PATENT DOCUMENT

Publication Number: US-10436731-B2
Application Number: US-201816048139-A
Country: US
Kind Code: B2

Title: Low heat transfer encapsulation for high sensitivity and low power environmental sensing applications

Abstract:
A miniature gas sensing device includes a silicon-based substrate including an opening. A first membrane is formed over the silicon-based substrate and a first portion of the first membrane covers the opening. A gas sensing layer is formed over a number of electrodes disposed over a first surface of the first portion of the first membrane and one or more heating elements. A permeable enclosure encapsulating the gas sensing layer can maintain thermal energy density over the gas sensing layer at a level sufficient to destroy a target gas to allow measuring a zero baseline.

Claims:
What is claimed is: 
     
       1. A miniature gas sensing device, the device comprising:
 a silicon-based substrate including an opening; 
 a first membrane formed over the silicon-based substrate, a first portion of the first membrane configured to cover the opening; 
 a gas sensing layer formed over a plurality of electrodes disposed over a first surface of the first portion of the first membrane; 
 one or more heating elements; and 
 a permeable enclosure encapsulating the gas sensing layer and configurable to maintain thermal energy density over the gas sensing layer at a level sufficient to destroy a target gas to allow measuring a zero baseline. 
 
     
     
       2. The device of  claim 1 , wherein the permeable enclosure includes one or more restricted flow holes. 
     
     
       3. The device of  claim 2 , wherein at least one of the one or more restricted flow holes includes a shutter valve mechanism operable to at least partially open or close the one or more restricted flow holes. 
     
     
       4. The device of  claim 1 , wherein at least one the one or more heating elements or an auxiliary heating element are operable to raise a temperature of a cavity of the permeable enclosure to destroy the target gas and enable zero baseline measurement. 
     
     
       5. The device of  claim 4 , wherein the one or more heating elements are operable at a nominal temperature and the auxiliary heating element is operable to be turned off to allow a target gas measurement. 
     
     
       6. The device of  claim 1 , wherein a measured zero baseline corresponds to registering by the gas sensing layer a zero level of measured target gas, and wherein the measured zero baseline enables an absolute target gas measurement. 
     
     
       7. The device of  claim 1 , wherein the permeable enclosure include one or more notches in one or more sidewalls of the permeable enclosure to allow gas exchange between a cavity of the permeable enclosure and outside of the permeable enclosure. 
     
     
       8. The device of  claim 1 , wherein the gas sensing layer comprises a permeable coating that allows the target gas to defuse into the gas sensing layer. 
     
     
       9. The device of  claim 8 , wherein the permeable coating comprises a material with variable electrical resistance, and wherein the variable electrical resistance is variable with a concentration of a defused target gas. 
     
     
       10. The device of  claim 1 , wherein the permeable enclosure comprises a material with low thermal conductivity including glass. 
     
     
       11. The device of  claim 1 , wherein the permeable enclosure comprises:
 a glass sidewall surrounding the first portion of the first membrane and being bonded to the silicon-based substrate at a first end of the glass sidewall; and 
 a second membrane attached to the glass sidewalls at a second end of the glass sidewall. 
 
     
     
       12. The device of  claim 11 , further comprising an auxiliary heating element, wherein the auxiliary heating element is operable to heat up a gas content of the permeable enclosure. 
     
     
       13. The device of  claim 11 , wherein the second membrane includes one or more restricted flow holes, and wherein an auxiliary heating element is formed over a first side of the second membrane not facing the gas sensing layer, and wherein the one or more heating elements are formed over a second surface the first portion of the first membrane. 
     
     
       14. The device of  claim 11 , wherein the second membrane is attached to the glass sidewalls by disposing a bonding layer, wherein the bonding layer is partially disposed to leave openings that form one or more restricted flow holes, and wherein the one or more heating elements are formed over a second surface the first portion of the first membrane. 
     
     
       15. The device of  claim 11 , wherein the second membrane comprise a silicon based double hollow membrane including a plurality of cavities, and wherein at least some of the plurality of cavities have one or more holes. 
     
     
       16. The device of  claim 15 , wherein at least some of the plurality of cavities are closed cavities, and wherein at least some of the closed cavities are vacuumed and sealed. 
     
     
       17. A miniature gas sensing device, the device comprising:
 a silicon-based substrate including an opening; 
 a first membrane formed over the silicon-based substrate, a first portion of the first membrane configured to cover the opening; 
 one or more electrodes disposed over a first surface of the first portion of the first membrane; 
 a permeable gas sensing layer deposited over the one or more electrodes; 
 one or more heating elements formed over a second surface of the first portion of the first membrane; 
 a first spacer layer surrounding the first surface of the first portion of the first membrane, a first surface of the first spacer layer being attached to the first membrane; and 
 a permeable second membrane attached to a second surface of the first spacer layer to form a first permeable enclosure over the first surface of the first portion of the first membrane, the first permeable enclosure configurable to maintain thermal energy density over the permeable gas sensing layer at a level sufficient to destroy a target gas to allow measuring a zero baseline. 
 
     
     
       18. The device of  claim 17 , further comprising at least one of:
 an auxiliary heating element; 
 a via coupling the auxiliary heating element through the first spacer layer to conducting traces on the first membrane; and 
 a second permeable enclosure similar to the first permeable enclosure formed by a second spacer layer substantially similar to the first spacer layer and a third permeable membrane, the second permeable enclosure being assembled over the permeable second membrane. 
 
     
     
       19. A miniature gas sensing device, the device comprising:
 a silicon-based substrate including an opening; 
 a first membrane formed over the silicon-based substrate, a first portion of the first membrane configured to cover the opening; 
 one or more electrodes disposed over a first surface of the first portion of the first membrane; 
 a permeable gas sensing coating formed over the one or more electrodes; 
 one or more heating elements formed over a second surface of the first portion of the first membrane; 
 a spacer layer surrounding the first surface of the first portion of the first membrane, a first surface of the spacer layer being attached to the first membrane; and 
 a silicon based double hollow membrane including a plurality of cavities attached to a second surface of the spacer layer. 
 
     
     
       20. The device of  claim 19 , wherein at least some of the plurality of cavities have one or more holes, wherein at least some of the plurality of cavities are closed cavities, and wherein at least some of the closed cavities are vacuumed and sealed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 from U.S. Provisional Patent Application 62/538,585 filed Jul. 28, 2017, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present description relates generally to sensors, and more particularly, to low heat transfer encapsulation for high sensitivity and low power environmental sensing applications. 
     BACKGROUND 
     Miniature gas sensors for consumer electronics represent a technology category that could enable upcoming features and/or products in applications such as environmental and health monitoring, smart homes, internet of things (IoT), and a number of other applications. Metal oxide (MOX) gas sensors are among the most promising technologies to be integrated with consumer electronic devices, due to their small size, low power consumption, compatibility with semiconductor fabrication processes and relatively simple architecture. 
     An issue with many environmental sensors is the baseline drift, where the baseline may change with an environmental condition such as variations in chemistry, temperature or other conditions of the environment. The baseline drift of a sensor can be addressed, for example, by a suitable compensation. A drift in sensitivity of a sensor, however, can be major issue that can drastically affect the measurement results. Therefore, environmental sensors capable of performing absolute measurements are desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain features of the subject technology are set forth in the appended claims. However, for purposes of explanation, several embodiments of the subject technology are set forth in the following figures. 
         FIG. 1  is a schematic diagram illustrating an example of an encapsulated low-heat-transfer miniature gas sensing device, in accordance with one or more aspects of the subject technology. 
         FIGS. 2A, 2B and 2C  are schematic diagrams illustrating examples of an encapsulated low-heat-transfer miniature gas sensing device manufacturable by integrated circuit (IC) fabrication processes, in accordance with one or more aspects of the subject technology. 
         FIGS. 3A-3B  are schematic diagrams illustrating examples of an encapsulated low-heat-transfer double hollow membrane miniature gas sensing device, in accordance with one or more aspects of the subject technology. 
         FIG. 4  is a schematic diagram illustrating an example of an encapsulated low heat-transfer double-membrane miniature gas sensing device, in accordance with one or more aspects of the subject technology. 
         FIG. 5  is a flow diagram illustrating an example of a method of operation of an encapsulated low-heat-transfer miniature gas sensing device, in accordance with one or more aspects of the subject 
         FIG. 6  is a block diagram illustrating an example wireless communication device, within which one or more miniature gas sensors of the subject technology can be integrated. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. However, the subject technology is not limited to the specific details set forth herein and may be practiced without one or more of the specific details. In some instances, structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology. 
     In one or more aspects of the subject technology, solutions for producing encapsulated low-heat-transfer miniature gas sensors are provided. The gas sensors of the subject technology include advantageous features such as improved stability, longer lifetime, enhanced sensitivity drift prevention, and capability to perform absolute measurements at part per million (ppb) levels. The disclosed solutions can be employed for long-term implementation of environmental and health sensing and hazardous gas species detection in applications such as smart homes, internet of things (IoT), and other applications. The subject technology enables a differential measurement including a measurement of the baseline. The baseline measurement is performed after the target gas is destroyed and does no longer exist in the sensor cavity. 
       FIG. 1  is a schematic diagram illustrating an example of an encapsulated low-heat-transfer miniature gas sensing device  100 , in accordance with one or more aspects of the subject technology. The encapsulated low-heat-transfer miniature gas sensing device  100  (hereinafter “gas sensor  100 ”) includes a silicon-based substrate  110  including an opening  115 , a first membrane  120 , a gas sensing layer  140  formed over a number of electrodes  130  disposed over the membrane  120 , one or more heating elements  132 , a permeable enclosure  150  covering the gas sensing layer  140  and a casing  180 . The silicon based substrate can be silicon substrates made of a silicon wafer. The electrodes  130  are disposed over a first surface  122  (e.g., top surface) of a first portion of the first membrane  120  that covers the opening  115 . 
     In some implementations, the electrodes  130  can be made of metals such as copper (Cu), aluminum (Al), silver (Ag), graphite (C), titanium (Ti), gold (Au), or other suitable metals, alloys or compounds. The electrodes  130  may be plated on the first membrane  120  in the form of a number of strips, for example, with suitable dimensions and distances. 
     In some implementations, the gas sensing layer  140  is made of a metal oxide, for example, a granular metal oxide semiconductor material including tin dioxide (SnO 2 ), tungsten trioxide (WO 3 ) and/or zinc oxide (ZnO2). The gas sensing layer  140  may detect a target gas and convert the concentration of the gas target into an electrical resistance. The gas sensing layer  140  is formed on the electrodes  130 , which are capable of sensing the electrical resistance that represents the target gas concentration. 
     The permeable enclosure  150  encapsulates the gas sensing layer  140  and can maintain thermal energy density over the gas sensing layer  140  at a sufficiently high level to destroy (e.g., decompose) a target gas (e.g., ozone) to allow measuring a zero baseline. The target gas may be a different gas depending on the application. For example, the target gas may be volatile organic compounds (VOCs), which can include elements such as hydrogen, oxygen, fluorine, chlorine, bromine, sulfur and nitrogen. VOCs can be found, for example, in fragrances, detergents and gassing from burning furniture and hardwood floors including formaldehyde or other chemicals. In other implementations, the gas sensor  100  may be configured to sense other target gases. 
     The permeable enclosure  150  can include one or more restricted flow openings (holes)  152 . In some implementations, one or more of the restricted flow openings  152  may include a shutter valve mechanism. The shutter valve mechanism may be operable to at least partially open or close the restricted flow openings  152 . The shutter valve mechanisms can be controlled by a microcontroller or a general processor, for example, of a host device (e.g., a smart phone or a smart watch) with which the gas sensor  100  is integrated. In some implementations, the gas sensor  100  may include one or more auxiliary heating elements  160 . The auxiliary heating elements  160  can be on built (e.g., deposited) over an external surface of the permeable enclosure  150 , in some implementations. The permeable enclosure  150  can include openings  170  (e.g., notches) made at a lower portion of the permeable enclosure  150  near the first membrane  120 . The encapsulation by the permeable enclosure  150 , the heating elements  132  and the (optional) auxiliary heating elements  160  can facilitate providing a high temperature (e.g., within a range of about 150-300° C.) environment inside a first cavity  155  of the permeable enclosure  150 . The high temperature is sufficient to cause the ozone target gas to thermally decompose so that a concentration of the ozone gas is practically reduced to approximately zero. This allows the gas sensor layer  140  to register a zero target gas level. The high temperature for causing thermal decomposition of other target gases can be different than for ozone. 
     In some implementations, the heating elements  132  and the auxiliary heating elements  160  are micro electromechanical system (MEMS) hotplates and can include titanium nitride, which is compatible with complementary metal-oxide semiconductor (CMOS) process and has a high melting point (e.g., 2950° C.), although other suitable metals may be used. The heating elements  132  and the auxiliary heating elements  160  can be independently controlled (e.g., by a microcontroller or a general processor) and can be used to regulate the temperature of the gas sensing layer  140  and the cavity  155 . For example, the temperature of the gas sensing layer  140  may be set to nominal temperature (e.g., within a range of about 250-350° C.) by the heating elements  132 . In some aspects, the microcontroller or the general processor can be in the host device. In some aspects, the heating elements  132  can be used to regenerate the sensing capabilities of the gas sensing layer  140 . 
     The openings  170  allow fresh target gas to enter the first cavity  155  for target gas concentration measurement phase. In some implementations, the casing  180  may be a metallic casing, for example, made of aluminum, stainless steel, titanium, or other metals or alloys. The casing  180  includes an opening (hole)  182  for allowing gas exchange between a second cavity  185  and the outside environment. In the following sections of the disclosure, various implementations of the miniature gas sensing device of the subject technology are disclosed. 
       FIGS. 2A, 2B and 2C  are schematic diagrams illustrating examples of an encapsulated low-heat-transfer miniature gas sensing device manufacturable by integrated circuit (IC) fabrication processes, in accordance with one or more aspects of the subject technology. The example encapsulated low-heat-transfer miniature gas sensing device  200 A (hereinafter “gas sensor  200 A”) shown in  FIG. 2A  is similar to the gas sensor  100  of  FIG. 1 , except that the casing  180  is not shown (or does not exist), the permeable enclosure  150  of  FIG. 1  is implemented by the permeable enclosure  240 , and the heating elements  232  are built on a second surface  124  of the first membrane  120 . The structure and functionalities of the substrate  110 , the first membrane  120 , the electrodes  130  and the gas sensor layer  140  are as described with respect to  FIG. 1 . The structure and functionalities of the heating elements  232  are the similar to the heating elements  132  of  FIG. 1 . 
     In some implementation, the permeable enclosure  240  is built separately and is bonded to the first membrane  120  using a bonding layer  212  (e.g., a cap bonding frame made of, for example, epoxy). In some implementation, the permeable enclosure  240  includes a sidewall  210 , a bond frame  214  and a permeable lid  220  including one or more restricted flow holes  222 . In some implementations, the restricted flow holes  222  may include shutter valve mechanisms operable to at least partially open or close the restricted flow holes  222 . The shutter valve mechanisms can be controlled by a microcontroller or a general processor, for example, of a host device (e.g., a smart phone or a smart watch). 
     In some implementations, the permeable enclosure  240  can be fabricated by employing fabrication techniques used in the integration circuit (IC) fabrication technology. For example, the sidewall  210  can be made of a glass wafer that is predrilled to form the cavity  215  and subsequently ground to a suitable thickness (e.g., within a range of about 40-60 μm). The sidewall width (e.g., thickness in the horizontal direction) of the glass sidewall  210  is much higher (e.g., within a range of about 200-500 μm) than the thickness of the sidewalls of the permeable enclosure  150  of  FIG. 1  and is significantly more effective in providing low heat transfer and thermal isolation. The thermal isolation allows heating the cavity  155  with lower power consumption, thus making the gas sensor  100  a lower power device. 
     The bond frame  214  can be a glass-to-silicon bond formed, for example, by using a known anodic bonding process. In one or more implementations, the permeable lid  220  is a silicon oxide layer that is first deposited on a silicon wafer (e.g., a handle wafer) and patterned and etched to create the restricted flow holes  222 . The silicon wafer is then ground off from the silicon oxide layer. 
     The example encapsulated low-heat-transfer miniature gas sensing device  200 B (hereinafter “gas sensor  200 B”) shown in  FIG. 2B  is similar to the gas sensor  200 A of  FIG. 2A , except for an auxiliary heating elements  260  formed on top surface of the permeable lid  220 , as shown in  FIG. 2B . The structure and functionalities of the auxiliary heating elements  260  is similar to those of the auxiliary heating elements  160  of  FIG. 1 , described above. 
     The example encapsulated low-heat-transfer miniature gas sensing device  200 C (hereinafter “gas sensor  200 C”) shown in  FIG. 2C  is similar to the gas sensor  200 A of  FIG. 2A , except that the permeable lid  220  does not include the restricted flow holes  222  of  FIG. 2A  and includes, instead, an opening  216 . The opening  216  can be formed at one or more locations (e.g., near for corners) on the bond frame  214 , as shown in the top view  270  of the gas sensor  200 C. In the example implementation shown in  FIG. 200C  and top view  270 , the top view of the gas sensor  200 C has a square shape, but the subject technology is not limited to this shape. 
       FIGS. 3A-3B  are schematic diagrams illustrating examples of an encapsulated low-heat-transfer double hollow membrane miniature gas sensing device, in accordance with one or more aspects of the subject technology. The example encapsulated low-heat-transfer double hollow membrane miniature gas sensing device  300 A (hereinafter “gas sensor  300 A”) shown in  FIG. 300A  is similar to the gas sensor  200 A of  FIG. 2A , except that the permeable enclosure  240  of  FIG. 2A  is replaced with a permeable enclosure  330 . The structure and functionalities of the substrate  110 , the first membrane  120 , the electrodes  130  and the gas sensor layer  140  are as described with respect to  FIG. 1 . The permeable enclosure  330  includes a double hollow membrane  320  and a sidewall  310 . The double hollow membrane  320  includes number of cavities separated by inner walls  326 . One or more of the cavities have one or more holes. For example, each of the cavities  330  has one hole on a top layer  324  and each of the cavities  325  has two holes, one hole (e.g.,  322 ) on the top layer  324  and another hole (e.g.,  323 ) on a bottom layer  328 . 
     In some implementations, the permeable enclosure  330  is separately fabricated by employing IC fabrication techniques and is attached to the first membrane  120  using a bonding layer  312  similar to the bonding layer  212  of  FIG. 2A . 
     The example encapsulated low-heat-transfer double hollow membrane miniature gas sensing device  300 B (hereinafter “gas sensor  300 B”) shown in  FIG. 300B  is similar to the gas sensor  300 A of  FIG. 3A , except that some of the cavities (e.g.,  332 ) have no holes and are vacuumed and sealed to provide lower heat transfer resulting in additional thermal isolation. The additional thermal isolation can further cause increasing the temperature of the cavity  315  in the target gas decomposition stage and thereby help with lowering the power consumption of the sensor device. Thus, the gas sensors  300 A and  300 B can be designed to operate at lower power than the existing miniature gas sensor, while having the additional advantage of absolute target gas concentration. 
       FIG. 4  is a schematic diagram illustrating an example of an encapsulated low heat-transfer double-membrane miniature gas sensing device  400 , in accordance with one or more aspects of the subject technology. The example encapsulated low-heat-transfer double-membrane miniature gas sensing device  400  (hereinafter “gas sensor  400 ”) shown in  FIG. 4  is similar to the gas sensor  200 B of  FIG. 2B , except for the additional permeable enclosure  430  and a through-silicon-via (TSV)  432  coupled to an auxiliary heating element  260 . The permeable enclosure  430  is similar to the permeable enclosure  240  of  FIG. 2  and is fabricated separately, as discussed above with respect to  FIG. 2A , and is attached to the permeable lid  220  by using a bonding layer  412 . The permeable enclosure  420  includes one or more restricted flow holes  422 . In some implementations, the restricted flow holes  422  may include shutter valve mechanisms operable to at least partially open or close the restricted flow holes  422 . The shutter valve mechanisms can be controlled by a microcontroller or a general processor, for example, of a host device (e.g., a smart phone or a smart watch). The additional permeable enclosure  430  with a cavity  415  that can be sealed can provide a low heat transfer environment above the auxiliary heating element  260 , thereby allowing reaching higher temperatures within the cavity  215  at lower heating power. The auxiliary heating element  260  is coupled through the TSV  432  to a bonding layer  312  that can be wire-bonded to an external pad for provision of power for the auxiliary heating element  260 . 
       FIG. 5  is a flow diagram illustrating an example of a method  500  of operation of an encapsulated low-heat-transfer miniature gas sensing device, in accordance with one or more aspects of the subject technology. The operations of the method  500  may be controlled by a microcontroller or a general processor, for example, of a host device (e.g., a smart phone or a smart watch) with which the encapsulated low-heat-transfer miniature gas sensing device (e.g., the gas sensor  100  of  FIG. 1 ) is integrated. The method  500  starts with operation  510 , where the target gas (e.g., ozone) is destroyed (e.g., decomposed) by applying a high temperature (e.g., for a 30 second period). The high temperature (e.g., within a range of about 130-260° C.) may be provided by an auxiliary heating element (e.g.,  160  of  FIG. 1 ) and maintained by the low-heat-transfer environment provided by a permeable enclosure of the subject technology (e.g.,  150  of  FIG. 1, 240  of  FIG. 2A and 330  of  FIG. 3A ). In some implementations, the controller may also use the heating elements  132  to further raise the temperature. 
     At operation  520  the controller waits (does not make any changes) for the environment inside the enclosure cavity (e.g.,  155  of  FIG. 1 ) to reach an equilibrium. In the equilibrium, the resistance value of the gas sensing layer (e.g.,  140  of  FIG. 1 ), as read by the controller, reaches a steady value (e.g., baseline resistance R 0 ) corresponding to zero concentration of the target gas. The controller then changes the temperature, at operation  530 , to an optimal measurement temperature and turns off the auxiliary heating element. The optimal measurement temperature can be different for different gas sensing layers. 
     At operation  540 , the controller waits for desorption of the target gas into the sensing gas layer to reach a state of equilibrium. At the state of equilibrium, the resistance value of the gas sensing layer, as read by the controller, reaches a steady value (R g ) corresponding to an actual concentration of the target gas. The controller then registers the resistance value (R g ) and converts (at operation  550 ), the resistance value to a target gas concentration value using a suitable conversion table. The conversion table stored in a memory of the host device can convert a resistance signal (e.g., R g /R 0 ) to a corresponding value for the target gas concentration. In some implementations the above discussed operations can be performed in a periodic fashion with, for example, 60 seconds of low temperature and 30 seconds of high temperature. 
       FIG. 6  is a block diagram illustrating an example wireless communication device, within which one or more miniature gas sensors of the subject technology can be integrated. The wireless communication device  600  may comprise a radio-frequency (RF) antenna  610 , a receiver  620 , a transmitter  630 , a baseband processing module  640 , a memory  650 , a processor  660 , a local oscillator generator (LOGEN)  670 , and a sensor  680 . In various embodiments of the subject technology, one or more of the blocks represented in  FIG. 6  may be integrated on one or more semiconductor substrates. For example, the blocks  620 - 670  may be realized in a single chip or a single system on a chip, or may be realized in a multi-chip chipset. 
     The receiver  620  may comprise suitable logic circuitry and/or code that may be operable to receive and process signals from the RF antenna  610 . The receiver  620  may, for example, be operable to amplify and/or down-convert received wireless signals. In various embodiments of the subject technology, the receiver  620  may be operable to cancel noise in received signals and may be linear over a wide range of frequencies. In this manner, the receiver  620  may be suitable for receiving signals in accordance with a variety of wireless standards, Wi-Fi, WiMAX, Bluetooth, and various cellular standards. In various embodiments of the subject technology, the receiver  620  may not require any SAW filters and few or no off-chip discrete components such as large capacitors and inductors. 
     The transmitter  630  may comprise suitable logic circuitry and/or code that may be operable to process and transmit signals from the RF antenna  610 . The transmitter  630  may, for example, be operable to up-convert baseband signals to RF signals and amplify RF signals. In various embodiments of the subject technology, the transmitter  630  may be operable to up-convert and amplify baseband signals processed in accordance with a variety of wireless standards. Examples of such standards may include Wi-Fi, WiMAX, Bluetooth, and various cellular standards. In various embodiments of the subject technology, the transmitter  630  may be operable to provide signals for further amplification by one or more power amplifiers. 
     The duplexer  612  may provide isolation in the transmit band to avoid saturation of the receiver  620  or damaging parts of the receiver  620 , and to relax one or more design requirements of the receiver  620 . Furthermore, the duplexer  612  may attenuate the noise in the receive band. The duplexer may be operable in multiple frequency bands of various wireless standards. 
     The baseband processing module  640  may comprise suitable logic, circuitry, interfaces, and/or code that may be operable to perform processing of baseband signals. The baseband processing module  640  may, for example, analyze received signals and generate control and/or feedback signals for configuring various components of the wireless communication device  600 , such as the receiver  620 . The baseband processing module  640  may be operable to encode, decode, transcode, modulate, demodulate, encrypt, decrypt, scramble, descramble, and/or otherwise process data in accordance with one or more wireless standards. 
     The processor  660  may comprise suitable logic, circuitry, and/or code that may enable processing data and/or controlling operations of the wireless communication device  600 . In this regard, the processor  660  may be enabled to provide control signals to various other portions of the wireless communication device  600 . The processor  660  may also control transfers of data between various portions of the wireless communication device  600 . Additionally, the processor  660  may enable implementation of an operating system or otherwise execute code to manage operations of the wireless communication device  600 . In some aspects, the processor  660  may perform the functionality of the controller discussed above, for example, with respect to  FIG. 4 . 
     The memory  650  may comprise suitable logic, circuitry, and/or code that may enable storage of various types of information such as received data, generated data, code, and/or configuration information. The memory  650  may comprise, for example, RAM, ROM, flash, and/or magnetic storage. In various embodiment of the subject technology, information stored in the memory  650  may be utilized for configuring the receiver  620  and/or the baseband processing module  640 . In some aspects, the memory  650  may store values of the resistances R 0  and R g  and target gas concentrations as discussed above, for example, with respect to  FIG. 4 . 
     The local oscillator generator (LOGEN)  670  may comprise suitable logic, circuitry, interfaces, and/or code that may be operable to generate one or more oscillating signals of one or more frequencies. The LOGEN  670  may be operable to generate digital and/or analog signals. In this manner, the LOGEN  670  may be operable to generate one or more clock signals and/or sinusoidal signals. Characteristics of the oscillating signals such as the frequency and duty cycle may be determined based on one or more control signals from, for example, the processor  660  and/or the baseband processing module  640 . 
     In some implementations, the sensor  680  may be a miniature gas sensor of the subject technology, for example, any of the gas sensors  100 ,  200 A,  200 B,  200 C,  300 A,  300 B and  400  discussed above with respect to  FIGS. 1, 2A-2C .  3 A- 3 B and  4 . 
     In operation, the processor  660  may configure the various components of the wireless communication device  600  based on a wireless standard according to which it is desired to receive signals. Wireless signals may be received via the RF antenna  610  and amplified and down-converted by the receiver  620 . The baseband processing module  640  may perform noise estimation and/or noise cancellation, decoding, and/or demodulation of the baseband signals. In this manner, information in the received signal may be recovered and utilized appropriately. For example, the information may be audio and/or video to be presented to a user of the wireless communication device, data to be stored to the memory  650 , and/or information affecting and/or enabling operation of the wireless communication device  600 . The baseband processing module  640  may modulate, encode and perform other processing on audio, video, and/or control signals to be transmitted by the transmitter  630  in accordance with various wireless standards. 
     The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the subject disclosure. 
     The predicate words “configured to”, “operable to”, and “programmed to” do not imply any particular tangible or intangible modification of a subject, but, rather, are intended to be used interchangeably. For example, a processor configured to monitor and control an operation or a component may also mean the processor being programmed to monitor and control the operation or the processor being operable to monitor and control the operation. Likewise, a processor configured to execute code can be construed as a processor programmed to execute code or operable to execute code. 
     A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A phrase such as a configuration may refer to one or more configurations and vice versa. 
     The word “example” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs. 
     All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” Furthermore, to the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim.

Metadata:
Filing Date: 20180727
Publication Date: 20191008
Grant Date: 20191008
Priority Date: 20170728
Inventors: MOTTA, PAULO S.
RIBEIRO, ROBERTO M.
YEH, RICHARD
Assignee: APPLE INC
CPC Classifications: [{"code": "G01N27/123", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N27/128", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N27/128", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N27/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "B81B7/0061", "inventive": true, "first": false, "tree": "[]"}, {"code": "B81B7/0087", "inventive": true, "first": false, "tree": "[]"}, {"code": "B81B2201/0214", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81B7/0061", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N27/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01N27/123", "inventive": true, "first": false, "tree": "[]"}, {"code": "B81B2201/0214", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N27/128", "inventive": true, "first": false, "tree": "[]"}, {"code": "B81B7/0087", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N27/123", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 65137901