APPARATUS FOR STERILISING A CHANNEL OF A SURGICAL SCOPING DEVICE

Abstract

Various embodiments provide a sterilisation apparatus for sterilising a channel of a surgical scoping device. The apparatus includes: a gas supply having a conduit to deliver an ionisable gas to the channel of the surgical scoping device; and, a sterilisation instrument, separate from the gas supply and the conduit, configured to be inserted through the channel of a surgical scoping device. The sterilisation instrument includes an elongate probe. The elongate probe includes: a transmission line for conveying radiofrequency (RF) electromagnetic (EM) energy and/or microwave EM energy; and, a probe tip connected at the distal end of the transmission line for receiving the RF and/or microwave EM energy, the probe tip comprising an electrode assembly configured to produce an electric field from the received RF and/or microwave frequency EM energy to generate a plasma of the ionisable gas delivered to the channel from the gas supply.

Claims

1. A sterilisation apparatus for sterilising a channel of a surgical scoping device, the apparatus comprising: a gas supply having a conduit to deliver an ionisable gas to the channel of the surgical scoping device, a sterilisation instrument, separate from the gas supply and the conduit, configured to be inserted through the channel of a surgical scoping device, the sterilisation instrument comprising: an elongate probe comprising: a transmission line for conveying radiofrequency (RF) electromagnetic (EM) energy and/or microwave EM energy, and a probe tip connected at the distal end of the transmission line for receiving the RF and/or microwave EM energy, the probe tip comprising an electrode assembly configured to produce an electric field from the received RF and/or microwave frequency EM energy to generate a plasma of the ionisable gas delivered to the channel from the gas supply.

2. A sterilisation apparatus according to claim 1, the sterilisation apparatus further comprising a gas-tight adapter configured to be connectable to the scoping device, the gas-tight adapter having a passage therethrough to allow the sterilisation instrument to be introduced into the channel of the scoping device through the gas-tight adapter.

3. A sterilisation apparatus according to claim 2, wherein the gas-tight adapter comprises a pressure relief valve.

4. A sterilisation apparatus according to claim 2, wherein the gas supply is configured to be connectable to the adapter in order to deliver the ionisable gas to the channel of the surgical scoping device.

5. A sterilisation apparatus according to claim 2, wherein the passage through the gas-tight adapter comprises a seal to ensure the adapter is gas-tight when the sterilisation instrument is positioned in the passage.

6. A sterilisation apparatus according to claim 2, wherein the gas-tight adapter comprises a luer lock fitting for fixing the gas-tight adapter to the surgical scoping device.

7. A sterilisation apparatus according to claim 2, further comprising a closure device configured to seal a distal end of the channel of the surgical scoping device.

8. A sterilisation apparatus according to claim 7, wherein the gas supply is connectable to the closure device to deliver the ionisable gas to the channel of the surgical scoping device.

9. A sterilisation apparatus according to claim 7, wherein the closure device comprises a pressure relief valve.

10. A sterilisation apparatus according to claim 2, wherein electrode assembly comprises a first electrode and a second electrode arranged to define a volume therebetween, and the first electrode and the second electrode are configured to receive the RF and/or microwave energy from the transmission line to set up an electric field in the volume for producing a plasma of the ionisable gas; and wherein the probe tip comprises an inlet to allow ionisable gas to flow from the channel of the surgical scoping device and into the volume defined between the first electrode and the second electrode.

11. A sterilisation apparatus according to claim 10, wherein the transmission line comprises a coaxial cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor from the outer conductor, the second electrode comprises an extension of the outer conductor of the coaxial cable beyond the dielectric material of the coaxial cable, and the first electrode comprises an extension of the inner conductor of the coaxial cable beyond the dielectric material of the coaxial cable and along a central axis of the second electrode to define the volume between the first electrode and the second electrode; wherein the first electrode and the second electrode are configured to receive the RF and/or microwave energy from the coaxial cable to set up an electric field in the volume between the first electrode and the second electrode for striking a plasma therein, and wherein the probe tip includes an outlet for releasing plasma from the volume.

12. A sterilisation apparatus according to claim 11, wherein the second electrode comprises at least one aperture to define the inlet in the probe tip to allow ionisable gas to flow from the channel of the surgical scoping device and into the volume.

13. A sterilisation apparatus according to claim 11, wherein the first electrode comprises a conductive cap mounted on a distal end of the extension of the inner conductor, wherein the conductive cap is spaced away from the distal end of the second electrode to define a gap between the cap and the second electrode to define the outlet.

14. A sterilisation apparatus according to claim 13, wherein the conductive cap comprises at least one aperture to define the inlet in the probe tip to allow ionisable gas to flow from the channel of the surgical scoping device and into the volume.

15. A sterilisation apparatus according to claim 12, wherein the probe tip further comprises a piece of insulating dielectric material positioned between the first electrode and the second electrode.

16. A sterilisation apparatus according to claim 12, wherein the elongate probe has a diameter of 1 mm or less.

17. A sterilisation apparatus according to claim 12, wherein the gas supply is configured to supply gas to the channel of the surgical scoping device at a variable flow rate.

18. A sterilisation apparatus according to claim 12, wherein the sterilization instrument does not comprise a conduit to convey ionisable gas for generation of a plasma by the electrode assembly.

Description

SUMMARY OF THE FIGURES

[0031] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0032] FIG. 1 shows a schematic diagram of a sterilisation apparatus according to an embodiment of the present invention, and a generator for supplying energy thereto;

[0033] FIG. 2 shows a schematic diagram of a sterilisation apparatus according to a second embodiment of the present invention in use;

[0034] FIG. 3 shows a schematic diagram of a sterilisation apparatus according to a third embodiment of the present invention in use;

[0035] FIG. 4 shows a cross-section view of a first probe tip which may be used with embodiments of the present invention;

[0036] FIG. 5 shows a cross-section view of a second probe tip which may be used with embodiments of the present invention; and

[0037] FIG. 6 shows a cross-section view of an adapter which may be used with embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0039] FIG. 1 shows a sterilisation apparatus 10 according to an embodiment of the present invention, and a generator 1000 for supplying energy thereto. The sterilisation apparatus 10 comprises a sterilisation instrument having an elongate probe comprising a transmission line provided by a coaxial cable 12 with a probe tip 14 at its distal end. For example, the probe tip 14 may be a probe tip as described below with respected to FIG. 4 or 5. The generator 1000 is connected to the coaxial cable 12 at its proximal end, and is configured to supply radiofrequency (RF) and/or microwave frequency electromagnetic (EM) energy in order to facilitate the production of plasma by an electrode assembly at the probe tip 14. The apparatus 10 also comprises a gas supply 16 having a gas conduit 18, separate from the sterilisation instrument, to deliver an ionisable gas to the channel of a surgical scoping device, in a manner which will be described in more detail below. The gas supply 16 may be a canister of gas, as shown, but any suitable gas supply may be used. Preferably the gas supply 16 provides an inert gas, such as Argon. Although not shown in FIG. 1, in some examples the gas supply 16 may comprise a gas flow controller allowing the flow rate of gas to be varied. For example, the gas flow rate may be between 0.2 and 10 litres per minute, and may be varied automatically or manually by a user. For example, the flow rate may be increased when the probe tip is towards the distal end of the channel in a scoping device in order to ensure that a suitable supply of gas is available for production of a plasma.

[0040] During a sterilisation process, with the probe tip 14 positioned within a channel of a scoping device, the generator 1000 supplies RF and/or microwave frequency EM energy to the probe tip. The gas supply 16 simultaneously supplies gas directly to the channel via the gas conduit 18. The RF and/or microwave energy and supplied gas are combined at the probe tip 14 to generate a thermal or non-thermal plasma, which is emitted from the probe tip 14 to contact a surface of the channel to destroy or eliminate micro-organisms. Examples of plasma generation in a similar manner are disclosed in WO 2009/060213 A1, for example.

[0041] The generator 1000 may be controlled to determine whether the generated plasma is a non-thermal or thermal plasma. For example, the supply microwave energy may have a power and/or duty cycle that is selectable to produce non-thermal or thermal plasma. Preferably, the generator is operated to produce a non-thermal plasma having a temperature of less than 41° C., which can help avoid damage to the scoping device.

[0042] The apparatus 10 may further include a withdrawal device (not shown) coupled to the coaxial cable 12 and operable to withdraw the coaxial cable 12 through the channel at a predetermined rate.

[0043] In use, the sterilisation instrument is inserted through the channel of a surgical scoping device, and the gas conduit is arranged to deliver gas directly to the channel of the scoping device. For example, both the sterilisation instrument and the gas conduit may be provided to a proximal end of the channel or to a distal end of the channel. Alternatively, the sterilisation instrument and the gas conduit may be provided to opposing ends of the channel. Comparative advantages of these arrangements are described herein.

[0044] FIG. 2 shows a sterilisation apparatus 20 according to a further embodiment of the invention, the apparatus 20 being shown in use for cleaning a surgical scoping device. The elongate probe is positioned within an instrument channel of an insertion tube 104 of a surgical scoping device. The coaxial cable 22 of the elongate probe passes into the channel through the handle 102 of the scoping device, at the proximal end of the insertion tube 104 and instrument channel, and reaches the distal end of the insertion tube 104 where the electrode assembly of the probe tip (not shown) produces a plasma for sterilising and cleaning the instrument channel. For example, the probe tip may be a probe tip as described below with respected to FIG. 4 or 5. The coaxial cable 22 is connected to a generator at its proximal end (not shown), as described above with respect to FIG. 1, and conveys energy from the generator to the probe tip to enable the probe tip to generate an electric field for producing a thermal or non-thermal plasma. To sterilise and clean the channel, the elongate probe may be moved in a proximal and/or distal direction while such plasma is generated at the probe tip.

[0045] In this arrangement, a distal end of the gas conduit 24 of the apparatus 20 is also connected to a proximal end of the insertion tube 104 to deliver ionisable gas into the instrument channel. The gas conduit 24 is connected to a gas supply at its proximal end (not shown), as described above with respect to FIG. 1. The gas supply is thereby able to substantially fill the instrument channel with ionisable gas in order to provide a suitable atmosphere for the probe tip to strike and sustain a plasma. By delivering ionisable gas to the instrument channel in this way, there is no need for the elongate probe to comprise a lumen for conveying gas to the probe tip, and so the elongate probe is simpler and cheaper to manufacture, and is also more compact allowing channels of small diameters (e.g. around 1 mm or less) to also be cleaned and sterilised by the apparatus of the present invention.

[0046] In this embodiment, the apparatus 20 further comprises a gas-tight adapter 28. The adapter 28 is configured to be connected to the handle 102 of the scoping device, and in particular may be configured to fit to an input port for the instrument channel of the scoping device, and provides a passage through which the elongate probe is introduced into the channel of the scoping device. The passage comprises a seal, such as an O-ring, which ensures that the adapter is gas-tight while the sterilisation instrument is positioned in the passage, but allows the elongate probe to be moved in proximal and distal directions for cleaning and sterilisation of the channel. The distal end of the gas conduit 24 is connected to the adapter 28, and the adapter 28 has a corresponding conduit to provide ionisable gas into the channel such that the probe tip is able to produce a plasma of the gas. The adapter 28 helps to ensure that the atmosphere within the channel is suitable for production of a plasma, for example by ingress of air which could otherwise displace or dilute gas provided via the conduit 24 and thereby reduce plasma production. In order to be fixed to the handle 102 of the scoping device, the adapter 28 may comprise a luer lock fitting, though it will be appreciated that any suitable gas-tight fitting may be chosen. As the adapter 28 is configured to receive both the coaxial cable 22 and the gas conduit 24, the sterilisation apparatus 20 is particularly easy to use, as only one connection to the scoping device is required. This may be particularly advantageous when the apparatus 20 is to be transferred between multiple scoping devices for quick cleaning and sterilisation of the instrument channels.

[0047] For closing the distal end of the channel through the insertion tube 104, the sterilisation apparatus comprises a closure device in the form of a cap 26 which is configured to fit over the distal end of the insertion tube 104 of the surgical scoping device. For example, the cap 26 may be generally cylindrical with an open end to fit over the insertion tube 104 and a closed end to prevent gas from escaping. The cap 26 may be made of a gas-impermeable material, such as a plastic material, for example rubber or the like, and is suitably dimensioned to ensure a tight fit with the distal end of the insertion tube 104. The cap 26 may help to prevent ingress of ambient air which could displace or dilute ionisable gas provided to the channel through the conduit 24. However, in some examples it is believed that the cap 26 may not be necessary if the flow rate of ionisable gas through the conduit 24 is high enough, as the gas flow from the distal end of the channel may be sufficient to prevent ingress of ambient air. Nevertheless, the cap 26 may be preferable, particularly where a low flow rate of gas is used. As shown in FIG. 2, the cap 26 comprises a pressure relief valve 27 which may be positioned on the closed end of the cap 26. In this way, the cap 26 is adapted to allow venting of excess gas or air from the channel through the pressure relief valve 27 when a predetermined pressure is reached. By providing the valve 27 in the cap 26, it may be ensured that there is a flow of gas through the channel when the apparatus 20 is in use, which may be particularly advantageous in ensuring that gas is continuously passing over the probe tip in order to produce a thermal or non-thermal plasma. For example, the valve 27 may be adapted to vent gas when the pressure is about or slightly above atmospheric pressure.

[0048] FIG. 3 shows a further embodiment of a sterilisation apparatus 30 according to an embodiment of the invention, the apparatus 30 being shown in use for cleaning a surgical scoping device. The elongate probe of the apparatus 30 is positioned within an instrument channel of an insertion tube 104 of a surgical scoping device. The coaxial cable 32 of the elongate probe passes into the channel through the handle 102 of the scoping device, at the proximal end of the insertion tube 104 and of the instrument channel, and reaches the distal end of the insertion tube 104 wherein the electrode assembly of the probe tip (not shown) produces a plasma for sterilising and cleaning the instrument channel. For example, the probe tip may be a probe tip as described below with respected to FIG. 4 or 5. The coaxial cable 32 is connected to a generator at its proximal end (not shown) as described above with respect to FIG. 1, and conveys energy from the generator to the probe tip, where an electric field is produced to generate a plume of thermal or non-thermal plasma. To sterilise and clean the channel, the elongate probe may be moved in a proximal and/or distal direction while plasma is produced at the probe tip.

[0049] In this arrangement, a distal end of the gas conduit 34 of the apparatus 30 is connected to a distal end of the insertion tube 104 to deliver gas into the instrument channel. The gas conduit 34 is connected to a gas supply at its proximal end (not shown), as described above with respect to FIG. 1. The gas conduit 34 is connected to the distal end of the insertion tube 104 by a closure device in the form of a cap 36 which is configured to fit over the distal end of the insertion tube 104 and which has a corresponding gas conduit therethrough to allow gas to enter the instrument channel. For example, the cap 36 may be generally cylindrical and may have an open end to fit over the insertion tube 104 and a connector at an opposing end for connection to the distal end of the gas conduit 34. The cap 36 may be made of a gas-impermeable material, for example a plastic material such as rubber or the like, and is suitably dimensioned to ensure a tight fit with the distal end of the insertion tube 104. As well as providing an inlet for gas from the gas conduit 34, the cap 36 may help to prevent ingress of ambient air which could displace or dilute gas provided to the channel through the conduit 34.

[0050] A gas-tight adapter 38 is provided at the proximal end of the surgical scoping device, and is configured to be connected to the handle 102. The adapter 38 may be configured to fit to an input port for the instrument channel of the scoping device, and provides a passage through which the elongate probe is introduced into the channel of the scoping device. As described above with respect to FIG. 2, this passage may comprise a seal, such as an O-ring, to ensure that the passage is gas-tight when the sterilisation instrument is positioned in the passage. The adapter 38 helps to ensure that the atmosphere within the channel is suitable for production of a plasma, for example by ingress of air which could otherwise displace or dilute gas provided via the conduit 34 and thereby reduce plasma production. In order to be fixed to the handle 102 of the scoping device, the adapter 38 may comprise a luer lock fitting, though it will be appreciated that any suitable gas-tight fitting may be chosen. In this embodiment, the gas-tight adapter 38 comprises a pressure relief valve 39, which is configured to allow venting of excess gas or ait from the channel through the pressure relief valve 39 when a predetermined pressure is reached. Preferably, the predetermined pressure may be about or slightly above atmospheric pressure.

[0051] The sterilisation apparatus 30 thereby provides for the sterilisation instrument and the gas conduit to be provided at opposing ends of the instrument channel which is to be sterilised. This may be particularly advantageous in cleaning channels which are entirely or substantially entirely occluded by the coaxial cable 32, which would inhibit a flow of gas to the probe tip if gas were to be introduced at the proximal end of the instrument channel.

[0052] FIG. 4 shows a cross-section view of a probe tip 40 which may be used with embodiments of the present invention. The probe tip 40 shown uses extension of inner and outer conductors of a coaxial cable to provide an electrode assembly having first and second electrodes, but it will be appreciated that in some examples the probe tip 40 may be provided as a separate component, or that either of the first and second electrodes may be separate from the coaxial cable.

[0053] The probe tip 40 comprises a first electrode 42 and a second electrode 44 which is coaxial with the first electrode 42. A dielectric material 46 is provided coaxially between the first electrode 42 and the second electrode 44. For example, the dielectric material 46 may be the dielectric of the coaxial cable. The second electrode 44, comprising an extension of the outer conductor of the coaxial cable, extends beyond the dielectric material 46 in a distal direction to define an internal volume 48. For example, the second electrode 44 may have a length of 5 mm or less, such as around 3 mm, beyond the distal end of the dielectric material 46. The first electrode 42, comprising an extension of the inner conductor of the coaxial cable beyond the dielectric material 46 in a distal direction, extends into the internal volume 48. For example, the first electrode 42 may run along a central, longitudinal axis of the second electrode 44, and thereby define the volume between the first electrode 42 and the second electrode 44, which may be referred to as the internal volume 48. As shown in FIG. 4, the first electrode 42 may be substantially linear, but it will be appreciated that the first electrode could also take other shapes in the internal volume 48, for example the first electrode 42 may form a helix.

[0054] The distal end of the probe tip 40 is open to define an inlet for allowing ionisable gas from the channel of the scoping device to enter the internal volume 48, where the gas may be struck to form a plasma. The opening, or a portion of the opening, at the distal end may also define an outlet for releasing plasma from the internal volume 48. For example, the second electrode 44 may be generally cylindrical and open at its distal end to define the inlet and the outlet. Gas may flow into the internal volume 48 where a plasma is struck by an electric field generated between the first electrode 42 and the second electrode 44 when RF and/or microwave EM energy is delivered thereto from the generator. The plasma which is produced is released through the outlet in order to sterilise and clean the sidewall of the instrument channel of a surgical scoping device. In some embodiments, the electric field between the first electrode 42 and the second electrode 44 may be increased by positioning a piece of insulating dielectric material, such as quartz, between the electrodes. For example, a cylindrical piece of quartz may be fitted over the first electrode 42 within the internal volume 48 to increase impedance and thus facilitate the creation of a high electric field to strike and sustain a plasma. In some examples, the second electrode 44 may comprise a number of apertures (i.e. one or more) which provide inlets enabling ionisable gas to flow into the internal volume 48. The apertures may also provide outlets through which plasma may be released from the internal volume 48. A flow of gas and plasma may be established through the internal volume 48 due to the production of plasma.

[0055] FIG. 5 shows a cross-section view of a second probe tip 50 which may be used with embodiments of the present invention. The probe tip 50 is generally similar to that shown in FIG. 4 so corresponding elements have been given corresponding reference numerals, and description thereof is not repeated.

[0056] In the probe tip 50 shown in FIG. 5, the first electrode 52 extends beyond the distal end of the second electrode 44 and a conductive cap 54 is mounted at the distal end of the first electrode 52. The conductive cap 54 may be provided as a disc of metal, such as copper, silver, gold or plated steel for example. In other embodiments, the cap 54 may be made of a ceramic material. The cap 54 is spaced away from the distal end of the second electrode 44 to define an outlet 56 through which plasma may be released from the internal volume 48. For example, the conductive cap 54 may be spaced around 0.5 mm away from the distal end of the second electrode 44. The outlet 56 defined in this way is generally annular, and so plasma which is generated by the probe tip 50 is preferentially directed towards the sidewalls of the channel in the scoping device for more effective cleaning and sterilisation. In some embodiments, the conductive cap 54 may comprise a number (i.e. one or more) of apertures therethrough, which may provide inlets allowing ionisable gas to flow into the internal volume 48 from the channel in order to be struck to produce a plasma.

[0057] FIG. 6 shows a cross-sectional view of an adapter 60 which may be used in embodiments of the present invention. In particular, the adapter 60 may be used in an arrangement such as shown in FIG. 2 as it is configured to be connectable to a gas conduit for delivering ionisable gas to the channel of a scoping device.

[0058] The adapter 60 comprises a gas-tight body 62 which is configured to fit to the channel of a scoping device (for example, by fitting to the handle of a scoping device) to allow a sterilisation instrument to be introduced to the channel. For example, the body 62 may be made of a plastics material or the like, though any other suitable material (e.g. metal) may also be used. In the embodiment shown in FIG. 6, the adapter 60 is also configured to allow ionisable gas to be introduced to the channel of the scoping device through the gas-tight body 62.

[0059] In particular, the adapter 60 comprises a first luer lock fitting 63 to allow the gas-tight body 62 to fit to the channel of the scoping device, preferably by fitting to the handle of a scoping device as described above. Within the body 62, the adapter 60 comprises a branched passage 64 having two inlets and a single outlet, wherein the outlet is at the luer lock fitting 63 such that the outlet leads to the channel of the scoping device when the adapter 60 is in use.

[0060] At a first inlet of the passage 64 there is a port 65 which is configured to receive the elongate probe of the sterilisation device. At or about the port 65 there is a seal 66, which may be an O-ring or a flanged seal or the like, to ensure that when the elongate probe is present in the passage 64 the adapter 60 is gas-tight such that no ionisable gas may leak from the channel of the scoping device and no air may enter the channel. However, the port 65, seal 66 and the passage 64 are configured to allow the elongate probe to be moved in proximal and distal directions to sterilise the channel of the scoping device.

[0061] At a second inlet of the passage 64 there is a second luer lock fitting 67 to which a gas conduit from a gas supply may be connectable. In this way, the passage 64 may provide a conduit for passing gas from the gas supply to the channel of the scoping device. In other embodiments, the adapter 60 may not comprise a second luer lock fitting 67 (for example, where ionisable gas is delivered to the distal end of the channel of the scoping device) and the passage 64 may therefore not need to be a branched passage.

[0062] In some examples, the adapter 60 may comprise a pressure relief valve (not shown), which may be configured to vent gas when the pressure within the adapter 60 (and therefore within the channel of the scoping device) is about or slightly above atmospheric pressure). For example, the pressure relief valve may replace the second luer lock fitting 67, or may be positioned elsewhere on the body 62 of the adapter 60.

[0063] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0064] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0065] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0066] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0067] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0068] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example +/−10%.