TECHNICAL FIELD
The present invention relates to a sensor apparatus and a method for detecting environmental factors, and more specifically, to an acoustic device which produces different resonant vibrational frequencies and/or modal patterns following exposure of the acoustic device to a given environmental factor, and to an arrangement which is operable for reading out an array of such acoustic device sensors.
BACKGROUND OF THE INVENTION
The prior art is replete with numerous examples of material inspection systems and other devices such as seen in U.S. Pat. Nos. 6,134,006, 6,175,411, 6,401,540, 6,486,962, and 6,836,336 and which are useful for imaging traveling or resonant waves in a medium. Heretofore, these devices have been used to investigate the microstructural form and composition of an object. Further, many manufactures have begun manufacturing and marketing various “microassay kits” which are utilized to detect various materials, including chemicals and biological organisms. These microassay kits, as a general matter, can usually be rapidly processed, and permit the use of smaller quantities of analytes in the processing of same. A further parallel effort has been undertaken to provide arrays of micro-sensors that can rapidly detect the presence of a wide range of analytes. An example of this type of approach is the “lab on a chip” approach. These devices, after use, are often read out or interpreted by using a microscope. Typically, a color change in the device will indicate the presence of a substance or organism to be detected. This method can be implemented manually or by an automated image analysis.
As the size and complexity of these prior art arrays increase, the problems of accurately reading the data produced from these complex arrays has become increasingly difficult. Furthermore, in the fabrication of the micro-sensor arrays which utilize various electronic sensors, the ability to accurately read or gather a useful and accurate electrical output from the various electric sensors becomes increasingly difficult as the electrical wiring density increases. As could be expected, an increased wire density leads to “cross talk” between adjacent electrical conductors that may be coupled to different electrical sensors in the same array.
A sensor apparatus and method for detecting various environmental factors which avoids the shortcomings attendant with the prior art practices utilized heretofore is the subject matter of the present application.
SUMMARY OF THE INVENTION
Therefore, one aspect of the present invention relates to a sensor apparatus which includes an acoustic device which has a characteristic resonant vibrational frequency and mode pattern when exposed to a source of acoustic energy, and which further, when exposed to an environmental factor, produces a different resonant vibrational frequency and/or mode pattern when exposed to the same source of acoustic energy.
Another aspect of the present invention is to provide an array which includes a plurality of acoustic devices which are operable to change their respective acoustic response when exposed to an environmental factor, and an imaging assembly associated with the array of acoustic devices and which is useful in reading, measuring, or otherwise detecting changes in the acoustic response of the plurality of the respective acoustic devices after they have been exposed to the environmental factor.
Another aspect of the present invention relates to a sensor apparatus which includes an acoustic device which has a characteristic resonant vibrational frequency, and mode pattern, when exposed to acoustic energy; an assembly for transmitting acoustic energy to the acoustic device; a source of acoustic energy of a given frequency which is supplied to the acoustic device; and an assembly for imaging the acoustic device to determine the resonant vibrational frequency and/or modal pattern of the acoustic device when the acoustic device is exposed to the source of acoustic energy.
Still further, another aspect of the present invention relates to a method for detecting an environmental factor which includes the steps of providing an acoustic device having an acoustic property which includes a characteristic resonant vibrational frequency and mode pattern when exposed to acoustic energy; exposing the acoustic device to an environment which has an environmental factor to be detected, and wherein the acoustic property of the acoustic device changes following the exposure of the acoustic device to the environmental factor; supplying a source of acoustic energy to the acoustic device; imaging the acoustic device following exposure of the acoustic device to the environmental factor and while supplying the source of acoustic energy to the acoustic device; and determining whether the resonant frequency and mode pattern of the acoustic device has changed as a result of exposure to the environmental factor.
These and other aspects of the present invention will be described in greater detail hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are described below with reference to the following accompanying drawings.
FIG. 1 is a greatly simplified depiction of a first form of a sensor apparatus of the present invention.
FIG. 2 is a greatly simplified, graphical depiction of a second form of a sensor apparatus of the present invention.
FIG. 3 is a plan view of the second form of the sensor apparatus as seen in FIG. 2.
FIG. 4 is a plan view of a third form of a sensor apparatus of the present invention.
FIG. 5 is a greatly simplified, and enlarged view of a portion of the third form of the sensor apparatus as seen in FIG. 5.
FIG. 6 is a perspective, greatly enlarged view of a portion of the sensor apparatus as seen in FIG. 5, and which shows the response of the third form of the sensor apparatus after being exposed to an environmental factor.
FIG. 7A is a depiction of a pair of sensors having a thin film bulk resonator design and which illustrates the mode pattern displayed by the respective sensor when exposed to acoustic energy having a frequency of 21.006467 MHz, and before exposure to an environmental factor to be detected.
FIG. 7B is a depiction of the same pair of resonators as seen in FIG. 7A, but illustrating the mode pattern displayed by each when exposed to acoustic energy having a frequency of 21.006200 MHz, and following exposure to an environmental factor to be detected.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
The sensor apparatus of the present invention and the methodology for detecting an environmental factor is best understood by the numeral 10 in FIG. 1 and following. As seen therein, the sensor apparatus 10 has first, second and third forms which are generally indicated by the numerals 11, 12 and 13. Referring now to FIG. 1, it will be seen that the sensor apparatus 10 has an underlying supporting surface or substrate 14 which has an upwardly facing surface 15. Mounted on the upwardly facing surface are a plurality of acoustic devices here depicted as consecutive rows of individual cantilevered members which are generally indicated by the numeral 20. As seen most clearly by reference to FIG. 2, which shows a second form of the invention whereby the cantilevered members are oriented in another arrangement, each of the cantilevered members 20 has a first end 21, and a distal second end 22. Mounted on the second end 22 is an environmentally sensitive surface 23 which when exposed to an environmental factor may subsequently experience a change in thickness; damping; stiffness; Young's modulus dimensional; material properties such as elasticity, for example and/or combinations thereof. While only a small region of the distal end is covered by the environmentally sensitive surface or coating, it should be recognized that the entire surface area between the first and second ends 21, and 22 may be covered by the environmentally sensitive surfaces 23. The cantilever member 20 is held in spaced relation relative to the upwardly facing surface 15 by a support member 30. As seen in FIGS. 1-4, for example, the plurality of acoustic devices 20 can be positioned in an array 40 as seen in FIGS. 1 and 2 for example, and which are operable to respond to different environmental factors as will be discussed in greater detail hereinafter. In the arrangement as seen in FIG. 1 and following, it should be understood that the first, second and third forms of the invention 11, 12 and 13, respectively, each include at least one acoustic device 20 which has a characteristic resonant vibrational frequency, and mode pattern, when exposed to a source of acoustic energy and which is generally indicated by the numeral 50. Further, when exposed or following exposure to an environmental factor, as will be described below, these same acoustic devices as understood in the first, second and third forms of the invention 11, 12 and 13 produce a different resonant vibrational frequency and/or mode pattern when subsequently exposed to the same source of acoustic energy 50. This is illustrated most clearly by a study of FIGS. 5, 6, 7A and 7B, respectively.
In the arrangement as seen with respect to the first, second and third forms of the invention 11, 12 and 13 which are generally graphically depicted, it will be appreciated that the acoustic device selected, such as 20, may be selected from the group which includes quartz crystal microbalances; surface acoustic wave transducers; and thin film bulk, linear and/or torsional acoustic resonators. Yet further, the environmental factor that the first, second and third forms of the invention 11, 12, and 13 can detect are selected from the non-limiting group comprising biological; chemical; thermal; acoustic; electromagnetic and/or combinations thereof. In some instances, the acoustic device as shown in the several forms of the invention, may increase in mass following exposure to the environmental factor. On the other hand, various forms of the invention may be designed such that the acoustic device may experience a decrease in mass following exposure to the environmental factor(s) discussed above. In any event, the acoustic device selected, as may be provided in the first, second and third forms 11, 12 and 13, experience physical changes following the exposure to the environmental factor. These changes may result, as noted above, in changes to the mass, thickness; damping; stiffness; Young's modulus of the acoustic device and/or combinations thereof. As noted, when the acoustic device is subsequently exposed to the same source of acoustic energy it produces a different resonant vibrational frequency or mode pattern which can be visually detected, and which conclusively demonstrates the presence of the environmental factor. This is clearly illustrated in FIGS. 7A and 7B, for example. This arrangement can also be calibrated to indicate the quantity of the environmental factor which was exposed to apparatus 10.
In the arrangement as seen in FIG. 1 and FIG. 5, for example, it should be understood that the several different acoustic devices as may be seen in the first, second and third forms of the invention 11, 12 and 13 may be placed into an array 40, and wherein the plurality of acoustic devices are operable to respond to different environmental factors which can be read or otherwise detected substantially simultaneously. As should be understood, the source of acoustic energy 50 may be provided or otherwise supplied to the first, second and third forms of the invention 11, 12 and 13 at a single frequency, or may be provided at a plurality of frequencies. Still further, the source of acoustic energy 50 may be supplied by the ambient environment. Additionally, it should be understood that the environmentally sensitive surface 23 may comprise a commercially produced molecularly imprinted polymer 24 which has an affinity for and/or which bonds to a specific organic or inorganic chemical, microorganism, or biological material. In the arrangements as illustrated, the source of acoustic energy 50 may be derived from an energy source which is selected from the non-limiting group including, but not limited to, electrostatic; capacitive; thermal; optical; acoustic; magnetic; piezoelectric; mechanical; and/or combinations thereof. In the arrangement as shown, generally any source of acoustic energy 50 may be useful in the practice of the present invention.
As seen in FIG. 1, the first form of the invention 11 includes a plurality of these acoustic devices, here illustrated as the cantilevered members 20, which are positioned in consecutive linear rows. The individual cantilevered members 20 may be rendered operable to detect a single environmental factor or multiple environmental factors all from the same array 40.
As will be discussed below, and by reference to FIGS. 7A and 7B, it should be understood that the sensors may be disposed in a side-by-side orientation and which are individually operable to respond to different environmental factors. Referring now to FIG. 4, the third form 13 of the sensor apparatus 10 is shown, and which includes groups of acoustic sensors 60 which again, like the first and second forms 11 and 12 of the invention 10, are operable to detect various environmental factors that might be exposed to same. The groups of acoustic sensors 60 are positioned on a supporting substrate 61, and are made up of individual acoustic sensors 62 which are disposed in spaced relationship one to the other as seen in FIG. 5. As shown therein, the individual acoustic sensors 62 have a first end 63 and an opposite second end 64 which are affixed to the supporting substrate 61. The individual acoustic sensors further have an upwardly facing, and deformable surface 65 which has been treated or otherwise coated, or supplied with an environmentally sensitive surface 66 such as a molecular imprinted polymers as earlier discussed with respect to the first form of the invention 11. As seen in FIGS. 5, 6, 7A and 7B, the groups of acoustic sensors 60 are exposed to the environmental factors as earlier described and they are operable to change their acoustic characteristics similar to that which was described with respect to the first form of the invention 11, that is, once exposed to the environmental factor they produce a different resonant vibrational frequency and/or mode pattern when exposed to the same source of acoustic energy such as 50. As should be understood, an assembly for transmitting the given acoustic energy to the acoustic device 51 is provided and is only generally illustrated in FIG. 1. It will be seen by reference to FIG. 6, that the plurality of acoustic sensors 60, as illustrated therein, have been previously exposed to an environmental factor which has caused the mass of the individual acoustic sensors 62 to change thereby deforming the upwardly facing surface 65. This results in a change in the acoustic characteristics of these same devices once they are exposed to a source of acoustic energy such as 50.
Referring now to FIG. 7A, individual groups of acoustic sensors 60 are shown, and which have been rendered operable to detect a selected environmental factor. FIG. 7A depicts an actual mode pattern which is displayed from pairs of micromachined vibratory think film bulk resonator structures when these same acoustic devices are exposed to a source of acoustic energy 50 which has a frequency of 21.006467 MHz, and prior to the exposure of the acoustic devices 60 to the selected environmental factor. Referring now to FIG. 7B, the same groups of acoustic sensors 60, are shown, and which illustrate the mode pattern of the same groups of acoustic sensors 60 following exposure to the selected environmental factor, and when exposed to acoustic energy 50 having a different frequency of about 21.006200 MHz. As can be seen, the change in the mode pattern as illustrated by a comparison of FIGS. 7A and 7B demonstrates that the groups of sensors 60 have been exposed to the selected environmental factor.
FIGS. 2 and 3 show the second form 12 of the sensor apparatus 10 and which includes a plurality of acoustic devices, as illustrated, and which include various cantilevered members generally indicated by the numeral 20. As best seen by a study of FIG. 2, the sensor apparatus 10 includes an assembly 70 for imaging an acoustic device, such as 20, following the exposure of the acoustic device to the environmental factor, as earlier described, and while the acoustic device is being exposed to the source of acoustic energy 50 to determine the resonant frequency and/or modal pattern of the acoustic devices involved. The assembly for imaging the acoustic devices 70 produces a visibly discernible image of mode pattern of the respective acoustic devices as seen most clearly by reference to FIGS. 7A and 7B, respectively. The assembly for imaging an acoustic device 70 following the exposure of the acoustic device(s) to the environmental factor is shown in a greatly simplified arrangement. Other devices which will work with equal success are those shown in U.S. Pat. No. 6,836,336, 6,134,006, 6,175,411 and 6,486,962, the teachings of which are all incorporated by reference herein. For ease of illustration, however, the assembly for imaging the acoustic device 70 generally includes a digital camera 71 or other video device which is capable of forming a discernible video image of the respective acoustic devices from coherent light which is directed at and reflected from the acoustic device 20 (FIGS. 7A and 7B). The digital camera or video device 71 is operably coupled with a camera lens which is generally indicated by the numeral 72. Positioned in spaced relation relative to the camera lens is an imaging lens 73. Further, a laser 74 is positioned in spaced relation therebetween the digital camera 71, and the imaging lens 73. The laser, in the present arrangement, is a non-contacting, coherent light emitting device which directs a beam of light, as will be discussed below, at the plurality of vibratory acoustic devices 20. The imaging device 70 further includes a beam splitter 80, which is positioned in spaced relation relative to the laser 74. Still further, first and second reflecting mirrors 81 and 82 are provided to direct the emitted beam of light along a given course of travel, as will be discussed below. The imaging assembly 70 further includes a reference beam modulator 83. Additionally, a photorefractive material 84 is provided, and which is generally indicated by the numeral 84.
As seen in FIG. 2, it is understood that the laser 74 produces a first object light beam 90, and a second reference light beam which is generally indicated by the numeral 100. In the arrangement as seen in FIG. 2, the imaging lens 73 is configured to focus the object beam 90, following reflection from the acoustic devices 20, which are in an array, onto a desired location of the photorefractive material 84. The imaging lens 73 has a conventional design presently understood in the art. In the arrangement as shown, and upon being reflected off the plurality of cantilevered members 20, the object beam 90 has been impressed with information defining the given vibrational displacement amplitude, and vibrational phase of the plurality of acoustic sensors 20 which are shown in that view. The object beam 90 is combined to interfere with the reference beam 100, and which takes place within the photorefractive material 84 by way of a two-wave anisotropic self-diffraction, with or without polarization rotation. An equivalent arrangement using a four wave anisotropic self diffraction could also be employed with equal success. In the arrangement as seen in FIG. 2, the object and reference beams 90 and 100 are mutually coherent so as to interfere within the photorefractive material 84. The reference beam modulator 83 operates on reference beam 100 to produce a phase modulated reference beam. The phase modulated reference beam and the reflected object beam 90 interfere within and pass through the photorefractive material 84 so as to create a space charged field having a magnitude which is directly proportional to the vibration displacement. The space charge field produces an index of refraction grating by the electro-optic effect which contains information of the vibration state of the plurality of acoustic devices or cantilevered members 20 as shown in FIG. 4. The photorefractive material 84 has a given response time wherein the induced grating within the photorefractive substance 84 passes the reflected object beam 90, and reference beam 100. Object beam 90, and reference beam 100 interfere within the photorefractive material 84 to create a space charged field and resulting induced grating which develops within the response time of the photorefractive material 84. In this regard, the object beam 90 is reflected off of the vibrating acoustic devices or cantilevered members 20 having a vibration displacement amplitude and a vibration phase. The photorefractive material 84 passes the reflected object beam 90 and the reference beam 100 such that their interference therein creates a spaced charged field induced grating having a diffraction efficiency which is directly proportional to the vibration displacement for small amplitudes. This displacement of the acoustic devices or cantilevered members 20 which is induced by the acoustic energy 50 is then captured as a digital video image in the digital camera or video device 71 which is provided. The results are seen in FIG. 7A and 7B. As illustrated in FIG. 2, it will be seen that the assembly for imaging the acoustic device 70 is operable to image a plurality of acoustic devices 20 substantially simultaneously and without the shortcomings attendant with the earlier prior art practices which have been described earlier in this application.
Operation
The operation of the described embodiment of the present invention is believed to be readily apparent and is briefly summarized at this point.
As seen in the various drawings, the sensor apparatus 10 of the present invention includes an acoustic device, such as 20 or 60, which has a characteristic resonant vibrational frequency and mode pattern when exposed to a source of acoustic energy 50. Still further, the source of acoustic energy 50 has a given frequency which is supplied to the acoustic devices noted. In addition to the foregoing, an assembly for imaging the acoustic device 70 is provided. The imaging device is operable to determine the resonant frequency and/or modal pattern of the acoustic device 60 when the acoustic device is exposed to the source of acoustic energy 50. As seen in the drawings, a plurality of acoustic devices 20 or 60 may be deployed in an array 40. As seen in FIG. 2, the assembly for imaging the acoustic device 70 may image each of the plurality of acoustic devices substantially simultaneously. As earlier discussed, the source of acoustic energy 50 may be a separate source, or may, in the alternative, be provided by the ambient environment. As illustrated, the acoustic device 20 has a surface area 22, 65 which may be treated to bond to a specific chemical or biological material or otherwise react to another environmental factor, which may be physical, material or anything of whatever nature which is in the environment. For example, when a biological material bonds to same, the acoustic device, such as 20, experiences a change in its physical characteristics (an increasing mass) and which, at least in part, influences an acoustic response of the acoustic device 20. The change in the acoustic response may include, at least in part, a resulting different resonant vibrational frequency and/or mode when exposed to the source of acoustic energy 50. As earlier discussed, the changes in the physical characteristics of the acoustic device 20, 60 which effects the acoustic response of the acoustic device relates to a change in mass; thickness; stiffness; damping; Young's Modulus, dimension, material properties such as elasticity, for example, and/or combinations thereof. The surface area of the acoustic device may mount, for example, in one form, a molecularly imprinted polymer which has an affinity for, and/or bonds to the specific chemical or biological materials which comprise, at least in part, the environmental factor which is to be detected. As earlier discussed, the source of acoustic energy may be derived from nearly any available source of acoustic energy, such as, for example, electrostatic; capacitive; thermal; optical; acoustic; magnetic; piezoelectric; mechanical and/or combinations thereof. In the invention as shown, an assembly for imaging the acoustic device 70 is provided, and which includes, without limitation, a non-contacting coherent light emitting device, such as the laser 74, which directs a beam of light 90 at the plurality of vibrating acoustic devices 20, and which is reflected from same; and a photorefractive material 84 which could conceivably be incorporated into a dynamic photorefractive holographic interferometer. Further, the imaging assembly 70 includes a video assembly which may comprise a digital camera 71 for capturing the reflected light 90, and which produces a video image of the vibrational movements of each of the acoustic devices 20. As shown in FIG. 2, the assembly for imaging the acoustic device 70 is not operably coupled with the respective acoustic devices 20. Still further, the several acoustic devices 20 may be vibrated by the source of acoustic energy 50 at a single resonant frequency, at multiple frequencies and/or which is moved or otherwise swept through a range of frequencies, depending upon the circumstances. In the present invention 10, the plurality of acoustic devices are vibrated by a source of acoustic energy 50 at a resonant frequency which lies within a range of about 100 Hz to about 5 GHz. As seen in the various drawings, the surface area of any array 40 is typically less than about 100 square millimeters, although it is conceivable that larger arrays could be constructed.
In the arrangement as shown, the plurality of acoustic devices 20, 60 as seen in the various forms of the invention 11, 12 and 13 has an intrinsic response to an environmental factor, as earlier described, which results in a different resonant vibrational frequency and/or mode when the acoustic device is exposed to the acoustic energy 50.
In the drawings, a method for detecting an environmental factor is shown, and which includes the steps of providing an acoustic device 20, 60 having an acoustic property which includes a characteristic resonant vibrational frequency, and mode pattern, when exposed to acoustic energy 50. The method further includes a step of exposing the acoustic device 20, 60 to an environment which has an environmental factor to be detected, and wherein the acoustic property and/or resulting acoustic response of the acoustic device 20, 60 changes following the exposure of the acoustic device to the environmental factor. The method for detecting an environmental factor further includes the step of supplying a source of acoustic energy 50 to the acoustic device, and a further step of imaging the acoustic device 70 following the exposure of the acoustic device to the environmental factor and while the supplying the source of acoustic energy 50 to the acoustic device. The methodology of the present invention further includes a step of determining whether the resonant frequency and/or mode pattern of the acoustic device 20, 60 has been changed as a result of exposure to the environmental factor. As earlier described, the step of providing the acoustic device 20, 60 may further comprise a step of providing a plurality of acoustic devices, and arranging the plurality of acoustic devices in an array 40. As earlier noted, the environmental factor to be detected may comprise a plurality of different environmental factors which are selected from the group comprising biological; chemical; physical; material; thermal; acoustic; electromagnetic and/or combinations thereof. In the arrangements as illustrated, the method for imaging the acoustic device 70 further comprises the steps of directing and reflecting a beam of coherent light 90 off of the acoustic device 20, 60; and capturing a video image from a video device 71 of the vibrational movement of the several acoustic devices 20, 60 from the captured coherent light. In the arrangements as shown, the step of imaging the acoustic device further comprises imaging the plurality of acoustic devices substantially simultaneously.
Therefore, it will be seen, that the present invention provides a convenient means whereby a plurality of environmental factors can be easily detected, and readily read or identified from a micro-sensor array which is relatively small in size, and convenient to use. The present sensor apparatus 10 can be used in a wide range of commercial and military applications and provides a convenient means for rapidly detecting possibly adverse environmental factors in a manner not possible heretofore. Still further, the present invention offers a novel methodology of reading arrays of variously designed sensors which are responsive to all manner of sources of vibrational or acoustic energy, and which have been rendered useful in detecting any desired environmental factor as discussed above.
In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.
Patent Application
20060255689
