Patent Publication Number: US-2021186357-A1

Title: Non-invasive analyte sensor device

Description:
FIELD 
     This disclosure relates generally to apparatus, systems and methods of non-invasively detecting an analyte via spectroscopic techniques using non-optical frequencies such as in the radio or microwave frequency bands of the electromagnetic spectrum. More specifically, this disclosure relates to a non-invasive analyte sensor that includes a transmit antenna and a receive antenna where the transmit and receive antennas are decoupled from one another. 
     BACKGROUND 
     There is interest in being able to detect and/or measure an analyte within a target. One example is measuring glucose in biological tissue. In the example of measuring glucose in a patient, current analyte measurement methods are invasive in that they perform the measurement on a bodily fluid such as blood for fingerstick or laboratory-based tests, or on fluid that is drawn from the patient often using an invasive transcutaneous device. There are non-invasive methods that claim to be able to perform glucose measurements in biological tissues. However many of the non-invasive methods generally suffer from: lack of specificity to the analyte of interest, such as glucose; interference from temperature fluctuations; interference from skin compounds (i.e. sweat) and pigments; and complexity of placement, i.e. the sensing device resides on multiple locations on the patient&#39;s body. 
     SUMMARY 
     This disclosure relates generally to apparatus, systems and methods of non-invasively detecting an analyte via spectroscopic techniques using non-optical frequencies such as in the radio or microwave frequency bands of the electromagnetic spectrum. A non-invasive analyte sensor described herein includes at least one transmit antenna (which may also be referred to as a transmit element) that functions to transmit a generated transmit signal in a radio or microwave frequency range of the electromagnetic spectrum into a target containing an analyte of interest, and at least one receive antenna (which may also be referred to as a receive element) that functions to detect a response resulting from transmission of the transmit signal by the transmit antenna into the target. 
     The transmit and receive antennas are decoupled from one another which helps to improve the detection capability of the non-invasive analyte sensor. The decoupling between the transmit and receive antennas can be achieved using any one or more techniques that causes as much of the signal as possible that is transmitted by the transmit antenna to enter the target and that minimizes or even eliminates the amount of electromagnetic energy that is directly received by the receive antenna from the transmit antenna without traveling into the target. The decoupling can be achieved by one or more intentionally fabricated configurations and/or arrangements between the transmit and receive antennas that is sufficient to decouple the transmit and receive antennas from one another. In one non-limiting embodiment, the decoupling can be achieved by the transmit antenna and the receive antenna having intentionally different geometries from one another. Intentionally different geometries refers to different geometric configurations of the transmit and receive antennas that are intentional, and is distinct from differences in geometry of transmit and receive antennas that may occur by accident or unintentionally, for example due to manufacturing errors or tolerances. 
     Another technique to achieve decoupling of the transmit and receive antennas is to use an appropriate spacing between each antenna, depending upon factors such as output power, size of the antennas, frequency, and the presence of any shielding, so as to force a proportion of the electromagnetic lines of force of the transmit signal into the target so they reach the analyte, thereby minimizing or eliminating as much as possible direct receipt of electromagnetic energy by the receive antenna directly from the transmit antenna without traveling into the target. This technique helps to ensure that the response detected by the receive antenna is measuring the analyte and is not just the transmitted signal flowing directly from the transmit antenna to the receive antenna. In one embodiment, the sensor can use a first pair of transmit and receive antennas that have a first spacing therebetween, and a second pair of transmit and receive antennas that have a second spacing therebetween that differs from the first spacing. 
     The techniques described herein can be used to detect the presence of the analyte of interest, as well an amount of the analyte or a concentration of the analyte within the target. The techniques described herein can be used to detect a single analyte or more than one analyte. The target can be any target, for example human or non-human, animal or non-animal, biological or non-biological, that contains the analyte(s) that one may wish to detect. For example, the target can include, but is not limited to, human tissue, animal tissue, plant tissue, an inanimate object, soil, a fluid, genetic material, or a microbe. The analyte(s) can be any analyte, for example human or non-human, animal or non-animal, biological or non-biological, that one may wish to detect. For example, the analyte(s) can include, but is not limited to, one or more of blood glucose, blood alcohol, white blood cells, or luteinizing hormone. 
     In one embodiment, a non-invasive analyte sensor system can include a decoupled antenna array having at least one transmit antenna and at least one receive antenna that are decoupled from one another. The at least one transmit antenna and the at least one receive antenna are positioned and arranged relative to a target containing at least one analyte of interest so that the at least one transmit antenna can transmit a transmit signal into the target, and so that the at least one receive antenna can detect a response. A transmit circuit is electrically connectable to the at least one transmit antenna. The transmit circuit is configured to generate a transmit signal to be transmitted by the at least one transmit antenna, where the transmit signal is in a radio or microwave frequency range of the electromagnetic spectrum. In addition, a receive circuit is electrically connectable to the at least one receive antenna. The receive circuit is configured to receive a response detected by the at least one receive antenna resulting from transmission of the transmit signal by the at least one transmit antenna into the target containing the at least one analyte of interest. 
     In one embodiment, the decoupling can be achieved by an intentional difference in geometry between the at least one transmit antenna and the at least one receive antenna. In another embodiment, decoupling can be achieved by arranging the at least one transmit antenna and the at least one receive antenna with an appropriate spacing therebetween that is sufficient to decouple the at least one transmit antenna and the at least one receive antenna. 
     In another embodiment described herein, a non-invasive analyte sensor system can include a sensor housing and a decoupled detector array attached to the sensor housing. The decoupled detector array can have at least one transmit element and at least one receive element. The at least one transmit element can have a first geometry and the at least one receive element can have a second geometry that is geometrically different from the first geometry. In addition to or separately from the different geometries, an appropriate spacing can be provided between the at least one transmit element and the at least one receive element that is sufficient to decouple the transmit and receive elements from one another. The at least one transmit element is positioned and arranged to transmit a transmit signal into a target containing at least one analyte of interest and the at least one receive element is positioned and arranged to be able to detect a response. In this embodiment, the at least one transmit element consists of a strip of conductive material having at least one lateral dimension thereof greater than a thickness dimension thereof, and the strip of conductive material of the at least one transmit element is disposed on a substrate. In addition, in this embodiment, the at least one receive element consists of a strip of conductive material having at least one lateral dimension thereof greater than a thickness dimension thereof, and the strip of conductive material of the at least one receive element is disposed on a substrate which can be the same substrate or a different substrate than the at least one transmit element. A transmit circuit is attached to the sensor housing and is electrically connectable to the at least one transmit element, where the transmit circuit is configured to generate a transmit signal to be transmitted by the at least one transmit element, with the transmit signal being in a radio or microwave frequency range of the electromagnetic spectrum. In addition, a receive circuit is attached to the sensor housing, and is electrically connectable to the at least one receive element. The receive circuit is configured to receive a response detected by the at least one receive element resulting from transmission of the transmit signal by the at the least one transmit element into the target containing the at least one analyte of interest. 
     In still another embodiment described herein, a non-invasive analyte sensor system can include a sensor housing and a detector array attached to the sensor housing. The detector array can have at least one transmit element and at least one receive element that are decoupled from one another. The at least one transmit element can have a first geometry and the at least one receive element can have a second geometry that is geometrically different from the first geometry. In addition to or separately from the different geometries, an appropriate spacing can be provided between the at least one transmit element and the at least one receive element that is sufficient to decouple the transmit and receive elements from one another. The at least one transmit element is positioned and arranged to transmit a transmit signal into a target containing at least one analyte of interest and the at least one receive element is positioned and arranged to be able to detect a response. In this embodiment, the at least one transmit element and the at least one receive element can both consist of a strip of conductive material disposed on a substrate. A transmit circuit is disposed within the sensor housing and is electrically connected to the at least one transmit element. The transmit circuit is configured to generate a transmit signal to be transmitted by the at least one transmit element, where the transmit signal has at least two frequencies, each of which is in a range of about 10 kHz to about 100 GHz, for example about 300 MHz to about 6000 MHz. A receive circuit is also disposed within the sensor housing and is electrically connected to the at least one receive element. The receive circuit is configured to receive a response detected by the at least one receive element resulting from transmission of the transmit signal by the at least one transmit element into the target containing the at least one analyte of interest. In addition, a rechargeable battery is disposed within the sensor housing for providing electrical power to the detector array, the transmit circuit and the receive circuit. 
    
    
     
       DRAWINGS 
       References are made to the accompanying drawings that form a part of this disclosure, and which illustrate embodiments in which the apparatus, systems and methods described in this specification can be practiced. 
         FIG. 1  is a schematic depiction of a non-invasive analyte sensor system with a non-invasive analyte sensor relative to a target according to an embodiment. 
         FIGS. 2A-C  illustrate different example orientations of antenna arrays that can be used in the sensor system described herein. 
         FIGS. 3A-3I  illustrate different examples of transmit and receive antennas with different geometries. 
         FIGS. 4A, 4B, 4C and 4D  illustrate additional examples of different shapes that the ends of the transmit and receive antennas can have. 
         FIG. 5  is a schematic depiction of a sensor device according to an embodiment. 
         FIG. 6  is a flowchart of a method for detecting an analyte according to an embodiment. 
         FIG. 7  is a flowchart of analysis of a response according to an embodiment. 
         FIG. 8  illustrates a tabletop device that incorporates the non-invasive analyte sensor system described herein. 
         FIG. 9  illustrates a system that incorporates the tabletop device of  FIG. 8 . 
         FIG. 10  illustrates another embodiment of a tabletop device that incorporates the non-invasive analyte sensor system described herein. 
     
    
    
     Like reference numbers represent like parts throughout. 
     DETAILED DESCRIPTION 
     The following is a detailed description of apparatus, systems and methods of non-invasively detecting an analyte via spectroscopic techniques using non-optical frequencies such as in the radio or microwave frequency bands of the electromagnetic spectrum. A non-invasive analyte sensor includes a transmit antenna (which may also be referred to as a transmit element) that functions to transmit a generated transmit signal that is in a radio or microwave frequency range of the electromagnetic spectrum into a target containing an analyte of interest, and a receive antenna (which may also be referred to as a receive element) that functions to detect a response resulting from transmission of the transmit signal by the transmit antenna into the target. The transmit antenna and the receive antenna are decoupled from one another which improves the detection performance of the sensor. 
     The transmit antenna and the receive antenna can be located near the target and operated as further described herein to assist in detecting at least one analyte in the target. The transmit antenna transmits a signal, which has at least two frequencies in the radio or microwave frequency range, toward and into the target. The signal with the at least two frequencies can be formed by separate signal portions, each having a discrete frequency, that are transmitted separately at separate times at each frequency. In another embodiment, the signal with the at least two frequencies may be part of a complex signal that includes a plurality of frequencies including the at least two frequencies. The complex signal can be generated by blending or multiplexing multiple signals together followed by transmitting the complex signal whereby the plurality of frequencies are transmitted at the same time. One possible technique for generating the complex signal includes, but is not limited to, using an inverse Fourier transformation technique. The receive antenna detects a response resulting from transmission of the signal by the transmit antenna into the target containing the at least one analyte of interest. 
     The transmit antenna and the receive antenna are decoupled (which may also be referred to as detuned or the like) from one another. Decoupling refers to intentionally fabricating the configuration and/or arrangement of the transmit antenna and the receive antenna to minimize direct communication between the transmit antenna and the receive antenna, preferably absent shielding. Shielding between the transmit antenna and the receive antenna can be utilized. However, the transmit antenna and the receive antenna are decoupled even without the presence of shielding. 
     The signal(s) detected by the receive antenna can be analyzed to detect the analyte based on the intensity of the received signal(s) and reductions in intensity at one or more frequencies where the analyte absorbs the transmitted signal. An example of detecting an analyte using a non-invasive spectroscopy sensor operating in the radio or microwave frequency range of the electromagnetic spectrum is described in WO 2019/217461, the entire contents of which are incorporated herein by reference. The signal(s) detected by the receive antenna can be complex signals including a plurality of signal components, each signal component being at a different frequency. In an embodiment, the detected complex signals can be decomposed into the signal components at each of the different frequencies, for example through a Fourier transformation. In an embodiment, the complex signal detected by the receive antenna can be analyzed as a whole (i.e. without demultiplexing the complex signal) to detect the analyte as long as the detected signal provides enough information to make the analyte detection. In addition, the signal(s) detected by the receive antenna can be separate signal portions, each having a discrete frequency. 
     In one embodiment, the sensor described herein can be used to detect the presence of at least one analyte in a target. In another embodiment, the sensor described herein can detect an amount or a concentration of the at least one analyte in the target. The target can be any target containing at least one analyte of interest that one may wish to detect. The target can be human or non-human, animal or non-animal, biological or non-biological. For example, the target can include, but is not limited to, human tissue, animal tissue, plant tissue, an inanimate object, soil, a fluid, genetic material, or a microbe. Non-limiting examples of targets include, but are not limited to, a fluid, for example blood, interstitial fluid, cerebral spinal fluid, lymph fluid or urine, human tissue, animal tissue, plant tissue, an inanimate object, soil, genetic material, or a microbe. 
     The analyte(s) can be any analyte that one may wish to detect. The analyte can be human or non-human, animal or non-animal, biological or non-biological. For example, the analyte(s) can include, but is not limited to, one or more of blood glucose, blood alcohol, white blood cells, or luteinizing hormone. The analyte(s) can include, but is not limited to, a chemical, a combination of chemicals, a virus, a bacteria, or the like. The analyte can be a chemical included in another medium, with non-limiting examples of such media including a fluid containing the at least one analyte, for example blood, interstitial fluid, cerebral spinal fluid, lymph fluid or urine, human tissue, animal tissue, plant tissue, an inanimate object, soil, genetic material, or a microbe. The analyte(s) may also be a non-human, non-biological particle such as a mineral or a contaminant. 
     The analyte(s) can include, for example, naturally occurring substances, artificial substances, metabolites, and/or reaction products. As non-limiting examples, the at least one analyte can include, but is not limited to, insulin, acarboxyprothrombin; acylcarnitine; adenine phosphoribosyl transferase; adenosine deaminase; albumin; alpha-fetoprotein; amino acid profiles (arginine (Krebs cycle), histidine/urocanic acid, homocysteine, phenylalanine/tyrosine, tryptophan); andrenostenedione; antipyrine; arabinitol enantiomers; arginase; benzoylecgonine (cocaine); biotinidase; biopterin; c-reactive protein; carnitine; pro-BNP; BNP; troponin; carnosinase; CD4; ceruloplasmin; chenodeoxycholic acid; chloroquine; cholesterol; cholinesterase; conjugated 1-β hydroxy-cholic acid; cortisol; creatine kinase; creatine kinase MM isoenzyme; cyclosporin A; d-penicillamine; de-ethylchloroquine; dehydroepiandrosterone sulfate; DNA (acetylator polymorphism, alcohol dehydrogenase, alpha 1-antitrypsin, cystic fibrosis, Duchenne/Becker muscular dystrophy, analyte-6-phosphate dehydrogenase, hemoglobin A, hemoglobin S, hemoglobin C, hemoglobin D, hemoglobin E, hemoglobin F, D-Punjab, beta-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1, Leber hereditary optic neuropathy, MCAD, RNA, PKU,  Plasmodium vivax , sexual differentiation, 21-deoxycortisol); desbutylhalofantrine; dihydropteridine reductase; diptheria/tetanus antitoxin; erythrocyte arginase; erythrocyte protoporphyrin; esterase D; fatty acids/acylglycines; free β-human chorionic gonadotropin; free erythrocyte porphyrin; free thyroxine (FT4); free tri-iodothyronine (FT3); fumarylacetoacetase; galactose/gal-1-phosphate; galactose-1-phosphate uridyltransferase; gentamicin; analyte-6-phosphate dehydrogenase; glutathione; glutathione perioxidase; glycocholic acid; glycosylated hemoglobin; halofantrine; hemoglobin variants; hexosaminidase A; human erythrocyte carbonic anhydrase I; 17-alpha-hydroxyprogesterone; hypoxanthine phosphoribosyl transferase; immunoreactive trypsin; lactate; lead; lipoproteins ((a), B/A-1, β); lysozyme; mefloquine; netilmicin; phenobarbitone; phenytoin; phytanic/pristanic acid; progesterone; prolactin; prolidase; purine nucleoside phosphorylase; quinine; reverse tri-iodothyronine (rT3); selenium; serum pancreatic lipase; sissomicin; somatomedin C; specific antibodies (adenovirus, anti-nuclear antibody, anti-zeta antibody, arbovirus, Aujeszky&#39;s disease virus, dengue virus,  Dracunculus medinensis, Echinococcus granulosus, Entamoeba histolytica , enterovirus,  Giardia duodenalisa, Helicobacter pylori , hepatitis B virus, herpes virus, HIV-1, IgE (atopic disease), influenza virus,  Leishmania donovani , leptospira, measles/mumps/rubella,  Mycobacterium leprae, Mycoplasma pneumoniae , Myoglobin,  Onchocerca volvulus , parainfluenza virus,  Plasmodium falciparum , polio virus,  Pseudomonas aeruginosa , respiratory syncytial virus,  rickettsia  (scrub typhus),  Schistosoma mansoni, Toxoplasma gondii, Trepenoma pallidium, Trypanosoma cruzi /rangeli, vesicular  stomatis  virus,  Wuchereria bancrofti , yellow fever virus); specific antigens (hepatitis B virus, HIV-1); succinylacetone; sulfadoxine; theophylline; thyrotropin (TSH); thyroxine (T4); thyroxine-binding globulin; trace elements; transferrin; UDP-galactose-4-epimerase; urea; uroporphyrinogen I synthase; vitamin A; white blood cells; and zinc protoporphyrin. 
     The analyte(s) can also include one or more chemicals introduced into the target. The analyte(s) can include a marker such as a contrast agent, a radioisotope, or other chemical agent. The analyte(s) can include a fluorocarbon-based synthetic blood. The analyte(s) can include a drug or pharmaceutical composition, with non-limiting examples including ethanol; cannabis (marijuana, tetrahydrocannabinol, hashish); inhalants (nitrous oxide, amyl nitrite, butyl nitrite, chlorohydrocarbons, hydrocarbons); cocaine (crack cocaine); stimulants (amphetamines, methamphetamines, Ritalin, Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine); depressants (barbiturates, methaqualone, tranquilizers such as Valium, Librium, Miltown, Serax, Equanil, Tranxene); hallucinogens (phencyclidine, lysergic acid, mescaline, peyote, psilocybin); narcotics (heroin, codeine, morphine, opium, meperidine, Percocet, Percodan, Tussionex, Fentanyl, Darvon, Talwin, Lomotil); designer drugs (analogs of fentanyl, meperidine, amphetamines, methamphetamines, and phencyclidine, for example, Ecstasy); anabolic steroids; and nicotine. The analyte(s) can include other drugs or pharmaceutical compositions. The analyte(s) can include neurochemicals or other chemicals generated within the body, such as, for example, ascorbic acid, uric acid, dopamine, noradrenaline, 3-methoxytyramine (3MT), 3,4-Dihydroxyphenylacetic acid (DOPAC), Homovanillic acid (HVA), 5-Hydroxytryptamine (5HT), and 5-Hydroxyindoleacetic acid (FHIAA). 
     Referring now to  FIG. 1 , an embodiment of a non-invasive analyte sensor system with a non-invasive analyte sensor  5  is illustrated. The sensor  5  is depicted relative to a target  7  that contains an analyte of interest  9 . In this example, the sensor  5  is depicted as including an antenna array that includes a transmit antenna/element  11  (hereinafter “transmit antenna  11 ”) and a receive antenna/element  13  (hereinafter “receive antenna  13 ”). The sensor  5  further includes a transmit circuit  15 , a receive circuit  17 , and a controller  19 . As discussed further below, the sensor  5  can also include a power supply, such as a battery (not shown in  FIG. 1 ). 
     The transmit antenna  11  is positioned, arranged and configured to transmit a signal  21  that is the radio frequency (RF) or microwave range of the electromagnetic spectrum into the target  7 . The transmit antenna  11  can be an electrode or any other suitable transmitter of electromagnetic signals in the radio frequency (RF) or microwave range. The transmit antenna  11  can have any arrangement and orientation relative to the target  7  that is sufficient to allow the analyte sensing to take place. In one non-limiting embodiment, the transmit antenna  11  can be arranged to face in a direction that is substantially toward the target  7 . 
     The signal  21  transmitted by the transmit antenna  11  is generated by the transmit circuit  15  which is electrically connectable to the transmit antenna  11 . The transmit circuit  15  can have any configuration that is suitable to generate a transmit signal to be transmitted by the transmit antenna  11 . Transmit circuits for generating transmit signals in the RF or microwave frequency range are well known in the art. In one embodiment, the transmit circuit  15  can include, for example, a connection to a power source, a frequency generator, and optionally filters, amplifiers or any other suitable elements for a circuit generating an RF or microwave frequency electromagnetic signal. In an embodiment, the signal generated by the transmit circuit  15  can have at least two discrete frequencies (i.e. a plurality of discrete frequencies), each of which is in the range from about 10 kHz to about 100 GHz. In another embodiment, each of the at least two discrete frequencies can be in a range from about 300 MHz to about 6000 MHz. In an embodiment, the transmit circuit  15  can be configured to sweep through a range of frequencies that are within the range of about 10 kHz to about 100 GHz, or in another embodiment a range of about 300 MHz to about 6000 MHz. In an embodiment, the transmit circuit  15  can be configured to produce a complex transmit signal, the complex signal including a plurality of signal components, each of the signal components having a different frequency. The complex signal can be generated by blending or multiplexing multiple signals together followed by transmitting the complex signal whereby the plurality of frequencies are transmitted at the same time. 
     The receive antenna  13  is positioned, arranged, and configured to detect one or more electromagnetic response signals  23  that result from the transmission of the transmit signal  21  by the transmit antenna  11  into the target  7  and impinging on the analyte  9 . The receive antenna  13  can be an electrode or any other suitable receiver of electromagnetic signals in the radio frequency (RF) or microwave range. In an embodiment, the receive antenna  13  is configured to detect electromagnetic signals having at least two frequencies, each of which is in the range from about 10 kHz to about 100 GHz, or in another embodiment a range from about 300 MHz to about 6000 MHz. The receive antenna  13  can have any arrangement and orientation relative to the target  7  that is sufficient to allow detection of the response signal(s)  23  to allow the analyte sensing to take place. In one non-limiting embodiment, the receive antenna  13  can be arranged to face in a direction that is substantially toward the target  7 . 
     The receive circuit  17  is electrically connectable to the receive antenna  13  and conveys the received response from the receive antenna  13  to the controller  19 . The receive circuit  17  can have any configuration that is suitable for interfacing with the receive antenna  13  to convert the electromagnetic energy detected by the receive antenna  13  into one or more signals reflective of the response signal(s)  23 . The construction of receive circuits are well known in the art. The receive circuit  17  can be configured to condition the signal(s) prior to providing the signal(s) to the controller  19 , for example through amplifying the signal(s), filtering the signal(s), or the like. Accordingly, the receive circuit  17  may include filters, amplifiers, or any other suitable components for conditioning the signal(s) provided to the controller  19 . In an embodiment, at least one of the receive circuit  17  or the controller  19  can be configured to decompose or demultiplex a complex signal, detected by the receive antenna  13 , including a plurality of signal components each at different frequencies into each of the constituent signal components. In an embodiment, decomposing the complex signal can include applying a Fourier transform to the detected complex signal. However, decomposing or demultiplexing a received complex signal is optional. Instead, in an embodiment, the complex signal detected by the receive antenna can be analyzed as a whole (i.e. without demultiplexing the complex signal) to detect the analyte as long as the detected signal provides enough information to make the analyte detection. 
     The controller  19  controls the operation of the sensor  5 . The controller  19 , for example, can direct the transmit circuit  15  to generate a transmit signal to be transmitted by the transmit antenna  11 . The controller  19  further receives signals from the receive circuit  17 . The controller  19  can optionally process the signals from the receive circuit  17  to detect the analyte(s)  9  in the target  7 . In one embodiment, the controller  19  may optionally be in communication with at least one external device  25  such as a user device and/or a remote server  27 , for example through one or more wireless connections such as Bluetooth, wireless data connections such a 4G, 5G, LTE or the like, or Wi-Fi. If provided, the external device  25  and/or remote server  27  may process (or further process) the signals that the controller  19  receives from the receive circuit  17 , for example to detect the analyte(s)  9 . If provided, the external device  25  may be used to provide communication between the sensor  5  and the remote server  27 , for example using a wired data connection or via a wireless data connection or Wi-Fi of the external device  25  to provide the connection to the remote server  27 . 
     With continued reference to  FIG. 1 , the sensor  5  may include a sensor housing  29  (shown in dashed lines) that defines an interior space  31 . Components of the sensor  5  may be attached to and/or disposed within the housing  29 . For example, the transmit antenna  11  and the receive antenna  13  are attached to the housing  29 . In some embodiments, the antennas  11 ,  13  may be entirely or partially within the interior space  31  of the housing  29 . In some embodiments, the antennas  11 ,  13  may be attached to the housing  29  but at least partially or fully located outside the interior space  31 . In some embodiments, the transmit circuit  15 , the receive circuit  17  and the controller  19  are attached to the housing  29  and disposed entirely within the sensor housing  29 . 
     The receive antenna  13  is decoupled or detuned with respect to the transmit antenna  11  such that electromagnetic coupling between the transmit antenna  11  and the receive antenna  13  is reduced. The decoupling of the transmit antenna  11  and the receive antenna  13  increases the portion of the signal(s) detected by the receive antenna  13  that is the response signal(s)  23  from the target  7 , and minimizes direct receipt of the transmitted signal  21  by the receive antenna  13 . The decoupling of the transmit antenna  11  and the receive antenna  13  results in transmission from the transmit antenna  11  to the receive antenna  13  having a reduced forward gain (S 21 ) and an increased reflection at output (S 22 ) compared to antenna systems having coupled transmit and receive antennas. 
     In an embodiment, coupling between the transmit antenna  11  and the receive antenna  13  is 95% or less. In another embodiment, coupling between the transmit antenna  11  and the receive antenna  13  is 90% or less. In another embodiment, coupling between the transmit antenna  11  and the receive antenna  13  is 85% or less. In another embodiment, coupling between the transmit antenna  11  and the receive antenna  13  is 75% or less. 
     Any technique for reducing coupling between the transmit antenna  11  and the receive antenna  13  can be used. For example, the decoupling between the transmit antenna  11  and the receive antenna  13  can be achieved by one or more intentionally fabricated configurations and/or arrangements between the transmit antenna  11  and the receive antenna  13  that is sufficient to decouple the transmit antenna  11  and the receive antenna  13  from one another. 
     For example, in one embodiment described further below, the decoupling of the transmit antenna  11  and the receive antenna  13  can be achieved by intentionally configuring the transmit antenna  11  and the receive antenna  13  to have different geometries from one another. Intentionally different geometries refers to different geometric configurations of the transmit and receive antennas  11 ,  13  that are intentional. Intentional differences in geometry are distinct from differences in geometry of transmit and receive antennas that may occur by accident or unintentionally, for example due to manufacturing errors or tolerances. 
     Another technique to achieve decoupling of the transmit antenna  11  and the receive antenna  13  is to provide appropriate spacing between each antenna  11 ,  13  that is sufficient to decouple the antennas  11 ,  13  and force a proportion of the electromagnetic lines of force of the transmitted signal  21  into the target  7  thereby minimizing or eliminating as much as possible direct receipt of electromagnetic energy by the receive antenna  13  directly from the transmit antenna  11  without traveling into the target  7 . The appropriate spacing between each antenna  11 ,  13  can be determined based upon factors that include, but are not limited to, the output power of the signal from the transmit antenna  11 , the size of the antennas  11 ,  13 , the frequency or frequencies of the transmitted signal, and the presence of any shielding between the antennas. This technique helps to ensure that the response detected by the receive antenna  13  is measuring the analyte  9  and is not just the transmitted signal  21  flowing directly from the transmit antenna  11  to the receive antenna  13 . In some embodiments, the appropriate spacing between the antennas  11 ,  13  can be used together with the intentional difference in geometries of the antennas  11 ,  13  to achieve decoupling. 
     In one embodiment, the transmit signal that is transmitted by the transmit antenna  11  can have at least two different frequencies, for example upwards of 7 to 12 different and discrete frequencies. In another embodiment, the transmit signal can be a series of discrete, separate signals with each separate signal having a single frequency or multiple different frequencies. 
     In one embodiment, the transmit signal (or each of the transmit signals) can be transmitted over a transmit time that is less than, equal to, or greater than about 300 ms. In another embodiment, the transmit time can be than, equal to, or greater than about 200 ms. In still another embodiment, the transmit time can be less than, equal to, or greater than about 30 ms. The transmit time could also have a magnitude that is measured in seconds, for example 1 second, 5 seconds, 10 seconds, or more. In an embodiment, the same transmit signal can be transmitted multiple times, and then the transmit time can be averaged. In another embodiment, the transmit signal (or each of the transmit signals) can be transmitted with a duty cycle that is less than or equal to about 50%. 
       FIGS. 2A-2C  illustrate examples of antenna arrays  33  that can be used in the sensor system  5  and how the antenna arrays  33  can be oriented. Many orientations of the antenna arrays  33  are possible, and any orientation can be used as long as the sensor  5  can perform its primary function of sensing the analyte  9 . 
     In  FIG. 2A , the antenna array  33  includes the transmit antenna  11  and the receive antenna  13  disposed on a substrate  35  which may be substantially planar. This example depicts the array  33  disposed substantially in an X-Y plane. In this example, dimensions of the antennas  11 ,  13  in the X and Y-axis directions can be considered lateral dimensions, while a dimension of the antennas  11 ,  13  in the Z-axis direction can be considered a thickness dimension. In this example, each of the antennas  11 ,  13  has at least one lateral dimension (measured in the X-axis direction and/or in the Y-axis direction) that is greater than the thickness dimension thereof (in the Z-axis direction). In other words, the transmit antenna  11  and the receive antenna  13  are each relatively flat or of relatively small thickness in the Z-axis direction compared to at least one other lateral dimension measured in the X-axis direction and/or in the Y-axis direction. 
     In use of the embodiment in  FIG. 2A , the sensor and the array  33  may be positioned relative to the target  7  such that the target  7  is below the array  33  in the Z-axis direction or above the array  33  in the Z-axis direction whereby one of the faces of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned to the left or right sides of the array  33  in the X-axis direction whereby one of the ends of each one of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned to the sides of the array  33  in the Y-axis direction whereby one of the sides of each one of the antennas  11 ,  13  face toward the target  7 . 
     The sensor  5  can also be provided with one or more additional antenna arrays in addition the antenna array  33 . For example,  FIG. 2A  also depicts an optional second antenna array  33   a  that includes the transmit antenna  11  and the receive antenna  13  disposed on a substrate  35   a  which may be substantially planar. Like the array  33 , the array  33   a  may also be disposed substantially in the X-Y plane, with the arrays  33 ,  33   a  spaced from one another in the X-axis direction. 
     In  FIG. 2B , the antenna array  33  is depicted as being disposed substantially in the Y-Z plane. In this example, dimensions of the antennas  11 ,  13  in the Y and Z-axis directions can be considered lateral dimensions, while a dimension of the antennas  11 ,  13  in the X-axis direction can be considered a thickness dimension. In this example, each of the antennas  11 ,  13  has at least one lateral dimension (measured in the Y-axis direction and/or in the Z-axis direction) that is greater than the thickness dimension thereof (in the X-axis direction). In other words, the transmit antenna  11  and the receive antenna  13  are each relatively flat or of relatively small thickness in the X-axis direction compared to at least one other lateral dimension measured in the Y-axis direction and/or in the Z-axis direction. 
     In use of the embodiment in  FIG. 2B , the sensor and the array  33  may be positioned relative to the target  7  such that the target  7  is below the array  33  in the Z-axis direction or above the array  33  in the Z-axis direction whereby one of the ends of each one of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned in front of or behind the array  33  in the X-axis direction whereby one of the faces of each one of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned to one of the sides of the array  33  in the Y-axis direction whereby one of the sides of each one of the antennas  11 ,  13  face toward the target  7 . 
     In  FIG. 2C , the antenna array  33  is depicted as being disposed substantially in the X-Z plane. In this example, dimensions of the antennas  11 ,  13  in the X and Z-axis directions can be considered lateral dimensions, while a dimension of the antennas  11 ,  13  in the Y-axis direction can be considered a thickness dimension. In this example, each of the antennas  11 ,  13  has at least one lateral dimension (measured in the X-axis direction and/or in the Z-axis direction) that is greater than the thickness dimension thereof (in the Y-axis direction). In other words, the transmit antenna  11  and the receive antenna  13  are each relatively flat or of relatively small thickness in the Y-axis direction compared to at least one other lateral dimension measured in the X-axis direction and/or in the Z-axis direction. 
     In use of the embodiment in  FIG. 2C , the sensor and the array  33  may be positioned relative to the target  7  such that the target  7  is below the array  33  in the Z-axis direction or above the array  33  in the Z-axis direction whereby one of the ends of each one of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned to the left or right sides of the array  33  in the X-axis direction whereby one of the sides of each one of the antennas  11 ,  13  face toward the target  7 . Alternatively, the target  7  can be positioned in front of or in back of the array  33  in the Y-axis direction whereby one of the faces of each one of the antennas  11 ,  13  face toward the target  7 . 
     The arrays  33 ,  33   a  in  FIGS. 2A-2C  need not be oriented entirely within a plane such as the X-Y plane, the Y-Z plane or the X-Z plane. Instead, the arrays  33 ,  33   a  can be disposed at angles to the X-Y plane, the Y-Z plane and the X-Z plane. 
     Decoupling Antennas Using Differences in Antenna Geometries 
     As mentioned above, one technique for decoupling the transmit antenna  11  from the receive antenna  13  is to intentionally configure the transmit antenna  11  and the receive antenna  13  to have intentionally different geometries. Intentionally different geometries refers to differences in geometric configurations of the transmit and receive antennas  11 ,  13  that are intentional, and is distinct from differences in geometry of the transmit and receive antennas  11 ,  13  that may occur by accident or unintentionally, for example due to manufacturing errors or tolerances when fabricating the antennas  11 ,  13 . 
     The different geometries of the antennas  11 ,  13  may manifest itself, and may be described, in a number of different ways. For example, in a plan view of each of the antennas  11 ,  13  (such as in  FIGS. 3A-I ), the shapes of the perimeter edges of the antennas  11 ,  13  may be different from one another. The different geometries may result in the antennas  11 ,  13  having different surface areas in plan view. The different geometries may result in the antennas  11 ,  13  having different aspect ratios in plan view (i.e. a ratio of their sizes in different dimensions; for example, as discussed in further detail below, the ratio of the length divided by the width of the antenna  11  may be different than the ratio of the length divided by the width for the antenna  13 ). In some embodiments, the different geometries may result in the antennas  11 ,  13  having any combination of different perimeter edge shapes in plan view, different surface areas in plan view, and/or different aspect ratios. In some embodiments, the antennas  11 ,  13  may have one or more holes formed therein (see  FIG. 2B ) within the perimeter edge boundary, or one or more notches formed in the perimeter edge (see  FIG. 2B ). 
     So as used herein, a difference in geometry or a difference in geometrical shape of the antennas  11 ,  13  refers to any intentional difference in the figure, length, width, size, shape, area closed by a boundary (i.e. the perimeter edge), etc. when the respective antenna  11 ,  13  is viewed in a plan view. 
     The antennas  11 ,  13  can have any configuration and can be formed from any suitable material that allows them to perform the functions of the antennas  11 ,  13  as described herein. In one embodiment, the antennas  11 ,  13  can be formed by strips of material. A strip of material can include a configuration where the strip has at least one lateral dimension thereof greater than a thickness dimension thereof when the antenna is viewed in a plan view (in other words, the strip is relatively flat or of relatively small thickness compared to at least one other lateral dimension, such as length or width when the antenna is viewed in a plan view as in  FIGS. 3A-I ). A strip of material can include a wire. The antennas  11 ,  13  can be formed from any suitable conductive material(s) including metals and conductive non-metallic materials. Examples of metals that can be used include, but are not limited to, copper or gold. Another example of a material that can be used is non-metallic materials that are doped with metallic material to make the non-metallic material conductive. 
     In  FIGS. 2A-2C , the antennas  11 ,  13  within each one of the arrays  33 ,  33   a  have different geometries from one another. In addition,  FIGS. 3A-I  illustrate plan views of additional examples of the antennas  11 ,  13  having different geometries from one another. The examples in  FIGS. 2A-2C and 3A -I are not exhaustive and many different configurations are possible. 
     With reference initially to  FIG. 3A , a plan view of an antenna array having two antennas with different geometries is illustrated. In this example (as well as for the examples in  FIGS. 2A-2C and 3B-3I ), for sake of convenience in describing the concepts herein, one antenna is labeled as the transmit antenna  11  and the other antenna is labeled as the receive antenna  13 . However, the antenna labeled as the transmit antenna  11  could be the receive antenna  13 , while the antenna labeled as the receive antenna  13  could be the transmit antenna  11 . Each of the antennas  11 ,  13  are disposed on the substrate  35  having a planar surface  37 . 
     The antennas  11 ,  13  can be formed as linear strips or traces on the surface  37 . In this example, the antenna  11  is generally U-shaped and has a first linear leg  40   a , a second linear leg  40   b  that extends perpendicular to the first leg  40   a , and a third linear leg  40   c  that extends parallel to the leg  40   a . Likewise, the antenna  13  is formed by a single leg that extends parallel to, and between, the legs  40   a ,  40   c.    
     In the example depicted in  FIG. 3A , each one of the antennas  11 ,  13  has at least one lateral dimension that is greater than a thickness dimension thereof (in  FIG. 3A , the thickness dimension would extend into/from the page when viewing  FIG. 3A ). For example, the leg  40   a  of the antenna  11  extends in one direction (i.e. a lateral dimension) an extent that is greater than a thickness dimension of the leg  40   a  extending into or out of the page; the leg  40   b  of the antenna  11  extends in a direction (i.e. a lateral dimension) an extent that is greater than a thickness dimension of the leg  40   b  extending into or out of the page; and the leg  40   c  of the antenna  11  extends in one direction (i.e. a lateral dimension) an extent that is greater than a thickness dimension of the leg  40   c  extending into or out of the page. Likewise, the antenna  13  extends in one direction (i.e. a lateral dimension) an extent that is greater than a thickness dimension of the antenna  13  extending into or out of the page. 
     The antennas  11 ,  13  also differ in geometry from one another in that the total linear length of the antenna  11  (determined by adding the individual lengths L 1 , L 2 , L 3  of the legs  40   a - c  together) when viewed in plan view is greater than the length L 13  of the antenna  13  when viewed in plan view. 
       FIG. 3B  illustrates another plan view of an antenna array having two antennas with different geometries. In this example, the antennas  11 ,  13  are illustrated as substantially linear strips each with a lateral length L 11 , L 13 , a lateral width W 11 , W 13 , and a perimeter edge E 11 , E 13 . The perimeter edges E 11 , E 13  extend around the entire periphery of the antennas  11 ,  13  and bound an area in plan view. In this example, the lateral length L 11 , L 13  and/or the lateral width W 11 , W 13  is greater than a thickness dimension of the antennas  11 ,  13  extending into/from the page when viewing  FIG. 3B . In this example, the antennas  11 ,  13  differ in geometry from one another in that the shapes of the ends of the antennas  11 ,  13  differ from one another. For example, when viewing  FIG. 3B , the right end  42  of the antenna  11  has a different shape than the right end  44  of the antenna  13 . Similarly, the left end  46  of the antenna  11  may have a similar shape as the right end  42 , but differs from the left end  48  of the antenna  13  which may have a similar shape as the right end  44 . It is also possible that the lateral lengths L 11 , L 13  and/or the lateral widths W 11 , W 13  of the antennas  11 ,  13  could differ from one another. 
       FIG. 3C  illustrates another plan view of an antenna array having two antennas with different geometries that is somewhat similar to  FIG. 3B . In this example, the antennas  11 ,  13  are illustrated as substantially linear strips each with the lateral length L 11 , L 13 , the lateral width W 11 , W 13 , and the perimeter edge E 11 , E 13 . The perimeter edges E 11 , E 13  extend around the entire periphery of the antennas  11 ,  13  and bound an area in plan view. In this example, the lateral length L 11 , L 13  and/or the lateral width W 11 , W 13  is greater than a thickness dimension of the antennas  11 ,  13  extending into/from the page when viewing  FIG. 3C . In this example, the antennas  11 ,  13  differ in geometry from one another in that the shapes of the ends of the antennas  11 ,  13  differ from one another. For example, when viewing  FIG. 3C , the right end  42  of the antenna  11  has a different shape than the right end  44  of the antenna  13 . Similarly, the left end  46  of the antenna  11  may have a similar shape as the right end  42 , but differs from the left end  48  of the antenna  13  which may have a similar shape as the right end  44 . In addition, the lateral widths W 11 , W 13  of the antennas  11 ,  13  differ from one another. It is also possible that the lateral lengths L 11 , L 13  of the antennas  11 ,  13  could differ from one another. 
       FIG. 3D  illustrates another plan view of an antenna array having two antennas with different geometries that is somewhat similar to  FIGS. 3B and 3C . In this example, the antennas  11 ,  13  are illustrated as substantially linear strips each with the lateral length L 11 , L 13 , the lateral width W 11 , W 13 , and the perimeter edge E 11 , E 13 . The perimeter edges E 11 , E 13  extend around the entire periphery of the antennas  11 ,  13  and bound an area in plan view. In this example, the lateral length L 11 , L 13  and/or the lateral width W 11 , W 13  is greater than a thickness dimension of the antennas  11 ,  13  extending into/from the page when viewing  FIG. 3D . In this example, the antennas  11 ,  13  differ in geometry from one another in that the shapes of the ends of the antennas  11 ,  13  differ from one another. For example, when viewing  FIG. 3D , the right end  42  of the antenna  11  has a different shape than the right end  44  of the antenna  13 . Similarly, the left end  46  of the antenna  11  may have a similar shape as the right end  42 , but differs from the left end  48  of the antenna  13  which may have a similar shape as the right end  44 . In addition, the lateral widths W 11 , W 13  of the antennas  11 ,  13  differ from one another. It is also possible that the lateral lengths L 11 , L 13  of the antennas  11 ,  13  could differ from one another. 
       FIG. 3E  illustrates another plan view of an antenna array having two antennas with different geometries on a substrate. In this example, the antenna  11  is illustrated as being a strip of material having a generally horseshoe shape, while the antenna  13  is illustrated as being a strip of material that is generally linear. The planar shapes (i.e. geometries) of the antennas  11 ,  13  differ from one another. In addition, the total length of the antenna  11  (measured from one end to the other) when viewed in plan view is greater than the length of the antenna  13  when viewed in plan. 
       FIG. 3F  illustrates another plan view of an antenna array having two antennas with different geometries on a substrate. In this example, the antenna  11  is illustrated as being a strip of material forming a right angle, and the antenna  13  is also illustrated as being a strip of material that forms a larger right angle. The planar shapes (i.e. geometries) of the antennas  11 ,  13  differ from one another since the total area in plan view of the antenna  13  is greater than the total area in plan view of the antenna  11 . In addition, the total length of the antenna  11  (measured from one end to the other) when viewed in plan view is less than the length of the antenna  13  when viewed in plan. 
       FIG. 3G  illustrates another plan view of an antenna array having two antennas with different geometries on a substrate. In this example, the antenna  11  is illustrated as being a strip of material forming a square, and the antenna  13  is illustrated as being a strip of material that forms a rectangle. The planar shapes (i.e. geometries) of the antennas  11 ,  13  differ from one another. In addition, at least one of the width/length of the antenna  11  when viewed in plan view is less than one of the width/length of the antenna  13  when viewed in plan. 
       FIG. 3H  illustrates another plan view of an antenna array having two antennas with different geometries on a substrate. In this example, the antenna  11  is illustrated as being a strip of material forming a circle when viewed in plan, and the antenna  13  is also illustrated as being a strip of material that forms a smaller circle when viewed in plan surrounded by the circle formed by the antenna  11 . The planar shapes (i.e. geometries) of the antennas  11 ,  13  differ from one another due to the different sizes of the circles. 
       FIG. 3I  illustrates another plan view of an antenna array having two antennas with different geometries on a substrate. In this example, the antenna  11  is illustrated as being a linear strip of material, and the antenna  13  is illustrated as being a strip of material that forms a semi-circle when viewed in plan. The planar shapes (i.e. geometries) of the antennas  11 ,  13  differ from one another due to the different shapes/geometries of the antennas  11 ,  13 . 
       4 A-D are plan views of additional examples of different shapes that the ends of the transmit and receive antennas  11 ,  13  can have to achieve differences in geometry. Either one of, or both of, the ends of the antennas  11 ,  13  can have the shapes in  FIGS. 4A-D , including in the embodiments in  FIGS. 3A-I .  FIG. 4A  depicts the end as being generally rectangular. FIG.  4 B depicts the end as having one rounded corner while the other corner remains a right angle.  FIG. 4C  depicts the entire end as being rounded or outwardly convex.  FIG. 4D  depicts the end as being inwardly concave. Many other shapes are possible. 
     Another technique to achieve decoupling of the antennas  11 ,  13  is to use an appropriate spacing between each antenna  11 ,  13  with the spacing being sufficient to force most or all of the signal(s) transmitted by the transmit antenna  11  into the target, thereby minimizing the direct receipt of electromagnetic energy by the receive antenna  13  directly from the transmit antenna  11 . The appropriate spacing can be used by itself to achieve decoupling of the antennas  11 ,  13 . In another embodiment, the appropriate spacing can be used together with differences in geometry of the antennas  11 ,  13  to achieve decoupling. 
     Referring to  FIG. 2A , there is a spacing D between the transmit antenna  11  and the receive antenna  13  at the location indicated. The spacing D between the antennas  11 ,  13  may be constant over the entire length (for example in the X-axis direction) of each antenna  11 ,  13 , or the spacing D between the antennas  11 ,  13  could vary. Any spacing D can be used as long as the spacing D is sufficient to result in most or all of the signal(s) transmitted by the transmit antenna  11  reaching the target and minimizing the direct receipt of electromagnetic energy by the receive antenna  13  directly from the transmit antenna  11 , thereby decoupling the antennas  11 ,  13  from one another. 
     Referring to  FIG. 5 , an example configuration of the sensor device  5  is illustrated. In  FIG. 5 , elements that are identical or similar to elements in  FIG. 1  are referenced using the same reference numerals. In  FIG. 5 , the antennas  11 ,  13  are disposed on one surface of a substrate  50  which can be, for example, a printed circuit board. At least one battery  52 , such as a rechargeable battery, is provided above the substrate  50 , for providing power to the sensor device  5 . In addition, a digital printed circuit board  54  is provided on which the transmit circuit  15 , the receive circuit  17 , and the controller  19  and other electronics of the second device  5  can be disposed. The substrate  50  and the digital printed circuit board  54  are electrically connected via any suitable electrical connection, such as a flexible connector  56 . An RF shield  58  may optionally be positioned between the antennas  11 ,  13  and the battery  52 , or between the antennas  11 ,  13  and the digital printed circuit board  54 , to shield the circuitry and electrical components from RF interference. 
     As depicted in  FIG. 5 , all of the elements of the sensor device  5 , including the antennas  11 ,  13 , the transmit circuit  15 , the receive circuit  17 , the controller  19 , the battery  52  and the like are contained entirely within the interior space  31  of the housing  29 . In an alternative embodiment, a portion of or the entirety of each antenna  11 ,  13  can project below a bottom wall  60  of the housing  29 . In another embodiment, the bottom of each antenna  11 ,  13  can be level with the bottom wall  60 , or they can be slightly recessed from the bottom wall  60 . 
     The housing  29  of the sensor device  5  can have any configuration and size that one finds suitable for employing in a non-invasive sensor device. In one embodiment, the housing  29  can have a maximum length dimension LH no greater than 50 mm, a maximum width dimension WH no greater than 50 mm, and a maximum thickness dimension Tx no greater than 25 mm, for a total interior volume of no greater than about 62.5 cm 3 . 
     In addition, with continued reference to  FIG. 5  together with  FIGS. 3A-3I , there is preferably a maximum spacing Dmax and a minimum spacing Dmm between the transmit antenna  11  and the receive antenna  13 . The maximum spacing Dmax may be dictated by the maximum size of the housing  29 . In one embodiment, the maximum spacing Dmax can be about 50 mm. In one embodiment, the minimum spacing Dmm can be from about 1.0 mm to about 5.0 mm. 
     With reference now to  FIG. 6  together with  FIG. 1 , one embodiment of a method  70  for detecting at least one analyte in a target is depicted. The method in  FIG. 6  can be practiced using any of the embodiments of the sensor device  5  described herein. In order to detect the analyte, the sensor device  5  is placed in relatively close proximity to the target. Relatively close proximity means that the sensor device  5  can be close to but not in direct physical contact with the target, or alternatively the sensor device  5  can be placed in direct, intimate physical contact with the target. The spacing between the sensor device  5  and the target  7  can be dependent upon a number of factors, such as the power of the transmitted signal. Assuming the sensor device  5  is properly positioned relative to the target  7 , at box  72  the transmit signal is generated, for example by the transmit circuit  15 . The transmit signal is then provided to the transmit antenna  11  which, at box  74 , transmits the transmit signal toward and into the target. At box  76 , a response resulting from the transmit signal contacting the analyte(s) is then detected by the receive antenna  13 . The receive circuit  17  obtains the detected response from the receive antenna  13  and provides the detected response to the controller  19 . At box  78 , the detected response can then be analyzed to detect at least one analyte. The analysis can be performed by the controller  19  and/or by the external device  25  and/or by the remote server  27 . 
     Referring to  FIG. 7 , the analysis at box  78  in the method  70  can take a number of forms. In one embodiment, at box  80 , the analysis can simply detect the presence of the analyte, i.e. is the analyte present in the target. Alternatively, at box  82 , the analysis can determine the amount of the analyte that is present. 
       FIG. 8  illustrates another example application of the non-invasive analyte sensor  5 . In this example, the sensor  5  is incorporated into a tabletop device  90 . The term “tabletop” is used interchangeably with “countertop” and refers to a device that is intended to reside on a top surface of a structure such as, but not limited to, a table, counter, shelf, another device, or the like during use. In some embodiments, the device  90  can be mounted on a vertical wall. The device  90  is configured to obtain a real-time, on-demand reading of an analyte in a user such as, but not limited to, obtaining a glucose level reading of the user using the non-invasive analyte sensor  5  incorporated into the device  90 . 
     The device  90  in  FIG. 8  is illustrated as being generally rectangular box shaped. However, the device  90  can have other shapes such as cylindrical, square box, triangular and many other shapes. The device  90  includes a housing  92 , a reading area  94 , for example on a top surface of the housing  92 , where the antennas  11 ,  13  of the sensor  5  are positioned to be able to obtain a reading, and a display screen  96 , for example on the top surface of the housing  92 , for displaying data such as results of a reading by the sensor  5 . Power for the device  90  can be provided via a power cord  98  that plugs into a wall socket. The device  90  may also include one or more batteries which act as a primary power source for the device  90  instead of power provided via the power cord  98  or the one or more batteries can act as a back-up power source in the event power is not available via the power cord  98 . 
     In operation of the device  90 , a user places a body part adjacent to (i.e. in contact with or close to but not in contact with) the reading area  94 . The body part can be any digit of the user&#39;s hand, such as the thumb, the index finger, the middle finger, the ring finger or the little finger; or the user&#39;s wrist; or any other body part of the user. A reading by the device  90  is triggered by the user. The device  90  can be configured in any manner with any form of a trigger mechanism to permit the user to trigger a reading. For example, the device  90  can be provided with a trigger button  100  located anywhere thereon that when pressed triggers a reading by the sensor  5 . Alternatively, the device  90  can include a proximity sensor, for example associated with the reading area  94 , that detects the presence of the user, such as the user&#39;s body part, adjacent to the reading area  94  and when detected initiates the reading. Alternatively, the device  90  can include a pressure sensor, for example associated with the reading area  94 , that detects contact of the user&#39;s body part with the reading area  94  and when contact is detected triggers the reading by the sensor  5 . Alternatively, the reading by the sensor  5  can be voice-triggered, for example by an optional microphone  102  of the device  90  that picks up a predetermined reading-initiating command that can be voiced by the user or a caregiver. 
     The results of a reading can be displayed on the display screen  96 . For example, assuming the analyte being detected is glucose, the user&#39;s glucose reading can be displayed on the display screen  96 . In addition (or alternatively), the results of the reading can be audibly presented by the device  90 , for example via one or more speakers  104 . The display screen  96  may be a touchscreen that permits user inputs, for example to scroll between different forms of display, or select different functionality of the device  90 . Alternatively, one or more input buttons (not shown) can be provided on the device  90  to allow user inputs. 
     An on/off power button or switch  106  can be provided anywhere on the device  90  to power the device  90  on and off. The on/off power button or switch  106  could also function as the trigger button instead of the trigger button  100 . Alternatively, the trigger button  100  may act as an on/off power button to power the device  90  on and off, as well as trigger a reading. In one embodiment, the device  90  can be provided with sleep functionality whereby the device  90  enters a low power sleep mode after a period of time of inactivity of the device  90 . In the sleep mode, the trigger mechanism and/or the microphone  102  on the device  90  can remain active waiting for suitable action to bring the device  90  out of the sleep mode and ready to take a reading. Examples of suitable actions include, but are not limited to, actuation of the trigger mechanism or recognition of an audible voice command. 
     In some embodiments, the device  90  can include data storage for storing individual readings for later historical analysis. Data for different individual users can also be stored in separate files for each user. 
       FIG. 10  illustrates another embodiment of the tabletop device  90  that is similar to the device  90  in  FIG. 8  and features that are similar to features in  FIG. 8  are referenced using the same reference numbers. In  FIG. 10 , instead of the display screen  96  being integrated into the device  90 , the display screen  96  is part of a separate device that is suitably connected to the device  90  for example by a cable  108  such as a USB cable. The separate display screen  96  in  FIG. 10  may receive power from the device  90 , or the separate display screen  96  may have its own power source. In one embodiment, the display screen  96  can be a television screen of a television. 
     Referring to  FIG. 9 , a system that incorporates the tabletop device  90  of either  FIG. 8  or  FIG. 10  is illustrated. In the illustrated system, the tabletop device  90  is in communication, either one-way or two-way communication, with one or more mobile devices  110  and/or with one or more other remote devices  114 . The mobile device(s)  110  can be, but is not limited to, the user&#39;s mobile device; a parent&#39;s mobile device; an aide, nurse, doctor or other medical professional mobile device; or any other mobile device. The mobile device(s)  110  can be a mobile phone, a smartwatch, a tablet device, a laptop computer, and the like. The remote device(s)  114  can be any device that is not a mobile device that is able to interact and communicate with the device  90 . For example, the device  114  can be a base station that is designed to interact with the device  90  and that may also interface with another remote device. The device  90  and the mobile device(s)  110  and/or the remote device(s)  114  can communicate with one another via a suitable network  112 , for example the internet or other network. In other embodiments, the device  90  and the mobile device(s)  110  and/or the remote device(s)  114  can directly communicate with each other, for example via a suitable short-range wireless communication technique such as Bluetooth®. 
     In the system of  FIG. 9 , the results of a reading by the tabletop device  90  can be transmitted, for example in real-time, to the mobile device(s)  110  and/or the remote device(s)  114 . For example, the results of the reading by the device  90  can be sent via phone call, email or by text message to the mobile device(s)  110  and/or the remote device(s)  114 , or directly via wireless communication. The mobile device(s)  110  and/or the remote device(s)  114  can include an App that is configured to operate with the device  90 . In one non-limiting implementation, the system in  FIG. 9  permits a reading, for example of an infant or a vulnerable adult, by the device  90  to be sent in real-time to a caregiver&#39;s (for example, a parent, aide, nurse, doctor or other medical professional) mobile device  110 . If the reading is abnormal, the caregiver can be alerted to that fact allowing the caregiver to render aid or arrange for aid to be rendered. In some embodiments, the signal received by the mobile device(s)  110  and/or the remote device(s)  114  can cause the mobile device(s)  110  and/or the remote device(s)  114  to emit an audible and/or visual alert based on the reading transmitted from the device  90 . The mobile device(s)  110  and/or the remote device(s)  114  may also send one or more signals to the device  90 . For example, a signal can be sent to the device  90  from the mobile device(s)  110  and/or the remote device(s)  114  after receiving a reading from the device  90  with instructions to the user to take an action or with information relating to the analyte sensed by the sensor. The instructions may be displayed on the display screen  96  of the device  90  and/or the device  90  may audibly present the instructions via the speaker  104 . 
     The interaction between the transmitted signal and the analyte may, in some cases, increase the intensity of the signal(s) that is detected by the receive antenna, and may, in other cases, decrease the intensity of the signal(s) that is detected by the receive antenna. For example, in one non-limiting embodiment, when analyzing the detected response, compounds in the target, including the analyte of interest that is being detected, can absorb some of the transmit signal, with the absorption varying based on the frequency of the transmit signal. The response signal detected by the receive antenna may include drops in intensity at frequencies where compounds in the target, such as the analyte, absorb the transmit signal. The frequencies of absorption are particular to different analytes. The response signal(s) detected by the receive antenna can be analyzed at frequencies that are associated with the analyte of interest to detect the analyte based on drops in the signal intensity corresponding to absorption by the analyte based on whether such drops in signal intensity are observed at frequencies that correspond to the absorption by the analyte of interest. A similar technique can be employed with respect to increases in the intensity of the signal(s) caused by the analyte. 
     Detection of the presence of the analyte can be achieved, for example, by identifying a change in the signal intensity detected by the receive antenna at a known frequency associated with the analyte. The change may be a decrease in the signal intensity or an increase in the signal intensity depending upon how the transmit signal interacts with the analyte. The known frequency associated with the analyte can be established, for example, through testing of solutions known to contain the analyte. Determination of the amount of the analyte can be achieved, for example, by identifying a magnitude of the change in the signal at the known frequency, for example using a function where the input variable is the magnitude of the change in signal and the output variable is an amount of the analyte. The determination of the amount of the analyte can further be used to determine a concentration, for example based on a known mass or volume of the target. In an embodiment, presence of the analyte and determination of the amount of analyte may both be determined, for example by first identifying the change in the detected signal to detect the presence of the analyte, and then processing the detected signal(s) to identify the magnitude of the change to determine the amount. 
     The terminology used in this specification is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.