Gas detector using a glover detector

Abstract

Gas detector devices, systems, and methods using a Golay cell are described herein. One device includes a microphone having a front surface with a sound collection aperture for receiving sound, a substrate, a gas cavity formed in the substrate such that the gas cavity is in gaseous communication with the sound collection aperture and the front surface forms a side surface of the gas cavity, and a window abutting the substrate to form the side surface of the gas cavity.

Description

[0001] This application is a divisional application with application number 201680071989.2. Technical Field

[0002] The present disclosure relates to devices, systems, and methods for creating and utilizing gas detectors using Golay cells. Background Art

[0003] Gas detection based on non-dispersive infrared (NDIR) technologies, particularly those operating in the mid-wavelength IR (MWIR) (3000-8000nm), often lacks efficient light sources. Furthermore, in applications where a high signal-to-noise ratio is desired, optical power must be increased. This can result in high power consumption, which in some applications can severely limit portable and / or wireless form factor operation.

[0004] Alternatively, more sensitive and lower noise detectors can be used in some implementations to achieve high performance without increasing power consumption. However, commercially available MWIR detectors can be expensive, and in such implementations, some detectors require cooling, which can add components to the system, among other possible issues. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 A gas detector device according to one or more embodiments of the present disclosure is illustrated.

[0006] Figure 2 A gas detector system according to one or more embodiments of the present disclosure is illustrated. DETAILED DESCRIPTION

[0007] This document describes gas detector devices, systems, and methods using a Colloids detector. One such gas detector using a Colloids detector includes: a microphone having a front surface with a sound-collecting hole for receiving sound; a substrate; an air cavity formed in the substrate such that the air cavity is in gaseous communication with the sound-collecting hole and the front surface forms a side surface of the air cavity; and a window adjacent to the substrate to form a side surface of the air cavity. The substrate, which provides the structural basis for the air cavity, may be a printed circuit board (PCB) containing electronic components electrically interconnected with the microphone or other components of the device into which the gas detector is provided.

[0008] This disclosure describes the creation and utilization of gas detectors using Colloids detectors, which can be used, for example, as low-cost light detectors capable of detecting very low levels of MWIR radiation, as well as implementations in NDIR. Detector embodiments of the present disclosure are based on the principles of Colloids detectors used in infrared and terahertz radiation detection. The Colloids detector designs of embodiments of the present disclosure can take advantage of the proliferation of low-cost, highly sensitive microelectromechanical systems (MEMS) microphones in the mobile phone industry. In some embodiments, the Colloids detector integrates the microphone with a gas chamber of comparable volume, using either the gas or the microphone as the optical absorber. That is, the absorbing material can be the gas and / or the microphone.

[0009] In embodiments of the present disclosure, a pressure sensing element (e.g., a diaphragm in a conventional Golay detector) is part of a MEMS microphone and can provide sensitive detection of pressure fluctuations in an air cavity due to absorption of electromagnetic radiation. As described above, this functionality would otherwise require much more expensive and / or complex instrumentation. In some embodiments of the present disclosure, the microphone structure itself can serve as a thermal sensor. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. The drawings illustrate, by way of illustration, how one or more embodiments of the present disclosure may be practiced.

[0010] These embodiments are described in sufficient detail to enable one of ordinary skill in the art to practice one or more embodiments of the present disclosure. It is understood that other embodiments can be utilized and process changes can be made without departing from the scope of the present disclosure.

[0011] As will be appreciated, elements shown in the various embodiments herein may be added, exchanged, combined, and / or eliminated to provide numerous additional embodiments of the present disclosure. The proportions and relative scales of the elements provided in the accompanying drawings are intended to illustrate embodiments of the present disclosure and should not be taken in a limiting sense.

[0012] refer to Figure 1 Directional terms such as "horizontal" and "vertical," "above" and "below" are used to describe the orientation of components depicted in the drawings. These terms are used for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0013] The figures herein follow a numbering convention in which the first digit or digits correspond to the figure number and the remaining digits identify an element or component in the figure. Similar elements or components between different figures may be identified by using similar digits. For example, 100 may refer to Figure 1 Component "00" in the , and similar components can be Figure 2 The number of citations is 200.

[0014] As used herein, "a" or "a number of" something may refer to one or more such things. For example, "a number of holes" may refer to one or more holes.

[0015] Figure 1 A gas detector device according to one or more embodiments of the present disclosure is illustrated. Figure 1 In the illustrated embodiment, device 100 includes: a microphone 102 having a front surface 104 and a sound-collecting hole 108; an air cavity 112 formed in substrate 110, such that air cavity 112 is in gaseous communication with hole 108, with the front surface forming a side surface of air cavity 112; and a window 114 adjacent to substrate 110 to form a side surface of air cavity 112. In some embodiments, the substrate may have electronic components 111 mounted on one or both sides of its surface. These components may be related to the functionality of the gas detector, or may be components unrelated to the functionality of the gas detector but located near the gas detector.

[0016] In some embodiments, the window can include optical properties that change the properties of light passing through the window. For example, the window can have diffusing or collimating properties designed into the window. In some embodiments, the window can also be a lens or a waveguide.

[0017] These optical properties can be achieved based on the formation of the interior of the window, the formation and / or preparation (e.g., polishing) of one or more sides of the window, and / or by using a coating applied to the window on one or more sides. The window can also be coated with an optical film to enhance or delay the transmission of light at certain wavelengths. In some embodiments, it may be beneficial to isolate or focus certain wavelengths for the purpose of improving detection. For example, the certain wavelengths that can be isolated or enhanced may be 3.3 and / or 3.4 microns for hydrocarbons, 4.3 microns for CO2, or 9 microns for ammonia.

[0018] In embodiments of the present disclosure, the gas cavity (formed by other elements of the device, such as one or more substrates, windows, and microphones) can be a closed chamber that does not allow interaction with the surrounding environment. Thus, the gas within the closed chamber can be selected to enhance sensitivity to the presence of a specific gas or a specific group of gases.

[0019] In some embodiments, the substrate may be a printed circuit board (PCB) type material or other suitable material. Additionally, in some embodiments, the structure including the substrate may have multiple layers rather than a single substrate layer, such as Figure 1 In various embodiments, the microphone and / or window can be attached to the substrate 110 such that the gas cavity 112 is hermetically sealed. Such embodiments allow for the formation of a gas-filled cavity that is fluidly connected to the microphone inlet port (i.e., hole 108) but isolated from ambient conditions.

[0020] When radiant power (e.g., light from a light source) 116 enters the gas cavity 112 through the window 114 and is absorbed by the gas and / or the microphone surface, a small amount of heat can be generated. The heat causes an increase in pressure that can be sensed by the microphone.

[0021] The fill gas in the cavity 112 can be selected to optimize the sensitivity and / or temperature range of the detector based on parameters such as, among others, specific heat, thermal conductivity, permeability, triple point, and / or chemical stability, among other parameters that can be utilized based on the operating conditions of the detector.

[0022] The fill gas can be, among other suitable gas types, for example, nitrogen, hydrogen, argon, krypton, xenon, hydrocarbons, fluorocarbons, or mixtures of the above. In various embodiments, the fill gas pressure can be less than or greater than ambient pressure.

[0023] For example, in some embodiments, the fill gas pressure can be in the range from 0.1 bar to 10 bar. An advantage of the detector is that it isolates the microphone from the surrounding environment, thus eliminating interference and instability due to environmental variables such as acoustic noise, pressure, density, humidity, chemicals, and particulates in the surrounding environment around the device.

[0024] One benefit of using a PCB is that electrical interconnections are formed to the microphone (e.g., through surface mount pads), so the detector can be an integral part of the PCB and connected to other components on the same board. In some applications, a user can have several of these devices (e.g., on the same substrate such as a PCB), each with a different gas in its respective gas cavity and they can be plugged into a larger system to enable gas detection. Additionally, in some embodiments, a single device (e.g., a structure of Figure 1 or a similar structure) can be used in a system (e.g., like a structure of Figure 2 or another suitable structure) and the device can be removed and replaced with another device that can sense one or more other gases. In other embodiments, multiple devices can be used simultaneously (e.g., on the same substrate or on different substrates) to sense multiple gases or can have the same gas in the gas cavity and can provide redundancy, which can be beneficial as it will provide increased certainty that the gas detection is correct.

[0025] Figure 2 A gas detector system is illustrated in accordance with one or more embodiments of the present disclosure. Figure 2 A gas detector design is shown that can be compact and have low power consumption in many implementations.

[0026] In Figure 2 In the embodiment, the optical wavelength detection element 202 and the light source 224 are mounted face-to-face on opposite ends of an optical cavity 232 , which may have a reflective inner surface finish 226 to promote maximum light entry into the detector 200 .

[0027] The light source may be, for example, one or more filament bulbs, microelectromechanical systems (MEMS) hot plates, light emitting diodes (LEDs), and / or lasers. Such components can potentially be advantageously paired with the detector embodiments described herein to provide a gas sensor with good performance.

[0028] The reflective surface need not be reflective to visible light in all applications, but may be reflective to one or more wavelengths to be used with respect to detecting a particular gas or gases within the gas cavity.

[0029] In some embodiments, the surface of the optical cavity can be textured. The texture can provide a more uniform light pattern directed to the detector. Additionally, in some embodiments, the surface can be non-reflective. At least a portion of the walls of the optical cavity 232 is permeable to ambient gases via a permeable material, holes (e.g., opening 228), or a porous medium (at least porous to wavelengths of light that would be useful for detection). Thus, the presence of a gas of interest in the surrounding environment that absorbs radiation can be detected by the detector upon observing a decrease in received radiation at a specific wavelength (e.g., such as 3.3 or 3.4 microns for hydrocarbons, 4.3 microns for CO2, or 9 microns for ammonia, among others).

[0030] To be sensitive to a specific gas, an optical bandpass filter may be added as an additional component in the light path or as a coating on the inner surface (closer to the microphone) or outer surface 234 of the detector window. In some cases, even if the gas cavity has a specific gas therein, there may still be a need to filter out ambient components that may have similar properties to the specific gas in the cavity.

[0031] In such cases, one or more filters, such as thin films, applied coatings, filters physically separated from the window, or other types of filters, can be placed in the path of the light from the light source to filter out ambient noise associated with these environmental components (which may be characteristic of a particular gas in the cavity that is mistaken). Such an implementation can also be performed in applications with multiple gases in the cavity. Examples of environmental components that can be filtered can include, for example, CO2, water vapor, or condensed water, among others.

[0032] In some embodiments in which modulated current or, for example, alternating current (AC) is utilized, because the Golay detector is only sensitive to modulated optical intensity, the light source must be modulated at a specific frequency (e.g., a frequency in the range of 3 to 1000 Hz). The gas detector of this configuration can operate at very low power because the Golay detector is able to detect very low levels of radiant power, and thus the light source can be powered at a corresponding low level.

[0033] Embodiments of the present disclosure can be configured as a micro Golay detector device in which the elongate dimension of the microphone assembly (the width of the widest side of the microphone) is 2-5 mm. With such embodiments, these devices can be used in small and / or portable applications, and such devices can have lower power consumption relative to devices on the order of 10-20 mm width dimension. Another benefit of micro Golay devices is reduced ability for contaminants to enter the device.

[0034] Embodiments of the present disclosure can be used in a wide range of optical-based gas detection, including detection of flammable gases, toxic gases, and other environmentally relevant gases such as C02and refrigerants. For example, Golay detector devices can be used as standalone detectors, among other implementations, for electromagnetic radiation from deep UV to terahertz frequencies.

[0035] In a first embodiment, a gas detector device using a Golay detector can include a microphone having a front surface with a sound collection aperture for receiving sound; a substrate; a gas cavity formed in the substrate such that the gas cavity is in gaseous communication with the sound collection aperture and the front surface forms a side surface of the gas cavity; and a window abutting the substrate to form the side surface of the gas cavity.

[0036] A second embodiment can include the gas detector device of the first embodiment, wherein the substrate includes a first substrate portion abutting the sound collection surface, and wherein the first substrate portion has an aperture formed through the first substrate portion, wherein a first end of the aperture is directed toward the sound collection surface; and a second substrate portion abutting the first substrate portion such that the second substrate portion forms a side surface of the gas cavity and the first substrate portion forms a top surface of the gas cavity such that the gas cavity is in gaseous communication with the aperture.

[0037] A third embodiment can include the gas detector device of the first or second embodiment, wherein the window allows light to be transmitted through the window.

[0038] A fourth embodiment can include the gas detector device of any of the first through third embodiments, wherein the window is opaque to all light not in a specific range of wavelengths.

[0039] A fifth embodiment can include the gas detector device of any of the first through fourth embodiments, wherein the gas cavity has ambient gas therein.

[0040] A sixth embodiment may include the gas detector device of any one of the first to fifth embodiments, wherein the gas cavity has only a specific gas therein.

[0041] A seventh embodiment may include the gas detector device of any one of the first to sixth embodiments, wherein the gas cavity has only a specific set of gases therein.

[0042] An eighth embodiment may include the gas detector device of any one of the first to seventh embodiments, wherein the cavity is sealed such that ambient gas cannot enter the cavity once the cavity is sealed.

[0043] In a ninth embodiment, a gas detection system using a Golays detector may include: a gas detector including a microphone having a front surface with a sound collecting hole for receiving sound; a substrate adjacent to the front surface of the microphone; an air cavity formed in the substrate so that the air cavity is gas-connected to the hole; a window adjacent to the substrate to form a side surface of the air cavity; an optical generating chamber; and a light source that directs light toward the gas detector.

[0044] A tenth embodiment may include the system of the ninth embodiment, wherein the light source is within the optical generation chamber.

[0045] An eleventh embodiment may include the system of the ninth or tenth embodiment, wherein the optical generation chamber is formed from at least one wall having a material including a gas permeable portion.

[0046] A twelfth embodiment may include the system of any of the ninth to eleventh embodiments, wherein the optical generation chamber is formed by an interior surface and at least a portion of the surface is reflective.

[0047] A thirteenth embodiment may include the system of any of the ninth to twelfth embodiments, wherein the optical generation chamber is formed by an inner surface and the entire inner surface is reflective.

[0048] A fourteenth embodiment may include the system of any of the ninth to thirteenth embodiments, wherein the light generation chamber is formed within the housing, and wherein the housing includes one or more openings to allow ambient gas to enter and exit the chamber.

[0049] A fifteenth embodiment may include the system of any of the ninth to fourteenth embodiments, wherein the light source is an infrared light source.

[0050] A sixteenth embodiment may include the system of any of the ninth to fifteenth embodiments, wherein the light source generates infrared light and the window is transparent to the generated infrared light, thereby allowing the light to pass through the window.

[0051] In a seventeenth embodiment, a gas detector using a Golay detector may include: a microphone having a sound collecting hole for receiving sound; a substrate having a first surface and a second surface adjacent to the sound collecting surface and an air cavity formed between the first surface and the second surface of the substrate, and wherein the air cavity is gas-connected to the sound collecting hole; and a window adjacent to the second surface of the substrate to seal the air cavity.

[0052] An eighteenth embodiment may include the gas detector of the seventeenth embodiment, wherein the microphone and the substrate are hermetically sealed together.

[0053] A nineteenth embodiment may include the gas detector of the seventeenth or eighteenth embodiment, wherein the substrate includes a plurality of layers.

[0054] A twentieth embodiment may include the gas detector of the nineteenth embodiment, wherein the layers of the substrate are hermetically sealed together.

[0055] In a twenty-first embodiment, a method for creating and utilizing a gas detector using a Golays detector may include: assembling a substrate to a microphone including a sound collecting hole, wherein the substrate includes an air cavity in fluid communication with the sound collecting hole; allowing one or more gases to enter the air cavity; assembling a window adjacent to the substrate to form a side surface of the air cavity; directing light from a light source through the window; detecting pressure fluctuations within the air cavity due to absorption of electromagnetic radiation from the light by the microphone; and determining the specific one or more gases within the air cavity.

[0056] A twenty-second embodiment may include the method of the twenty-first embodiment, further comprising hermetically sealing the microphone and the substrate together.

[0057] A twenty-third embodiment may include the method of the twenty-first or twenty-second embodiment, wherein detecting the pressure fluctuation includes receiving sound using a sound collecting hole of a microphone.

[0058] A twenty-fourth embodiment may include the method of any of the twenty-first to twenty-third embodiments, further comprising coating the window to provide optical properties such that the window is opaque to all light not within a specific wavelength range.

[0059] A twenty-fifth embodiment may include the method of any of the twenty-first to twenty-fourth embodiments, wherein the light source generates infrared light and the window is transparent to the generated infrared light, thereby allowing the light to pass through the window.

[0060] A twenty-sixth embodiment may include the method of any of the twenty-first to twenty-fifth embodiments, further comprising forming a light generation chamber including a light source.

[0061] A twenty-seventh embodiment may include the method of the twenty-sixth embodiment, wherein the optical generation chamber is formed within the housing, and wherein the housing includes one or more openings to allow ambient gas to enter and exit the chamber.

[0062] 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 technique may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments of the present disclosure.

[0063] It should be understood that the above description is carried out in an illustrative manner rather than a restrictive manner. After reading the above description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art.

[0064] The scope of the various embodiments of the present disclosure includes any other applications in which the above-described structures and methods are used.The scope of the various embodiments of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0065] In the preceding Detailed Description, various features are grouped together in the example embodiments illustrated in the accompanying drawings for the purpose of streamlining the disclosure. This disclosure should not be interpreted as reflecting an intention that the disclosed embodiments require more features than 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. Therefore, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

1. A gas detector device comprising: A plurality of Golays detectors are formed on a substrate, wherein each of the plurality of Golays detectors comprises: a microphone (102) having a front surface (104) with a sound collecting hole (108) for receiving sound; an air cavity (112) formed in the substrate (110) such that the air cavity (112) is in gaseous communication with the sound collecting hole (108) and the front surface (104) forms a side surface of the air cavity (112); and a window (114) adjacent to the substrate (110) to form a side surface of the air cavity (112), The gas cavity includes a filling gas, and the filling gas includes one or more of hydrogen, argon, nitrogen, krypton, xenon, hydrocarbons, and fluorocarbons; The microphone (102) and the window (114) are attached to the first side and the second side of the substrate, respectively, such that the air cavity (112) is hermetically sealed, wherein once the air cavity (112) is sealed, ambient gas cannot enter the air cavity (112). 2 . The gas detector apparatus of claim 1 , wherein a first gas in a first one of the plurality of Golays detectors has a different composition than a second gas in a second one of the plurality of Golays detectors. 3 . The gas detector apparatus of claim 1 , wherein the first gas in a first one of the plurality of Golays detectors has the same composition as the second gas in a second one of the plurality of Golays detectors.

4. The gas detector apparatus of claim 1, wherein the first gas in a first Golays detector of the plurality of Golays detectors is a mixture of a plurality of gases. The gas detector device of claim 1 , wherein the plurality of Golay detectors are configured to sense a plurality of gases simultaneously.

6. The gas detector device of claim 1, wherein the window is opaque to all light not within a specific wavelength range.

7. The gas detector device of claim 1, wherein the gas cavity has only a specific set of gases therein.

8. The gas detector device of claim 1, further comprising at least one light source (224).

9. The gas detector apparatus of claim 8, wherein the at least one light source is configured to direct light to each of the plurality of Golay detectors.

10. The gas detector device of claim 1, wherein the microphone (102) is isolated from the surrounding environment.

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