DYNAMIC SELECTIVE POLARIZATION MATCHING

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent

Application No. 62/713,233, filed August 1, 2018, the entire content of which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] (NOT APPLICABLE)

BACKGROUND

[0003] The invention relates to investigating or analyzing materials or entities of interest by the use of electric, electro-chemical, or magnetic means by investigating electrostatic variables. More specifically, the invention uses the fields of

electrostatics and dielectrophoresis with electronics to engage the analog matching filter for the purpose of detection of a variety of specific materials and compositions of matter including dielectric materials. The invention is suitable for use with products manufactured by DrawDown Detection Inc.

[0004] In recent years, advances in technology, internet, 3D printing, and communications have provided individuals the ability to create weapons using a variety of specific materials and compositions of matter, including explosives that are difficult to detect using traditional detectors and scanners. This has created a void in the ability to maintain the highest level of security for schools, office buildings, and other public and private areas.

[0005] The capability to detect dielectric materials (energetic materials) used on“soft targets” as a weapon of mass terror is an unmet need worldwide. Current capabilities such as search dogs, trace detection and physical inspections are effective when used at controlled check points. However, these capabilities are not effective for Standoff detection. Numerous guns and ammunition such as used in the 2017 Las Vegas Hotel shooting or Energetic materials used on Boston Marathon spectators, London subway riders and French cafe patrons are examples where Standoff detection may be useful. Standoff sensors could be used to detect the storage, transportation and placement of energetic materials prior to an attack.

BRIEF SUMMARY

[0006] Standoff sensors capable of locating from a distance would be an effective tool for public and private security and safety professionals. A widely deployed hand-held standoff sensor capable of alerting to the presence and location of a broad range of dielectric materials (energetic materials) could enable first responders to interdict, deactivate or isolate before an attack. Standoff detection would also provide deterrence wherever the sensor was available.

[0007] Standoff sensors operate in the ULF (near DC) frequency. The

Standoff Sensor of the described embodiments is passive and emits no detectable emissions. The Sensor acts as a transducer that converts electric field energy into a force aligning an internal member to the source of the electric field. Location information is displayed digitally. The Sensor employs an RC (capacitors and resistors) circuit and an impedance-matching filter circuit with bandpass frequency filtering in the ULF range.

[0008] Discriminatory detection of the target electric field is achieved by the selective relative permittivity of the capacitive elements of the detection circuit. The permittivity of the replicate property dielectric material and the configuration of the capacitive elements define the dielectric strength or minimum electric field for the detection.

[0009] Permittivity transmits (or“permits”) an electric field to charge the analog matching filter of the described embodiments and allows electric field charge to be stored and converted to a dielectrophoresis force. The selective permittivity is arranged in an analog matching filter in an RC circuit that enables the electric field stored charge to be converted to the dielectrophoretic force and enabling the detection. [0010] In an exemplary embodiment, an analog matching filter includes a first plate, a second plate coupled with the first plate and separated from the first plate via a spacer, and a replicate matching material fixed to an inside surface of the first plate. A conductive plate or sheet is fixed to an inside surface of the second plate. An electrical circuit connects the first plate to the conductive plate or sheet. The replicate matching material and the conductive plate or sheet generate an opposite polarization pattern carried by the electrical circuit that is based on a polarization pattern of a to- be-detected entity according to a spatial gradient of the to-be-detected entity local electric field distribution.

[0011] The first and second plates may be parallel. The first and second plates may be curved along longitudinal axes thereof. In this context, the inside surfaces of the first and second plates may be concave. The first and second plates may be formed of a polymer material such as acrylonitrile-butadiene- styrene (ABS). The spacer may be formed of nylon.

[0012] The electrical circuit may include a silver-coated copper wire electrically connected to the first plate and a primary conductive wire electrically connected to the conductive plate or sheet. The silver-coated copper wire and the first conductive wire may be connectable to an internal member. The electrical circuit may include a first resistor and a capacitor arranged in parallel on the primary conductive wire. The electrical circuit may include a second resistor in series with the first resistor and the capacitor.

[0013] The replicate matching material may be selected in accordance with dielectric polarization characteristics of the to-be-detected entity. The replicate matching material may include one or more dielectric materials.

[0014] In another exemplary embodiment, a sensor device for detecting an entity includes a housing, first and second analog matching filters of the described embodiments, and an internal member that is configured to react to the opposite polarization pattern carried by the electrical circuit. A switch coupled with the first and second analog matching filters selectively activates the first analog matching filter or the second analog matching filter. [0015] The replicate matching material of the first analog matching filter may be different from the replicate matching material of the second analog matching filter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which:

[0017] FIG. 1 is an end view of the analog matching filter arrangement;

[0018] FIG. 2 is a side view;

[0019] FIG. 3 is a chart showing electrical characteristics of the analog matching filter; and

[0020] FIG. 4 shows an exemplary application of the analog matching filter in a sensor device.

DETAILED DESCRIPTION

[0021] The described embodiments relate to an analog matching filter formed of compositions of matter using initially neutral material chosen to be an exact dielectric replicate of an entity to be detected via dielectrokinesis (phoresis). The analog matching filter is an essential element in triggering and also maximizing both the mechanical torque and energy replenishment modes using dielectrokinesis (phoresis) methods to detect entities.

[0022] This filtering action applies to a practically limitless range of materials to be detected as an entity of interest target. The detection materials include, for example, Amine: cyclo-tri-methylene-tri-nitr-amine (RDX formulated as C4)(also HMX and tetryl), cyclo-tetra-methylene-tetra-nitr-amine (HDX formulated as CX); Nitrate: penta-erythrite-tetra-nitrate (PETN plus RDX formulated as Semtex, ammonium-nitrate (plus select hydrocarbon oil formula as fertilizer bomb), glycerol- tri-nitrate (nitroglycerin formulated as dynamite) (also smokeless gunpowder);

Toluene: 2,4,6-tri-nitro-toluene (TNT), organic compounds, plastic (mixture of polymers and additives) for plastic dielectric material detection and the like. [0023] The dielectric replicate material comprising the analog matching filter functionally performs a spatial dielectric property matching between the entity of interest and a locator device to locate the entities. The filter enables the device to operate using the dielectrokinesis (phoresis) phenomena to specifically detect only those entities matching the dielectric response signature of the analog matching filter component. The dielectric signature includes both the dielectric constant and dielectric loss frequency spectra and all characteristic time constants controlling the polarization evolution/mechanics in external electric fields.

[0024] There are two primary elements for the dielectrokinesis entity location detection device to operate. The first element is an external electric field and spatial gradients thereof, and the second element is the selective dielectric analog matching filter of the described embodiments. As noted above, the external electric field and gradients thereof can be provided by the entity of interest itself as is the case when animate species or many inanimate entities are the entities of interest to be detected.

[0025] The analog matching filter of the described embodiments can be used with conventional electronic components (resistors, capacitors, inductors, transistors, etc.) in the overall operational design of the type of locator device used to detect the presence or absence of a specific entity of a predetermined type.

[0026] The external electric field and gradients thereof of the target entity defines a specific polarization pattern for the entity. In order to detect the target entity electric field and gradients thereof, it is necessary to impart an opposite polarization pattern on a detector element such as an antenna, dielectric collector or the like.

[0027] It has been discovered that specific combinations of materials provide the desired effects of the analog matching filter. FIG. 1 illustrates a filter 10 according to a first embodiment. As shown in FIG. 1, the filter 10 includes a replicate dielectric property matching material 12 within a spaced plate arrangement including a first plate 14 coupled with a second plate 16. As shown, the plates 14, 16 may be curved along their longitudinal axes with concave surfaces facing each other.

Alternatively, the plates 14, 16 may be parallel or constructed in different shapes.

The pair of plates 14, 16 disposed enclosing the replicate dielectric property matching material 12 are held at a preferred distance by nylon spacers 18 secured via a suitable fastener 20. The plates 14, 16 may be formed by acrylonitrile-butadiene- styrene (ABS), for example, or other suitable polymers.

[0028] Each plate 14, 16 may be provided with a hole 22 at ends thereof or in each of the four corners of the plates. The plates 14, 16 are held at a set distance determined by the replicate material 12 by two to four of the spacers 18 through the holes 22. Each of the fasteners 20 passes through one of the holes 22 in the plates 14, 16, through the spacer 18, through the opposing hole 22 in the opposite plate 14, 16, and a nut is applied to the threaded section of the fastener 20 to secure the plate 14, 16 and the spacers 18. The fastener 20 may be any suitable material such as stainless steel or nylon.

[0029] The replicate material 12 is disposed on an interior surface of the first plate 14 via an adhesive or the like such as cyanoacrylate. The amount of adhesive may be minimized so that the surface of the replicate material 12 is exposed and not encased by the adhesive. The replicate material 12 functionally performs a spatial dielectric property matching.

[0030] A silver coated copper wire 24 is connected to the first plate 14. The connection may be made in any suitable manner, and in an exemplary embodiment, the connection is made by drilling a hole in the cross section of the first plate 14 that is slightly larger than the diameter of the silver coated wire 24. An adhesive such as cyanoacrylate may be used to connect the first plate 14 at the drilled hole to the end of the silver-plated copper wire 24. The end of the silver coated silver wire 24 is inserted into the drilled hole in the first plate 14. The length of the wire 24 may be nominally two inches. The silver coated copper wire 24 serves to reduce impedance.

[0031] A first conductive wire 26 connects the silver coated copper wire 24 to a diode 28. The connections are made by solder or the like. The diode 28 allows current to flow from the wire 24 through the diode 28. A second conductive wire 30 connects the diode 28 to a second resistor 42 and an internal member 46 of a detector element (described below).

[0032] A copper plate or sheet 32 is attached to an interior surface of the second plate 16 by an adhesive, such as cyanoacrylate. A third conductive wire 34 connects the copper plate 32 to a first resistor 36 and a first capacitor 38 in parallel. The connections may be made by solder or other suitable alternative. The first resistor 36 and the first capacitor 38 serve to produce a time constant less than 10 Hz.

[0033] A fourth conductive wire 40 connects the first resistor 36 and the first capacitor 38 in parallel to a second resistor 42 in series. The connection may be made by solder or an alternative. The second resistor 42 serves to increase the total resistance in the path thereby adjusting the time constant of arrangement in the frequency range below 10 Hz.

[0034] A fifth conductive wire 44 connects the second resistor 42 to the diode

28. The connection of the fifth conductive wire 44 from the second resistor 42 and the diode 28 is connected by a sixth conductive wire 46 to an internal member. The internal member reacts to currents in the conductive wires according to the principles of the described embodiments. The first plate 14 containing the replicate material 12 is connected electrically to the copper plate 32. The arrangement permittivity transmits (or“permits”) an electric field to charge an analog matching filter, as described in the present application, and allows electric field charge to be stored and converted to a dielectrophoresis force. The selective permittivity is arranged in an analog matching filter in an RC circuit that enables the electric field stored charge to be converted to the dielectrophoretic force, thereby enabling the detection of an entity.

[0035] The values of the resistors, capacitors and diodes are determined by the replicate material selected. That is, these values will vary for different replicate materials.

[0036] The analog matching filter is capacitively coupled to an enclosure 48

(see FIG. 4) of the detector element. In one embodiment of the analog matching filter, the permittivity of the analog matching filter is below 1 Hz. Above 1 Hz, the analog matching filter does not permit a charge to be stored. Below 1 Hz, the analog matching filter permits storage of a charge that is transmitted from the internal member through the conductive wires and RC component. The stored charge is then converted to the dielectrophoresis force on the internal member. With reference to Figure 3 the phase shift indicates electron flow.

[0037] The replicate dielectric property matching material 12 is selected in accordance with the characteristics of the entity to be detected. That is, the replicate property matching material contains identical dielectric properties, time constants and related macroscopic friction coefficients to those of the entity material to be detected. Examples of suitable replicate dielectric property matching materials include: Amine: cyclo-tri-methylene-tri-nitr-amine (RDX formulated as C4)(also HMX and tetryl), cyclo-tetra-methylene-tetra-nitr-amine (HDX formulated as CX); Nitrate: penta- erythrite-tetra-nitrate (PETN plus RDX formulated as Semtex, ammonium-nitrate (plus select hydrocarbon oil formula as fertilizer bomb), glycerol-tri-nitrate

(nitroglycerin formulated as dynamite); Toluene: 2,4,6-tri-nitro-toluene (TNT), organic compounds, plastic (mixture of polymers and additives) for dielectric material detection and the like.

[0038] With reference to FIG. 4, first and second analog matching filters 10,

10’ may be placed within an enclosure 48 with suitable switching change via a selector switch 50 from one analog matching filter 10 to the other analog matching filter 10’, each having a different replicate property matching material for a specific detection target. The switching may be designed to select single or multiple Analog Matching Filters and the associated replicate property material providing

discrimination for triggering the dielectrophoresis force. The housing 48 includes a handle 52 and a sensor display 54 with suitable electronics and an internal member 46.

[0039] The dielectrokinesis (phoresis) phenomena can be used with the current analog matching filter 10 in at least two methodologies to enable the detection and location of specific entities of interest. The first methodology utilizes the dielectrophoresis force directly. This is usually observed via a torque“action at a distance” motion acting around a well-defined pivot point and line. An example of this application is described in commonly owned, U.S. Pat. No. 5,748,088, the disclosure of which is hereby incorporated by reference.

[0040] The second methodology is where an internal member has a fixed end and a freely moving end. In this second methodology the freely movable end of the internal member is moved via the dielectrophoresis force. The dielectrophoresis force acting on the internal member creates movement of the free end of the internal member. The dielectrophoresis force creates stress on the fixed end of the internal member. The dielectrophoresis force creates a stress along the longitudinal axis of the internal member. These stresses can be detected and used to drive an output display.

[0041] Static electrification proceeds via naturally-occurring contact charging

(static or dynamic) which includes transfer of electrons, ions, and other charged chemical species as well as via the interfacial triboelectric charging. Static electrification also proceeds via artificially-occurring industrial processes used in manufacturing the energetic material. The working hypothesis uses known static electrification effects as its basis. The spatial gradient effect is manifested where the high spatial gradient non-uniformity of the electric fields is largest, especially near the distribution’s geometrical edge where the static electrification has not occurred, and the electric fields are near zero. This effect is also known as the“fringing electric field” effect.

[0042] The very high electrical resistivity of energetic materials does not allow the static electrification charges to leak harmlessly to ground. On the contrary, the charges are continuously accumulated in the interfaces and on the surface (bulk quantity) building up very high local electrical surface voltages in the tens of kilovolts. The static electrification charges on energetic materials are very long- lasting, with characteristic times for exponential decay of 10 ² to 10 ⁶ seconds (days to months). This is generally referred to as near-DC frequency. The time constant depends on the inherent electrical resistivity of the high energetic materials or other materials and the dielectric energy storage constant and dissipation loss describing non-conducting energetic materials’ electric polarization properties. The ever-present nature of static electrification ensures that the long-lasting static electrification electric field patterns have significant spatial gradients. The voltages and electric field patterns decrease as distance increases from the surface of the energetic material. In addition, various inherent free-and bound-charge electron traps exist via surface chemistry effects on all materials, in particular high resistivity energetic materials.

See Table 2. These traps form pre-charged under layers for electrons, ions, and other chemical species transferred via static electrification.

[0043] The energetic material produces an electric field that is unique (see

Table 1) and detectable with the instant analog matching filter enabling the dielectrophoresis force. Each energetic material develops its own unique material- specific electric field spatial gradients. Each energetic material has a unique spatial gradient pattern from the combination of time-independent gradients from trapped ions/electrons and time-dependent gradient from triboelectric charging. Energetic material low resistivity predicts a time dependent changing electric field much lower than one Hz.

[0044] Electrical characteristics of the described analog matching filter were independently tested. The operational mode is an RC capacitive arrangement. The negative phase angle indicates that the current leads, voltage lags. See Fig 3. The reactive range of the analog matching filter is in the frequency range below 1 Hz.

[0045] Discriminatory detection of the target electric field is achieved by the selective relative permittivity of the capacitive elements of the detection circuit.

[0046] The electric field of travel is optimized along the lateral interface of different dielectric constants. For example, the lateral interface of the air at 1.0 and ground at 3 to 6. The electric field is partially air propagating and partially local ground propagating depending upon the relative materials’ input impedances.

[0047] The primary analytical technique used to characterize the dielectric polarization properties of energetic materials and other materials is dielectric spectroscopy. In this situation, we are interested in ULF frequency range (< 30 Hz), where the stored electric energy and the dissipated electric energy are measured simultaneously.

[0048] References supporting the described technological aspects are listed in

Table 3.

[0049] Table 1: Dielectric Constant of Energetic materials and Common

Materials

[0050] Table 2: Properties of Explosives

[0051] Table 3: Technical References

[0052] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.