Patent Publication Number: US-2023149946-A1

Title: Electromagnetic fluid filter using magnetostrictive sensors

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation application of U.S. Application Serial No. 17/122,074, entitled “ELECTROMAGNETIC FLUID FILTER USING MAGNETOSTRICTIVE SENSORS,” which was filed on Dec. 15, 2020, and which issued as U.S. Pat. No. 11,541,399 on Jan. 3, 2023, which is a continuation application of U.S. Application Serial No. 16/548,033, entitled “ELECTROMAGNETIC FLUID FILTER USING MAGNETOSTRICTIVE SENSORS,” which was filed on Aug. 22, 2019, and which issued as U.S. Pat. No. 10,940,486 on Mar. 9, 2021, which is a continuation application of U.S. Application Serial No. 15/190,824, entitled “ELECTROMAGNETIC FLUID FILTER USING MAGNETOSTRICTIVE SENSORS,” which was filed on Jun. 23, 2016, and which issued as U.S. Pat. No. 10,406,533 on Sep. 10, 2019, and which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Serial No. 62/184,052, filed Jun. 24, 2015, the entire disclosure of each of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     Foodborne illnesses are primarily caused by food contaminated with pathogenic microorganisms in the field or during food processing under insanitary conditions. Hence, surveillance of bacterial contamination of fresh produce through the food supply chain is of great importance to the food industry. However, such surveillance is a challenge since the food supply chain is a lengthy trail with many opportunities to cause food contamination. Food products may be cleaned at the harvesting site, transported to a warehouse, re-cleaned, and repackaged several times before reaching retail outlets. 
     Typical microbiological methods for pathogen detection, such as colony counting, immunoassay, and polymerase chain reaction (PCR), offer very high sensitivities. However, they require pre-analytical sample preparation, which generally includes sample collecting, separating target pathogen cells from food, increasing cell concentration, and achieving analysis volume from bulk samples before detection. These processes are time consuming, resulting in delays in obtaining the screening results. Also, only small samples (for example, 1 mL samples) may be evaluated for pathogens. More importantly, food samples have to be delivered to laboratories for culture preparation and analysis. Label-free biosensors are available in today’s market. However, they also require sample preparation prior to the actual testing (i.e. sampling from fresh produce, filtration and purification of the collected samples, and injection of the filtered/purified samples into a flow system where a biosensor resides). Due to the complexity of these test procedures and the requirements of expensive equipment and highly trained personnel, current food safety controls mainly rely on control of worker/environment hygiene in the food processing industry, rather than the direct pathogen detection. 
     Free-standing phage-based magnetoelastic biosensors have been investigated as a label-free wireless biosensor system for real-time pathogen detection. The magnetoelastic biosensor is typically composed of a magnetoelastic resonator that is coated with a bio-molecular recognition element that binds specifically with a target pathogen. Once the biosensor comes into contact with the target pathogen, binding occurs, causing an increase in the mass of the resonator resulting in a decrease in the resonant frequency of the sensor (as well as other characteristic frequencies of the sensor). 
     Fluids may be filtered for pathogens using a conventional bead filter. The bead filter may include many nanobeads, which may be coated with a bio-molecular recognition element that binds specifically with a target pathogen. To filter the fluid media, the nanobeads may be mixed throughout a relatively small sample (e.g., 1 gallon) of the fluid media, or the fluid media may be passed through a filter bed of nanobeads. However, the nanobeads may trap large debris that is not targeted by the biorecognition element, which may cause the filter to clog. 
     SUMMARY 
     According to one aspect, an electromagnetic filter element may include a support comb, a solenoid coupled to the support comb, and a plurality of elongated magnetic members. The support comb comprises a magnetic material and defines an opening. The solenoid is configured to, when energized, cause the support comb to generate a magnetic field. The plurality of magnetic members are arranged in a planar array positioned within the opening of the support comb. Each magnetic member comprises a first end and a second end, and the first end of each magnetic member is coupled to the support comb. In some embodiments, magnetization of the support comb may be controlled by the solenoid, each of the magnetic members may be magnetically coupled to the support comb, and each magnetic member may rotate about the first end of the magnetic member coupled to the support comb. In some embodiments, the first end of each magnetic member may be hingedly attached to the support comb. 
     In some embodiments, each magnetic member may comprise a magnetostrictive sensor comprising magnetostrictive material. Each magnetostrictive sensor may further comprise a biorecognition element to bind with a microorganism. The biorecognition element may comprise a bacteriophage that is genetically engineered to bind with the microorganism. In some embodiments, the support comb may comprise a high permeability magnetic material. 
     According to another aspect, an electromagnetic filter includes a transfer pipe that defines an interior volume and a plurality of electromagnetic filter elements positioned in the interior volume of the transfer pipe. Each of the electromagnetic filter elements comprises a support comb, a solenoid coupled to the support comb, and a plurality of elongated magnetic members. The support comb comprises a magnetic material and defines an opening. The opening describes a cross-section of the interior volume of the transfer pipe. The solenoid is configured to, when energized, cause the support comb to generate a magnetic field. The plurality of magnetic members are arranged in a planar array positioned within the opening of the support comb. Each magnetic member comprises a first end and a second end, and the first end of each magnetic member is coupled to the support comb. In some embodiments, each of the electromagnetic filter elements may have a different orientation of the plurality of magnetic members. In some embodiments, magnetization of each support comb may be controlled by the corresponding solenoid, each of the magnetic members may be magnetically coupled to the corresponding support comb, and each magnetic member may rotate about the first end of the magnetic member coupled to the corresponding support comb. In some embodiments, the first end of each magnetic member may be hingedly attached to the corresponding support comb. 
     In some embodiments, each magnetic member may comprise a magnetostrictive sensor comprising magnetostrictive material. Each magnetostrictive sensor may further comprise a biorecognition element to bind with a microorganism. The biorecognition element may comprise a bacteriophage that is genetically engineered to bind with the microorganism. In some embodiments, the support comb of each electromagnetic filter element may comprise a high permeability magnetic material. 
     According to another aspect, a method for fluid filtration comprises coupling a transfer pipe between a fluid source and a fluid destination, wherein the transfer pipe defines an interior volume and includes a plurality of electromagnetic filter elements positioned in the interior volume, wherein each of the electromagnetic filter elements comprises an electromagnet and a plurality of magnetic members positioned within the interior volume of the transfer pipe, wherein each magnetic member comprises a first end and a second end; energizing the electromagnet of each of the electromagnetic filter elements to cause the first end of each magnetic member to magnetically couple to the corresponding electromagnet of the electromagnetic filter element, wherein each magnetic member may rotate about the first end; and flowing a fluid media through the transfer pipe between the fluid source and the fluid destination in response to energizing the electromagnet of each of the electromagnetic filter elements. In some embodiments, the fluid media may comprise a liquid food product. In some embodiments, the fluid media may comprise process water, wash water, or irrigation water. 
     In some embodiments, each magnetic member may comprise a magnetostrictive sensor comprising magnetostrictive material. Each magnetostrictive sensor may further comprise a biorecognition element. 
     In some embodiments, the method may further include de-energizing the electromagnet of each of the electromagnetic filter elements in response to flowing the fluid media through the transfer pipe. In some embodiments, the method may further include collecting the magnetostrictive sensors in response to de-energizing the electromagnet of each of the electromagnetic filter elements and detecting microorganisms bound to the magnetostrictive sensors in response to collecting the magnetostrictive sensors. 
     In some embodiments, detecting the microorganisms may comprise applying a varying magnetic field, using a drive coil, to the magnetostrictive sensors; detecting a frequency response of the magnetostrictive sensors using a pickup coil, while applying the varying magnetic field; and determining whether a microorganism is present based on the detected frequency response of the magnetostrictive sensors. In some embodiments, detecting the microorganisms may further comprise positioning the pickup coil in proximity to the magnetostrictive sensors, wherein detecting the frequency response comprises detecting the frequency response in response to positioning the pickup coil. In some embodiments, detecting the microorganisms may include culturing the microorganisms bound to the magnetostrictive sensors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The concepts described in the present disclosure are illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements. The detailed description particularly refers to the accompanying figures in which: 
         FIG.  1    is a simplified schematic diagram of an electromagnetic filter element using magnetostrictive members; 
         FIG.  2    is a simplified cross-sectional diagram of a magnetostrictive sensor of the electromagnetic filter element of  FIG.  1   ; 
         FIG.  3    is a simplified schematic diagram of an electromagnetic filter including multiple electromagnetic filter elements of  FIGS.  1  and  2   ; 
         FIGS.  4 A and  4 B  are simplified schematic diagrams illustrating large debris passing through an electromagnetic filter element of  FIGS.  1 - 3   ; 
         FIG.  5    is a simplified schematic diagram of a system for detecting pathogens captured by an electromagnetic filter element of  FIG.  1   -4A and 4B; 
         FIG.  6    is an exemplary plot of magnetostrictive sensor frequency response that may be measured using the system of  FIG.  5   ; and 
         FIG.  7    is a simplified flow diagram of one embodiment of a method for fluid filtering and pathogen detection that may be performed using the electromagnetic filter element, electromagnetic filter, and system of  FIGS.  1 - 6   . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. 
     References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etcetera, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
     Referring now to  FIG.  1   , a simplified schematic diagram of one illustrative embodiment of an electromagnetic filter element  10  is shown. The electromagnetic filter element  10  includes a support comb  12  and multiple magnetic members  20  coupled to the support comb  12 . In use, as described further below, a solenoid  26  of the electromagnetic filter element  10  may be energized to create a magnetic field. A fluid flows through the electromagnetic filter element  10  and targeted contaminants such as pathogens bind to the magnetic members  20 . Large, non-binding debris may pass through the electromagnetic filter element  10 , pushing the magnetic members  20  out of the way. After the debris passes, the magnetic field generated by the electromagnetic filter element  10  forces the magnetic members  20  back to their original position. Thus, and as described further below, the electromagnetic filter element  10  may be used to filter and detect small concentrations of contaminants (such as pathogens) in large volumes of fluid. Thus, rather than analyzing small (e.g., 1 mL) samples of fluid, the electromagnetic filter element  10  may be used to detect the presence of pathogens in an entire volume of fluid. Additionally, the electromagnetic filter element  10  may be resistant to clogging in the presence of large debris. 
     As shown in  FIG.  1   , the electromagnetic filter element  10  includes the support comb  12 , which may be embodied as any magnetic material whose magnetization may be controlled by the solenoid  26 . For example, the support comb  12  may be made of a material with high permeability, such as silicon steel. The support comb  12  defines an interior opening  14  surrounded by two sides  16 ,  18 . The support comb  12  and the interior opening  14  are illustratively a planar rectangular in shape; however, in other embodiments the support comb  12  may have any shape that defines an interior opening  14 . 
     As shown, the electromagnetic filter element  10  includes multiple magnetic members  20  positioned in an array in the interior opening  14 . In the illustrative embodiment, each of the magnetic members  20  is a magnetostrictive sensor. The magnetostrictive sensors  20  are small devices made of a magnetostrictive and/or magnetoelastic material coated with a biorecognition element that binds to a particular target particle, such as a pathogen. For example, the biorecognition element may include antibodies or genetically engineered phages that bind to particular bacteria, such as  Salmonella  Typhimurium. The magnetostrictive material converts magnetic energy to mechanical energy and vice versa. In other words, magnetostrictive materials generate mechanical strain when the magnetic energy is applied and generate magnetic energy in response to mechanical strain. Throughout this disclosure, the terms magnetostrictive material and magnetoelastic material may be used interchangeably. In the illustrative embodiment, the magnetostrictive sensors  20  are embodied as thin strips of material that may be actuated into resonance by application of a varying magnetic field. The magnetostrictive sensors  20  are illustratively rectangular in shape; however, in other embodiments, any elongated shape may be used. Upon contact with the specific target pathogen, the pathogen binds with the biorecognition element and increases the mass of the magnetostrictive sensor  20 . This additional mass causes the characteristic frequency of the magnetostrictive sensors  20  to decrease. As described further below, the characteristic frequency may be measured by a pickup coil, allowing quantitative detection and characterization of the pathogen. One embodiment of a magnetostrictive sensor  20  is further described below in connection with  FIG.  2   . 
     As shown, each of the magnetic members  20  has an elongated shape with one end coupled to one of the sides  16 ,  18  the support comb  12  at a pivot point  22 . As shown, the magnetic members  20  are illustratively arranged in two ranks  24  within a planar array. The members  20  of each rank  24  are coupled to a respective side  16 ,  18  of the support comb  12 . The members  20  extend away from their respective side  16 ,  18  to cover the interior opening  14  of the support comb  12 . Each magnetic member  20  may rotate about the pivot point  22 , allowing large debris to pass through the interior opening  14  of the support comb  12 . As described further below, each magnetic member  20  may be coupled to the support comb  12  by a magnetic force. Additionally or alternatively, in some embodiments each magnetic member  20  may be mechanically attached to the support comb  12 , for example with a hinge. Additionally, although illustrated as including a single interior opening  14  with two ranks  24  of magnetic members  20 , it should be understood that in some embodiments the support comb  12  may have multiple interior openings  14  and/or additional ranks  24  of magnetic members  20 . 
     The illustrative electromagnetic filter element  10  further includes a solenoid  26  coupled to the support comb  12 . The solenoid  26  is connected to a power source  28 , which is configured to supply electrical current to the solenoid  26 . When energized by the power source  28 , the solenoid  26  and the support comb  12  together function as an electromagnet, generating a magnetic field. The magnetic field attracts the magnetic members  20  to the support comb  12 , coupling each magnetic member  20  to the support comb  12  at the pivot point  22 . As described further below, the magnetic field may be strong enough to couple the magnetic members  20  to the support comb  12  but also allow the magnetic members  20  to rotate about the pivot point  22  to allow large, non-binding debris to pass through the interior opening  14  of the support comb  12 . After the debris passes, the magnetic field causes the magnetic members  20  to re-align across the interior opening  14 . The strength of the magnetic field (and therefore the strength of the magnetic force acting on the magnetic members  20 ) may be adjusted by controlling the voltage and/or current supplied to the solenoid  26  or, in some embodiments, adjusting the number of windings and/or gauge of wire used to form the electromagnet. In some embodiments, the position that the magnetic members  20  attach to the support comb  12  may be controlled by coating the support comb  12  with a magnetic insulation layer using microelectronics fabrication techniques. The support comb  12  may be uncoated at the pivot points  22 , caused the magnetic members  20  to be attracted to the support comb  12  at the pivot points  22 . 
     Referring now to  FIG.  2   , a simplified schematic diagram of one illustrative embodiment of a magnetostrictive sensor  20  of the electromagnetic filter element  10  is shown. The sensor  20  includes a body  30  coated with an immobilized biorecognition element  32 . The body  30  is made from a magnetoelastic material, such as a magnetostrictive alloy. In one illustrative embodiment, the body  30  may be mechanically polished and cut (diced) from a strip of METGLAS™ 2826MB, which is commercially available from Honeywell Inc., of Conway, South Carolina. As shown, the body  30  has two ends  34 ,  36 . As shown in  FIG.  1   , one of the ends  34 ,  36  may be attached to a side  16 ,  18  of the support comb  12  at the pivot point  22 , and the other end  34 ,  36  extends away from the side  16 ,  18  to cover the interior opening  14  of the support comb  12 . Additionally, although illustrated as including a single side of the body  30  coated with the biorecognition element  32 , it should be understood that in some embodiments two or more sides of the body  30  may be coated with the biorecognition element  32 . 
     In the illustrative embodiment, each magnetostrictive sensor  20  has a length L, a thickness t, and a width w (not shown). For example, in some embodiments the magnetostrictive sensors  20  may be one millimeter in length, four millimeters in length, or another length. The magnetostrictive sensor  20  is in the shape of a thin strip, meaning that the length L is larger than the width w and much larger than the thickness t (i.e., L &gt; w » t). Upon application of a varying magnetic field, the dimensions of the magnetostrictive sensor  20  change. Accordingly, the magnetostrictive sensor  20  mechanically vibrates in response to the varying magnetic field. In particular, due to its thin strip shape, the magnetostrictive sensor  20  vibrates mainly longitudinally; in other words, when an oscillating external magnetic field is applied, the magnetostrictive sensor  20  vibrates between the length L and a length L′. The fundamental resonant frequency of this longitudinal oscillation is given as: 
     
       
         
           
             
               f 
               0 
             
             = 
             
               V 
               
                 2 
                 L 
               
             
           
         
       
     
      where V is the acoustic velocity of the material along its length L. Addition of a small mass (Δm « M) on the magnetostrictive sensor  20  surface causes a change in the resonant frequency (Δf). This resonant frequency change is proportional to the initial frequency f 0  and the mass added (Δm) and is inversely proportional to the initial sensor mass M. Assuming the added mass is uniformly distributed on the surface of the magnetostrictive sensor  20 , the resonant frequency change may be approximated as: 
     
       
         
           
             Δ 
             f 
             = 
             
               
                 
                   f 
                   0 
                 
                 Δ 
                 m 
               
               
                 2 
                 M 
               
             
               
               
             
               
                 Δ 
                 m 
                 &lt; 
                 &lt; 
                   
                 M 
               
             
           
         
       
     
      The negative sign in Equation (2) means that the resonant frequency of the magnetostrictive sensor  20  decreases with the increase of the mass load. The additional mass load on the magnetostrictive sensor  20  can be obtained by measuring the shift in the resonant frequency (or another characteristic frequency related to the resonant frequency). 
     When the magnetostrictive sensor  20  comes into contact with a target pathogen, the biorecognition element  32  immobilized on the magnetostrictive sensor  20  surface will bind/capture the target pathogen. This adds an additional mass load on the magnetostrictive sensor  20 . As described above, this additional mass causes a drop in a characteristic frequency of the magnetostrictive sensor  20 . Therefore, the presence of any target pathogens can be identified by monitoring for a shift in the characteristic frequency of the magnetostrictive sensor  20 . Additionally or alternatively, rather than a biorecognition element  32 , the magnetostrictive sensor  20  may include a chemical layer that similarly binds with one or more contaminants such as mercury or heavy metals. 
     The simple strip-shaped configuration of the illustrative magnetostrictive sensor  20  described above may make fabrication relatively easy and/or inexpensive. Additionally, the magnetostrictive sensors  20  are passive sensors that do not require on-board power. As described above, the magnetostrictive sensor  20  may be fabricated by mechanical methods (e.g., polish and dice) or by microelectronics fabrication methods (e.g., sputter deposit, thermal deposit, or electrochemical deposit). These methods can mass-produce fabricated magnetostrictive sensors  20  with very low cost. Additional details of illustrative magnetoelastic ligand detectors are described in U.S. Pat. No. 7,759,134 (“Magnetostrictive Ligand Sensor”), the entire disclosure of which is incorporated herein by reference. 
     As described above, the biorecognition element  32  may be immobilized on the surface of each magnetostrictive sensor  20  to bind a specific target pathogen. In some embodiments, the biorecognition element  32  may be embodied as a chemical binding element or an interaction layer immobilized on the body  30  of the magnetostrictive sensor  20 . For example, the biorecognition element  32  may be a traditional antibody. Additionally or alternatively, in some embodiments, the biorecognition element  32  may be a genetically engineered bacteriophage (“phage”). The use of phages as a substitute for antibodies offers a stable, reproducible, and inexpensive alternative. In particular, phages have high affinity for binding with target pathogen cells, the phage structure is robust and stable, and phages may bind target pathogens in air with certain humidity. Additionally or alternatively, the biorecognition element  32  may be embodied as DNA, RNA, proteins, aptamers, or other biorecognition elements. Specific ligand recognition devices that may be illustratively used as the biorecognition element  32 , as well as illustrative application methods, are discussed in U.S. Pat. Nos. 7,138,238 (“Ligand Sensor Devices and Uses Thereof”), 7,267,993 (“Phage Ligand Sensor Devices and Uses Thereof”), and 7,670,765 (“Method of Forming Monolayers of Phage-Derived Products and Used Thereof”), the entire disclosures of which are incorporated herein by reference. 
     Referring now to  FIG.  3   , a simplified schematic diagram of one illustrative embodiment of an electromagnetic filter  100  is shown. The electromagnetic filter  100  includes a transfer pipe  102  having two ends, an inlet  104  and an outlet  106 . The transfer pipe  102  may be embodied as any nonmagnetic material capable of transferring large volumes of fluid, such as PVC, plastic, or nonmagnetic metallic material, or as any other material that does not generate an excessively strong magnetic field. In use, as described further below, the transfer pipe  102  may be connected between a fluid source and a fluid destination, for example between two fluid tanks. Although illustrated as having a circular cross-section, it should be understood that in other embodiments the transfer pipe  102  be a square tube, spiral tube, or any other shaped tube capable of carrying fluid. 
     The electromagnetic filter  100  includes, within the transfer pipe  102 , a filter assembly  108 . The filter assembly  108  includes one or more electromagnetic filter elements  10 . The electromagnetic filter elements  10  may be positioned at different linear positions  110  within the nonmetallic transfer pipe  102 , essentially “stacking” the electromagnetic filter elements  10  within the nonmetallic transfer pipe  102 . Each of the electromagnetic filter elements  10  may be fixed or otherwise attached within the nonmetallic transfer pipe  102  at a different orientation  112 . For example, the support combs  12  of each electromagnetic filter element  10  may be positioned at different relative angles from each other, causing the magnetic members  20  to also be positioned at different relative angles. In some embodiments, by being positioned at different orientations  112 , the stack of electromagnetic filter elements  10  may completely cover a cross-section of the nonmetallic transfer pipe  102  with the magnetic members  20 . Each of the electromagnetic filter elements  10  may be removable from the filter assembly  108 . Although the illustrative electromagnetic filter  100  includes two electromagnetic filter elements  10 , it should be understood that in some embodiments the electromagnetic filter  100  may include many more electromagnetic filter elements  10 . 
     In use, as described further below, a fluid media  114  may flow through the transfer pipe  102  and the filter assembly  108 . The fluid media  114  may be embodied as any fluid that may include pathogens or other contaminant particles. For example, the fluid media  114  may be embodied as a liquid food product (e.g., milk or juice), process water, wash water (e.g., from washing fresh produce), irrigation water, blood or bodily fluids, oil, air, or other fluids. As shown, the fluid media  114  entering the inlet  104  of the transfer pipe  102  may include multiple non-binding particles  116  and binding particles  118 . The binding particles  118  may be embodied as any contaminant particle to be trapped and removed from the fluid media  114  by the electromagnetic filter  100 , such as a microorganism (e.g., bacteria, viruses, spores, mold, or other microorganisms, including pathogens), metallic particles, magnetic particles, chemicals, or any other particle or other contaminant that binds to the magnetic members  20  of the electromagnetic filter elements  10 . The non-binding particles  116  may be embodied as any other particle or debris included in the fluid media  114 , such as a non-binding food component. As the fluid media  114  flows through the filter assembly  108 , the binding particles  118  bind to the magnetic members  20  in the filter assembly  108  and are thereby removed from the fluid media  114 . The fluid media  114  leaving the outlet  106  of the transfer pipe  102  may include only non-binding particles  116  without including any binding particles  118  (or including a reduced concentration of binding particles  118 ). 
     Referring now to  FIG.  4 A , a simplified schematic diagram of an electromagnetic filter element  10  filtering fluid media  114  including a large non-binding particle  116  is shown. As shown, the non-binding particle  116 , for example a large piece of debris, passes through the internal opening  14  of the electromagnetic filter element  10 , and the magnetic members  20  are pushed by the non-binding particle  116  out of the way. Each magnetic member  20  may pivot, bend, flex, shift, or otherwise move about the pivot point  22 , allowing the non-binding particle  116  to pass through the electromagnetic filter element  10 . Because the non-binding particle  116  is not magnetic and does not bind to any biorecognition element of the magnetic members  20 , the non-binding particle  116  is not bound or otherwise trapped by the magnetic members  20 . 
     Referring now to  FIG.  4 B , a simplified schematic diagram of the electromagnetic filter element  10  after filtering the fluid media  114  including the large non-binding particle  116  is shown. As shown, the magnetic members  20  have returned to their original positions in the internal opening  14  of the electromagnetic filter element  10 . For example, the magnetic field generated by the solenoid  26  may force the magnetic members  20  back to their original positions. Thus, the non-binding particle  116  may pass through the electromagnetic filter element  10  without obstructing the electromagnetic filter element  10 , and the electromagnetic filter element  10  may continue to filter out binding particles  118 . 
     Referring now to  FIG.  5   , a system  200  for detecting pathogens trapped by an electromagnetic filter element  10  is shown. The system  200  includes an indexing plate  202  that includes multiple analysis wells  204 . The indexing plate  202  may be embodied as, for example, a silicon wafer that includes the analysis wells  204 . The indexing plate  202  may be moveable, for example with a three-axis translation stage, to allow precise positioning of the analysis wells  204 . Each of the analysis wells  204  may be filled with a fluid such as water or a cell growth medium. As shown, each of the analysis wells  204  may contain one or more magnetic members  20  from an electromagnetic filter element  10 . In the illustrative embodiment, the magnetic members  20  are magnetostrictive sensors coated with a biorecognition element that binds with a particular pathogenic microorganism. As described further below in connection with  FIG.  7   , when the solenoid  26  of the electromagnetic filter element  10  is de-energized, the magnetic members  20  may be released from the support comb  12  and may be transferred or otherwise collected in the analysis wells  204 . 
     The system  200  also includes a controller  206  coupled to a surface-scanning detector  214 . The surface-scanning detector  214  may be positioned over one or more of the analysis wells  204  of the indexing plate  202 . The surface-scanning detector  214  and/or the indexing plate  202  may be movable to position the detector  214  over a particular analysis well  204 . The surface-scanning detector  214  may further include a drive coil and a pickup coil. The controller  206  causes the drive coil to apply a varying magnetic field  216  to the magnetostrictive sensors  20 . The controller  206  measures a magnetic field  218  produced by the magnetostrictive sensors  20  in response to the varying magnetic field  216  using the pickup coil. The controller  206  determines a characteristic frequency of the magnetostrictive sensors  20  based on the measured magnetic field  218 . This characteristic frequency is related to the resonant frequency of the magnetostrictive sensors  20 , as well as other material properties (e.g., the magnetoelastic coupling coefficient) and the environment (e.g., friction forces or damping effects). As described further below, binding particles  118  present in the fluid media  114  flowed through the electromagnetic filter element  10  may bind with the magnetostrictive sensors  20 , causing an increase in the mass of the magnetostrictive sensors  20  and a corresponding decrease in the characteristic frequency. The system  200  may determine whether the binding particles  118  (e.g., a pathogen or other contaminant) are present by determining whether the characteristic frequency shifts. Multiple types of binding particles  118 , for example, multiple types of pathogens, may be detected simultaneously by using separate groups of magnetostrictive sensors  20 , with each group of magnetostrictive sensors  20  binding to a different type of binding particle  118 . Additionally, although described as including both a drive coil and a pickup coil, it should be understood that in some embodiments the surface-scanning detector  214  may include a single test coil to generate the varying magnetic field  216  and measure the magnetic field  218  produced by the magnetostrictive sensors  20 . In some embodiments, the surface-scanning detector  214  may include an array of pickup coils and/or test coils to measure the magnetic field  218  produced by magnetostrictive sensors  20  in several analysis wells  204  simultaneously. 
     As described briefly above, the system  200  includes the controller  206 . The controller  206  is responsible for activating or energizing electronically-controlled components of the system  200 , including the drive coil of the surface-scanning detector  214 . The controller  206  is also responsible for interpreting electrical signals received from other components of the system  200 , including the pickup coil. To do so, the controller  206  may include a number of electronic components commonly associated with units utilized in the control of electronic and electromechanical systems. For example, the controller  206  may include, amongst other components customarily included in such devices, a processor  208  and a memory device  210 . The processor  208  may be any type of device capable of executing software or firmware, such as a microcontroller, microprocessor, digital signal processor, or the like. The memory device  210  may be embodied as one or more non-transitory, machine-readable media. The memory device  210  is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the processor  208 , allows the controller  206  to perform pathogen detection using the other components of the system  200 . 
     The controller  206  also includes an analog interface circuit  212 , which may be embodied as any electrical circuit(s), component, or collection of components capable of performing the functions described herein. The analog interface circuit  212  converts output signals (e.g., from the pickup coil) into signals which are suitable for presentation to an input of the processor  208 . In particular, the analog interface circuit  212 , by use of a network analyzer, an analog-to-digital (A/D) converter, or the like, converts analog signals into digital signals for use by the processor  208 . Similarly, the analog interface circuit  212  converts signals from the processor  208  into output signals which are suitable for presentation to the electrically-controlled components associated with system  200  (e.g., the drive coil). In particular, the analog interface circuit  212 , by use of a variable-frequency signal generator, digital-to-analog (D/A) converter, or the like, converts digital signals generated by the processor  208  into analog signals for use by the electronically-controlled components associated with the system  200 . It is contemplated that, in some embodiments, the analog interface circuit  212  (or portions thereof) may be integrated into the processor  208 . 
     As also mentioned above, the surface-scanning detector  214  includes a drive coil and one or more pickup coil(s). In the illustrative embodiment, the drive coil is used as an energizing excitation source for the magnetostrictive sensors  20  and the pickup coil is used as a detector of signals received from the magnetostrictive sensors  20 . In some embodiments, the drive coil and/or the pickup coil may be a solenoid with loops having a generally rectangular cross-section. To improve performance of the system  200 , the drive coil and/or the pickup coil may be impedance-matched to the electrical circuitry of the controller  206 . In some embodiments, the surface-scanning detector  214  may include a test coil that performs the functions of both a drive coil and a pickup coil. 
     The system  200  may further include a magnetic field generator configured to generate a constant, uniform magnetic field  220 . The uniform magnetic field  220  extends through the analysis wells  204 . The uniform magnetic field  220  may align the magnetostrictive sensors  20 , which may improve the sensitivity, signal-to-noise ratio, or other operating characteristics of the magnetostrictive sensors  20  and thereby improve accuracy of the system  200 . The uniform magnetic field  220  may also bias the magnetostrictive sensors  20  during application of the varying magnetic field  216 , increasing the magnitude of the response signal  218 . The magnetic field generator may be embodied as any component capable of generating the uniform magnetic field  220 , for example, a pair of permanent magnet arrays or a Helmholtz coil. 
     Referring now to  FIG.  6   , an exemplary plot  300  illustrates results that may be measured when binding particles  118  are detected. Plot  300  illustrates signal amplitude against frequency ƒ. Curves  302 ,  304  illustrate the frequency response for the magnetostrictive sensors  20 . Curve  302  illustrates the frequency response for the magnetostrictive sensors  20  when not bound to any binding particle  118 , including a strong peak at the unloaded characteristic frequency. Curve  304  illustrates the frequency response of the magnetostrictive sensors  20  when bound to the binding particle  118 , including a smaller peak shifted from the unloaded characteristic frequency to a lower frequency by an amount Δƒ. These results may indicate that some of the magnetostrictive sensors  20  have bound with the binding particle  118  and experienced a frequency shift. 
     Referring now to  FIG.  7   , one illustrative embodiment of a method  400  that may be used for fluid filtration and pathogen detection with the electromagnetic filter  100  and the measurement system  200  is shown as a simplified flow diagram. The method  400  is illustrated as a series of blocks  402 - 428 , some of which may be optionally performed in some embodiments (and, thus, are shown in dashed lines). It will be appreciated by those of skill in the art that some embodiments of the method  400  may include additional or different processes and sub-processes. 
     The method  400  begins with block  402 , in which magnetostrictive sensors  20  are attached to the support comb  12  of one or more electromagnetic filter elements  10 . As described above, the magnetostrictive sensors  20  may be magnetically or mechanically attached to the support comb  12 , and each magnetostrictive sensor  20  can rotate about the pivot point  22 . In some embodiments, in block  404 , an electromagnet of the electromagnetic filter element  10  may be energized to attach the magnetostrictive sensors  20  to the support comb  12 . For example, the magnetostrictive sensors  20  may be arranged in a planar array on a surface such as the indexing plate  202 . The support comb  12  may be moved in proximity to the magnetostrictive sensors  20 , and the solenoid  26  may then be energized in order to magnetically attach the magnetostrictive sensors  20  to the support comb  12 . After being energized, the support comb  12  may be lifted from the surface, also lifting the magnetically attached magnetostrictive sensors  20 . 
     In block  406 , the electromagnetic filter elements  10 , including the magnetostrictive sensors  20 , are positioned in the filter assembly  108 . For example, the electromagnetic filter elements  10  may be inserted into the filter assembly  108 , which may include, for example, one or more rails, slots, or other mounting points to receive the electromagnetic filter elements  10 . As shown in  FIG.  3   , the filter assembly  108  may be positioned within the transfer pipe  102 . For example, the filter assembly  108  may also be inserted or otherwise positioned in the transfer pipe  102 , or the filter assembly  108  may be fixed within the transfer pipe  102 . By positioning the electromagnetic filter elements  10  in the transfer pipe  102 , the magnetostrictive sensors  20  are positioned within the interior volume of the transfer pipe  102 . In some embodiments, in block  408  the orientation  112  of the support combs  12  of each electromagnetic filter element  10  may be varied. Varying the orientation  112  may improve coverage by the magnetostrictive sensors  20  of the cross-section of the transfer pipe  102 . 
     In block  410 , the fluid media  114  flows through the transfer pipe  102  and the filter assembly  108 . As described above, the fluid media  114  may be embodied as any fluid that may include binding particles  118  such as pathogens or other contaminant particles. For example, the fluid media  114  may be embodied as a liquid food product, process water, wash water, irrigation water, blood or bodily fluids, oil, air, or other fluids. The inlet  104  of the transfer pipe  102  may be coupled to a fluid source and the outlet  106  may be coupled to a fluid destination (as well as any intermediate piping). For example, the inlet  104  of the transfer pipe  102  may be coupled to a large tanker truck full (e.g., 1500 gallons) of liquid food such as apple juice or milk, and the outlet  106  of the transfer pipe  102  may be coupled to a similarly-sized destination tank. As another example, the inlet  104  of the transfer pipe  102  may receive wash water created by washing a large amount of produce (e.g., produce from an entire field or other harvest). As the fluid media  114  flows through the filter assembly  108  and the electromagnetic filter elements  10 , any binding particles  118  in the fluid media  114  may bind with the magnetostrictive sensors  20  and become trapped within the filter assembly  108 . As illustrated in  FIGS.  4 A and  4 B , any large non-binding particles  116  (e.g., debris) in the fluid media  114  may cause the magnetostrictive sensors  20  to rotate about the pivot point  22  and allow the large debris to pass through the filter assembly  108 . Binding particles  118  may remain bound to the magnetostrictive sensors  20  even in the presence of large debris. Thus, a large amount of fluid media  114 , potentially including debris or other solid material (e.g., non-binding food components), may pass through the filter assembly  108  without clogging. The fluid media  114  may flow through the transfer pipe  102  and the filter assembly  108  until a large sample of the fluid media  114  has been filtered or until the fluid source has completely emptied into the fluid destination. 
     In the illustrative embodiment, the magnetostrictive sensors  20  trap one or more binding particles  118  that are bound by the biorecognition element of the magnetostrictive sensors  20 . However, it should be understood that in some embodiments the magnetostrictive sensors  20  may bind to any targeted organism, chemical contaminants, metallic or magnetic particles, or other contaminant particles. In some embodiments, some of the magnetostrictive sensors  20  may include different biorecognition elements to target different binding particles  118  (e.g., targeting multiple pathogens). Additionally, in some embodiments, the magnetic members  20  may bind to metallic particles or other magnetic particles in the fluid media  114  using magnetic effects, rather than a biorecognition element. 
     In block  412 , the electromagnetic filter elements  10  are removed from the filter assembly  108 . The magnetostrictive sensors  20  remain attached to the support comb  12  of each electromagnetic filter element  10 ; therefore, any binding particles  118  bound to the magnetostrictive sensors  20  are also removed from the filter assembly  108 . Additionally or alternatively, it should be understood that in some embodiments the entire filter assembly  108  may be removed from the transfer pipe  102 , the transfer pipe  102  may be disconnected from the fluid source and/or destination, or any other technique may be used to remove the electromagnetic filter elements  10 . 
     In block  414 , the magnetostrictive sensors  20  are released from the support combs  12  of the electromagnetic filter elements  10 . Prior to being released, the support combs  12  may be positioned appropriately to facilitate collecting the magnetostrictive sensors  20 . In some embodiments, in block  416 , the electromagnet of the electromagnetic filter element  10  may be de-energized or otherwise deactivated. For example, the solenoid  26  may be de-energized, releasing the magnetostrictive sensors  20  from the support comb  12 . 
     In block  418 , the magnetostrictive sensors  20  are captured in the analysis wells  204  of the indexing plate  202 . For example, the support comb  12  may be positioned over the indexing plate  202  prior to releasing the magnetostrictive sensors  20 . After the solenoid  26  is de-energized, the magnetostrictive sensors  20  may drop into the analysis wells  204 . In some embodiments, in block  420 , pathogens in the analysis wells  204  may be cultured. For example, the analysis wells  204  may include a cell growth medium and the indexing plate  202  may be stored, incubated, or otherwise given time to allow any pathogens in the analysis wells  204  to multiply. 
     In block  422 , the surface-scanning detector  214  is positioned over the analysis wells  204 . For example, the surface-scanning detector  214  may move and/or a three-axis translation stage may position the indexing plate  202  such that one or more of the analysis wells  204  are positioned in proximity to the surface-scanning detector  214 . The controller  206  may move the surface-scanning detector  214  over the analysis wells  204  in a pre-defined pattern such as a raster scan pattern. Additionally or alternatively, in some embodiments an array of pickup coils may be positioned over multiple analysis wells  204  for simultaneous measurement. 
     In block  424 , the drive coil of the surface-scanning detector  214  is activated to generate the varying magnetic field  216 . As described above, the varying magnetic field  216  causes the magnetostrictive sensors  20  to oscillate. The frequency of the varying magnetic field  216  may be varied through a range of frequencies. The range of frequencies may include a characteristic frequency of the magnetostrictive sensors  20  when the binding particle  118  has not been bound (i.e., when the sensors  20  are unloaded). For example, in some embodiments the range of frequencies applied by the drive coil may cover from 50% of unloaded characteristic frequency to slightly more than the unloaded characteristic frequency. Binding of binding particles  118  on the magnetostrictive sensor  20  surface is typically a small mass change, and the decrease in the characteristic frequency of the magnetostrictive sensors  20  due to this small mass change is normally less than 50% of the unloaded characteristic frequency of the magnetostrictive sensor  20 . Decreases in characteristic frequency beyond that range are unlikely to be due to binding of binding particles  118 . In some embodiments, the uniform magnetic field  220  may also be applied to the magnetostrictive sensors  20 . As described above, the uniform magnetic field  220  may bias the sensors  20  and increase the magnitude of the response signal  218 . Additionally, the uniform magnetic field  220  may align the sensors  20  in the direction of the uniform magnetic field  220 . This alignment of the sensors  20  causes the longitudinal oscillation of all (or, at least, most) of the sensors  20  to be in the same direction. In this way, the pickup coil may not need to align with individual sensors  20 . The magnetic flux picked up by the pickup coil may thus contain frequency response information for all (or, at least, most) of the sensors  20 . Additionally or alternatively, the uniform magnetic field  220  may polarize the magnetoelastic material of the sensors  20 , resulting in amplified and quasi-linear response. 
     In block  426 , the frequency response of the magnetostrictive sensors  20  is measured using the pickup coil, and any shift in resonant frequency of the magnetostrictive sensors  20  is determined. The controller  206  may monitor the characteristic frequency in real time or record data for later analysis. As described above, the magnetostrictive sensors  20  include the biorecognition element  32  that will bind with binding particles  118  upon contact. Binding with the binding particles  118  increases the mass of the magnetostrictive sensor  20 , which causes a characteristic frequency of the magnetostrictive sensor  20  to decrease. Thus, a measured shift in the resonant frequency indicates that the binding particles  118  were filtered out of the fluid media  114 . In some embodiments, the detection of the binding particles  118  may be repeated over time. For example, when culturing any pathogens in the analysis wells  204 , the resonant frequency of the magnetostrictive sensors  20  may be measured over time. A change in the resonant frequency may indicate that the pathogens filtered from the fluid media  114  are reproducing and therefore are live. The change in resonant frequency may also be measured to indicate the concentration of the measured pathogen in the original fluid media  114 . 
     In block  428 , it is determined whether additional analysis wells  204  should be measured. For example, the controller  206  may determine whether additional analysis wells  204  remain in a pre-programmed pattern of analysis wells  204 . As another example, additional analysis wells  204  may be measured after some elapsed time, such as when culturing pathogens in the analysis wells  204 . Of course, as described above, in some embodiments all of the analysis wells  204  may be measured simultaneously, for example using an array of pickup coils. If additional analysis wells  204  should be measured, the method  400  loops back to block  422 , in which the surface-scanning detector  214  may be positioned over additional analysis wells  204 . If no further analysis wells  204  remain to be measured, the method  400  may loop back to block  402  to re-load the electromagnetic filter elements  10  and perform additional filtration. 
     Although  FIG.  7    illustrates the operations of the method  400  as being performed in linear order, it should be understood that in some embodiments those operations may be performed in a different order and/or some of those operations may not be performed. For example, in some embodiments, the fluid media  114  may be filtered with the electromagnetic filter  100  as described in connection with blocks  402 - 410  without detecting the presence of the binding particles  118  or with detecting the presence of the binding particles  118  at a later time. As another example, an electromagnetic filter  100  may be assembled and loaded with magnetic members  20  as described above in connection with blocks  402 - 408  and then used to filter fluids at a later time. 
     While certain illustrative embodiments have been described in detail in the figures and the foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. There are a plurality of advantages of the present disclosure arising from the various features of the apparatus, systems, and methods described herein. It will be noted that alternative embodiments of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the apparatus, systems, and methods that incorporate one or more of the features of the present disclosure.