Abstract:
A wireless instrument and methods for the remote monitoring of a plurality of biological parameters is described. The instrument includes a means of receiving data from a plurality of sensors, a means for converting the sensor data to a digital format, a means for collating the digitised sensor data into a single digital data stream, a transmitter for modulating a carrier signal with the digital data stream to create a modulated signal suitable for wireless transmission, an antenna for generating a radiating electromagnetic field to be received by a remote receiver, and an electrical power source. In a further embodiment, an additional means is provided for including an identification code in the transmitted digital data stream. In a further embodiment, an additional means is provided for monitoring operational parameters of the instrument and the inclusion of the monitored operational parameters in the transmitted digital data stream. In a further embodiment, an additional means is provided that allows for receiving signals from a remote transmitter for the remote manipulation of the instrument. In a further embodiment, the electrical power source is rechargeable and a recharging means is provided. A method is described for encapsulating the instrument in a one-piece housing that may include additional materials for increasing the mass of the instrument.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     It is known that the remote sensing of biological parameters is an established practice in both human and veterinary medicine. The remote sensing of single biological parameters is common practice, however the determination of the health of a subject more often requires the monitoring of a plurality of biological parameters which includes but is not limited to temperature, acidity (more commonly referred to as pH), and heart rate. The state of the art in remote sensing has advanced significantly in recent years, producing smaller and more reliable sensors, especially with respect to pH. In addition, rapid advances in the integration and miniaturisation of electronic devices has made it possible to incorporate an increasing number of functions in a small volume while at the same time requiring smaller amounts of electrical power. Furthermore, the cost of these electronic devices has decreased dramatically, making the remote monitoring of a plurality of biological parameters not only technically possible but also monetarily feasible. To date, the technical and financial constraints encountered in the monitoring of biological parameters have made it impractical to monitor more than a single parameter.  
         [0002]     As mentioned earlier, the miniaturisation and reliability of certain biological sensors has been detrimental to the development of remote sensors for monitoring a plurality of biological parameters. A case in point is that of pH, which is an essential parameter in monitoring the health of ruminant animals, in particular dairy cows, but which requires long-term monitoring. Until recently, the measurement of pH relied upon sensors that were not only bulky but which were reliable for only short periods of time, after which they would require recalibration, which added significantly to the cost of such a system and which subsequently made such a system financially unattractive. It is now possible to obtain pH sensors that are not only considerably smaller in size but which can provide reliable measurements for periods of a year or more and at a cost that is considerably less than that of more contemporary instruments. It is well known in the dairy industry that a system that would enable the remote monitoring of both temperature and pH in dairy livestock without requiring periodic recalibration over a long period of time would offer a substantial economic savings to the industry by way of reducing the instances of loss of productivity due to a phenomenon known as acidosis, which can be so severe as to cause the death of an otherwise productive animal but which is easily prevented if the parameters of temperature and pH are monitored continuously.  
         [0003]     This is but a single instance in the applications that are possible when two or more biological parameters are measured simultaneously, and the number of applications is enormous in breadth. The state of the art is such that a method and apparatus for performing such monitoring of a plurality of biological parameters is now practical from both a technical and monetary standpoint, therefore the present invention.  
       SUMMARY OF THE INVENTION  
       [0004]     A wireless instrument and methods for the remote monitoring of a plurality of biological parameters is described, which includes a plurality of biological parameter sensors, a means for converting the measured sensor data to a digital format, a means for collating the digitised sensor data into a single digital data stream, a transmitter for modulating a carrier signal with the digital data stream to create a modulated signal suitable for wireless transmission, an antenna, and a source of electrical power. The invention further includes a one piece moulded housing that protects the internal electronics from the monitored biological environment.  
         [0005]     A detailed embodiment is described for converting the plurality of sensor data into digital format by way of an analogue multiplexer and an analogue-to-digital converter. A microprocessor or microcontroller is utilised for controlling the selection of the sensor data that is to be converted, collating the digitised sensor data into a digital data stream, managing the power distribution within the instrument, and a variety of additional functions. The invention further includes a transmitter and an antenna for the purpose of generating and radiating a modulated wireless signal that is intended to be received by a remote receiver. The invention further provides for including an amplifier in the transmitter for increasing the transmitted power. The invention further provides for including an identification number in the transmitted digital data stream. The invention further provides for including data pertaining to operational parameters of the instrument in the transmitted digital data stream. The invention further provides for including a receiver for receiving signals from a remote transmitter that are used to manipulate the instrument for the purpose of performing functions such as the calibration of the sensors. The invention further provides for a rechargeable electrical power source and a means for recharging the power source.  
         [0006]     An advantage of the present invention is that it provides a flexible platform for remotely monitoring any number of biological parameters. Another advantage is that the various sensors may be calibrated on demand without the need of disassembling the instrument. Yet another advantage is that the electrical power source may be recharged without the need of disassembling the instrument for the purpose of replacing batteries or other expendables. A further advantage is that the instrument is packaged in a one-piece housing made from inert materials that prevents contamination of the instrument by the monitored environment, prevents the instrument from making unintended contact with the monitored environment, and which is of a shape that prevents physical injury.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The invention is described in the schematics of FIGS.  1  to  8 , in which:  
         [0008]      FIG. 1  schematically illustrates the system of a wireless instrument for the purpose of monitoring a plurality of biological parameters;  
         [0009]      FIG. 2  schematically illustrates the method of converting the plurality of sensor data to a digital format by way of an analogue multiplexer and an analogue-to-digital converter;  
         [0010]      FIG. 3  schematically illustrates the method of generating a frequency modulated carrier signal;  
         [0011]      FIG. 4  schematically illustrates the method of generating an amplified frequency modulated carrier signal;  
         [0012]      FIG. 5  schematically illustrates the method of generating an amplitude modulated carrier signal;  
         [0013]      FIG. 6  schematically illustrates the method of generating an amplified amplitude modulated carrier signal;  
         [0014]      FIG. 7  schematically illustrates the method receiving a signal from a remote transmitter; and  
         [0015]      FIG. 8  schematically illustrates the method of remotely recharging a rechargeable electrical power storage device.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Referring to  FIG. 1 , the present invention of a wireless instrument for monitoring a plurality of biological parameters is described in schematic form. A series of sensors beginning with a first sensor  101 , a second sensor  102 , and ending with a last sensor  103  each measure their respective biological parameters and generate signals that represent the measure of their respective biological parameters. The first sensor  101  generates a first signal  107 , the second sensor  102  generates a second signal  108 , and the last sensor  103  generates a last signal  109 . In addition to the measurement of biological parameters, one or more sensors may be used for the monitoring of one or more performance parameters of the wireless instrument itself. The first signal  107 , second signal  108 , and last signal  109  are then conducted to a converter  111  which selects the signals individually, converts the signals to a digital format when necessary, and generates a digital output signal  112  which is then conducted to a processor  117 . Those who are familiar with the art will recognise that the converter  111  includes analogue multiplexers, analogue-to-digital converters, and digital multiplexers in combinations that are needed to select the plurality of sensor data individually, convert them to digital form when necessary, and produce a single digital output signal. Processor  117  controls the selection of sensor data to be conducted from converter  111  to processor  117  as output signal  112  by way of control signal  113 .  
         [0017]     Processor  117  collects the various digitised sensor data from converter  111 , which it then processes to form an output digital data stream  118  which is then conducted to transmitter  120 . The output digital data stream  118  may also contain an identification number. The output digital data stream  118  may also comprise some means of error correction. Transmitter  120  then uses the output digital data stream  118  to generate a modulated radio frequency (RF) output signal  121  which is then conducted to an antenna  122  which generates a radiating electromagnetic signal that is received by a remote receiver.  
         [0018]     Electrical power for the wireless instrument is provided by the power source  114 , which may be a fixed battery or a rechargeable storage device. Referring again to  FIG. 1 , from power source  114  sensor  101  receives electrical power  104 , sensor  102  receives electrical power  105 , sensor  103  receives electrical power  106 , converter  111  receives electrical power  110 , processor  117  receives electrical power  115 , and transmitter  120  receives electrical power  119 . The regulation and distribution of electrical power from power source  114  to the various functions may be controlled by processor  117  by way of control signal  116 .  
         [0019]     Those who are familiar with the art will recognise that the processor  117  includes a Read Only Memory (ROM), a Random Access Memory (RAM), a clock oscillator, and all other functions that have come to be associated with highly integrated programmable digital devices commonly referred to as microcontrollers. It will also be recognised by those who are familiar with the art that certain microcontrollers further include analogue multiplexers and analogue-to-digital converters, which makes it possible to provide the converter  111  and the processor  117  in a single device.  
         [0020]     As was stated earlier, the converter  111  includes analogue multiplexers, analogue-to-digital converters, and digital multiplexers in combinations that are needed to select the plurality of sensor data individually, convert them to digital form, and produce a single digital output signal. A common form for the converter  111  is illustrated schematically in  FIG. 2 . Here, the converter  207  consists of an analogue multiplexer  208  and a single analogue-to-digital converter  210 . A first signal  202  from the first sensor  201  is coupled to the first port of the analogue multiplexer  208 . A second signal  204  from the second sensor  203  is coupled to the second port of the analogue multiplexer  208 . Finally, a last signal  206  from the last sensor  205  is coupled to the last port of the analogue multiplexer  208 . A control signal  212  controls the analogue multiplexer  208  to select one of the analogue signals to form signal  209  which is coupled to the input of the analogue-to-digital converter  210  which then produces the digital output signal  211 . As was stated earlier, the sensors  201 ,  203 , and  205  may be a combination of biological parameter monitoring sensors and instrument monitoring sensors.  
         [0021]     Those who are familiar with the art readily understand that not all circumstances of converting a plurality of sensor data individually to a digital signal can be accomplished by the converter of  FIG. 2  alone. Situations exist wherein one or more sensors may have a digital signal output while others have an analogue signal output. In such situations, it will be necessary to perform the overall function of converting each sensor signal individually to a single digital signal by making use of a combination of analogue multiplexers, digital multiplexers, and analogue-to-digital converters.  
         [0022]     Referring back to  FIG. 1 , the transmitter  120  receives the digital data stream  119  from processor  117 , producing a modulated RF output signal  121 . In practice, such a transmitter requires at least a carrier generator for frequency modulation (FM) and binary frequency shift key (BFSK) applications. The transmitter  301  described schematically in  FIG. 3  is capable of producing FM and BFSK modulated RF signals. A carrier generator  303 , such as an oscillator, is shifted in frequency by a modulating signal  302 , which in the present invention is the digital data stream  118  from the processor  117  of  FIG. 1 , to produce an FM or BFSK modulated RF output signal  304 . In some applications, the RF power produced by the transmitter of  FIG. 3  is insufficient to provide reliable communications, and in such instances it may be suitable to include an amplifier stage to increase the output power. Such a transmitter is shown schematically as  401  in  FIG. 4  where a carrier generator  403 , such as an oscillator, is modulated by a modulating signal  402 , which in the present invention is the digital data stream  118  from the processor  117  of  FIG. 1 , producing an FM or BFSK modulated RF signal  404  which is then amplified by a power amplifier  405 , producing an amplified FM or BFSK modulated RF output signal  406 .  
         [0023]     Other forms of modulation such as Amplitude Shift Key (ASK), On/Off Key (OOK) and Binary Phase Shift key (BPSK) require the addition of an amplitude modulator. The transmitter  501  shown schematically in  FIG. 5  is capable of producing ASK, OOK, and BPSK modulated signals. A carrier generator  503 , such as an oscillator, generates a carrier signal  504  which is coupled to an amplitude modulator  505  where it is modulated by an input modulating signal  502 , which in the present invention is the digital data stream  118  from the processor  117  of  FIG. 1 , to produce an ASK, OOK, or BPSK modulated RF output signal  506 . In some applications, the RF power produced by the transmitter of  FIG. 5  is insufficient to provide reliable communications, and in such instances it may be suitable to include an amplifier stage to increase the output power. Such a transmitter is shown schematically as  601  in  FIG. 6  where a carrier generator  603 , such as an oscillator, generates a carrier signal  604  which is coupled to an amplitude modulator  605  where it is modulated by a modulating signal  602 , which in the present invention is the digital data stream  118  from the processor  117  of  FIG. 1 , producing an ASK, OOK, or BPSK modulated RF signal  606  which is then amplified by a power amplifier  607 , producing an amplified ASK, OOK, or BPSK modulated RF output signal  608 .  
         [0024]     Those familiar with the art will recognise that the transmitter power efficiency of the frequency modulated transmitter  301  of  FIG. 3  and the amplitude modulated transmitter  501  of  FIG. 5  can be improved by coupling the modulated RF output signal  121  of  FIG. 1  to the antenna  122  of  FIG. 1  by way of a Class E or Class F network. Those familiar with the art will also recognise that the transmitter power efficiency of the amplified frequency modulated transmitter  401  of  FIG. 4  can be improved by using a Class C, Class E, or Class F for amplifier  405 . Similarly, those familiar with the art will also recognise that the transmitter power efficiency of the amplified amplitude modulated transmitter  601  of  FIG. 6  can be improved by using a Class C, Class E, or Class F for amplifier  607 .  
         [0025]     For applications using sufficiently low carrier frequencies, a microcontroller can perform the functions of carrier signal generation and modulation, making it entirely possible to realise the converter  111 , processor  117 , and transmitter  120  of  FIG. 1  in a single microcontroller  123 , yielding an extremely small and power efficient wireless biological monitoring instrument. Further, the power amplifier  405  of  FIG. 4  and the power amplifier  607  of  FIG. 6  may be realised by way of producing the RF output signal  121  of  FIG. 1  differentially, which results in a 6 dB increase in RF output power. This is an efficient and cost effective method of realising an amplifier circuit that is commonly known as a bridge amplifier. Making use of such a method of amplification yields a cost effective biological monitoring instrument of increased range that is both physically small and power efficient.  
         [0026]     Some applications may require remote manipulation of the instrument, such as for calibration of the various sensors. For this purpose, a receiver for receiving signals from a remote transmitter may be included in the instrument, and such a receiver is described schematically in  FIG. 7 . Here, an antenna  701  receives signals  702  from a remote transmitter and couples the signals to a receiver  703 , which produces a demodulated output signal  704 . This demodulated signal is then coupled to a converter  705 , such as a bit slicer, which produces a received output digital signal  706  which is coupled to a processor  707 . Processor  707  decodes the received digital signal, sending instructions  708  to the instrument for the purpose of executing functions in response to the received digital signal. In practice, the function of processor  707  may be provided by the processor  117  of the microcontroller  123  of  FIG. 1 . Further, some microcontrollers may provide means for realising the converter  705  of  FIG. 7 , such as a voltage comparator, which will provide a cost effective method for including the receiver  700  in the instrument.  
         [0027]     In certain applications, the consumption of electrical power by the instrument may be such that the power source  114  of  FIG. 1  may be provided by a battery. In certain applications, one or more sensors may have a serviceable lifetime such that the sensor or sensors will expire before the battery. Still other applications may require that a rechargeable source of electrical power be provided, such applications including situations in which battery size is limited due to overall size limitations or where it is intended that the instrument be used repeatedly for short periods of time. Further, the mechanical nature of the instrument, which is to be discussed later, is such that the periodic replacement of expendables such as batteries is not possible. In such applications, the present invention may include a rechargeable source of electrical power for the power source  114  of  FIG. 1 , and such a rechargeable power source is illustrated schematically in  FIG. 8 . Here, a rechargeable electrical power storage device  804 , such as a battery or a capacitor, receives a charging current  803  from a recharging circuit  802 . The recharging circuit  802  is coupled to a remote source of electrical power by way of a coupling device  801 , which is shown in  FIG. 8  as being an inductive pickup loop, which is commonly used in practice for the realisation of contactless recharging devices.  
         [0028]     The general nature of biological parameter monitoring instruments such as the present invention is that they are to be used inside the human or animal subject, which is commonly referred to as in vivo. It is well known by those familiar with the art that the operating environment of in vivo instruments such as the present invention is hostile to electronic devices and therefore a means of protecting such instruments from the in vivo environment is necessary. At the same time, the human or animal subject needs to be insulated from electrical voltages and possibly chemicals used in the various biological parameter sensors that may be detrimental to the health of the human or animal subject. Additionally, the human or animal subject needs to be protected from sharp edges and projections that may be injurious. To this effect, it is intended that the present invention be fully encapsulated in a moulding material, such as a resin or epoxy, that is both electrically insulating and inert to chemicals both inside and outside the instrument. It is also the intention of the present invention that the exterior surface of the encapsulation be entirely free of sharp edges and projections. Such a method of encapsulation suggests a variety of physical forms, one of which is that of a large pill, commonly referred to as a bolus, which is an elongated shape having rounded edges and ends.  
         [0029]     Regardless as to whether the present invention is to be used for either short-term or long-term monitoring applications, the assemblage of the housing by way of multiple pieces and sealing gaskets is seen to be impractical, as such assemblies cannot fully guarantee that the seals will not ultimately fail and be breached, resulting in damage or failure of the instrument and risking injury to the subject. Therefore, it is intended that the housing of the present invention is to consist of a one-piece encapsulation of the aforementioned moulding material, and that such encapsulation will have features that will allow for the various biological sensors to make physical contact with the monitored environment whenever necessary.  
         [0030]     Certain applications of the present invention will require that the instrument be made such that it will be heavy or rather have a high specific gravity. Such an application would include an instrument that is to be ingested by a ruminant animal, such as a dairy cow, where the instrument is to remain in the rumen stomach for an extended period of time. For such applications, the encapsulating moulding material may be mixed with an inert material such as glass beads or ceramic power which will increase the density or specific gravity of the encapsulating moulding material and thereby increase the mass of the instrument.