Impedance resonance sensor for real time monitoring of different processes and methods of using same

Processes and apparatuses are provided for contactless measuring or monitoring in-situ and in real time composition or other electromagnetic impedance correlated properties of liquid or gaseous substances or bulk materials. One or more apparatus may include a resonance type impedance sensor having at least two coils, at least one coil of the at least two coils being at least one excitation coil connectable to at least one alternating current source with frequency sweep, at least one other coil of the at least two coils being at least one sensing coil connectable to at least one data processing system. The one or more methods may include calculating changes in amplitude and resonant frequency induced by electromagnetic interaction between said sensor and object to determine impedance of said object under test; and matching said impedance with predetermined calibration data to determine said chemical or physical properties of said object under test.

BACKGROUND OF THE INVENTION

The present invention relates in general to one or more methods and apparatuses for determining selected properties and various constituents concentration in liquids, gaseous and solid solutions as well as determining other properties such as density and moisture content of many varieties of solid and gaseous materials. More particularly, the present invention relates to one or more methods and apparatuses for determining concentration of individual components within a mixture by utilizing method of Electrochemical Impedance Spectroscopy which measures the electric properties of a medium as a function of frequency.

Determination of mixture composition is a commonly encountered need. It is no wonder that huge amount of inventions are dedicated to this important task. One of possible means is to analyze electrical properties of target mixture. Most commonly means for determining mixture composition are contact electrode methods. Unfortunately, prior devices are deficient for a plurality of reasons, including, but not limited to, the fact that one or more sensors of such prior devices lack the desired sensitivity, the one or more sensors must be located in inconvenient location(s) with respect to the composition/object being evaluated or tested, etc. As such, there is a need in the art to create an improved invention with enhanced sensitivity for determining one or more mixture compositions or for otherwise obtaining data from an object under test.

It would also be desirable to provide an invention that permits the ideal location of the sensors and/or other components thereof with respect to the composition and/or the object under test.

SUMMARY OF THE INVENTION

The invention relates to electrical devices and, more particularly, to a highly sensitive impedance resonant (IR) sensor with a sensing head, which is an open-core or air core sensing inductor with excitation and sensing coils.

Several improvements of Impedance Resonance (IR) sensor apparatuses and methods of use are disclosed. One or more aspects of the present invention also may be employed in conjunction with a suitable IR sensor, including, but not limited to, the IR sensor of co-pending U.S. patent application Ser. No. 12/887,887, Filing Date: Sep. 22, 2010, the entirety of which is incorporated herein by reference. These improvements of the present invention supplement basic variant with additional advanced merits and attributes. Two disclosed modifications or improvements bear a relation to one or more methods for acquiring results of measurement made by at least one sensor. Other modification(s) or improvement(s) enhance sensitivity of the at least one sensor by exploiting change of a sensing coil distributing capacitance (turn-to-turn capacitance) while immersing the sensing coil into, adjacent to, or near at least one liquid, gaseous or bulk material object under test. Another modification or improvement relates to the location of the one or more sensing and excitation coils. This additional or alternative modification or improvement unveils the possibility of placing the sensing coil into a vessel whereas the excitation coil encompasses the vessel.

In accordance with one or more purposes and/or aspects of the present invention, as embodied and/or broadly described herein, one or more embodiments of the present invention may use both modified and basic variants of the IR sensor. At least one embodiment may use the IR sensor with an immersible sensing coil for evaluating properties of a liquid, such as, but not limited to, an oil, motor oil, milk, chlorine concentration in water, moisture in soil, dextrose concentration in saline, etc. At least one embodiment of the invention may determine the presence of one or more selected, or predetermined, elements in one or more lubrication oils by means of an electromagnetic field probing same based on resonance impedance technology, and may alert an end-user of the device when a concentration of at least one of the preselected harmful constituents measured by one of the IR sensors exceeds an allowable, or a predetermined, concentration level. At least an additional embodiment of the invention may be dedicated to measuring the concentration of one or more milk ingredients. At least a further embodiment of the invention may be used to measure soil moisture. Yet a further embodiment of the invention may operate to measure a dextrose concentration in saline. Still, yet another embodiment of the invention may be dedicated to the measurement of a residual chlorine concentration in tap water.

An apparatus, method for monitoring without contact in situ and real time of selected properties and various constituents concentration in liquids, gaseous and solid solutions as well as determining other properties such as density and moisture content of many varieties of solid and gaseous materials, are disclosed. The invention also includes an Impedance Resonance (IR) sensor model for use for selected samples with the above-described aspects. In one embodiment, the invention determines presence of selected elements in lubrication oils based on an effect of resonance impedance characteristics of the solution on an electromagnetic field, and alerts an end-user when concentration of one of the preselected harmful constituents by one of the IR sensors exceeds allowable concentration levels. Change of the conductivity and dielectric properties of the solution will change the impedance of the IR sensor's excitation or sensing coil. The harmful constituent's concentration indication is determined based on one or more solution properties, temperature and quantity of the solution.

The invention relates to electrical devices and, more particularly, to a highly sensitive impedance resonant (IR) sensor with a sensing head, which is an open-core or air core sensing inductor with excitation and sensing coils.

Additionally or alternatively, a resonance type impedance sensor, which is a multicoil open-core or air-core inductor, may include at least two coils, at least one coil of the at least two coils being at least one excitation coil connectable to at least one alternating current source with frequency sweep, at least one other coil of the at least two coils being at least one sensing coil connectable to at least one data processing system, wherein: (i) upon electrical connection to said current source, said at least one excitation coil is capable of propagating an energy to said at least one sensing coil, which is capable of generating a probing electromagnetic field, (ii) said at least one sensing coil is designed in such a way that intrinsic inductance L, capacitance C, and resistance R parameters of said at least one sensing coil are capable of providing resonance conditions for measuring of object under test impedance at predetermined frequency, said object under test capable of being at least one of conductive, semi-conductive and non-conductive, and (iii) said at least one sensing coil is not connected to a capacitance means located externally to said at least one sensing coil such that said at least one sensing coil is capable of measuring at least one of conductance and one or more dielectric properties of at least a part of said object under test falling within a sensing area or range of said at least one sensing coil.

DETAILED DESCRIPTION

1 Structure and Principle of Operation of at Least One Embodiment of an IR Sensor with an Open-Circuit Sensing Coil

1.1 Modification/Improvement in which Information is Obtained from Excitation Coil

A schematic electrical circuit of one embodiment of a sensor of the present invention is shown inFIG. 1. Similar to the sensor disclosed in our U.S. patent application Ser. No. 12/887,887, the entirety of which is incorporated herein by reference, the sensor of the present invention comprises a two-coil inductor with an open or air core. One coil, i.e., a coil1, is an excitation coil, and the second coil, i.e., a coil2, is a sensing or measurement coil.

At least one embodiment of the sensor operates as follows: A frequency-based sweep generator3, which functions as the source of a variable-frequency electric field, feeds the excitation coil1. The frequency variation range of the generator includes resonance frequency of the sensing coil2. Being in an electromagnetic coupling with the sensing coil2, the excitation coil1brings the latter into a state of self-resonance. The condition of self-resonance leads to a significant increase in the intensity of the electromagnetic field induced by the inductor, e.g., by its sensing coil. A test object placed into this electromagnetic field develops eddy currents and/or vortex displacement currents, which, in turn, generate their own electromagnetic fields that are perceived by the sensing coil. Such interaction changes not only the resonance frequency but also the amount of dissipated electromagnetic energy. In order to compensate for this loss of energy, the current in the circuit comprising the frequency-based sweep generator3and the excitation coil automatically increases. This process is similar to transfer of a transformer from the idle mode to the under-load mode of operation. Such variation in flow of electromagnetic energy can be registered by a high-frequency ammeter4and a voltmeter5, but the use of only an ammeter is sufficient.

1.2 Modification/Improvement in which Information is Obtained from at Least One Sensing Coil and at Least One Excitation Coil

FIG. 2shows at least one embodiment of a sensor including a modification wherein information is obtained from both the sensing coil and the excitation coil of the sensor. Similar to the sensor shown inFIG. 1, the sensor of the present embodiment ofFIG. 2is a two-coil inductor with an open or air core. One coil is an excitation coil11, and the second coil is a sensing or measurement coil12. A distinguishing feature of the sensor of this embodiment is formation of the signal, which corresponds to impedance characteristics of a test object, with use not only of a sensing coil circuit (components12and16) but also with participation of the excitation coil (components11,13,14and15).

As explained above, impedance of the test object affects electrical parameters not only in the sensing circuit, which is in the state of resonance, but also in the excitation circuit. The current that flows through the excitation coil grows proportionally with the amount of electromagnetic energy dissipated from the test object. Such change in the current increases voltage amplitude on a bypass resistor15, and a data acquisition unit14registers the voltage increase.

Electrical characteristics of the sensing circuit of the highly sensitive IR sensor of the invention change in the same or similar manner as described in the aforementioned pending U.S. patent application Ser. No. 12/887,887. Interaction of the sensor with the test object changes resonance frequency and resonance amplitude, which are registered by a data acquisition unit16.

A useful measurement signal may be formed by using various combinations of data obtained by the data acquisition units14and16. For example, the following data can be used:

For example, in at least one embodiment of a CMP (Chemical Mechanical Polishing) sensor developed by the applicant on the basis of the present invention, a useful signal (data obtained from the sensor) is formed by using an RF/IF (radio frequency/intermediate frequency) Gain and Phase Detector, which comprises a dual-channel demodulating logarithmic amplifier with a phase detector. Characteristics of this instrument are as follows: operating frequency range of about 0 to about 2.7 GHz; minimal output signal of about 30 mV, which corresponds to −20×Log(Vex/Vm)=−30 dB; and maximal output signal of about 1.8V, which corresponds to −20×Log(Vex/Vm)=+30 dB.

Resonance frequency can be determined by means of:a) frequency sweeping and searching of the maximum (or minimum) value of the useful signal; orb) using information obtained from a phase detector (this method is based on one of the fundamental conditions of resonance, i.e., the absence of a phase shift between forced oscillations that are induced by the excitation circuit and natural electromagnetic oscillations of the sensing coil).
1.3 Modification/Improvement of a Sensing Coil Included in the Structure of One or More IR Sensors of the Invention with Sensitivity Improved Based on an Effect of the Dependence of Turn-to-Turn Capacitance from Dielectric Properties of Liquid, Powdered, or Gaseous Test Object(s) that Fill(s) a Space Between Turns and Layers of the Aforementioned Sensing Coil

In our pending U.S. patent application Ser. No. 12/887,887, the entirety of which is incorporated herein by reference, we focused on the fact that in order to improve sensitivity of the IR sensor to dielectric properties of the test object, it is useful to minimize natural capacitance of the sensing circuit. The sensing circuit of aforementioned sensor comprises the sensing coil only, and turn-to-turn capacitance of the sensing coil is considered as a “parasitic” one. The demand for minimization of turn-to-turn capacitance is absolutely justifiable for all the examples used in the aforementioned patent application. In examples of that patent application, a substance that fills the space between the turns and layers of the sensing coil before beginning the measurement process remains the same during the measurement process. For a sensor of this application (e.g., where the sensing coil is immersed into a test object), measurement conditions are quite different since in this case the useful signal includes changes caused in the turn-to-turn and in the interlayer capacitance of the sensing coil by the material of the test object that fills the spaces between the turns of the coil. In order to enhance this effect, a coil with a rectangular rather than a circular cross-section is preferably used, as shown inFIG. 3. In this case, the surface area of the so-called “turn-to-turn” capacitance is considerably increased.

FIG. 4andFIG. 5illustrate other design embodiments of sensing coils that use turn-to-turn capacitance to improve sensitivity of the IR sensor.

An excitation coil may have different positions relative to a sensing coil:a) in a cylindrically shaped sensing coil (FIG. 3), the excitation coil may be arranged at the end face (left or right) of the sensing coil or may embrace the sensing coil in any location, as described below in Section 1.4;b) in a flatly shaped sensing coil (FIG. 4andFIG. 5), the excitation coil may surround the sensing coil being in the same plane therewith; alternatively, the excitation coil may be located on either side and in proximity to the sensing coil in a plane parallel with the latter; and/orc) the excitation coil may be arranged as described below in Section 1.4.

Any of the three methods (two of which are described above in Sections 1 and 2 and one in our aforementioned patent application Ser. No. 12/887,887, which is incorporated herein by reference in its entirety) can be used to obtain information from the IR sensor of the invention.

In Section 2.1 an example of one or more possible applications for these kinds of sensors is discussed below, and given measurements results therefor correspond to, and indicate, degradation of motor oil.

1.4 Modification/Improvement of at Least One IR Sensor of the Present Invention Wherein at Least One Sensing Coil is Immersed into or Near a Test Object Material Located in a Tube (or Vessel) and with an Excitation Coil Located Outside the Tube (or Vessel)

In at least one embodiment, the sensing coil32is located inside a tube or vessel, while the excitation coil31is located outside the tube or the vessel (FIG. 6). This structure is based on the principle of an IR sensor with the open-loop type of sensing coil described in Section 1 of this specification. The frequency-based sweep generator33comprises a variable-frequency source. Preferably, the resonance frequency of the sensing coil32is included in the frequency variation range. Measurement data are obtained from a high-frequency ammeter34.

While not intended to be an exhaustive list of the structural arrangements of, or ways to use, one or more IR Sensors of the present invention, several embodiments of one or more IR Sensors are disclosed herein to illustrate how the one or more IR Sensors may be used to evaluate one or more properties of various types of object(s) under test (whether liquid, solid, gaseous or otherwise), such as, but not limited to, oil, motor oil, milk, chlorine in water, slurry, etc.

Use of an IR Sensor to Evaluate Properties of Motor Oil

Description of experiment:

1. Three samples of motor oil were obtained from auto repair shop:fresh new oil;motor oil after 3678 miles of usage; andmotor oil after 7801 miles of usage.

2. The samples were placed in three vials of 15 cc volume.

3. An IR sensor having a sensing coil of the type shown inFIG. 3has been immersed in each of the vials by turns.

Results of the measurement are shown inFIG. 7,FIG. 8, andFIG. 9.

Use of at Least One System of IR Sensors for Real Time Monitoring of a Quality of Slurry During a CMP Process

At least one embodiment of the invention is directed to real time monitoring quality of slurry during a CMP process. It is critical to reduce wafer defects during the polishing process and lower cost of ownership in current and next generation CMP tools. To maintain CMP slurry health during usage, it is essential to monitor and control slurry's chemical (e.g., oxidizer and additive levels and their decay behavior), as well as abrasive properties, including particles size distribution (PSD), large particle counts (LPC), density, etc. The method allows in real time monitoring of the oxidizer concentration as well as the abrasive particle information in CMP slurry blends. This works on the principles of chemometrics, which is a two-phase process. In the first “calibration” phase, samples with known property values are measured by the system. A mathematical procedure then determines the correlation between the measured spectra and true property values. The output of this phase is a “model” that optimally calculates the parameter values from the measured spectra of the calibration samples. In the second “measurement” phase, unknown samples are measured by the system employing the model to produce estimates of the property values.

The system may comprise of various types of IR sensors designed for measurement of liquids. The system may include one or more sensors that have no contact with the slurry as described in U.S. patent application Ser. No. 12/887,887, sensors as described in U.S. provisional patent application No. 61/566,267, such as in paragraph 1.3 thereof, as described herein, etc.

IR Measuring of Somatic Cell Count, Lactose Concentration and Fat Content in Milk

Using a standard potentiostat we identified areas where an electrical field influences various milk components.FIG. 10shows a “screen shot” or graph of five different milk samples scanned with a potentiostate in a frequency range from about 10-about 170 MHz. We can see on the screen shot/graph areas where graph plots for different milk samples split in amplitude. These are areas where phenomena of impedance spectroscopy take place. In those areas, influence of each individual constituent can be defined. These scans show a large number of possible frequencies that could be used for measurement of milk components.

In order to identify the best fitted frequencies, we used three milk samples with the minimum and maximum concentrations of target constituent: 1) skim milk (about 0% fat) and 3.2% pasteurized milk to identify the frequency of monitoring fat content; 2) pasteurized 3.2% fat milk and farm milk with fat about 3.2% but with great difference in Somatic Cell Count (SCC) to define the frequency where SCC has the strongest response; and 3) 3.2% pasteurized milk with lactose free milk and the second sample with lactose and about the same fat content (3.2%) to define the frequency where lactose has the strongest response.

Using data from the potentiostate we defined that at frequency of about ˜126 MHz we got sufficient sensitivity for measuring SCC, at frequency of about ˜117 MHz to lactose, and at frequency of about ˜131 MHz to milk fat. Those data permitted us to calculate measuring circuits' parameters at frequencies close to those identified. We constructed measuring circuits (coils) and mounted them on a fixture (FIG. 11). We placed milk specimens with known characteristics in vials and recorded signal gain-frequency variations.

In our experiments, the concentration of lactose was changed by dilution of whole milk with lactose free milk, and the concentration of milk fat was changed by dilution of 3.2% milk with skim milk. In the experiments shown in series 1, no lactose or fat were present in the milk samples. Contrary, the experiments in series 4 scans showed maximum content of lactose (FIG. 12) and fat in milk (FIG. 13). Series 2 and 3 correctly showed increasing levels of lactose and fat in milk samples. Experiments with measuring lactose and fat were made with samples where known concentrations were diluted. All experiments related to SCC were confirmed experimentally by DCC (DeLaval Cell Counter), scans of SCC shown onFIG. 14. We used just one kind of milk and added to it cells to change SCC concentration. The signal reading correlated with SCC at fixed frequency is not monotonic (FIG. 15).

The process of measuring fat content in milk is similar to measuring SCC (FIG. 15) that was described above. The signal reading correlated with milk fat at fixed frequency is inFIG. 16.FIG. 15andFIG. 16show non-monotonic constituents' response to IR probing and measuring of those constituents. Preferably, such probing and/or measuring is done with two sensors per each constituent. The experiments with milk show the possibility to monitor each of the constituents' concentration in their natural range of fluctuation in very complex structures.

The mathematical simulation of constituents measuring where probing with IR yields non-monotonic graphs help to define two frequencies for building sensors.FIG. 17is a graph depicting the two results of 127.34 MHz and 127.42 MHz. These frequencies are data for constructing measuring coils for SCC.

Thus, we have identified new problems in the analytic arts, and have provided new solutions for these as well as for known problems in the art. Using a multiple-sensor system of this invention, it is now possible to measure multiple different constituents simultaneously, in real-time, and without increasing risks associated with either removing samples from a stream of production or from contaminating the stream with unwanted materials introduced during sampling.

IR Measuring of Soil Moisture

For identifying areas of electrical field frequencies where soil moisture gives good response, a potentiostate has been used.FIG. 18shows a “screen shot” or graph of three soil samples with different moisture scanned with a potentiostate in a frequency range from 0 to 500 MHz. We can see on the screen shot/graph areas where graph plots for different soil samples split in amplitude. These are areas where phenomena of impedance spectroscopy take place. In those areas, influence of moisture may be defined. These scans show a large number of possible frequencies that could be used for measurement of soil moisture.

Using data from the potentiostate we defined that at frequency from about 170 MHz to about 190 MHz we got sufficient sensitivity for measuring moisture. Those data permitted us to configure one or more IR sensor operating frequencies substantially close to those identified. Gain-frequency variations of the IR sensor are shown inFIG. 19. As it can be seen fromFIG. 19, the changing of moisture from about 0% to about 20% causes a change of: (i) IR sensor resonant amplitude from ˜about 9700 mV to about 7000 mV; and (ii) IR sensor resonant frequency from ˜about 185 MHz to about 175 MHz. Thus sensitivity of the IR sensor is about 135 mV of resonant amplitude on one percent of soil moisture and about 5 MHz of resonant frequency on one percent of soil moisture.

Use of an Impedance Resonance Sensor for Real Time Contactless Monitoring of Glucose in Saline

One of the key components of intravenous solutions/drips (IVs) is saline, which is also known as, for example, the 0.9% sodium chloride (NaCl) solution. It is used frequently in IVs for patients who cannot take fluids orally and have developed or are in danger of developing dehydration or hypovolemia. Saline is typically the first fluid used when hypovolemia is severe enough to threaten the adequacy of blood circulation, and has long been believed to be the safest fluid to give quickly in large volumes. Also, saline solution could be used to deliver various drugs intravenously. Because Normal Saline is a close approximation to the osmolarity of NaCl in blood, we used it to conduct our experiments to verify if IR sensor technology could be used for identification of glucose concentration and, most importantly, to verify the possibility of using IR sensors for contactless identification of harmful levels of glucose in blood in real time.

Description of experiment:

1. We prepared saline solution by adding 9 g of NaCl to 1000 ml of distilled water.

2. In the saline solution was added glucose to make the following samples with glucose concentration of: 5000, 2000, 1000, 500, 250 and 125 mg/dL.

3. The samples were placed by turns in an IR sensor test fixture as shown inFIG. 11.

4. All measurements were conducted by sweeping frequency in a range from 96 to 100 MHz.

The below presented measurements from our experiments show quite promising results that give us a high degree of confidence that development of non-direct contact with a blood medical device to measure the level of glucose in the blood is possible when using IR sensor technology.

Results of the measurement are shown inFIG. 20,FIG. 21, and Table 1.

A monitoring device measures the concentration of glucose in a patient's tissue, blood, or other bodily fluids; provides an indication of the rate of change of such concentration; and determines whether the measured concentration and rate of change are within certain preset or predetermined limits. If not, an audible and/or visual alarm signal is generated. The patient monitoring system includes at least one IR sensor that is placed on the patient, where it produces sensor signals related to the concentration of the glucose in the blood that is being measured. The sensor's signals are displayed on the device's screen, or are delivered through a suitable interconnect cable to a monitor. The device interprets the sensor signals by applying a previously determined calibration to quantitatively determine the glucose concentration value. The glucose concentration value thus determined is then processed in order to determine the rate of change, is stored (to create a history or record), and may also be displayed in large, easy-to-read numerals. Rate of change information (trend) may also be numerically or graphically displayed.

As of today, we have conducted a number of experiments to identify frequencies at which we can distinguish different concentrations of glucose in the 0.9% sodium chloride solution that is also known as, for example, a Normal Saline (“NS”)*. The output voltage of the IR sensor in relationship to the glucose concentration of 5000, 2000, 1000, 500, 250, and 125 mg/dl at a selected range of frequencies is presented inFIG. 20. Glucose concentrations were selected based on our understanding that the level of sugar of up to about 125 mg/dL is considered more or less normal and everything above that threshold will indicate various stages of diabetes, with anything above about 500 mg/dl indicating lethal levels.

All experiments were conducted with the sodium chloride 0.9% solution in order to eliminate the influence of any other liquid parameters and because most of intravenous glucose solutions are using similar concentrations of the sodium chloride (NaCl).Normal saline—is the commonly-used term for a solution of 0.90% of NaCl, about 300 mOsm/L or 9.0 g per liter. NS is used frequently in intravenous drips (IVs) for patients who cannot take fluids orally and have developed or are in danger of developing dehydration or hypovolemia. As explained above, NS is typically the first fluid used when hypovolemia is severe enough to threaten the adequacy of blood circulation, and has long been believed to be the safest fluid to give quickly in large volumes. Because Normal Saline is a close approximation to the osmolarity of NaCl in blood we used it to conduct our experiments.

Use of an Impedance Resonance Sensor for Real Time Contactless Measurements of Residual Chlorine in Tap Water

In order to test effectiveness of the IR sensor for measuring residual chlorine in tap water we used a solution of POWER POWDER® PLUS containing Calcium Hypochlorite—73% as active ingredient (according to specification for that product which when mixed with water provides at least 70% Available Chlorine). To prevent contamination of water by residual chlorine in tap water, we used Alhambra® drinking water that we normally drink in our lab. For measuring residual chlorine concentration, we used SenSafe™ Free Chlorine Water Check Test Strips (USEPA Approved), which are sold by Industrial Test Systems, Inc., located in Rock Hill, S.C. (www.sensafe.com), with detection range: 0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.5, 2, 2.6, 4, 6 ppm (mg/L). During our experiment, we used prior configured IR sensor. While various arrangements of the IR sensor's sensing element may be used, the IR sensor's sensing element used for this example is shown inFIG. 11. For laboratory experiments/measurements, it is convenient to use a sensor encompassing a vial, but for industrial in-situ measurements applications, the same sensor could encompass a pipe through which tap water or any other liquid will flow. Indeed, various types of vessels or tubes may be employed.

Results of the measurements are represented in Table 2 and inFIG. 22.

FIG. 22shows that the IR sensor that we used for our experiments has very high sensitivity between 0.01 and 0.1 mg/L. The sensitivity of the sensor at high concentrations could be significantly increased by application of one or more additional or alternative configured specific sensing coil or coils.

At least one embodiment of the sensor that pertains to the present application is similar to one disclosed in our pending U.S. patent application Ser. No. 12/887,887, Filing Date: Sep. 22, 2010, the entirety of which is incorporated herein by reference.