阅读说明：本技术 一种超耐洗双功能可穿戴电子织物及其制备方法 (Super-washable dual-function wearable electronic fabric and preparation method thereof ) 是由 崔银花 张少辉 吕景春 谢小保 施庆珊 于 2021-06-18 设计创作，主要内容包括：本发明公开了一种超耐洗双功能可穿戴电子织物及其制备方法。它在织物基底上,加入氯化铁与5-磺基水杨酸进行反应,反应结束后加入导电聚合物单体以原位聚合的方式得到导电聚合物@织物,然后通过电化学沉积将花状结晶的银修饰到导电聚合物@织物上,得到银花修饰的导电聚合物/银花@织物。本发明提供了一种全新的纺织品的修饰方法,有效提高了导电纺织品的灵敏度和检测范围,多层组合应用于双功能压力/应变传感器。可以检测到0-900kPa的超宽压力区间,且灵敏度能达到17.41kPa～(-1)。该设计方案构筑的传感器显示了超高的动、静态稳定性,可被用来跟踪多种人体物理信号。(The invention discloses a super-washable dual-function wearable electronic fabric and a preparation method thereof. Ferric chloride and 5-sulfosalicylic acid are added to a fabric substrate to react, a conductive polymer monomer is added after the reaction is finished to obtain a conductive polymer @ fabric in an in-situ polymerization mode, and then the conductive polymer/silver @ fabric modified by silver in a flower-shaped crystal is modified on the conductive polymer @ fabric through electrochemical deposition to obtain the conductive polymer/silver @ fabric modified by silver. The invention provides a brand-new textile modification method, which effectively improves the sensitivity and detection range of the conductive textile, and the multilayer combination is applied to the difunctional pressure/strain sensor. Can detect an ultra-wide pressure interval of 0-900kPa, and the sensitivity can reach 17.41kPa ‑1 . The sensor constructed by the design scheme shows ultrahigh dynamic and static stability, and canIs used to track a variety of physical signals of the human body.)

1. A preparation method of a wearable electronic fabric with super washing-resistant and double functions is characterized in that,

adding ferric chloride and 5-sulfosalicylic acid on a fabric substrate to react, adding a conductive polymer monomer after the reaction is finished to obtain a conductive polymer @ fabric in an in-situ polymerization mode, and then modifying the conductive polymer @ fabric with the flower-shaped crystallized silver through electrochemical deposition to obtain the conductive polymer/silver @ fabric modified by the silver.

2. The method according to claim 1, wherein the conductive polymer monomer is any one of pyrrole, aniline and thiophene; the fabric substrate is any one of knitted fabric, woven fabric and non-woven fabric.

3. The method of claim 1, wherein the step of adding ferric chloride to react with 5-sulfosalicylic acid is carried out by adding 0.36mol L of the fabric substrate to a final concentration^-1Ferric chloride and 0.36mol L^-1In a solution of 5-sulfosalicylic acidAfter the reaction is finished, adding a conductive polymer monomer to react in an in-situ polymerization mode to ensure that the concentration of the conductive polymer reaches 0.12mol L^-1To obtain the conductive polymer @ fabric.

4. The method of claim 3, wherein the fabric substrate is applied to a final concentration of 0.36mol L^-1Ferric chloride and 0.36mol L^-1The 5-sulfosalicylic acid solution is reacted at the reaction temperature of 0 ℃ for 12 to 18 hours.

5. The preparation method of claim 3, wherein the monomer added with the conductive polymer is reacted in an in-situ polymerization manner, the reaction temperature is 0-6.5 ℃, and the reaction time is 12 h.

6. The method of claim 1, wherein the electrochemical deposition is performed by a three-electrode system of an electrochemical workstation, the working electrode is a conductive polymer @ fabric, the reference electrode is saturated Ag/AgCl, the counter electrode is a platinum wire electrode, the applied voltage is-0.4V, and the electrodeposition time is 30-240 s.

7. A conductive polymer/silver @ fabric obtainable by the process according to any one of claims 1 to 6.

8. A multi-layer pressure sensor comprising a flexible substrate layer laminated from top to bottom, a noble metal electrode layer deposited on the flexible substrate, a plurality of conductive polymer/silver @ fabric layers of claim 7, a noble metal electrode layer deposited on the flexible substrate, and a flexible substrate layer.

9. The multi-layered pressure sensor according to claim 8, wherein the flexible substrate is Eco-Flex, PDMS or PET.

10. A strain sensor comprising the conductive polymer/silver @ fabric of claim 1 and two-sided electrodes.

The technical field is as follows:

the invention relates to the field of wearable electronic devices, in particular to a super-washable dual-function wearable electronic fabric and a preparation method thereof.

Background art:

wearable electronic equipment has wide application prospect in the fields of sports, health, aerospace and the like. Fabric is one of the most suitable materials for wearable devices, and electronic fabrics have become an important component of wearable devices due to their comfort and safety. The performance of the electronic fabric has great promotion space. In one aspect, the woven and knitted structure provides the fabric with a certain stretch function. If elastic fibers are added to the fabric, the wearable function of the fabric can be further improved. On the other hand, among conductive materials applicable to fabric modification, conductive polymers have the characteristics of low weight, easy preparation, high conductivity and high biocompatibility. And the conductive polymer has elasticity and plasticity almost as much as those of the textile. On the basis, reasonable and controllable modification can be further carried out on the fabric, so that the practical application of the fabric in the wearable field is improved.

The invention content is as follows:

the invention aims to provide a wearable electronic fabric with super washing-resistant and double functions and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

the wearable electronic fabric with the ultra-washable and dual functions is prepared by the following method:

adding ferric chloride and 5-sulfosalicylic acid to a fabric substrate for reaction, adding a conductive polymer monomer after the reaction is finished to obtain a conductive polymer @ fabric in an in-situ polymerization mode, and then modifying the conductive polymer @ fabric with the flower-shaped crystallized silver through electrochemical deposition to obtain the conductive polymer/silver @ fabric modified by the silver, namely the super-washable dual-function wearable electronic fabric.

The conductive polymer monomer is any one of pyrrole, aniline and thiophene.

The fabric substrate is any one of knitted fabric, woven fabric and non-woven fabric.

Preferably, the reaction between the added ferric chloride and the 5-sulfosalicylic acid is carried out by adding the fabric substrate to a final concentration of 0.36mol L^-1Ferric chloride and 0.36mol L^-1The 5-sulfosalicylic acid solution is reacted, and after the reaction is finished, a conductive polymer monomer is added to react in an in-situ polymerization mode to ensure that the concentration of the conductive polymer reaches 0.12mol L^-1To obtain the conductive polymer @ fabric.

Preferably, the fabric substrate is added to the fabric substrate at a final concentration of 0.36mol L^-1Ferric chloride and 0.36mol L^-1The 5-sulfosalicylic acid solution is reacted at the reaction temperature of 0 ℃ for 12 to 18 hours.

Preferably, the conductive polymer monomer is added to react in an in-situ polymerization mode, the reaction temperature is 0-6.5 ℃, and the reaction time is 12 hours.

The electrochemical deposition is carried out through a three-electrode system of an electrochemical workstation, a working electrode is a conductive polymer @ fabric, a reference electrode is saturated Ag/AgCl, a counter electrode is a platinum wire electrode, the applied voltage is-0.4V, and the electrodeposition time is 30-240 s.

The second purpose of the invention is to provide a multi-layer pressure sensor constructed by polypyrrole/silver flower @ knitted fabric, which comprises a flexible substrate layer, a noble metal electrode layer, a multi-layer conductive polymer/silver flower @ fabric layer, a noble metal electrode layer and a flexible substrate layer, wherein the flexible substrate layer, the noble metal electrode layer and the flexible substrate layer are stacked from top to bottom.

The flexible substrate has a wide selection range, and is generally selected from Eco-Flex, PDMS, PET and the like.

The noble metal electrode is made of gold, silver or chromium.

It is a third object of the present invention to provide a strain sensor comprising a conductive polymer/silver @ fabric and two side electrodes.

Preferably, the electrode can be a copper foil or nickel cloth electrode.

The rosette-shaped silver grows on the fabric substrate synthesized by the conductive high molecular polymer in situ through an electrochemical deposition process to be modified, so that the sensitivity and the pressure/strain working range of the constructed pressure/strain sensor are greatly widened. The invention solves the problem of insufficient stability of the current wearable electronic fabric. The resulting electronic textile is able to withstand minimal electrical signal drift even after repeated stretching and machine washing. The fabric is provided with comfort and safety, and the surface roughness and conductivity are improved due to electrochemical deposition modification, so that the conductive fabric is expected to be applied to various wearable devices.

The invention provides a brand-new textile modification method, which effectively improves the sensitivity and detection range of the conductive textile, and the multilayer combination is applied to the difunctional pressure/strain sensor. Can detect an ultra-wide pressure interval of 0-900kPa, and the sensitivity can reach 17.41kPa^-1. The sensor constructed by the design scheme shows ultrahigh dynamic and static stability and can be used for tracking various physical signals of human bodies.

Description of the drawings:

FIG. 1 is a Scanning Electron Microscope (SEM) image of a conductive polymer/silver @ fabric obtained in example 1 with an electrochemical deposition time controlled at 30 s;

FIG. 2 is a Scanning Electron Microscope (SEM) image of the conductive polymer/silver @ fabric obtained in example 1 with the electrochemical deposition time controlled at 60 s;

FIG. 3 is a Scanning Electron Microscope (SEM) image of the conductive polymer/silver @ fabric obtained in example 1 with the electrochemical deposition time controlled at 120 s;

FIG. 4 is a Scanning Electron Microscope (SEM) image of the conductive polymer/silver @ fabric obtained in example 1 with the electrochemical deposition time controlled at 240 s;

FIG. 5 is a schematic structural diagram of a pressure sensor constructed based on a multilayer conductive polymer/silver @ fabric;

FIG. 6 is a schematic structural diagram of a strain sensor constructed based on a single layer of conductive polymer/silver @ fabric;

FIG. 7 is a graph showing the sensitivity of a pressure sensor constructed based on a single layer of conductive polymer/silver @ fabric obtained at different deposition times (30,60,120,240s) over different pressure ranges;

FIG. 8 is a schematic diagram of the pressure sensing mechanism of a pressure sensor constructed based on a multilayer conductive polymer/silver @ fabric (120 s);

FIG. 9 is the sensitivity of different layers of conductive polymer/silver @ fabric (120s) in example 1 at different pressure intervals;

FIG. 10 is a graph showing the sensitivity statistics of the conductive polymer/silver flower @ fabric (120S) of example 1 after multiple washes over different pressure zones, wherein 3 transversal pillars are a set of 3 pressure zones, namely S1, S2 and S3;

fig. 11 is a sensitivity statistic plot of the conductive polymer/silver flower @ fabric (120s) in example 1 after multiple washes in different strain intervals, where 4 transversal pillars are a set of 4 four strain ranges, i.e. GF1, GF2, GF3 and GF 4;

FIG. 12 is a Scanning Electron Microscope (SEM) image of the conductive polymer/silver @ fabric (120s) of example 1 before multiple washes;

FIG. 13 is a Scanning Electron Microscope (SEM) image of the conductive polymer/silver @ fabric (120s) of example 1 after multiple washes.

The specific implementation mode is as follows:

in order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described in accordance with the drawings are exemplary only, and the invention is not limited to these embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not so relevant to the present invention are omitted.

Example 1

Soaking 5cm by 5cm knitted fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1The pyrrole solution is used for leading the pyrrole to generate in-situ polymerization reaction (the mass difference between the polypyrrole @ knitted fabric substrate and the knitted fabric substrate), the polymerization temperature is 5 ℃, the time is 12 hours, and the concentration of the polypyrrole reaches 0.12mol L^-1And preparing the polypyrrole @ knitted fabric. The polypyrrole/silver @ knitted fabric is manufactured by using an electrochemical workstation of a three-electrode system. The working electrode is 1 x 1.5cm²The polypyrrole @ knitted fabric has a reference electrode of saturated Ag/AgCl, a platinum wire electrode as a counter electrode, an applied voltage of-0.4V and an electrolyte containing 1mmol L of L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

Polypyrrole/silver @ knitted fabrics with different shapes are prepared under different electrodeposition time (30,60,120 and 240s), corresponding Scanning Electron Microscope (SEM) images are shown in figures 1-4, and structural schematic diagrams of a multilayer pressure sensor and a strain sensor constructed by the polypyrrole/silver @ knitted fabrics are shown in figures 5 and 6.

The pressure sensor includes: the flexible substrate layer comprises a flexible substrate layer 3, a precious metal electrode layer 2 deposited on the flexible substrate, a multi-layer polypyrrole/silver @ knitted fabric layer 1, a precious metal electrode layer 2 deposited on the flexible substrate and the flexible substrate layer 3 which are stacked from top to bottom. The flexible substrate 3 has a wide selection range, and is generally selected from Eco-Flex, PDMS, PET, and the like. The noble metal electrode is made of gold, silver or chromium.

The strain sensor includes: the single-layer polypyrrole/silver flower @ knitted fabric comprises a single-layer polypyrrole/silver flower @ knitted fabric 1 and electrodes on two sides, wherein the electrodes can be copper foil electrodes or nickel cloth electrodes 4.

First, by comparing the sensitivities of polypyrrole/silver @ knitted fabrics with different morphologies prepared under different electrodeposition times (30,60,120,240s) of a single layer, it can be seen that the sensitivity of the sensor tends to be saturated at 120s, and the sensitivity does not substantially increase any more when the sensitivity exceeds 120s (fig. 7). Therefore, the performance of the subsequently assembled multilayer polypyrrole/silver @ knit based pressure sensor was tested by unrolling the polypyrrole/silver @ knit prepared at a deposition time of 120 s.

For convenience in explaining the pressure sensing behavior based on the fabric layering structure, fig. 8 shows one possible working mechanism. Since multiple layers of fabric are stacked together, there are numerous points of cross contact and empty space. Essentially, the working mechanism of the sensor is based on piezoresistive effect. The resistance change is mainly controlled by the connections and gaps in the fabric network structure, where polypyrrole and silver help to establish the conductive path. When no external force is applied, multiple air gaps exist between the layers of the multi-layer polypyrrole/silver @ knit resulting in a higher initial resistance. The initial resistance can be calculated as:

R_Total＝R_a+R_b+R

wherein R is_aIs the resistance of the top fabric electrode, R_bIs the resistance of the bottom fabric electrode and R is the contact resistance. Upon application of pressure, the sensor deforms primarily in the vertical direction. Under the influence of the effective deformation, the conduction path is adjusted accordingly, resulting in a resistance R_a、R_bAnd R decreases. As the pressure further increases, the resistance further decreases as the contact area continues to increase.

With the multilayer stacking of the polypyrrole/silver @ knit, the sensitivity of the textile sensor to different ranges of pressure is further improved, as shown in fig. 9. In order to further study the trend of the change in the sensing properties (pressure/strain sensing) of the samples (selected single-layer polypyrrole/silver @ knit fabrics) after multiple washes, three sets of control experiments (refer to GB/T8629-. FIG. 11 shows the statistical strain sensitivity GF over four strain ranges (four strain ranges: 0-18%, 18-40%, 40-65%, 65-100%). Experiments have shown that the obtained electronic textile can withstand minimal electrical signal drift even after repeated stretching and machine washing. Figures 12 and 13 are Scanning Electron Microscope (SEM) images of the polypyrrole/silver @ knit before and after multiple washes.

Example 2

Soaking 5cm by 5cm knitted fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1The thiophene in the thiophene cyclohexane solution is subjected to in-situ polymerization reaction until the concentration of the polythiophene reaches 0.12mol L^-1(the difference in mass between the polythiophene @ knit substrate and the knit substrate) was such that the polymerization temperature was 5 ℃ and the time was 12 hours, thereby producing a polythiophene @ knit. The polythiophene/silver @ knitted fabric is made by using an electrochemical workstation of a three-electrode system. The working electrode is 1 x 1.5cm²The reference electrode is saturated Ag/AgCl, the platinum wire electrode is a counter electrode, the applied voltage is-0.4V, and the electrolyte contains 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 3

Soaking 5cm by 5cm knitted fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1Aniline cyclohexane solution of (1). Aniline is subjected to in-situ polymerization until the concentration of polyaniline reaches 0.12mol L^-1(the mass difference between the polyaniline @ knitted fabric substrate and the knitted fabric substrate) is that the polymerization temperature is 5 ℃ and the time is 12 hours, so that the polyaniline @ knitted fabric is prepared. The manufacturing method of the polyaniline/silver flower @ knitted fabric is an electrochemical workstation using a three-electrode system. The working electrode is 1 x 1.5cm²The polyaniline @ knitted fabric is characterized in that a reference electrode is saturated Ag/AgCl, a platinum wire electrode is used as a counter electrode, the applied voltage is-0.4V, and the electrolyte contains 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 4

Soaking 5cm by 5cm woven fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1Is prepared by dissolving pyrrole in cyclohexane. Pyrrole is subjected to in-situ polymerization until the concentration of polypyrrole reaches 0.12mol L^-1(the polypyrrole @ woven fabric substrate and the woven fabric substrate are poor in quality), the polymerization temperature is 5 ℃, and the time is 12 hours, so that the polypyrrole @ woven fabric is prepared. The polypyrrole/silver @ woven fabric is made by an electrochemical workstation using a three-electrode system. The working electrode is 1 x 1.5cm²The polypyrrole @ woven fabric is characterized in that a reference electrode is saturated Ag/AgCl, a platinum wire electrode is used as a counter electrode, the applied voltage is-0.4V, and the electrolyte contains 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 5

Soaking 5cm by 5cm woven fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1In solution in thiophene cyclohexane. The thiophene is subjected to in-situ polymerization reaction until the concentration of the polythiophene reaches 0.12mol L^-1(the polythiophene @ woven fabric substrate and the woven fabric substrate are poor in quality), the polymerization temperature is 5 ℃, and the polymerization time is 12 hours, so that the polythiophene @ woven fabric is prepared. The polythiophene/silver flower @ woven fabric is made by an electrochemical workstation using a three-electrode system. The working electrode is 1 x 1.5cm²The polythiophene @ woven fabric is characterized in that a reference electrode is saturated Ag/AgCl, a platinum wire electrode is used as a counter electrode, the applied voltage is-0.4V, and the electrolyte contains 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 6

Soaking 5cm by 5cm woven fabric substrate in 10ml solution containing ferric chloride and 5-sulfosalicylic acid 0.36mol L each^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1Aniline cyclohexane solution of (1). Then adding aniline to carry out in-situ polymerization reaction until the concentration of polyaniline reaches 0.12mol L^-1(the quality of the polyaniline @ woven fabric substrate is poor) and the polymerization temperature is 5 ℃ and the time is 12 hours, so that the polyaniline @ woven fabric is prepared. The manufacturing method of the polyaniline/silver flower @ woven fabric is an electrochemical workstation using a three-electrode system. The working electrode is 1 x 1.5cm²The polyaniline @ woven fabric has a reference electrode of saturated Ag/AgCl, a platinum wire electrode of-0.4V and electrolyte containing 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 7

5cm by 5cm nonwoven fabric substrate was soaked in 10ml of a solution containing 0.36mol L each of ferric chloride and 5-sulfosalicylic acid^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1Is prepared by dissolving pyrrole in cyclohexane. Pyrrole is subjected to in-situ polymerization until the concentration of polypyrrole reaches 0.12mol L^-1(poor quality polypyrrole @ nonwoven substrate to nonwoven substrate) was polymerized at 5 ℃ for 12 hours to produce polypyrrole @ nonwoven. The polypyrrole/silver @ nonwoven fabric was made using an electrochemical workstation using a three electrode system. The working electrode is 1 x 1.5cm²The polypyrrole @ non-woven fabric has a reference electrode of saturated Ag/AgCl and a platinum wire electrode of-0.4V, and the electrolyte contains 1mmol L of electrolyte^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 8

5cm by 5cm nonwoven fabric substrate was soaked in 10ml of a solution containing 0.36mol L each of ferric chloride and 5-sulfosalicylic acid^-1In solution ofThe reaction temperature was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.12mol L was added^-1In solution in thiophene cyclohexane. The thiophene is subjected to in-situ polymerization reaction until the concentration of the polythiophene reaches 0.12mol L^-1(Polythiophene @ nonwoven substrates are poor quality nonwoven substrates) and the polymerization temperature is 5 ℃ for 12 hours, producing a polythiophene @ nonwoven. The polythiophene/silver @ nonwoven fabric was made using an electrochemical workstation using a three electrode system. The working electrode is 1 x 1.5cm²The polythiophene @ non-woven fabric has a reference electrode of saturated Ag/AgCl, a platinum wire electrode of-0.4V and an applied voltage, wherein the electrolyte contains 1mmol L of electrolyte^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

Example 9

5cm by 5cm nonwoven fabric substrate was soaked in 10ml of a solution containing 0.36mol L each of ferric chloride and 5-sulfosalicylic acid^-1The reaction temperature in the solution (2) was 0 ℃ and the reaction time was 15 hours. Further, 10ml of 0.36mol L was added^-1Aniline cyclohexane solution of (1). Aniline is subjected to in-situ polymerization until the concentration of polyaniline reaches 0.12mol L^-1(poor quality of polyaniline @ nonwoven substrate and nonwoven substrate) polymerization temperature was 5 ℃ and time was 12h, making polyaniline @ nonwoven. The polyaniline/silver flower @ nonwoven fabric is made using an electrochemical workstation with a three electrode system. The working electrode is 1 x 1.5cm²The polyaniline @ non-woven fabric has a reference electrode of saturated Ag/AgCl, a platinum wire electrode of-0.4V and an electrolyte of 1mmol L^-1Silver nitrate, 2mmol L^-130mmol L of sodium citrate^-1Potassium nitrate.

The remainder refer to example 1.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.