Abstract:
An apparatus and method for the repeatable detection and recording of low-threshold molecular electromagnetic signals. The sample material and detection apparatus are contained with a magnetically shielded faraday cage to shield them from extraneous electromagnetic signals. The detection apparatus includes a detection coil and Super Conducting Quantum Interference Device (“SQUID”). White noise is injected external to the SQUID and the signals emitted by the sample material enhanced by stochastic resonance.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus and method for detecting low-frequency molecular electromagnetic signals.  
         BACKGROUND OF THE INVENTION  
         [0002]    It has recently become apparent that all molecules emit very low-threshold electromagnetic emissions, or signals. The detection of molecular electromagnetic signals opens up numerous opportunities in the fields of science, medicine and industry. For example, if the low-threshold molecular electromagnetic signal of a food contaminate could be detected during production and packaging, less reliable existing methods of detecting contamination could be eliminated. Another potential use of such molecular electromagnetic signals is the detection of substances within the human body, including, but not limited to, antigens, antibodies, parasites, viruses, abnormal cells, etc.  
           [0003]    However, recognition of a particular electromagnetic signal first requires the measurement and categorization of such a signal. Existing apparatuses and methods for the detection of molecular electromagnetic signals do not detect a pure, repeatable signal. One known method for the detection and processing of electromagnetic signals is placing a sample substance in a shielded enclosure, subjecting the sample to electromagnetic excitation and detecting the excited signals with the use of a detection coil. This method results in a poor signal quality because of the relative lack of sensitivity of the apparatus and method used. In addition, excitation of the sample substance can result in a pattern of signals that are different than the electromagnetic signals of the substance in its natural state.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to providing an apparatus and method for the repeatable detection and recording of low-threshold molecular electromagnetic signals. The present invention includes a magnetically shielded faraday cage to shield the sample material and detection apparatus from extraneous electromagnetic signals. The invention further includes within the magnetically shielded faraday cage a coil for injecting white or gaussian noise, a nonferrous tray to hold the sample, a gradiometer to detect the low-threshold molecular electromagnetic signals, a superconducting quantum interference device (“SQUID”), and a preamplifier.  
           [0005]    The apparatus is used by placing a sample within the magnetically shielded faraday cage in close proximity to the noise coil and gradiometer. White noise is injected through the noise coil and modulated until the molecular electromagnetic signal is enhanced through stochastic resonance. The enhanced molecular electromagnetic signal, shielded from external interference by the faraday cage and the field generated by the noise coil, is then detected and measured by the gradiometer and SQUID. The signal is then amplified and transmitted to any appropriate recording or measuring equipment. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0007]    [0007]FIG. 1 is an isometric view of one embodiment of a molecular electromagnetic signaling detection apparatus formed in accordance with the present invention;  
         [0008]    [0008]FIG. 2 is an enlarged, detail view of the faraday cage and its contents shown in FIG. 1; and  
         [0009]    [0009]FIG. 3 is an enlarged, cross sectional view of one of the attenuation tubes shown in FIGS. 1 and 2.  
         [0010]    [0010]FIG. 4 is a cross-section view of the faraday cage and its contents shown in FIG. 2.  
         [0011]    [0011]FIG. 5 is a cross-section view of an alternative embodiment of the invention shown in FIGS. 1 through 4.  
         [0012]    [0012]FIG. 6 is an enlarged, detail view of the frames supporting the coils of the Helmholtz transformer described herein. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring to FIG. 1, there is shown a faraday cage  10  contained within a larger magnetic shielding cage  40 , which is further comprised of copper wire. Referring to FIG. 2, the faraday cage  10  is open at the top, and includes side openings  12  and  14 . The faraday cage  10  is further comprised of three copper mesh cages  16 ,  18  and  20 , nestled in one another. Each of the copper mesh cages  16 ,  18  and  20  is electrically isolated from the other cages by dielectric barriers (not shown) between each cage.  
         [0014]    Side openings  12  and  14  further comprise attenuation tubes  22  and  24  to provide access to the interior of the faraday cage  10  while isolating the interior of the cage from external sources of interference. Referring to FIG. 3, attenuation tube  24  is comprised of three copper mesh tubes  26 ,  28  and  30 , nestled in one another. The exterior copper mesh cages  16 ,  18  and  20  are each electrically connected to one of the copper mesh tubes  26 ,  28  and  30 , respectively. Attenuation tube  24  is further capped with cap  32 , with the cap having hole  34 . Attenuation tube  22  is similarly comprised of copper mesh tubes  26 ,  28  and  30 , but does not include cap  32 .  
         [0015]    Referring again to FIG. 2, a low density nonferrous sample tray  50  is mounted in the interior of the faraday cage  10 . The sample tray  50  is mounted so that it may be removed from the faraday cage  10  through the attenuation tube  22  and side opening  12 . Three rods  52 , each of which is greater in length than the distance from the center vertical axis of the faraday cage  10  to the outermost edge of the attenuation tube  22 , are attached to the sample tray  50 . The three rods  52  are adapted to conform to the interior curve of the attenuation tube  22 , so that the sample tray  50  may be positioned in the center of the faraday cage  10  by resting the rods in the attenuation tube. In the illustrated embodiment, the sample tray  50  and rods  52  are made of glass fiber epoxy. It will be readily apparent to those skilled in the art that the sample tray  50  and rods  52  may be made of other nonferrous materials, and the tray may be mounted in the faraday cage  10  by other means.  
         [0016]    Referring again to FIG. 2, mounted within the faraday cage  10  and above the sample tray  50  is a cryogenic dewar  100 . In the disclosed embodiment, the dewar  100  is adapted to fit within the opening at the top of faraday cage  10  and is a Model BMD-6 Liquid Helium Dewar manufactured by Tristan Technologies, Inc. The dewar  100  is constructed of a glass-fiber epoxy composite. A gradiometer  110  with a very narrow field of view is mounted within the dewar  100  in position so that its field of view encompasses the sample tray  50 . In the illustrated embodiment, the gradiometer  110  is a first order axial detection coil, nominally 1 centimeter in diameter, with a 2% balance, and is formed from a superconductor. The gradiometer can be any form of gradiometer excluding a planar gradiometer. The gradiometer  110  is connected to the input coil of one low temperature direct current superconducting quantum interference device (“SQUID”)  120 . In the disclosed embodiment, the SQUID is a Model LSQ/20 LTS dc SQUID manufactured by Tristan Technologies, Inc. It will be recognized by those skilled in the art that high temperature or alternating current SQUIDs can be used without departing from the spirit and scope of the invention. In an alternative embodiment, the SQUID  120  includes a noise suppression coil  124 .  
         [0017]    The disclosed combination of gradiometer  110  and SQUID  120  have a sensitivity of 20 microTesla/{square root}Hz when measuring magnetic fields.  
         [0018]    The output of SQUID  120  is connected to a Model SP Cryogenic Cable  130  manufactured by Tristan Technologies, Inc. The Cryogenic Cable  130  is capable of withstanding the temperatures within and without the dewar  100  and transfers the signal from the SQUID  120  to Flux-Locked Loop  140 , which is mounted externally to the faraday cage  10  and dewar  100 . The Flux-Locked Loop  140  in the disclosed embodiment is an iFL-301-L Flux Locked Loop manufactured by Tristan Technologies, Inc.  
         [0019]    Referring to FIG. 1, the Flux Locked Loop  140  further amplifies and outputs the signal received from the SQUID  120  via high-level output circuit  142  to an iMC-303 iMAG® SQUID controller  150 . The Flux-Locked Loop  140  is also connected via a model CC-60 six meter fiber-optic composite connecting cable  144  to the SQUID controller  150 . The fiber-optic connecting cable  144  and SQUID controller  150  are manufactured by Tristan Technologies, Inc. The controller  150  is mounted externally to the magnetic shielding cage  40 . The fiber-optic connecting cable  144  carriers control signals from the SQUID controller  150  to the Flux Locked Loop  140 , further reducing the possibility of electromagnetic interference with the signal to be measured. It will be apparent to those skilled in the art that other Flux-Locked Loops, connecting cables, and Squid controllers can be used without departing from the spirit and scope of the invention.  
         [0020]    The SQUID controller  150  further comprises high resolution analog to digital converters  152 , a standard GP-IB bus  154  to output digitalized signals, and BNC connectors  156  to output analog signals. In the illustrated embodiment, the BNC connectors are connected to a dual trace oscilloscope  160  through patch cord  162 .  
         [0021]    Referring to FIG. 2, a two-element Helmholtz transformer  60  is installed to either side of the sample tray  50  when the sample tray is fully inserted within the faraday cage  10 . In the illustrated embodiment, the coil windings  62  and  64  of the Helmholtz transformer  60  are designed to operate in the direct current to 50 kilohertz range, with a center frequency of 25 kilohertz and self-resonant frequency of 8.8 megahertz. In the illustrated embodiment, the coil windings  62  and  64  are generally rectangular in shape and are approximately 8 inches tall by 4 inches wide. Other Helmholtz coil shapes may be used but should be shaped and sized so that the gradiometer  110  and sample tray  50  are positioned within the field produced by the Helmholtz coil. Each of coil windings  62  and  64  is mounted on one of two low density nonferrous frames  66  and  68 . The frames  66  and  68  are hingedly connected to one another and are supported by legs  70 . Frames  66  and  68  are slidably attached to legs  70  to permit vertical movement of the frames in relation to the lower portion of dewar  100 . Movement of the frames permits adjustment of the coil windings  62  and  64  of the Helmholtz transformer  60  to vary the amplitude of white noise received at gradiometer  110 . The legs  70  rest on or are epoxied onto the bottom of the faraday cage  10 . In the illustrated embodiment, the frames  66  and  68  and legs  70  are made of glass fiber epoxy. Other arrangements of transformers or coils may be used around the sample tray  50  without departing from the spirit and scope of the invention.  
         [0022]    Referring to FIG. 4, there is shown a cross-sectional view of the faraday cage and its contents, showing windings  62  of Helmholtz transformer  60  in relation to dewar  100  and faraday cage  10 . Note also in FIG. 4 the positioning of sample tray  50  and sample  200 .  
         [0023]    Referring to FIG. 5, there is shown an alternative embodiment in which the Helmholtz coil windings  62  and  64  are fixed in a vertical orientation and an additional noise coil  300  is positioned below sample tray  50 . The windings of the additional noise coil  300  are substantially perpendicular to the vertical windings  62  and  64  of Helmholtz transformer  60 , and the windings of the additional noise coil  300  are thus substantially in parallel orientation to the bottom of faraday cage  10 .  
         [0024]    In this alternative embodiment, noise would be fed to noise coil  300  from an identical twisted pair wire (not shown) as that supplying the Helmholtz coil. The noise source would originate with the same noise generator used to supply noise to the Helmholtz coil. Noise would be sampled either at the noise generator via an additional noise output connection, or via a balanced splitter from an output connection to the noise generator. Attenuation of the noise signal at additional noise coil  300  would be through an adjustable RF signal attenuation circuit, of which many are available commercially, or via a suitable series of fixed value RF attenuation filters.  
         [0025]    Referring to FIG. 6, a detail of the frames supporting the coils of Helmholtz transformer  60  may be seen; the reference point of FIG. 6 is 90 degrees from the view of FIG. 4, and omits the faraday cage  10 . Frames  66  and  68  are disposed to show the coil windings of the Helmholtz coil in a substantially vertical position and parallel to one another. Frames  66 ′ and  68 ′ illustrate the rotation of said frames about the axis of the hinged connection joining said frames, so as to dispose the coil windings of the Helmholtz transformer in an non-parallel relationship with one another.  
         [0026]    Referring again to FIG. 1, an amplitude adjustable white noise generator  80  is external to magnetic shielding cage  40 , and is electrically connected to the Helmholtz transformer  60  through filter  90  by electrical cable  82 . Referring to FIG. 3, cable  82  is run through side opening  12 , attenuation tube  24 , and through cap  32  via hole  34 . Cable  82  is a co-axial cable further comprising a twisted pair of copper conductors  84  surrounded by interior and exterior magnetic shielding  86  and  88 , respectively. In other embodiments, the conductors can be any nonmagnetic electrically conductive material, such as silver or gold. The interior and exterior magnetic shielding  86  and  88  terminates at cap  32 , leaving the twisted pair  84  to span the remaining distance from the end cap to the Helmholtz transformer  60  shown in FIG. 1. The interior magnetic shielding  86  is electrically connected to the exterior copper mesh cage  16  through cap  32 , while the exterior magnetic shielding is electrically connected to the magnetically shielded cage  40  shown in FIG. 1.  
         [0027]    Referring to FIG. 1, the white noise generator  80  can generate nearly uniform noise across a frequency spectrum from zero to 100 kilohertz. In the illustrated embodiment, the filter  90  filters out noise above 50 kilohertz, but other frequency ranges may be used without departing from the spirit and scope of the invention.  
         [0028]    White noise generator  80  is also electrically connected to the other input of dual trace oscilloscope  160  through patch cord  164 .  
         [0029]    Referring to FIGS. 1, 2 and  3 , a sample of the substance  200  to be measured is placed on the sample tray  50  and the sample tray is placed within the faraday cage  10 . In the first embodiment, the white noise generator  80  is used to inject white noise through the Helmholtz transformer  60 . The noise signal creates an induced voltage in the gradiometer  110 . The induced voltage in the gradiometer  110  is then detected and amplified by the SQUID  120 , the output from the SQUID is further amplified by the flux locked loop  140  and sent to the SQUID controller  150 , and then sent to the dual trace oscilloscope  160 . The dual trace oscilloscope  160  is also used to display the signal generated by white noise generator  80 .  
         [0030]    The white noise signal is adjusted by altering the output of the white noise generator  80  and by rotating the Helmholtz transformer  60  around the sample  200 , shown in FIG. 2. Rotation of the Helmholtz transformer  60  about the axis of the hinged connection of frames  66  and  68  alters its phasing with respect to the gradiometer  110 . Depending upon the desired phase alteration, the hinged connection of frames  66  and  68  permits windings  62  and  64  to remain parallel to one another while rotating approximately 30 to 40 degrees around sample tray  50 . The hinged connection also permits windings  62  and  64  to rotate as much as approximately 60 degrees out of parallel, in order to alter signal phasing of the field generated by Helmholtz transformer  60  with respect to gradiometer  110 . The typical adjustment of phase will include this out-of-parallel orientation, although the other orientation may be preferred in certain circumstances, to accommodate an irregularly-shaped sample  200 , for example. Noise is applied and adjusted until the noise is 30 to 35 decibels above the molecular electromagnetic emissions sought to be detected. At this noise level, the noise takes on the characteristics of the molecular electromagnetic signal through the well known phenomenon of stochastic resonance. The stochastic product sought is observed when the oscilloscope trace reflecting the signal detected by gradiometer  110  varies from the trace reflecting the signal directly from white noise generator  80 . In alternative embodiments, the signal can be recorded and or processed by any commercially available equipment.  
         [0031]    In an alternative embodiment, the method of detecting the molecular electromagnetic signals further comprises injecting noise 180° out of phase with the original noise signal applied at the Helmholtz transformer  60  through the noise suppression coil  124  of the SQUID  120 . The stochastic product sought can then be observed when the oscilloscope trace reflecting the signal detected by gradiometer  110  becomes non-random.  
         [0032]    Regardless of how the noise is injected and adjusted, the stochastic product can also be determined by observing when an increase in spectral peaks occurs. The spectral peaks can be observed as either a line plot on oscilloscope  160  or as numerical values, or by other well known measuring devices.  
         [0033]    The present invention provides a method and apparatus for detecting extremely low-threshold molecular electromagnetic signals without external interference. The present invention further provides for the output of those signals in a format readily usable by a wide variety of signal recording and processing equipment.  
         [0034]    While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.