IE46145B1 - Improvements in or relating to apparatus for emitting high-frequency electromagnetic waves - Google Patents

Abstract

The apparatus comprises a low-voltage supply (10), an emitter circuit (11 - 12 - 14) for producing high-frequency electric signals and connected to the supply, and at least one antenna (9), the antenna generating a high-frequency and low-energy electromagnetic field, and as a result not being capable of producing a significant heating effect. The antenna (9) comprises at least one conductor on a substrate made of an electrically insulating material, which is preferably supple and flexible.

Description

The present invention relates to apparatus for emitting high-frequency electromagnetic waves, in particular to a patient's body, and including an antenna for applying the electromagnetic waves.

Such apparatus can be applied in very many fields and in particular in all those where research, development and industry require the application of an electromagnetic field under extremely accurate conditions as regards location’and/or power. In prior art apparatus, when it is desired to produce a strong electromagnetic field over a small area, or a concentrated field, or one which is distributed in a precise pattern, or again when it is desired to shift the field continuously or discreetly, recourse’ is usually had to very bulky and generally somewhat inaccurate apparatus. However, the bulk considerably restricts possible uses and the general trend towards miniaturisation poses problems which cannot be solved simply by a change of scale. It is clear that there are techniques, such as those used in astronautics, which are relying to a greater and greater extent on equipment which is extremely light and extremely versatile in production and in use. If for example it is desired to produce an electromagnetic field in areas which are difficult of access or in objects which are small in size, the use of conventional antennae soon presents problems.

Furthermore, in certain instances, it is desirable that the apparatus is capable of emitting low-frequency electrical fields or currents, at the same time as or alternately with trains of electromagnetic waves.

There are many kinds of apparatus in the prior art for generating electrical currents or for producing magnetic, electrical or electromagnetic fields which operate in fairly varied frequency bands. Such apparatus may operate either as current generators or as field emitters may do so for either temporary or long-term use on the premises of the person giving treatment or hy the patient's bed. They may operate continuously or intermittently. Such apparatus are more bulky and less transportable the higher the level of the energy given out and because high voltages are normally used. The therapeutic effects are generally considered to depend on the amount of energy received in the tissues to be treated and on certain other physical, and especially thermal, parameters.

Such apparatus should only be used where there is qualified medical staff and if the patient is brought to the place of use, which often involves frequency and painful journeys. Because of this, there are numerous occasions on which people fail to take treatment which could bring about a significant reduction in the healing period, for example in cases of immobilisation in plaster following bone fractures.

To avoid any confusion, the basic vocabulary will be reviewed taking the example of medical and other biological applications as a basis.

When use is made of electrical currents, at least two electrodes are employed, these electrodes being applied to the patient, who becomes a conductive element in the circuit. This chiefly produces various physical and chemical effects (a thermal Joule effect, ionophoresis which provides for the passage of ions through the tissues, etc) and nerve effects (a motor exciting effect). Amongst the electrical currents used are galvanic (continuous) and faradic and interrupted galvanic (pulsed).

Use has also been made in the prior art, of what have for long been known as short waves which are generated by so-called short-wave diathermy apparatus. One way of applying short-waves to a patient is to create a capactive, and thus purely electrical, field by means of electrodes which may be in the form of plates or flexible pads which are positioned on either side of, and at a - 46145 distance from, the patient, the patient becoming a dielectric element. The di-electric losses then give rise to heating of the body tissues. Another way of applying short-waves is to produce an electric field using only one electrode or plate with the patient forming an earth, spaced from the body which, again, gives rise to heating of the body tissues and could result in a sparking phenomenon between patient and electrode if the apparatus is not used correctly. Further, short-waves have been applied by induction coils, which may he formed hy coiling a co-axial cable, and which produce a magnetic field that generates eddy currents within the body which are transformed into heat. As with plate and pad electrodes, the induction coils must he spaced from the patient if harmful effects, such as burns are to be avoided. All such short-wave treatments are based on the premise that the therapeutic effect is dependent upon the heating action which is ensured hy high operating voltages and a continuous emission.

Apparatus is also known for producing pulsed electromagnetic waves which do not produce any significant thermal effects on the patient's body. With such apparatus, the therapeutic effect is considered to he due to the applied electrical forces that are many times higher than those possible with short-wave diathermy apparatus since heat tolerance is no longer a factor. The pulsed electromagnetic waves are applied to a patient's body, by means of a coil-type electrode which must be positioned at a distance from the body, in hursts of high intensity requiring the use of even higher voltages than the shortwave diathermy apparatus to achieve the higher electrical forces considered to he necessary to obtain the desired therapeutic effect. One form of such apparatus utilizes voltages in the range of 600 to 2000 watts, has a peak power of 1400 watts and the pulset waves provide an average induced power of about 40 watts. The electrode transfers this energy to the patient in the form of an electromagnetic field which is of high energy at the electrode. Such high voltage apparatus also suffer from the disadvantages previously mentioned.

Accordingly, an object of the present invention is to provide apparatus for emitting high frequency electromagnetic waves in which the aforesaid disadvantages are reduced or eliminated.

To this end, the present invention consists in apparatus for emitting high-frequency electromagnetic waves, said apparatus comprising low-voltage power supply means, circuit means for producing high-frequency, electrical signals, said circuit means having an input and an output, means for connecting said input to said power supply means, and at least one antenna which is applicable directly to a patient's body, and which is connected or connectible to the output of said circuit means, for producing at the antenna a low energy high-frequency electromagnetic field without significant thermal effects on the body, said antenna comprising at least one conductor which is carried by a support of an electrically insulating material and which includes a length of conductive material arranged in a predetermined pattern.

Hereinafter, the energy will in all cases be measured at the point of use. If for example what are involved are medical applications of the apparatus, the energy measured will be that received at the skin of the patient in the area being treated.

Thus, low voltage apparatus constructed in accordance with the present invention can utilize voltages of less than 50 V and energies of less than 100 mW per cm of receiving surface, thereby enabling harmful thermal effects to be avoided, bulk to be considerably reduced, and highfrequency emitting antennae to be used which can he placed in contact with the patient's body and which do not give rise to the normal dangers, such as sparking for example which would convert the apparatus into an electrical lancet, as could occur with present day high-energy apparatus. It will be appreciated that the antenna does not set up a flow of electrical current between the apparatus and the patient, as is the case with low-frequeney current emitting electrodes which operate in direct electrical contact, but produces an electromagnetic field in the body and does not need a co-operating antenna to produce the electromagnetic field (like the plates or electrodes used as parts of a capacitor in conventional short-wave diathermy apparatus).

Although, the apparatus constructed in accordance with the invention, is primarily for use in the medical and veterinary fields the apparatus also has other biological applications.

Studies have now shown that many elementary crystalline structures exhibit behaviour which is extremely interesting from the technical and scientific points of view when they are subjected to electromagnetic fields.

This is true both of liquid crystals and of many other structures and in particular of living matter.

It is apparent from these studies that minimal energies, i.e. energies of relatively low level, are able to act in an optimum fashion if they are applied with the . field carefully localised. Experience has shown that in certain cases energies of the order of a few mVl/cm or Λ even a few/AW/fcm have significant effects. The advantage of the apparatus constructed according to the invention is that, as has been emphasised, they are not bulky ahd difficult to transport. In particular they are suitable for use under conditions where this would have been difficult hitherto, by virtue of the fact that the antenna can be introduced into confined areas or areas 614 5 difficult to get at and by virtue of the fact that they emit electromagnetic fields in a region which is defined geometrically with great accuracy, the emitted power being distributed or concentrated in an equally accurate manner in the area which it i3 desired to subject to the field so emitted. It is found that in very many applications very low energy levels are all that are needed, whereas with conventional apparatus, where the field is difficult to concentrate because of the large size of the apparatus and the antenna, it is necessary to have recourse to high energy levels, which means a considerable amount of waste. The need to maintain a distance from the patient, in particular because high voltage is used, likewise increases inaccuracies in use and in the measurement of the amount of energy received by the surface to be treated.

It is easy with apparatus constructed in accordance with the invention to achieve a very accurate distribution with all energies of less than 100 mW/cm , which is adequate for very many applications.

By selecting in particular the shape of the emitting antenna and the method of supplying it, it is open to the man skilled in the art to apportion, and possibly shift, the field while at the same time regulating its density in the working area.

In medical use, energy levels of less than 100, and even of less than 10 mW/cm avoid, in particular, the familiar harmful effects which are found with certain prior art apparatus. Experience has also shown that the form of the emissions (contour of field, frequency, amplitude) has an appreciable effect on the effectiveness or dangerousness of the apparatus. Furthermore, apparatus constructed according to the invention, unlike prior art apparatus, allow treatment to he given simultaneously at high frequency and by other technical means, such as 43145 .ionphoresis, motor exciting currents, interferential currents, or ultrasonics.

The antenna can be of generally small dimensions and is preferably mounted on an easily handled support to allow, in a miniaturisation context, an electromagnetic field to he emitted with precision, as defined above, in particular by reason of the fact that the antenna is in practice in mechanical contact with the patient and usually electrioally isolated from him or her. For this, the antenna is preferably produced by printing the conductor on a flexible insulating surface. Such printing enables the antenna to be placed on all kinds of support and in particular in areas which are difficult of access, such as inside a cavity or in the interstices of a composite material. What is more, it makes it possible to obtain, on the same support or different supports, a lay-out comprising a plurality of antennae which may or may not be interconnected and which, when fed in sequence for example, allow the field to be shifted. Furthermore, antennae can be designed for implanting in a body.

In the medical applications which are alluded to above, the results achieved have proved particularly effective and it can be conceded that current research indicates that a major factor in the therapeutic effect of the treatment is the molecular re-ordering in the electromagnetic field. It should also he emphasised, that, although it is possible to envisage having one or more electromagnetically emitting high-frequency antennas and one or more electrical current emitting electrodes on the same or different supports, the function performed by the current emitting electrodes is known per se from the prior art, where extensive use is made of the application of current hy means of plates, grids, bars and the like.

In order that the invention may be more readily understood, reference will now be made, by way of example, 6145 l'to the accompanying drawings in which:Fig. 1 shows a schematic general view of an apparatus for emitting high-frequency electromagnetic waves and constructed according to the invention, Fig. 2 shows a block diagram of a circuit used in the apparatus of Fig. 1, Fig. 3 shows a diagram of the signal emitted by means of the circuit of Fig. 2, and Fig. 4 shows an embodiment of the circuit of Fig. 2.

The apparatus shown in the drawings is small and simple and allows both an electromagnetic field to be emitted by means of an antenna and an electrical current to be emitted by means of two electrodes. It is clear as has been emphasised previously that, the invention is primarily concerned with the emission of a high-frequency electromagnetic field by the antenna and that the supply circuit can if so required be arranged to supply electrodes with electrical currents.

The apparatus shown in Fig. 1 comprises low voltage power supply means which is accommodated in a housing 1 and which may be a battery, transformer or the like. The power supply means is connectible by means of a cable 3 to a circuit (to be described) for producing high frequency electromagnetic waves, the circuit being arranged within a main housing 2. The circuit has three output terminals on the housing 2: two terminals 4 and 5 for the connection of low-frequency current-emitting electrodes 7 and 8 via respective leads and plugs, and one terminal 6 for the connection of an antenna 9 for producing a high30 frequency electromagnetic field. The electrodes 7 and 8 may be of widely varying kinds and are used to apply an electric current to the patient to be treated. They may be formed by plates, tapes, grids, sheets, or even needles so that they may be capable of being implanted if required or necessary. As will be seen, one of the electrodes is .earthed and the other is live. To place the electrodes in position, any conventional method may be used, such a conductive paste which provides goods electrical transmission.

The antenna 9, which is carried by a support which may be a flexible insulating sheet, carries at least one conductor formed by a length of conductive material arranged in a predetermined pattern and constituting a conductive circuit. The conductive material may be printed on the sheet or be a wire bonded to the sheet. This flexible sheet may be used in a protective pouch (not shown) which is flexible and insulating and which avoids surface phenomena arising from contact of the conductor with the patient's skin.. Alternatively, a lacquer or film may be used to insulate the conductor from the patient's skin.

This kind of flexible antenna can be applied directly to the area to be treated of the patient's body and the electromagnetic field produced thereby does not have any significant thermal effect on the body. The man skilled in the art can select the form of the pattern of the conductor and this allows the distribution of the field to be accurately determined and in particular the energy density. In Pig. 1, the pattern is formed by two spirals which are joined at both ends, the outer end being connected to 6 by means of a conductive wire and a plug. It is particularly useful for the antenna to be interchangeable, i.e. for the supporting sheet to be detachably secured to the housing 2 by any suitable means, such as adhesive, press fasteners, plug-in connections such as plug-in edge connectors well known in the art, or the like. A plug-in edge connection for example may replace the system consisting of the terminal 6 and the wire shown in Pig. 1 but this has not been illustrated since it will be apparent to those skilled in the art. The interchangeable nature of the antenna makes it possible for the form of antenna to be changed and in particular for operations to take place tinder completely aseptic conditions when there is a change of patient. As will be seen, the housing 2 may be sufficiently small to enable the assembly comprising the housing 2 and the antenna 9 to be positioned easily in areas which are difficult of access and in particular on the patient himself underneath a dressing, bandage, splint, plaster or the like.

The circuit for producing the high-frequency electromagnetic waves will now be described with reference to Fig. 2. The circuit is of solid state form and comprises a multivibrator 11, a pulse shaper 12 and a high frequency stage 14 which are disposed in the housing 2 of Fig. 1.

The multivibrator 11 has an input which is connected to the low-voltage power supply means 10 which is disposed in the housing 1 of Fig. 1. The multivibrator generates lowfrequency electrical signals which are fed via its output to the input of the pulse shaper 12 which shapes these signals. The shaped electrical signals are connected at a terminal 13 forming one output of the pulse shaper and are fed through another output of the pulse shaper to the high -frequency stage 14 which produces high-frequency electromagnetic waves which are transmitted through its output terminal 15 to the antenna 9.

If the HF signals are transmitted in regular successive trains (first waveform in Fig. 3), as they are in a preferred embodiment of the invention, the electrical signals emitted at 13 may be of the type shown at E1, i.e. trains of pulses.

As regards the high frequency, operations take place for example at 27.125 ± 0.125 MHz, which is within one of the bands set aside for high-frequency medical use.

The length of the HF wave trains may be of the order of 10 to 100 microseconds, and the repetition frequency of the successive trains may be of the order of 1Hz to .10,000 Hz.

As regards the electrical signals, the voltage applied to the electrodes 7 and 8 is generally of the order of 5 to 10 volts and preferably of the order of 5 to 6 volts, the intensity of the current flowing in the part to he treated being very low.

Fig. 4 shows in more detail the circuit components of the multivibrator 11, pulse shaper 12 and HF stage 14 in the block diagram of Fig. 2. The oscillator assembly governs the frequency of the HF wave trains and/or of the successive electrical signals and is made up of conventional elements as shown hy the conventional representations thereof. There are many integrated circuits which can be used as oscillators of this kind. The signals are transmitted to a device 17 to allow the HF and electrical signals to he shaped. The device 17 may he a 74, 121 integrated circuit (international coding; such an integrated circuit is made inter alia hy Sescosem and Texas Instruments). At terminal 18 are received the electrical signals which, in association with the earth 19, represent the signals at terminals 4 and 5 of Pig· 1· At terminals 10, 11 of the 174, 121 circuit is inserted an assembly 21 for regulating the length of the HF wavetrains or the electrical signals, 20 being connected to the power supply.

From terminal 6 of the 74, 121 circuit are emitted signals which are passed to an HF emitter 22 which is quartz controlled hy crystal 23 to the selected frequency set hy capacitor 24. The HF wave trains are transmitted to the antenna at terminal 25 via an 1C circuit 26 for matching to the antenna. If 16 corresponds to 11 (Fig, 2), and 21 correspond to 12, and 22, 23, 24 and 26 correspond to 14. Terminals 18 and 19 correspond to 13, i.e. to 7 and 8 (Fig. l), and terminal 25 corresponds to 15 (Fig. 2) and 6 (Fig. l). >46145 In Fig. 3, electrical pulses whose sign is opposite •'from the pulses shown in solid lines are shown in broken lines at S'2. This illustrates the possibility of emitting in all cases, be they E1, E2 or others, either positive going pulses, or negative going pulses, or alternating pulses.

In the present examples, the antennae will always be insulated from the patient by means of, for example, a simple lacquer with which they are coated or an insulating material sheath or pouch, whereas when electrodes are used the best possible electrical contact needs to be provided with the patient. When for example antennae and electrodes are printed on the same support, they can be placed on either side of the support, which will allow the antennae when situated on the opposite side from the patient to be electrically insulated. It is clear that the man skilled in the art will be able to make many modifications. It is of course possible to accommodate both the power supply means and supply circuit in a common housing either in situ on the antenna or separate from it, instead of in separate housings 1 and 2. Furthermore, the electrodes may be located on the antenna support.

Different antennas on the same or different supports may be fed simultaneously or in sequence to shift, the field. It is of course possible to vary the strength of the field.

Certain specific and important medical and biological applications have been found and in particular those involving the use of very small antennas in particular regions, for example in acupuncture where the action of the acupuncture needle may be combined with electromagnetic emission, or even better, substituted for it.

The needle may for example be placed at the centre of the turns of the antenna conductor either in isolation from it or in contact with it. It is equally possible not to use needles, small antennas being positioned at the position of the needle points normally used in acupuncture.

Due to their small dimensions, housings such as 2 may in particular he fitted in situ on the antenna and its support, and in particular this will allow connections to be made very easily by press-fasteners, at least one of which is conductive. As was emphasised above, the form of the antenna support may he adapted to its intended use, for example by making it of cylindrical or conical shape or in the shape of the finger of a glove, to allow it to enter cavities.

As has been emphasised, it is possible, if desired, to associate electrodes with the electromagnetic field emitter to allow an electrical current to flow, the electrodes being in electrical contact with the skin of the patient and the antenna being insulated, for example by being printed on the other face of the support as described above.

It is also possible to make use, on supports of various forms, of antennae which are fed sequentially, as has been mentioned, and to create a moving fieldί for example by placing a series of antennae similar to that shown in Pig. 1 in a circle on a support in the shape of a disc. The field can be caused to travel round in steps, antenna, by antenna, which allows treatment to be given to a large area such as the chest or face. Similarly, by placing a number of antennae along a longitudinal strip and feeding them in sequence, it is possible to treat the spinal column or any other elongated member. By rolling a long support provided with a plurality of antennae in a line into a cylinder, it is possible to obtain a field which travels round in steps, antenna by antenna, around limbs or inside a cavity for example. The man skilled in the art will thus he able to shape the antenna and their support and arrange to feed'-them simultaneously or in sequence an dictated by the medical or other applications for which they are used. An application has been found for such antennas in many other fields for example in the biological field for terating seeds.

Mention was made above of a frequency of 27.125 MHz. However, it appears that a relatively wide frequency band may be useful. In fact if the example given is based on a frequency of 27· 125 MHz, which is substantially equivalent to a wave-length of 11 m, this is only because this frequency is allotted to medical apparatus.

In fact millimetric, centimetric, decimetric and metre wave-lengths all prove effective depending on the sphere of applications, but are not currently used principally for statutory reasons. It is therefore necessary to make provision for it to be possible for apparatus according to the invention to be used, where international agreements permit, at frequencies other than those quoted in the example. Thus high frequency in the present text should be understood to mean this wide band of frequencies and the corresponding wavelengths.

Claims (21)

1 1. Apparatus for emitting high-frequency electromagnetic waves, said apparatus comprising low-voltage power supply means, circuit means for producing high-frequency, electrical signals, said circuit means having an input and 5 an output, means for connecting said input to said power supply means, and at least one antenna which is applicable directly to a patient's body and which is connected or connectible to the output of said circuit means, for producing at the antenna a low energy high-frequency 10 electromagnetic field without significant thermal effects on the body, said antenna comprising at least one conductor which is carried by a support of an electrically insulating material and which includes a length of conductive material arranged in a predetermined pattern. 15

2. Apparatus according to claim 1, including means for insulating the conductor from a body to which the antenna is to be applied.

3. Apparatus according to claim 1 or 2, wherein said support is flexible. 20

4. Apparatus as claimed in claim 3, wherein said at least one conductor is printed on said support.

5. Apparatus according to claim 1 or 2, wherein said support is shaped to conform to a part of a patient's body or be inserted into a body cavity. 25

6. Apparatus as claimed in any one of claims 1 to 5, wherein said circuit means is of solid state form.

7. Apparatus as claimed in any one of claims 1 to 6, and having an antenna output of not more than lOmW per square centimetre. 5°

8. Apparatus according to any one of claims 1 to 7, including means matching said antenna to the output of said circuit means.

9. Apparatus according to any one of claims 1 to 8, wherein said circuit means includes means for producing 35 low-frequency electrical pulses having an input connected 4614S 1 to said power supply means and an output, and a pulse shaping stage having an input connected to the output of the means for producing low-frequency electrical pulses and an output, and wherein said circuit means further 5 includes a high-frequency stage having an input which is connected to said output of said pulse shaping stage.

10. Apparatus according to claim 9, wherein the high frequency stage includes a high frequency emitter controlled by a quartz crystal to a preselected frequency. 10

11. Apparatus according to claim 9 or 10, wherein said means for producing low-frequency electrical pulses comprises means for generating pulses to control said high frequency stage to emit trains of said electromagnetic waves at repetition frequencies of between 1Hz and 10,000 Hz. 15

12. Apparatus according to any one of claims 9 to 11, wherein the pulse shaping stage has a further output and wherein the apparatus includes an earth terminal and currentemitting electrodes of which one is connectible to the further output of said pulse shaping stage and the other is 20 connectible to said earth terminal.

13. Apparatus as claimed in claim 12, wherein at least one of said current-emitting electrodes is carried by said support.

14. Apparatus according to claim 12 or 13, wherein said 25 pulse shaping stage includes means for supplying lowfrequency electrical pulses alternately to the two outputs of said pulse shaping stage to alternately energize said current emitting electrodes and said antenna.

15. Apparatus according to any one of claims 1 to 14, 30 including a housing within which said circuit means is situated, said housing being sufficiently small to be placed with said antenna on the patient's body.

16. Apparatus according to claim 15, wherein said lowvoltage power supply means is a battery which is disposed 35 inside said housing. 1

17. Apparatus according to claim 15 or 16, including means detachably securing the antenna support to the housing.

18. Apparatus according to any one of claims 1 to 17, comprising a plurality of antennae, said circuit means 5 comprising a plurality of outputs and means for connecting said antennae respectively to said outputs.

19. Apparatus according to claim 18, as appendant to any one of claims 9 to 14, wherein the high frequency stage includes means for supplying the antennae in sequence. 10

20. Apparatus for emitting high-frequency electromagnetic waves, substantially as hereinbefore described with reference to Figs.Ito3 of the accompanying drawings.

21. Apparatus for emitting high-frequency electromagnetic waves, substantially as hereinbefore described with reference 15 to Figs. 1 to 4 of the accompanying drawings.