Abstract:
An acoustic wave sensor system, comprising a plurality of acoustic wave sensing devices for detecting a multiplicity of varying conditions wherein each acoustic wave sensina device among the plurality of acoustc wave sensing devices is an independent component for detecting at least one condition of the multiplicty of varying conditions and a common interrogation component that communicates with each acoustic wave sensing device among the plurality of acoustic wave sensor devices for providing an interrogation signal to each acoustic wave sensing device thereof. A transmitter and receiver unit can also be provided that communicates with the common interrogation component and the plurality of acoustic wave sensing devices and which transmits an interrogation signal from the common interrogation component to the at least one acoustic wave sensing device among the plurality of acoustic wave sensing devices and which receives sensor data from at least one acoustic wave sensing device.

Description:
TECHNICAL FIELD 
   Embodiments are generally related to acoustic wave sensing devices, such as Surface Acoustic Wave (SAW), Bulk Acoustic Wave (BAW), acoustic plate mode (APM) and other similar acoustic wave components. Embodiments are also related to wireless sensors and applications thereof. Embodiments are additionally related to pressure, friction, torque, acceleration, rotation rate and engine oil quality sensors utilized in automotive and aerospace applications. 
   BACKGROUND OF THE INVENTION 
   Surface acoustic wave (SAW) devices are utilized in a number of industrial, commercial, consumer and military applications. SAW technology Is generally characterized by its reliance on acoustic energy and electrical/acoustic transducers. SAW components are based on devices in which radio frequency signals are converted to acoustic signals and confined within a small substrate made from, for example, Lithium Niobate or other piezoelectric crystalline materials. SAW waves propagate at relatively low speed with reference to radio waves and, as such, a small substrate may produce relatively long time delays. SAW devices are useful, however, for example, in devices such as filters utilized in wireless applications and sensors utilized in various environmental detection applications, such as pressure, torque and/or temperature sensors. 
   SAW devices are manufactured from a SAW wafer. Such components are typically manufactured with quartz, which is utilized because the quartz provides for minimal hysteresis, high temperature stability, low creep, low aging and improved long-term stability. 
   BRIEF SUMMARY OF THE INVENTION 
   The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
   It is, therefore, one aspect of the present invention to provide for an improved sensor apparatus and system. 
   It is another aspect of the present invention to provide for an acoustic wave sensor system. 
   The aforementioned aspects of the invention and other objectives and advantages can now be achieved as described herein. An acoustic wave sensor system, comprising a plurality of acoustic wave sensing devices for detecting a multiplicity of varying conditions and a common interrogation component that communicates with each acoustic wave sensing device among the plurality of acoustic wave sensor devices for providing an interrogation signal to each acoustic wave sensing device thereof. A transmitter and receiver unit can also be provided that communicates with the common interrogation component and the plurality of acoustic wave sensing devices and which transmits an interrogation signal from the common interrogation component to the at least one acoustic wave sensing device among the plurality of acoustic wave sensing devices and which receives sensor data from at least one acoustic wave sensing device. The common interrogation component can be, for example, a Digital Signal Processor (DSP), a transceiver, a RF switch, a mixer component, an oscillator and/or a Phase Locked Loop (PLL) circuit. The acoustic wave sensing device can be, for example, a SAW, BAW, or APM sensor. The system disclosed herein can be utilized within, for example, automotive applications and for identifying and detecting tire-pressure, engine in-cylinder pressure, friction, engine torque, acceleration, rotation rate, in-cabinet air quality, gaseous composition of fuel cell applications, and engine oil quality (e.g., viscosity, particulate and/or corrosivity). Even when one or more of the acoustic wave sensing devices utilize different modes of waves (e.g., SAW, BAW, APM, etc.), such acoustic wave sensing devices can share a common interrogation component (DSP, mixer, oscillator, PLL, DFT, etc.). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention. 
       FIG. 1  illustrates a perspective view of an acoustic wave sensor apparatus that can be implemented in accordance with an embodiment; 
       FIG. 2  illustrates a block diagram of an acoustic wave sensor system that can be implemented in accordance with a preferred embodiment; 
       FIG. 3(   a ) illustrates a block diagram of an acoustic wave torque sensor system that can be implemented in accordance with one embodiment; 
       FIG. 3(   b ) illustrates a block diagram of an acoustic wave pressure sensor system that can be implemented in accordance with one embodiment; 
       FIG. 4  illustrates a block diagram of an acoustic wave pressure sensor system that can be implemented in accordance with the embodiment depicted in  FIG. 3(   a ); 
       FIG. 5  illustrates a block diagram of an acoustic wave torque sensor system that can be implemented in accordance with the embodiment depicted in  FIG. 3(   b ); 
       FIG. 6  illustrates a block diagram of a tire condition sensor system that can be implemented in accordance with another embodiment; and 
       FIG. 7  illustrates a system composed of a unit comprising an interrogation unit  206  and a transmitter/receiver unit in accordance with another embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the present invention and are not intended to limit the scope of the invention. 
     FIG. 1  illustrates a perspective view of an acoustic wave sensor apparatus  100  that can be implemented in accordance with an embodiment. Apparatus  100  includes one or more acoustic wave resonators  104 ,  106 , and  108  formed on a piezoelectric substrate  102 . Each resonator  104 ,  106 , and  108  can be configured on substrate  102  as an Interdigital Transducer (IDT) or an IDT electrode. Resonator or IDT  104  can be connected to antenna  110 ,  112 . A Radio Frequency (RF) interrogation signal  114  can be provided to antenna  110  as indicated by arrow  116 . 
   An RF response signal  119  can be transmitted from antenna  112  as indicated by arrow  115 . Note that resonator  108  can be configured as a reflector rather than an IDT, depending upon design considerations. Apparatus  100  therefore constitutes a passive wireless acoustic wave sensor device. Apparatus  100  may be, for example, a SAW, BAW, APM or other similar acoustic wave sensor devices, depending upon design considerations. If apparatus  100  is implemented as an Acoustic Plate Mode (APM) device rather than a SAW or BAW device, substrate  102  can be provided as a quartz plate. 
   Piezoelectric substrate  102  can be formed from a variety of substrate materials, such as, for example, quartz, lithium niobate (LiNbO 3 ), lithium tantalite (LiTaO 3 ), Li 2 B 4 O 7 , GaPO 4 , langasite (La 3 Ga 5 SiO 14 ), ZnO, and/or epitaxially grown nitrides such as Al, Ga or Ln, to name a few. Interdigital transducers  104 ,  106  and/or  108  can be formed from materials, which are generally divided into three groups. First, IDT  104 ,  106  and/or  108  can be formed from a metal group material (e.g., Al, Pt, Au, Rh, Ir Cu, Ti, W, Cr, or Ni). Second, IDT  104 ,  106  and/or  108  can be formed from alloys such as NiCr or CuAl. Third, IDT  104 ,  106  and/or  108  can be formed from metal-nonmetal compounds (e.g., ceramic electrodes based on TiN, CoSi 2 , or WC). 
     FIG. 2  illustrates a block diagram of an acoustic wave sensor system  200  that can be implemented in accordance with a preferred embodiment. Note that in  FIGS. 1-2 , identical or similar parts or components are generally indicated by identical reference numerals. As indicated above, component  108  may or may not be provided as an IDT. This depends on the choice of the designer wishing to Implement varyIng embodiments. If component  108  is provided in the context of a reflector configuration upon substrate  102  rather than as an IDT or resonator, then a high frequency electromagnetic wave (e.g., interrogation signal  114 ) can be emitted by the interrogation unit  205  depicted in  FIG. 2 , and is received by the antenna  110  of the acoustic wave transponder or IDT  104 . 
   The IDT  104  that is connected to the antenna  110  transforms, with the assistance of an inverse piezoelectric effect, the received signal into an acoustic wave, such as, for example, a SAW. The signal (SAW, BAW, etc.) propagates on the crystal substrate  102  towards the reflector or reflector components  108 . The reflector(s)  108  can be placed in a particular pattern that reflects part of the incoming wave. What returns to the IDT  104  and/or  106  is a high-frequency series of echoes, which are transduced back into an electromagnetic signal. This is the response signal  119  that is sent through the antenna and back to the interrogation unit  206  depicted in  FIG. 2 . The RF response signal  119  carries information about the location and quantity of the reflections together with the information of the propagation and reflection properties of the acoustic wave signal. The interrogation unit  206  evaluates the amplitude, frequency and time of the signal and determines the identification number or calculates the sensor value. Note that interrogation unit  206  can be utilized in the context of system  200  whether or not component  108  is implemented as a reflector or an IDT. 
   The acoustic wave sensor or sensing device  100  can be implemented in the context of a variety of different types of sensing applications. For example, the acoustic wave sensing device  100  can be implemented as a gaseous composition sensor, such as, for example, a hydrogen sensor, a carbon monoxide sensor, an oxygen sensor, an exhaust NOx sensor, or an exhaust SO 2  sensor. The acoustic save sensing device  100  can also be implemented as a shaft torque sensor such as that depicted in  FIG. 3(   a ) or an acceleration sensor. The acoustic wave sensing device  100  can also be configured to function as a tire pressure sensor, an engine cylinder pressure sensor or a tire friction sensor. 
   The acoustic wave sensing device  100  can also be implemented as an engine oil quality sensor, such as, for example, an oil viscosity sensor, a total acid number (TAN) sensor, a total base number (TBN) sensor, or an oil particulate sensor. The acoustic wave sensing device  100  can also be implemented as a SAW sensor, a BAW sensor, an APM sensor or an SH-SAW sensor, depending upon design considerations. The acoustic wave sensing device  100  can also be, for example, a cantilever sensor, a cantilever sensor array, or a tuning fork sensor, again depending upon design considerations. 
     FIG. 3(   a ) illustrates a block diagram of an acoustic wave torque sensor system  300  that can be implemented in accordance with one embodiment. Note that in  FIGS. 1-3(   b ), identical or similar parts or elements are generally indicated by identical reference numerals. System  300  generally includes a component  302  that is subject to torque as indicated by arrow  301 . Component  302  can be, for example, a shaft utilized in automotive engine or aerospace application. The acoustic wave sensor device  100 , which may be, for example, a SAW, BAW, APM and/or other acoustic wave sensor apparatus can be located on the component  302  in order to obtain torque data. The ability to detect torque plays an important role in automatic controllers for a great variety of complex mechanical systems. In the configuration depicted in  FIG. 3(   a ), the interrogation unit  206  is shown in communication with a transmitter/receiver unit  304  which transmits and receives respective signals  114 ,  119  from antennas  110 ,  112  associated with acoustic wave sensor apparatus  100 . 
     FIG. 3(   b ) illustrates a block diagram of an acoustic wave pressure sensor system  312  that can be implemented in accordance with another embodiment. The components depicted in  FIG. 3(   b ) are similar to those depicted in  FIG. 3(   a ), the difference being that the acoustic wave sensor apparatus  100  is located within a tube  310  through which a fluid  311  flows. The acoustic wave sensor apparatus  100  depicted in  FIG. 3(   b ) is thus utilized for detecting pressure within tube  310 . 
     FIG. 4  illustrates a block diagram of an acoustic wave pressure sensor system  400  that can be implemented in accordance with the embodiment depicted in  FIG. 3(   a ). System  400  generally includes an antenna  402  that provides a signal  404  that is provided as RF data through an RF stage  406  and then an IF stage  408  followed by another RF stage  410  and a stage  412  at a frequency of approximately  70 Mhz. A null signal  412  can be provided to a component or stage  414  and then to a logarithmic amplifier  416  and finally to an Analog-to-Digital (ND) converter  418 . Note that several other A/D converters  420 ,  422  are also provided in the context of system  400 . A  100  Mhz- 2 . 7 Ghz frequency synthesizer  442  can also be provided which provides a signal to stage  408  (which may be a mixer). Components  444 ,  446  and  448  are also provided along with components  426  to  440 . Note that component  426  can generate a clock signal, while component  430  may function as a switch that provides a burst signal. Data output from A/D converters  418 ,  420 ,  422  can be provided to a computer  424  for processing. 
   Note that the interrogation unit utilized in the context of system  400  can be implemented as, for example, an interrogation unit similar to those utilized in radar applications. Interrogation units can be constructed, which are based on pulse radars, pulse compression radar and FMCW radar architectures if desired, although non-radar interrogation units can also be utilized, depending upon the desired embodiments. System  400  can be utilized to achieve optimal values over a broad frequency range. In the example depicted in  FIG. 4 , system  400  is provided in the context of a heterodyne receiver architecture with a 70 MHz IF stage and a limiter amplifier with radio signal strength indicator output (RSSI)  417 . 
   With an exchangeable IF SAW filter, a system bandwidth of 36 MHz can be achieved. To compensate coherent crosstalk in the IF-stage as well as the DC-offset of the mixer  408  following the use of logarithmic amplifier  416  and a DC-offset of the A/D converters  418 ,  420 , and/or  422 , a GaAS FET switch  430  can be inserted between an IF filter and the logarithmic amplifier  416 . It can be appreciated that the configuration depicted in  FIG. 4  represents only one example and is not considered a limiting feature of the embodiments disclosed herein. 
     FIG. 5  illustrates a block diagram of an acoustic wave torque sensor system  500  that can be implemented in accordance with the embodiment depicted in  FIG. 3(   b ). In the configuration depicted in  FIG. 5 , one or more SAW resonators  524  and  526  are provided. Note that such resonators are analogous to resonators  104 ,  106  depicted in  FIG. 1 . Resonators  524  and  526  are connected to a ground  528 . Coupler components  516  and  518  can also be provided in the context of system  500 . Coupler  516 , for example, is connected to a ground  522  and coupler  518  is connected to a ground  520 . 
   An output signal  512  can be generated by an amplifier  510  and sent through a resistor component  514  to coupler  516 , and an input signal  513  can be generated from coupler  516  and input to an amplifier  515 . Note that a mixer  534  can mix signals generated from amplifier  515  and also from a VCO  532  that receives summation data from a summation unit  530 . Similarly, a mixer  506  generates data that is transmitted to a summation unit  508  that provides output data to amplifier  510  that in turn forms a part of the output signal  512  described above. 
   Data from mixer  506  is also output as a differential frequency  502 . An oscillator  562  is also provided, which provides a signal to the summation unit  530  and to another summation unit  560 . Output from the summation unit  560  is provided to a VCO  558  which in turn provides data to a mixer  556  and to the summation unit  508 . Data generated from mixer  556  is provided as a differential frequency  554  and then to an amplifier  552  and thereafter to a mixer  550  whose output generates a differential frequency  548 , followed by input to an integrator  546  whose output is provided to the summation unit  560 . 
   Output from the mixer  534  is provided as a differential frequency  536  and then to an amplifier  538 . The output from amplifier  538  is provided as input to a mixer  540  whose output produces a differential frequency  542  that is fed to an integrator  544 . Output from the integrator  544  is then fed to the summation unit  530  along with output from the oscillator  562 . 
     FIG. 6  illustrates a block diagram of a tire condition sensor system  600  that can be implemented in accordance with another embodiment. Note that in  FIGS. 1-6 , identical or similar parts or elements are generally indicated by identical reference numerals. System  600  generally incorporates the use of the acoustic wave sensor apparatus  100 , which is located within a tire  602  and for detecting environmental conditions such as pressure and/or temperature within tire  602 . 
   The system disclosed herein can be utilized within, for example, automotive applications and for identifying and detecting pressure, friction, engine torque, acceleration, rotation rate and engine oil quality (e.g., viscosity and/or corrosivity). Even when one or more of the acoustic wave sensing devices utilize different modes of waves (e.g., SAW, BAW, APM, etc.), such acoustic wave sensing devices can share a common interrogation component (DSP, mixer, oscillator, PLL, DFT, etc.). 
   The systems disclosed herein can be designed to lower the cost of component implementation by designing the entire system together. For example, if an oil quality sensor is added to a vehicle system, the interrogation component or interrogation unit  206  can be shared by the existing torque sensor. Thus, the cost of the wireless oil quality sensor can be close to or even lower than a wired oil quality sensor system. In another embodiment, the system can be modified to incorporate a wireless and passive tire pressure sensor such as that depicted in  FIG. 6 . In still a further alternative embodiment, the system can be modified to include gas sensors, such as hydrogen and CO sensors inside a vehicle cabinet (e.g., in the case of fuel cell applications), along with emission gas sensors for emission control. Further, one or more such interrogation units  206  can be connected with a system bus (e.g., CAN bus) such as a CAN-SAW wireless bush/antenna throughout an automotive vehicle or aerospace body frame. 
     FIG. 7 , for example, illustrates a system  700  composed of a unit  712  composed of the interrogation unit  206  and the transmitter/receiver unit  304 . An antenna  713  is associated with unit  712  and transmits data to and from a plurality of acoustic wave sensing devices, such as an acoustic wave temperature sensor  702 , an acoustic wave oil quality sensor  704 , and an acoustic wave torque sensor  706 , an acoustic wave pressure sensor  708  and/or an acoustic wave gas sensor  710 . Note that the acoustic wave temperature sensor  702 , the acoustic wave oil quality sensor  704 , the acoustic wave torque sensor  706 , the acoustic wave pressure sensor  708  and the acoustic wave gas sensor  710  are respectively associated with antennas,  703 ,  705 ,  707 ,  709 , and  711 . Each of the sensors  702 - 710  depicted in  FIG. 7  can function structurally and similarly to the acoustic wave sensor  100  described earlier. 
   It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many otherdifferent systems or application. Also that various presently unforseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.