WO2016096022A1

WO2016096022A1 - Sensing oxygen

Info

Publication number: WO2016096022A1
Application number: PCT/EP2014/078575
Authority: WO
Inventors: Mihai N. Mihaila; Viorel Avramescu
Original assignee: Honeywell International Inc.
Priority date: 2014-12-18
Filing date: 2014-12-18
Publication date: 2016-06-23

Abstract

Sensing oxygen methods and systems are described herein. One or more embodiments for sensing oxygen can include creating a first vibration spectrum associated with a sensing material, creating a second vibration spectrum associated with an additive material, wherein the first vibration spectrum includes a first vibration frequency and the second vibration spectrum includes a second vibration frequency, comparing the first vibration frequency to the second vibration frequency to identify a correlated vibration frequency peak, and selecting, based on the correlated vibration frequency peak, the additive material.

Description

SENSING OXYGEN

Technical Field

The present disclosure relates to sensing oxygen and methods and systems for such sensing.

Background

Sensing oxygen can be conducted in a laboratory by using

SrTio.4Feo.6O2 8 (STFO) and monitoring the STFO film resistance. Additives can be added to increase and/or decrease sensitivity. Using metal-oxide (MOX) gas sensors, the position of the sensitivity peaks can differ from oxide to oxide, due to its composition, and on the particular gas molecule to be sensed.

Composition analysis can aid in chemical analysis, imaging, qualitative, and quantitative data collection, among other applications. The composition of a substance or mixture can be determined, for example, via Raman spectroscopy or other methods. Raman spectroscopy is a technique that can characterize a chemical composition and observe vibrational, rotational, and/or other low frequency modes of the composition in a system.

In some Raman spectroscopy models, a monochromatic light (e.g., a laser) near infrared or ultraviolet range, can be used to scatter molecules and observe vibration of a material via atomic vibration. The vibration of the material can be sequenced, such that peaks can be distinguished. The resulting peak positions can differ among chemical compositions.

In previous approaches, it was theorized that the resulting sensitivity peak of a MOX-based sensor relied upon absorption-desorption of both oxygen species and the analyte from the substrate. However,

experimentation does not thoroughly support the absorption-desorption model. Further, the criterion for how to select suitable additive(s) for a given material to generate an accurate result is empirical. Brief Description of the Drawings

Figure 1 illustrates an example of sensitivity to oxygen versus temperature in accordance with one or more embodiments of the present disclosure.

Figure 2 illustrates an example of a comparison between a sensitivity to oxygen versus temperature and a first vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 3 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 4 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 5 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 6 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 7 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 8 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 9 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. Figure 10 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 1 1 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 12 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 13 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure.

Figure 14 illustrates an example of sensing oxygen in accordance with one or more embodiments of the present disclosure.

Detailed Description

Sensing oxygen in accordance with embodiments of the present disclosure can provide criteria on how to select an additive material for a sensing material, which when mixed with the sensing material, can increase sensitivity of the sensing material to oxygen. Accordingly, methods and devices for sensing oxygen are described herein.

For example, one embodiment for sensing oxygen can include creating a first vibration spectrum associated with a sensing material, creating a second vibration spectrum associated with an additive material, wherein the first vibration spectrum includes a first vibration frequency and the second vibration spectrum includes a second vibration frequency, comparing the first vibration frequency to the second vibration frequency to identify a correlated vibration frequency peak, and selecting, based on the correlated vibration frequency peak, the additive material.

As discussed previously, sensing oxygen in accordance with embodiments of the present disclosure, can provide criteria on how to select an additive material, such as an oxide(s), to be mixed (e.g., added, incorporated) with a sensing material to increase sensitivity of the sensing material to oxygen. For example, embodiments of the present disclosure can identify metal oxides that can increase the sensitivity of SrTio.4Feo.6O2 8 (STFO) to oxygen based on a vibration frequency from vibration spectra. Embodiments of the present disclosure can identify criteria for STFO based oxygen sensing additives and/or combinations.

In the following detailed description, reference is made to the accompanying drawings that form a part hereof. The drawings show by way of illustration how one or more embodiments of the disclosure may be practiced.

These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice one or more embodiments of this disclosure. It is to be understood that other embodiments may be utilized and that process changes may be made without departing from the scope of the present disclosure.

As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, combined, and/or eliminated so as to provide a number of additional embodiments of the present disclosure. The proportion and the relative scale of the elements provided in the figures are intended to illustrate the embodiments of the present disclosure, and should not be taken in a limiting sense.

The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 102 may reference element "sensitivity vs. temperature graph" in Figure 1 , and a similar element may be references as 202 in Figure 2. As used herein, "a" or "a number of something can refer to one or more such things. For example, "sensing material" can refer to one or more sensing materials.

Figure 1 illustrates an example of sensitivity to oxygen versus temperature in accordance with one or more embodiments of the present disclosure. In one embodiment, a sensing material can be selected.

Sensing material can be a chemical material, compound, mixture, etc. The sensing material can be, in some instances, a metal oxide. For example, the sensing material can be a compound, such as SrTio.4Feo.6O2 8 (STFO). The STFO can be used to sense oxygen by monitoring its film resistance.

Sensing material can be temperature dependent. Meaning, the sensitivity of the sensing material can be more or less sensitive at a given temperature.

As illustrated in Figure 1 , a graph 100 depicts a relationship 102 between sensitivity 106 and temperature 104 of STFO. Sensitivity 106 can be represented by an R value. Temperature 104 can be measured in degrees Celsius, although other scales and/or units of measurement for temperature can be used (e.g., Fahrenheit, Kelvin, etc.) in different embodiments.

The graphical relationship 102, of sensitivity 106 and temperature

104, reveals the sensitivity of a sensing material in relation to temperature variation. For example, the graphical relationship 102 can illustrate STFO sensitivity to oxygen in relation to temperature. The graphical relationship 102, as illustrated in Figure 1 , depicts a STFO temperature-sensitivity peak 108 at 338 degrees Celsius.

The temperature-sensitivity peak 108 can be based on a sensor response as a function of temperature. The temperature-sensitivity peak 108 can indicate the temperature at which the sensing material (e.g., STFO) sensitivity is at a threshold (e.g., maximum). In other words, a graphical relationship can indicate an association between sensitivity and temperature (e.g., temperature-sensitivity peak) at which a sensing material (e.g., STFO) senses oxygen at a peak point at a particular temperature. For example, the STFO temperature-sensitivity peak 108 depicted in Figure 1 at 338 degrees Celsius can indicate STFO can sense oxygen at the peak point (e.g., temperature-sensitivity peak 108) at 338 degrees Celsius.

In some embodiments, the temperature-sensitivity peak 108 of a sensing material can be correlated with a corresponding vibration spectrum, as discussed further in relation to Figures 2.

Figure 2 illustrates an example of a comparison between a sensitivity to oxygen versus temperature and a first vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 2, a comparison 201 between a graphical relationship 202 (sensitivity versus temperature) of STFO and a vibration spectrum 210 of STFO can be correlated. The vibration spectrum 210 of STFO can be a Raman vibration spectrum of the STFO.

Similar to Figure 1 , a sensing material can be selected and the graphical relationship 202 can indicate an association between sensitivity 206 and temperature 204 of STFO (e.g. the sensing material) to oxygen. The graphical relationship 202 can indicate a temperature-sensitivity peak 208 for STFO (e.g., the sensing material). For instance, as depicted in Figures 1 and 2, the temperature-sensitivity peak for 208 for STFO can be 338 degrees Celsius.

A vibration spectrum of a material, can be obtained (e.g., created) for a material using Raman spectroscopy. As previously discussed, Raman spectroscopy can utilize a monochromatic light near infrared or ultraviolet range, to scatter molecules and measure and/or observe vibration of a material via atomic vibration. The vibration of the material can be

sequenced, such that peaks can be distinguished, resulting in a vibration spectrum. The resulting peak positions, or vibration frequencies, can differ among chemical compositions.

Raman spectroscopy can be used to create a vibration spectrum, which can include unique vibration frequencies, using materials, such as sensing materials and/or additive materials. To produce the vibration spectrum, Raman spectroscopy can measure a material using absorbance units 214 (e.g., absorption) and a Raman shift wavenumber 212 (e.g., wavelength). That is, the vibration spectrum can be created by measuring absorption (e.g., 214) as a function of wavelength (e.g., 212). Absorbance units 214 represent the absorption of infrared light from the particular material (e.g. sensing material, additive material). The wavenumber can represent the excitation wavelength, which is a value that may be related to energy.

Atomic vibration of different materials (e.g., sensing material, additive material) can, for example, produce vibration frequencies corresponding to the absorbance 214 and wavelength 212 of associated with a particular material (e.g., sensing material, additive materials, molecules, compounds, mixtures, etc.). Thus, the vibration spectrum created can depict vibration frequencies related to absorption and energy unique to the particular material (e.g., sensing material, additive material).

Some embodiments of the present disclosure can include creating a first vibration spectrum associated with a sensing material (e.g., a first Raman vibration spectrum of the sensing material). For example, a vibration spectrum 210 can be created for sensing material, STFO. The absorbance units 214 and Raman shift wavenumber 212 of STFO can be measured to produce the vibration spectrum, which can include vibration frequencies 216 unique to STFO.

As illustrated in Figure 2, the vibration frequencies 216 associated with the STFO vibration spectrum 210 can include 89.3 cm^"1, 139.0 cm^"1, 191.0 cm^"1, 241 .6 cm^"1, 295.9 cm^"1, 358.5 cm^"1, 424.9 cm^"1, 538.6 cm^"1, and 623.2 cm^"1, among others. In some embodiments, the vibration spectrum 210 associated with a sensing material can include an amplitude. In some instances, the amplitude and frequency rates can be different from a crystallographic facet to another of the sensing material. In some embodiments, a graphical relationship (e.g., temperature versus sensitivity) can be compared to a vibration spectrum of a sensing material. For example, the graphical relationship 202 (e.g., temperature 204, sensitivity 206, and temperature-sensitivity peak 208) of STFO can be compared to the vibration spectrum 210 of STFO (e.g., the Raman vibration spectrum of STFO). The comparison may determine an equivalent frequency value (e.g., cm^"1 value) associated with the temperature-sensitivity peak 208.

In some instances, the comparison between the graphical

relationship 202 and the vibration spectrum 210 (e.g., Raman vibration spectrum) is possible when the equivalent frequency value of the

temperature is calculated (e.g., in cm^"1 value). For example, the

temperature 204 (e.g., Kelvin, etc.) from the temperature-sensitivity peak 208 of the sensing material (e.g., STFO), can be multiplied by the

Boltzmann constant 8.617 x 10^"5eV/°C, and the product (e.g., number, resulting sum, etc.) of such calculation can be multiplied again by the wavenumber equivalent of 1 meV=8.06 cm^"1. The result can indicate

424.4cm^"1 is the equivalent frequency value in wavenumbers (e.g., the cm^"1 value) of 338 degrees Celsius. That is, the measured temperature- sensitivity peak for STFO may be at 338 degrees Celsius, which is the equivalent frequency value of 424.9 cm^"1 of a band (e.g., Raman band) in the STFO vibration frequencies 216.

In some embodiments, the sensing material can include at least one member of a group consisting of: SnO2, ZnO, Ιη2θ3, ZrO2, AI2O3, T1O2, SrTiOs, V2O3, WOa, CeO₂, Fe₂O₃, Bi₂O₃, Co₃O₄, O2, H2, CO, H2S, SO2, NO2, NO, NH3, CH4, ΟβΗ_δ, toluene, xylene, pentane, O3, ethanol, methanol, acetone, chlorobenzene, and formaldehyde, or combinations thereof. That is, the sensing material from at least one member of the group listed above can compare its respective temperature-sensitivity graph to its respective vibration spectrum to determine a respective equivalent frequency value (e.g., temperature-sensitivity peak cm^"1 equivalent). In some embodiments, a first vibration spectrum and the second vibration spectrum can be created from Raman spectroscopy, infrared spectroscopy, inelastic electron tunneling spectroscopy, or inelastic neutron scattering, or other methods. The first vibration spectrum and the second vibration spectrum can be compared to determine an additive that may increase sensitivity of the sensing material to oxygen, as discussed further in relation to Figure 3.

Figure 3 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 3, a comparison 301 between a vibration spectrum 310 of STFO and a vibration spectrum of LaFeO₃ to identify a correlated vibration frequency peak is made (e.g., created).

The vibration spectrum 310 of STFO (e.g., a first vibration spectrum) may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 310 may include measuring the absorbance units 314 (e.g., absorption) as a function of wavelength 312 to create vibration frequencies 316, in a manner analogous to that previously described herein. Further, the vibration frequencies 316 (e.g., a first vibration frequency) associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

In some embodiments, a second vibration spectrum associated with an additive material can be created using Raman spectroscopy. An additive material can be a metal oxide, a compound, a mixture, among other materials. The second vibration spectrum can include a second vibration frequency. That is, the second vibration spectrum can depict a second vibration frequency that is unique to the additive material (e.g., metal oxide, compound, etc.). For example, as illustrated in Figure 3, a partial vibration spectrum associated with LaFeO₃ is depicted, and includes a partial vibration frequency 322 unique to LaFe0₃.

In some examples, the first vibration frequency and the second vibration frequency may be different. That is, the vibration frequencies (e.g., 316, etc.) may depict different peaks, indicating different absorbance units (e.g., 314) and/or wavelengths (e.g., 312) for different materials, such as sensing materials and additive materials. However, in some instances the different first and second vibration frequencies may share a similar frequency, such as frequency 424.9cm^"1, as discussed further in relation to 318.

The first vibration frequency (e.g., 316) may be compared to the second vibration frequency (e.g., 322) to identify a correlated vibration frequency peak 318. The correlated vibration frequency peak can correspond to a particular frequency of 424.9cm^"1 , as discussed previously herein in connection to Figure 2 (e.g., the measured temperature-sensitivity peak for STFO may be 338 degrees Celsius, which is the equivalent frequency value of 424.9 cm^"1 associated with the STFO vibration frequencies 216).

The correlated vibration frequency peak 318 is the frequency value of 424.9 cm^"1, which the first and second vibration spectra reflect a similar vibration frequency peak (via respective vibration frequencies) at, or close to, 424.9 cm^"1. The correlated vibration frequency peak 318 (424.9cm^"1) is a vibration frequency possessed by the first and second vibration frequencies that occurs at, or close to, similar absorption (e.g., 314) and wavelengths cm^"1. That is, the first and second vibration frequencies possess a particular frequency at 424.9cm^"1 (e.g., the correlated vibration frequency peak 318).

The correlated frequency peak 318 shared by the sensing material and additive material vibration frequencies may indicate whether an additive material is likely to increase a sensing material sensitivity to oxygen. For example, an additive material possessing the particular frequency of 424.9cm^"1 can indicate a conforming additive material. A conforming additive material is a material, such as a metal oxide, that may increase the sensitivity of STFO to oxygen. An additive oxide may be conforming (e.g., good match) for a sensing material based on the correlated frequency peak 318 (e.g., particular vibration frequency at, or close to, 424.9 cm^"1). For example, as illustrated in Figure 3, based on the respective vibration frequencies of the materials, the correlated vibration frequency peak 318 indicates LaFeO₃ may be a suggested additive to STFO to increase sensitivity to oxygen based on the similar vibration frequency at 424.9 cm^"1.

In some embodiments, an additive material (e.g., metal oxide) possessing the vibration frequency at or close to the correlated frequency peak 318 (424.9cm^"1) can indicate increased electron charge transfer from a material (e.g., sensing material, additive material, oxide, etc.). An increased electron transfer can indicate the particular additive as good additive material, meaning the additive material may increase a sensing material (e.g., STFO, metal oxide) sensitivity to oxygen.

In some embodiments, the first vibration frequency can be compared to a plurality of different vibration frequencies associated with a plurality of different metal oxides. That is, the first vibration frequency can be compared to a plurality of vibration frequencies associated with a plurality of additive materials to identify conforming additive materials among the plurality of additive materials. For example, a Raman spectrum associated with STFO (e.g., 310) may be compared to a plurality of Raman vibration spectra associated with respective additive materials. The additive material(s) depicting a vibration frequency at, or close to, 424.9cm^"1 may be identified as a conforming additive.

An additive material may be selected based on the correlated vibration frequency peak, in some embodiments. Selecting the additive material can include mixing the selected additive material to the sensing material, which may increase sensitivity of the sensing material. The selected additive may increase sensitivity of the sensing material to oxygen. For example, selecting the additive material LaFeO₃ to sensing material STFO may increase sensitivity of STFO to oxygen.

In some embodiments, an additive material can be selected to be added to the sensing material. The additive material can include, for example: Nd₂0₃, PdO, Bi₂0₃, Y₂0₃, ln₂0₃, Te0₂, Ga₂0₃, Ti0₂, Ag₂0, ZnO, among others, as discussed further in relation to Figures 4-13.

Figure 4 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 4, a comparison 401 between a vibration spectrum 410 of STFO and a partial vibration spectrum of Nd₂O₃ indicates that these spectra may be correlated.

The vibration spectrum 410 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 410 may include measuring the absorbance units 414 (e.g., absorption) as a function of wavelength 412 to create vibration frequencies 416, in a manner analogous to that previously described herein. Further, the vibration frequencies 416 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 4 illustrates an example comparison 401 between the vibration frequency 416 of STFO and the vibration frequency 446 associated with Nd₂O₃. As depicted in Figure 4, Nd₂O₃ may possess a frequency peak around 424.4cm^"1 , which is close (e.g., near) to the frequency value 424.9 cm^"1 , indicating a correlated vibration frequency peak 418.

The correlated vibration frequency peak 418 at, or near, 424.9 cm^"1 may be identified, indicating Nd₂O₃ may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 418 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen).

Figure 5 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 5, a comparison 501 between a vibration spectrum 510 of STFO and a partial vibration spectrum of Ag₂O indicates that these spectra may be correlated.

The vibration spectrum 510 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 510 may include measuring the absorbance units 514 (e.g., absorption) as a function of wavelength 512 to create vibration frequencies 516, in a manner analogous to that previously described herein. Further, the vibration frequencies 516 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 5 illustrates an example comparison 501 between the vibration frequency 516 of STFO and the vibration frequency 548 associated with Ag₂O. As depicted in Figure 5, Ag₂O may possess a frequency peak at 429 cm^"1, which is close (e.g., near) to the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 518.

The correlated vibration frequency peak 518 at, or near, 424.9 cm^"1 may be identified, indicating Ag₂O may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 518 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Figure 6 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 6, a comparison 601 between a vibration spectrum 610 of STFO and a partial vibration spectrum associated with PdO indicates that these spectra may be correlated.

The vibration spectrum 610 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 610 may include measuring the absorbance units 614 (e.g., absorption) as a function of wavelength 612 to create vibration frequencies 616, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 616 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 6 illustrates an example comparison 601 between the vibration frequency 616 of STFO and the vibration frequency 650 associated with PdO. As depicted in Figure 6, PdO may possess a frequency peak at 425cm^"1, which is close (e.g., near) to the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 618.

The correlated vibration frequency peak 618 at, or near, 424.9 cm^"1 may be identified, indicating PdO may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 618 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen).

Figure 7 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 7, a comparison 701 between a vibration spectrum 710 of STFO and a partial vibration spectrum of Bi₂O₃ indicates that these spectra may be correlated. The vibration spectrum 710 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 510 may include measuring the absorbance units 714 (e.g., absorption) as a function of wavelength 712 to create vibration frequencies 716, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 716 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 716 in connection with Figure 2).

Figure 7 illustrates an example comparison 701 between the vibration frequency 716 of STFO and the vibration frequency 752 associated with Bi₂O₃. As depicted in Figure 7, Bi₂O₃ may possess a frequency peak which is close (e.g., near) to the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 718.

The correlated vibration frequency peak 718 at, or near, 424.9 cm^"1 may be identified, indicating Bi₂O₃ may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 718 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen).

Figure 8 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 8, a comparison 801 between a vibration spectrum 810 of STFO and a partial vibration spectrum of Y₂O₃ indicates that these spectra may be correlated.

The vibration spectrum 810 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 810 may include measuring the absorbance units 814 (e.g., absorption) as a function of wavelength 812 to create vibration frequencies 816, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 816 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 8 illustrates an example comparison 801 between the vibration frequency 816 of STFO and the vibration frequency 854 associated with Y₂O₃. As depicted in Figure 8, Y₂O₃ may possess a frequency band around 408 cm^"1, which extends on both sides of the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 818.

The correlated vibration frequency peak 818 at, or near, 424.9 cm^"1 may be identified, indicating Y2O3 may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 818 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) and may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Figure 9 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 9, a comparison 901 between a vibration spectrum 910 of STFO and a partial vibration spectrum of ln₂O₃ that these spectra may be correlated.

The vibration spectrum 910 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 910 may include measuring the absorbance units 914 (e.g., absorption) as a function of wavelength 912 to create vibration frequencies 916, in a manner analogous to that previously described herein, in a manner analogous to that previously described herein. Further, the vibration frequencies 916 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 9 illustrates an example comparison 901 between the vibration frequency 916 of STFO and the vibration frequency 956 associated with ln₂O₃. As depicted in Figure 9, ln₂O₃ may possess a frequency band located around 420 cm^"1, which extends on both sides of the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 918.

The correlated vibration frequency peak 918 at, or near, 424.9 cm^"1 may be identified, indicating ln₂O₃ may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 918 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen).

Figure 10 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 10, a comparison 1001 between a vibration spectrum 1010 of STFO and a partial vibration spectrum of TeO₂ indicates that these spectra may be correlated.

The vibration spectrum 1010 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 1010 may include measuring the absorbance units 1014 (e.g., absorption) as a function of wavelength 1012 to create vibration frequencies 1016, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 1016 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2). Figure 10 illustrates an example comparison 1001 between the vibration frequency 1016 of STFO and the vibration frequency 1058 associated with TeO₂. As depicted in Figure 10, TeO₂ may possess a frequency peak at, or close (e.g., near) to, the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 1018.

The correlated vibration frequency peak 1018 at, or near, 424.9 cm^"1 may be identified, indicating TeO₂ may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 1018 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) and may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Figure 1 1 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 1 1 , a comparison 1 101 between a vibration spectrum 1 1 10 of STFO and a partial vibration spectrum of Ga₂O₃ indicates that these spectra may be correlated.

The vibration spectrum 1 1 10 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 1 1 10 may include measuring the absorbance units 1 1 14 (e.g., absorption) as a function of wavelength 1 1 12 to create vibration frequencies 1 1 16, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 1 1 16 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 216 in connection with Figure 2).

Figure 1 1 illustrates an example comparison 1 101 between the vibration frequency 1 1 16 of STFO and the vibration frequency 1 160 associated with Ga₂0₃. As depicted in Figure 1 1 , Ga₂0₃ may possess a frequency peak at 419 cm^"1, which is close (e.g., near) to the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 1 1 18.

The correlated vibration frequency peak 1 1 18 at, or near, 424.9 cm^"1 may be identified, indicating Ga20₃ may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 1 1 18 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) and may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Figure 12 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 12, a comparison 1201 between a vibration spectrum 1210 of STFO and a partial vibration spectrum of TiO₂ indicates that these spectra may be correlated.

The vibration spectrum 1210 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 1210 may include measuring the absorbance units 1214 (e.g., absorption) as a function of wavelength 1212 to create vibration frequencies 1216, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 1216 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 1216 in connection with Figure 2).

Figure 12 illustrates an example comparison 1201 between the vibration frequency 1216 of STFO and the vibration frequency 1262 associated with TiO₂. As depicted in Figure 12, TiO₂ may possess a frequency peak which is close (e.g., near) to the frequency value 424.9 cm , indicating a correlated vibration frequency peak 1218.

The correlated vibration frequency peak 1218 at, or near, 424.9 cm^"1 may be identified, indicating ΤΊΟ2 may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 1218 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) and may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Figure 13 illustrates an example of a comparison between a first vibration spectrum and a second vibration spectrum in accordance with one or more embodiments of the present disclosure. As illustrated in Figure 13, a comparison 1301 between a vibration spectrum 1310 of STFO and a partial vibration spectrum of ZnO that these spectra may be correlated.

The vibration spectrum 1310 of STFO may be analogous to the vibration spectrum previously described herein (e.g., vibration spectrum 210 in connection with Figure 2). For example, the vibration spectrum 1310 may include measuring the absorbance units 1314 (e.g., absorption) as a function of wavelength 1312 to create vibration frequencies 1316, in a manner analogous to that previously described herein in a manner analogous to that previously described herein. Further, the vibration frequencies 1316 associated with STFO may be analogous to the vibration frequencies previously described herein (e.g., vibration frequencies 1316 in connection with Figure 2).

Figure 13 illustrates an example comparison 1301 between the vibration frequency 1316 of STFO and the vibration frequency 1364 associated with ZnO. As depicted in Figure 12, ZnO may possess a frequency peak (e.g., sensitivity peak) which is close (e.g., near) to the frequency value 424.9 cm^"1, indicating a correlated vibration frequency peak 1318. The correlated vibration frequency peak 1318 at, or near, 424.9 cm may be identified, indicating ZnO may be an additive that can increase sensitivity of STFO to oxygen. A correlated vibration frequency peak 1318 may be analogous to the correlated vibration frequency peak previously described herein (e.g., first and second frequencies) and may include a frequency peak at, or close to 424.9cm^"1, indicating the additive material (e.g., second vibration spectrum) may increase the sensitivity of STFO to oxygen.

Using the method, system, and device embodiments of the present disclosure can provide criteria related to selecting an additive material that may increase the sensitivity of STFO to oxygen. Accordingly, embodiments of the present disclosure may increase sensitivity of the sensing material (e.g., STFO) to oxygen.

Figure 14 illustrates system for identifying sensing materials in accordance with one or more embodiments of the present disclosure. The illustrated system of Figure 14 includes a computing device 1430, a user interface 1436, a temperature sensor 1442, and the sensor 1444 that has the material that is being tested to determine its sensitivity.

Computing device 1430 can be any suitable computing device. For example, a laptop computer, a desktop computer, a microprocessor, or a mobile device (e.g., a mobile phone, a personal digital assistant, etc.), among other types of computing devices, could be suitable for embodiments of the present disclosure.

As shown in Figure 14, computing device 1430 can include a memory 1432 and a processor 1434 coupled to memory 1432. Memory 1432 can be any type of storage medium that can be accessed by processor 1434 to perform various examples of the present disclosure. For example, memory 1432 can be a non-transitory computer readable medium having computing device executable instructions (e.g., computer program instructions) stored thereon that are executable by processor 1434 to determine a sensitivity of the oxygen sensing material in accordance with one or more embodiments of the present disclosure. Memory 1432 can also contain data 1438 that can be used by the executable instructions to perform functions or data stored in memory, for example, from the sensors 1442 and/or 1444.

Memory 1432 can be volatile or nonvolatile memory. Memory 1432 can also be removable (e.g., portable) memory, or non-removable (e.g., internal) memory. For example, memory 1432 can be random access memory (RAM) (e.g., dynamic random access memory (DRAM) and/or phase change random access memory (PCRAM)), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory

(EEPROM) and/or compact-disc read-only memory (CD-ROM)), flash memory, a laser disc, a digital versatile disc (DVD) or other optical disk storage, and/or a magnetic medium such as magnetic cassettes, tapes, or disks, among other types of memory.

Further, although memory 1432 is illustrated as being located in computing device 1430, embodiments of the present disclosure are not so limited. For example, memory 1432 can also be located internal to another computing resource (e.g., enabling computer readable instructions to be downloaded over the Internet or another wired or wireless connection).

As shown in Figure 14, computing device 1430 can also include a user interface 1436. User interface 1436 can include, for example, a display (e.g., a screen). The display can be, for instance, a touch-screen (e.g., the display can include touch-screen capabilities). User interface 1436 (e.g., the display of user interface 1436) can provide (e.g., display and/or present) information to a user of computing device 1430.

Additionally, computing device 1430 can receive information from the user of computing device 1430 through an interaction with the user via user interface 1436. For example, computing device 1430 (e.g., the display of user interface 1436) can receive input from the user via user interface 1436. The user can enter the input into computing device 1430 using, for instance, a mouse and/or keyboard associated with computing device 1430, or by touching the display of user interface 1436 in embodiments in which the display includes touch-screen capabilities (e.g., embodiments in which the display is a touch screen).

As used herein, "logic" is an alternative or additional processing resource to execute the actions and/or functions, described herein, which includes hardware (e.g., various forms of transistor logic, application specific integrated circuits (ASICs)), as opposed to computer executable instructions (e.g., software, firmware) stored in memory and executable by a processor.

A computing device, as discussed above, can be utilized to identify sensitivity and temperatures at which materials operate best to sense oxygen. To do so, the computing device receives data from sensors 1442 and 1444. Sensor 1442 is utilized to sense temperature around sensor 1444 or the temperature of sensor 1442.

In this manner, a comparison of sensitivity and temperature (e.g., an example of which is provided in Figure 1 ), reveals the temperature variation of sensitivity. The temperature-sensitivity peak that is identified can indicate the temperature at which the sensing material sensitivity to oxygen is at a threshold (e.g., maximum). In this manner, the temperature at which a sensing material can best sense (e.g., detect) oxygen can be identified.

Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that any arrangement calculated to achieve the same techniques can be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments of the disclosure.

It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description.

The scope of the various embodiments of the disclosure includes any other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are grouped together in example embodiments illustrated in the figures for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the embodiments of the disclosure require more features than are expressly recited in each claim.

Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

What is claimed:

1. A method of sensing oxygen, comprising:

creating a first vibration spectrum associated with a sensing material;

creating a second vibration spectrum associated with an additive material, wherein the first vibration spectrum includes a first vibration frequency and the second vibration spectrum includes a second vibration frequency;

comparing the first vibration frequency to the second vibration frequency to identify a correlated vibration frequency peak; and

selecting, based on the correlated vibration frequency peak, the additive material.

2. The method of claim 1 , further comprising measuring a temperature- sensitivity peak of the sensing material, wherein the temperature-sensitivity peak is 338 degrees Celsius.

3. The method of claim 1 , wherein the correlated vibration frequency peak corresponds to a particular frequency of 424.9cm^"1.

4. The method of claim 1 , wherein the second vibration frequency is different from the first vibration frequency, wherein the different second vibration frequency is close to a particular frequency associated with the first vibration frequency.

5. The method of claim 1 , wherein the correlated vibration frequency peak indicates a conforming additive material.

6. The method of claim 1 , wherein the sensing material is STFO and the additive material is a metal oxide, and wherein adding the metal oxide to the STFO increases sensitivity of the STFO to oxygen.

7. The method of claim 1 , further comprising comparing the first vibration frequency to a plurality of vibration frequencies associated with a plurality of additive materials to identify conforming additive materials among the plurality of additive materials.

8. The method of claim 1 , further comprising mixing the selected additive material to the sensing material to increase sensitivity of the sensing material.

9. The method of claim 1 , wherein the correlated vibration frequency indicates an increase of electron charge transfer from the sensing material.

10. The method of claim 1 , wherein the sensing material includes at least one member of a group consisting of Sn02, ZnO, Ιη2θ3, Zr02, AI2O3, T1O2, SrTi03, V2O3, WO3, Ce0₂, Fe₂0₃, Bi₂0₃, Co₃0₄, θ2, H2, CO, 2S, SO2, NO2, NO, NH3, Ch , C₆H₆, toluene, xylene, pentane, O3, ethanol, methanol acetone, chlorobenzene, and formaldehyde, or combinations thereof.

11. A sensing oxygen system, comprising:

a temperature-sensitivity peak associated with a sensing material;

a first vibration spectrum associated with the sensing material and a second vibration spectrum associated with an additive material, wherein the first vibration spectrum includes a first vibration frequency and the second vibration spectrum includes a second vibration frequency; identify a correlated vibration frequency peak based a comparison of the first vibration frequency and the second vibration frequency; and

a selected additive material based on the correlated vibration frequency peak.

12. The system of claim 11 , wherein the correlated vibration frequency peak is a particular frequency of 424.9cm^"1.

13. The system of claim 12, wherein the temperature-sensitivity peak is 338 degrees Celsius and corresponds to the particular frequency of 424.9cm^-1.

14. The system of claim 11 , wherein the selected additive material increases sensitivity of the sensing material to oxygen.

15. The system of claim 11 , the first vibration frequency is compared to a plurality of different vibration frequencies associated with a plurality of different metal oxides.

16. The system of claim 1 1 , wherein the first vibration spectrum and the second vibration spectrum are created from Raman spectroscopy, infrared spectroscopy, inelastic electron tunneling spectroscopy, or inelastic neutron scattering.

17. A method of sensing oxygen, comprising:

measuring a temperature-sensitivity peak associated with a sensing material;

creating, using the sensing material, a first vibration spectrum; creating, using an additive material, a second vibration spectrum, wherein the first vibration spectrum includes a first vibration frequency and the second vibration spectrum includes a second vibration frequency;

comparing the first vibration frequency to the second vibration frequency to identify a correlated vibration frequency peak, wherein the correlated vibration frequency peak is a particular frequency associated with the temperature-sensitivity peak; and

selecting the additive material based on the correlated vibration frequency peak.

18. The method of claim 17, wherein the first and second vibration spectra are created based on a measurement of absorption as a function of wavelength.

19. The method of claim 17, wherein the particular frequency associated with the temperature-sensitivity peak is 424.9cm^"1.

20. The method of claim 17, wherein the temperature-sensitivity peak is based on a sensor response as a function of temperature.