxane (F-POSS). Dispersing POSS molecules into a polymeric matrix can increase the mechanical and thermal stability of the nanocomposite and reduce flammability, heat discharge, and viscosity while retaining many other crucial properties, such as but not limited to low weight, transparency, ductile failures, and tailorable surface properties. These unique POSS structural properties exhibit increased performance over their non-hybrid counter-parts.

[0044] A number of different approaches have been utilized to attempt to incorporate

POSS moieties into a polymer matrix, for example, copolymerization of POSS monomers with other monomers, grafting of POSS molecules into a preformed polymer chain, or physical blending with a polymer matrix by melt-mixing or solvent casting methods.

However, the interaction between the POSS nanoparticles and the polymer play a critical role in influencing the particle behavior and their spatial distribution in the polymer matrix. Very often, this results in the self-aggregation of POSS particles. By utilizing the self-segregation tendency of POSS molecules, while controlling its dispersion through cooperative surface interactions and locking it into well-defined loci in the polymer host, voltage output can be increased compared other polymer materials - thus yielding a better performing touch/force sensor.

[0045] Additional benefits of the XPC-F-POSS coating include: better transparency in the visible region achieved when compared to incumbent materials due to the intrinsic properties of the XPC-F-POSS blends; reduced layer thickness; enhanced dispersability of F- POSS in XPC matrix; ability to covalently attach F-POSS to XPC matrix photo-chemically in one single step; excellent processing advantages, such as coating, crosslinking, and dispersing; minimum number of processing steps; cost-effective solution; tolerant to harsh experimental processing conditions, such as chemical, thermal, abrasion, and UV resistant; multiple chemical binding sites for the copolymer; excellent functional substrate for use in nanotemplating, nanopatteming and self-assembling for thin film processes; and an excellent surface functionalization platform tool for different applications.

[0046] According to certain aspects, a coating includes: a polymer matrix, wherein the polymer matrix includes a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane, wherein the polycarbonate includes benzophenone moieties, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and wherein the isofluoropropyl polyhedral oligomeric

silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating.

[0047] The coating includes a polymer matrix containing a photoactive polycarbonate with benzophenone moieties (XPC) and isofluoropropyl polyhedral oligomeric

silsesquioxane (F-POSS). An example chemical structure is shown below.

where X = 95-99% and Y =1-5% [0048] According to certain aspects, the benzophenone moieties are in a

concentration of about 1% to about 5% by weight of the polycarbonate. The isofluoropropyl polyhedral oligomeric silsesquioxane can be in a concentration of about 0.5% to about 50% by weight of the polycarbonate.

[0049] The coating can have a thickness in the range from about 2 micrometers (pm) to about 100 pm.

[0050] According to certain aspects, the photoactive polycarbonate with

benzophenone moieties has a molecular weight selected such that the 2 parts of the polymer dissolves in 1 part of a solvent at a temperature of 71 °F (21.7 °C) and a pressure of 1 atmosphere. The solvent can be any solvent suitable for solubilizing the photoactive polycarbonate with benzophenone moieties. Examples of suitable solvents include dimethyl- formamide, dimethyl sulfoxide, N-methylpyrrolidione, dimethylacetamide, and

tetrahydrof iran. According to certain other aspects, the photoactive polycarbonate with benzophenone moieties has a molecular weight in the range of about 5,000 to 250,000.

[0051] The isofluoropropyl polyhedral oligomeric silsesquioxane molecules can have a tendency to self-aggregate. The self-aggregation can occur at or very near an outermost surface of the coating. According to certain aspects, the isofluoropropyl polyhedral oligomeric silsesquioxane aggregates are locked into place at or near an outermost surface of the coating after self-aggregation. It is believed that the benzophenone moieties allow cross- linking between the photoactive polycarbonate and the isofluoropropyl polyhedral oligomeric silsesquioxane. Moreover, the benzophenone moieties in the polymer matrix can allow cross- linking between the isofluoropropyl polyhedral oligomeric silsesquioxane molecules. In this manner, the isofluoropropyl polyhedral oligomeric silsesquioxane molecules can be locked into a specific location in the coating.

[0052] The coating can be used in a touch/force responsive sensor. The touch/force responsive sensor can be a triboelectric sensor. With reference to FIG. 2, the sensor can include a substrate; an electrode; and the coating, wherein the coating is adjacent to the electrode. The sensor can be a single electrode sensor (FIG. 2a) or a dual electrode sensor (FIG. 2b). FIG. 2c shows a graph of a common output voltage in volts (V) versus time in seconds (s) for the polymer matrix containing the isofluoropropyl polyhedral oligomeric silsesquioxane at a concentration of 9% by weight of the polymer matrix.

[0053] FIG. 3 shows a touch/force sensor operation. In operation, a touch/force input signal is detected when a material (e.g., a human finger) is applied to the coating. The event is detected via a voltage output, and the event is then sent for further processing to a processing unit for interpreting and displaying the event. FIG. 5 shows a touch/force device containing multiple contact pads and sensors, and the output voltage of the sensor.

[0054] The substrate can be made from any suitable material for use with a touch/force responsive sensor. Suitable examples of suitable substrate materials include, but are not limited to, polyethylene terephthalate, polyetherimide, glass, polyethylene naphthalate, polyimide, and other rigid or flexible substrates. The substrate can have a thickness in the range of about 10 pm to about 250 pm.

[0055] The electrode can be made from any suitable material for use with a touch/force responsive sensor. Suitable examples of suitable electrode materials include, but are not limited to, titanium, gold, aluminum, indium tin oxide (ITO), aluminum zin oxide (AZO), copper, silver nanowires, any other conductive material, and combinations thereof. The electrode can have a thickness in the range of about 25 nanometers (nm) to about 500 nm.

[0056] According to certain aspects, the sensor generates an output voltage in the range of about 1 to about 15 volts.

[0057] According to certain aspects and as shown in FIG. 1, a method of applying a coating to an electrode includes: dissolving a polymer including polycarbonate and benzophenone moieties into a solvent to form a first solution; mixing isofluoropropyl polyhedral oligomeric silsesquioxane into the first solution; allowing the isofluoropropyl polyhedral oligomeric silsesquioxane to dissolve to form a second solution, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties; spin coating the second solution onto the electrode to form the coating, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating; and exposing the coating to an ultraviolet light source, wherein after exposure, the isofluoropropyl polyhedral oligomeric silsesquioxane is locked into place.

[0058] The coated electrode can be used in a touch/force responsive sensor, as described above.

[0059] The step of dissolving the polymer in the solvent to form the first solution can be performed at a temperature in the range from about 71 °F to about 212 °F (21.7 °C to 100 °C). The polymer can be in a concentration in the range of about 3% to about 50% by weight of the first solution. The isofluoropropyl polyhedral oligomeric silsesquioxane can be in a concentration in the range from about 0.5% to about 50% by weight of the second solution. [0060] The step of exposing the coating to an ultraviolet light source can be performed at an exposure dose in the range from about 1 mW/cm ² to 50 mW/cm ² with dine exposure at 365 nm wavelength.

[0061] The methods can further include annealing the coating onto the electrode prior to the step of exposing the coating. Annealing can be performed at a temperature in the range from about 122 °F to about 428 °F (50 °C to 220 °C), a pressure from about 2 millibar (mbar) to about 1,013 mbar and a time in the range from about 1 hour (hr) to about 4 hr.

[0062] The methods can also include preparing the substrate; and depositing the electrode onto a surface of the substrate. Deposition can be performed by spin coating the coating onto the electrode. The spin coating can be performed in the range of about 500 revolutions per minute (rpm) to about 3,000 rpm.

[0063] Various combinations of elements of this disclosure are encompassed by this disclosure, e.g., combinations of elements from dependent claims that depend upon the same independent claim.

Aspects of the Disclosure

[0064] In various aspects, the present disclosure pertains to and includes at least the following aspects.

[0065] Aspect 1. A coating comprising:

a polymer matrix, wherein the polymer matrix comprises a polymer comprising a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane,

wherein the polycarbonate comprises benzophenone moieties,

wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and

wherein the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating.

[0066] Aspect 2. The coating according to Aspect 1, wherein the benzophenone moieties are in a concentration of about 1% to about 5% by weight of the polycarbonate.

[0067] Aspect 3. The coating according to Aspect 1 or 2, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is in a concentration of about 0.5% to about 50% by weight of the polycarbonate.

[0068] Aspect 4. The coating according to any of Aspects 1 to 3, wherein the coating has a thickness in a range from about 2 micron (pm) to about 100 pm.

[0069] Aspect 5. The coating according to any of Aspects 1 to 4, wherein the polymer has a molecular weight selected such that 2 parts of the polymer dissolves in 1 part of a solvent at a temperature of 21.7 °C and a pressure of 1 atmosphere, and wherein the solvent is selected from the group consisting of dimethyl-formamide, dimethyl sulfoxide, N- methylpyrrolidione, dimethylacetamide, and tetrahydrofuran.

[0070] Aspect 6. The coating according to any of Aspects 1 to 5, wherein the polymer has a molecular weight in a range of about 5,000 to 250,000.

[0071] Aspect 7. The coating according to any of Aspects 1 to 6, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane aggregates are locked into place at or near an outermost surface of the coating.

[0072] Aspect 8. A touch/force responsive sensor comprising:

a substrate;

an electrode; and

a coating, wherein the coating is adjacent to the electrode, and wherein the coating comprises a polymer matrix, wherein the polymer matrix comprises a polymer comprising a photoactive polycarbonate and isofluoropropyl polyhedral oligomeric silsesquioxane,

wherein the polycarbonate comprises benzophenone moieties,

wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties, and

wherein the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating.

[0073] Aspect 9. The sensor according to Aspect 8, wherein the substrate is selected from the group consisting of polyethylene terephthalate, polyetherimide, glass, polyethylene naphthalate, and polyimide.

[0074] Aspect 10. The sensor according to Aspect 8 or 9, wherein the substrate has a thickness in a range of about 10 pm to about 250 pm.

[0075] Aspect 11. The sensor according to any of Aspects 8 to 10, wherein the electrode is selected from the group consisting of titanium, gold, aluminum, indium tin oxide, aluminum zin oxide, copper, silver nanowires, any other conductive material, and combinations thereof.

[0076] Aspect 12. The sensor according to any of Aspects 8 to 11, wherein the electrode has a thickness in a range of about 25 nanometer (nm) to about 500 nm.

[0077] Aspect 13. The sensor according to any of Aspects 8 to 12, wherein the sensor generates an output voltage in a range of about 1 to about 15 volts.

[0078] Aspect 14. The sensor according to any of Aspects 8 to 13, further comprising a second substrate and a second electrode. [0079] Aspect 15. A method of applying a coating to an electrode comprising: dissolving a polymer comprising polycarbonate and benzophenone moieties into a solvent to form a first solution;

mixing isofluoropropyl polyhedral oligomeric silsesquioxane into the first solution; allowing the isofluoropropyl polyhedral oligomeric silsesquioxane to dissolve to form a second solution, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is covalently bonded to the benzophenone moieties;

spin coating the second solution onto the electrode to form the coating, wherein the isofluoropropyl polyhedral oligomeric silsesquioxane self-aggregates to form aggregates at or near an outermost surface of the coating; and

exposing the coating to an ultraviolet light source, wherein after exposure, the isofluoropropyl polyhedral oligomeric silsesquioxane is locked into place.

[0080] Aspect 16. The method according to Aspect 15, wherein the solvent is selected from the group consisting of dimethyl-formamide, dimethyl sulfoxide, N- methylpyrrolidione, dimethylacetamide, and tetrahydrofuran, and wherein the step of dissolving the polymer in the solvent to form the first solution is performed at a temperature in a range from about 21.7 degrees Celsius (°C) to 100 °C.

[0081] Aspect 17. The method according to Aspect 15 or 16, wherein the polymer is in a concentration in a range of about 3% to about 50% by weight of the first solution, and wherein the isofluoropropyl polyhedral oligomeric silsesquioxane is in a concentration in a range from about 0.5% to about 50% by weight of the second solution.

[0082] Aspect 18. The method according to any of Aspects 15 to 17, further comprising annealing the coating onto the electrode prior to the step of exposing the coating, wherein the annealing is performed at a temperature in a range from about 50 °C to 220 °C, a pressure in a range from about 2 millibar (mbar) to about 1,013 mbar, and a time in a range from about 1 hour (hr) to about 4 hr.

[0083] Aspect 19. The method according to any of Aspects 15 to 18, further comprising preparing a substrate and depositing the electrode onto a surface of the substrate, wherein deposition is performed by spin coating the coating onto the electrode at a speed of about 500 revolutions per minute (rpm) to about 3,000 rpm.

[0084] Aspect 20. The method according to any of Aspects 15 to 19, wherein the step of exposing the coating to an ultraviolet light source is performed at an exposure dose in a range from about 1 milliwatt per square centimeter (mW/cm ² ) to 50 mW/cm ² with dine exposure at a 365 nm wavelength. [0085] Aspect 21. The method according to any of Aspects 15 to 20, wherein the coated electrode is used in a touch/force responsive sensor.

EXAMPLES

[0086] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. Unless indicated otherwise, percentages referring to composition are in terms ofwt%.

[0087] There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.

[0088] To facilitate a better understanding of the present disclosure, the following examples of certain aspects of preferred aspects are given. The following examples are not the only examples that could be given according to the present disclosure and are not intended to limit the scope of the disclosure.

[0089] A triboelectric sensor was prepared as follows: Step 1: substrate preparation and cleaning. A 100 nm polyethylene terephthalate (PET) and polyetherimide (ULTEM ^® ) substrates were used to build the sensor. After cleaning the substrate in an ultrasonic cleaner using acetone, isopropanol (IPA), and deionized water, for 5 minutes in each solvent, it was blown-dried with high purity nitrogen.

[0090] Step 2: Electrode deposition and patterning. 50 nm titanium/ 100 nm gold electrodes were patterned using conventional photolithography techniques and electron beam evaporated. A 4 pm-thick AZ EC3027 positive photoresist (PR) was first spin coated on the substrate. The PR layer was then exposed with a broadband UV light source at a dose of 200 mJcm ² and a photomask to transfer the desired features. The PR was then developed using AZ 726 MIF developer. The Ti/Au electrodes were then deposited using an electron beam evaporator without breaking vacuum. Lift-off using acetone was performed lastly to remove the unwanted areas and complete the patterning process.

[0091] Step 3: Triboelectric layer deposition. Photoactive polycarbonate with benzophenone moieties (XPC) polymer was dissolved in a solvent of dimethyl-formamide (DMF) for 8 hours to have a 20 wt% solution. Isofluoropropyl polyhedral oligomeric silsesquioxane (F-POSS) in the appropriate loads (3 wt% to 23 wt%) were added to the solution and stirred until dissolved for around 8 hrs. Then, the solution was spin coated onto the electrodes at speed of 1,000 revolutions per minute (rpm), forming a layer having a thickness of 2.8 pm XPC-F-POSS blend. The film was annealed in a conventional oven for 4 hours at 100 °C under vacuum. The device was then exposed to UV light source with i-line (mean wavelength of 365 nm) with an energy dose of 21 mW/cm ² to create an optimum condition for the photochemical attachment of F-POSS to the XPC matrix.

[0092] FIG. 4 shows the polymeric coating layer XPC (4a), the polymeric coating layer with the addition of F-POSS (4b), and a graph comparing the single polymers versus the combination of the polymers (4c). As can be seen, the XPC-F-POSS blended polymer coating provided much higher voltage outputs than either the XPC or F-POSS alone. This indicates that a synergistic effect occurs with the combined polymer coating.

[0093] FIG. 6 is a graph of output voltage in volts versus F-POSS concentration in weight percent of the coating. As can be seen, the highest voltage output occurs at an F- POSS concentration of 15%, with the 18% and 21% concentrations yielding lower or the same outputs as the 9% and 12% concentrations. This indicates that lower concentrations can provide the same or better outputs compared to higher concentrations.

[0094] FIG. 7 is a graph of output voltage in volts versus electrical load in mega ohms

(MOhm) with an F-POSS concentration of 15 weight percent. As can be seen, output voltage increases with increasing resistance connected to the triboelectric touch sensor. Output voltage saturation is observed in the range of 500 MOhm to 1,000 MOhm. Resistance values plotted in logarithmic scale for clarity.

[0095] FIG. 8 is a graph of output voltage in volts versus coating layer thickness in micrometers with an F-POSS concentration of 15 weight percent and a resistance of 500 MOhm. As can be seen, the coating thickness of approximately 4.5 pm produced the highest voltage output, with a thickness of 3 pm being just slightly lower than the 4.5. Output voltage of the XPC-F-POSS blend remains relatively constant regardless of the active layer thickness. Films with thickness ranging from 2.8 pm to 80 pm were characterized without showing any significant output voltage difference. Thickness range of 2.8 pm to 10 pm is plotted for clarity of the figure. All values lie within the error margins.

[0096] FIG. 9 is a graph comparing output voltage in volts versus time in seconds for three different polymeric coatings. All materials characterized at same thickness of 2.8 pm and a resistance load of 500 MOhm. As can be seen, F-POSS shows a higher output voltage than XPC due to its intrinsic higher electronegativity. XPC-F-POSS blend (15 wt%) exhibits a higher output voltage than the individual polymers alone. XPC shows some intrinsic triboelectric properties with a maximum positive output voltage of around 0.3 Volts. The more electronegative F-POSS, due to the high fluorine content, is expected to show a higher output voltage than XPC and reaching nearly 2 Volts. Nonetheless, the blend of both materials, clearly exceeds the voltage output of films of the individual components reaching an average output voltage > 4 Volts. FIG. 9 clearly illustrates the advantage of the XPC-F- POSS blend (up to l5wt%) to the XPC matrix alone.

[0097] FIG. 10 is a graph comparing output voltage in volts for four different polymeric coatings. The graph demonstrates the superior performance of the XPC-F-POSS polymer compared to other conventional polymeric coatings that have previously been used for touch/force responsive sensors. A much higher voltage output is observed in films of XPC-F-POSS blend, which is more than 30% higher when compared with PVDF-TrFE (previously reported as one of the materials with the highest power output).

[0098] FIG. 11 is Raman spectra comparing three different polymeric coatings. (A) is shown for the XPC polymer alone; (B) is shown for XPC with 3 wt.% of F-POSS; and (C) is shown for XPC with 15 wt.% F-POSS. Raman inelastic radiation of the films was collected with DXR Raman microscopy system, equipped with CCD detector, and Olympus microscope. The spectrographs have 900 lines mm ¹ gratings with additional band-pass filter. Excitation laser lines at 533 and 632 nm were used. Spectra were collected in continuous mode with accumulation time of 16 s. Power at the sample was varied from 2 mW to 8 mW, and the laser was focused onto the sample using 10X objective. Overlay Raman spectra of (XPC), (F-POSS) and the nanocomposite film after crosslinking is shown in FIG. 11. In the region of 2873-2971 cm ¹ aliphatic hydrocarbon vibrational frequencies are noticeable corresponding to CFh and CEE stretching bands for both XPC, F-POSS, and the cross-linked nanocomposite blend. Clear differences in the Raman modes are evident in the fingerprinting region of the spectra (1800-300 cm ¹ ). Raman bands at 366 cm ¹ and 552 cm ¹ and 464 cm ¹ for non-cross-linked and native (F-POSS) spectrum are evident in the spectra. Upon crosslinking (F-POSS) onto the photoactive (XPC) substrate, these bands disappear or atenuate in intensity where a band characteristic of the cross-linked network appears at 485 cm ¹ . Furthermore, characteristic Raman vibrational bands of-O-Si-O of (F-POSS) cage at 1273 cm ¹ and characteristic Raman signatures of carbon fluorine (C-F) bonds in the fingerprint spectral area at 500-800 cm ¹ are shown in the spectra, corroborating the covalent attachment of (F-POSS) onto the surface of XPC as expected.

[0099] FIG. 12 shows optical surface profiles and 3D surface models of four different polymeric coatings, where a and e = XPC; b and f = 6 wt.% XPC-F-POSS; c and g = 12 wt.% XPC-F-POSS; and d and h = 15 wt. % XPC-F-POSS. The interface between the F-POSS and XPC is important in determining the electrical properties for future device application of these materials. To beter understand the nature of the F-POSS/XPC interface and the morphological changes that may occur in the film processing and cross-linking steps, optical surface profiling images using Zygo New 7300 interferometer were taken at different F- POSS loading in the nanocomposite film. FIG. 12 shows the surface maps and 3D surface models of XPC and selected XPC-F-POSS blends. Surface map and 3D surface model of native photoactive XPC surfaces and cross-linked nanocomposite surfaces with increasing (F- POSS) load are also shown in FIG. 12. It is important to note that the XPC surface apparently displayed smoother and less rough surfaces when compared with the cross-linked nanocomposite films with increasing F-POSS load (FIGS. l2a-d). However, all

nanocomposites films exhibit a coarse morphology and clustered structures sticking vertically out from the planar XPC photoactive substrate. These heterogeneous surface morphologies are indicative of the formation of F-POSS rich domains due to preferential migration of low surface energy F-POSS to outermost surface of the film. In this case, molecularly phase separated domains ensue due to the structural mismatch between the two components XPC and F-POSS in the blend. The net result is the formation of buried XPC inner phase and outermost fluorine rich regions with increasing spherical morphologies atributed to the increasing load of self-segregating F-POSS clusters in the blend.

[00100] FIG. 13 shows optical images of the four different polymeric coatings where a = 3 wt.% F-POSS -XPC; b = 9 wt.% F-POSS-XPC; c = 12 wt.% F-POSS-XPC; and d = 15 wt.% F-POSS-XPC. Optical images taken from different areas of the cross-linked films during Raman microscopy experiments in analogy to optical surface profiling images clearly exhibits dispersed clusters of F-POSS moieties across the film surfaces and, their Raman spectra neither change nor reveal any artifacts that may be created during the nanocomposite processing steps. With higher F-POSS loading in the blend, large black aggregates of presumably F-POSS species are also evident in the optical images (FIGS. l3c and l3d). Optical data analyses in all cases are supporting the observed monotonic increase of output voltage of the sensor device as the F-POSS loading is increased in the blend.

[00101] Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine- readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non volatile tangible computer-readable media, such as during execution or at other times.

Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.

[00102] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other aspects can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed aspect. Thus, the following claims are hereby incorporated into the Detailed Description as examples or aspects, with each claim standing on its own as a separate aspect, and it is contemplated that such aspects can be combined with each other in various combinations or permutations. The scope of the disclosure should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.