Electrolysis device and its operating method

Abstract

An oral care device 100 for calculus removal is provided. The oral care device has a control unit 102 configured to provide an electrical signal, such as an electrical signal that changes over time. The oral care device also has a pair of electrodes 104A, 104B that contact an aqueous solution. Each of the pair of electrodes is connected to the control unit and is configured to generate hydrogen ions from water in the aqueous solution and supply them to the oral cavity of the subject, particularly to the teeth of the subject. The change in the electrical signal controls the generation of hydrogen ions. The hydrogen ions thus generated lower the local pH of the teeth of the subject and assist in the dissolution of calculus thereon. The change in the electrical signal, such as a change over time, can provide control over the generation of hydrogen ions, as opposed to the uncontrolled generation of hydrogen ions via a non-varying voltage across a pair of electrodes provided by a DC power source, for example. Further, a method of operating such an oral care device is provided.

Description

Technical Field

[0001] The present invention relates to an apparatus having a pair of electrodes for electrolyzing water to generate hydrogen ions, particularly an oral care apparatus. The present invention further relates to a method of operating the apparatus.

Background Art

[0002] The accumulation of calcified deposits in the body can be problematic. An example of a calcified deposit is dental calculus.

[0003] Dental calculus or incipient dental calculus is a risk factor for gingivitis and periodontitis. Dental calculus has calcium phosphate crystal phases with different solubilities. The low water solubility of some of the calcium phosphate crystal phases can make the removal of dental calculus difficult.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Currently, dental calculus tends to be treated / removed only by dentists and dental hygienists using mechanical scalers or ultrasonic scalers.

[0005] It is desirable to provide additional options for dental calculus treatment / removal, particularly options that can be used by the patient themselves at home.

[0006] US2021 / 307500A1 discloses an electric toothbrush including a head and a handle connectable to the head and configured to supply a driving voltage to the head based on user control. The head includes a toothbrush head in which bristles and first and second electrodes spaced apart from each other are disposed.

[0007] US2021 / 330068A1 discloses an oral cleaning apparatus including a head portion, an RF electrode disposed in the head portion, and a non-conductive barrier disposed in the head portion to separate the electrodes from each other.

[0008] WO2014 / 099064A1 discloses a discharge irrigator for cleaning root canals during root canal treatment.

[0009] WO2007 / 047568A1 discloses an oral care device that generates chemicals in situ as needed by applying a potential to a pair of conductors in communication with an electrolyte. **Means for Solving the Problems**

[0010] The present invention is defined by the independent claims. The dependent claims define advantageous embodiments.

[0011] According to an example according to one aspect of the present invention, there is provided an oral care system, which has a control unit configured to provide an electrical signal and a pair of electrodes in contact with an aqueous solution. The pair of electrodes is connected to the control unit, and based on the electrical signal, at least one of the electrodes generates hydrogen ions from water in the aqueous solution and supplies them into the oral cavity of the subject. The electrical signal and the pair of electrodes are configured such that fluctuations in the electrical signal control the generation of the hydrogen ions.

[0012] The hydrogen ions can assist in lowering the local pH in the vicinity of the subject's teeth to aid in the dissolution of dental calculus. Changes in the electrical signal, such as temporal changes, can provide control over the generation of hydrogen ions, as opposed to the uncontrolled generation of hydrogen ions via a non-varying voltage across a pair of electrodes by, for example, a continuously applied DC power source. This allows the local pH to which the subject's teeth are exposed to be more precisely controlled, thereby facilitating the home use of the oral care device.

[0013] Note that the term "electrical signal" as used herein may refer to a voltage signal or a current signal.

[0014] In some embodiments, the fluctuations in the electrical signal limit the rate of change of hydrogen ion generation with respect to a non-varying voltage equivalent in magnitude to the peak amplitude of the electrical signal across a pair of electrodes supplied by, for example, a DC power source.

[0015] Alternatively or additionally, the variation of the electrical signal can promote the neutralization of hydrogen ions, for example, by having the electrical signal have a bidirectional waveform supplied to the electrodes or being defined by a bidirectional waveform. The promotion of neutralization by such a bidirectional waveform will be described in detail below in this document.

[0016] In some embodiments, the oral care device has an actuator. Such an actuator can move a cleaning element, for example, to clean inside the oral cavity of the subject.

[0017] For example, the movement of the actuator that causes the movement of the brush head and / or controls the pump of the irrigator included in the oral care device can be provided in parallel with the hydrogen ion generation, and the removal of tartar is promoted.

[0018] In embodiments where the oral care device includes an actuator, the actuator can be configured to move based on an electrical signal.

[0019] The term "move based on an electrical signal" in this context can mean that the actuator control signal provided by the control unit and the electrical signal are the same as each other to control the movement of the actuator, or that one of the actuator control signal and the electrical signal is based on the other of the actuator control signal and the electrical signal.

[0020] The movement of the actuator by the electrical signal supplied to the electrodes, in certain embodiments, in addition to assisting the control of hydrogen ion generation at a pair of electrodes by the electrical signal, can facilitate the provision of a specific cleaning movement, such as a reciprocating movement, by the actuator.

[0021] In some embodiments, the actuator control signal is in phase with the electrical signal. Thus, the movement of the actuator can be synchronized with the electrical signal supplied to the electrodes.

[0022] Alternatively, a phase difference can be intentionally defined between the actuator control signal and the electrical signal. Thus, the electrical signal can be desynchronized from the actuator control signal and from the movement of the actuator, such as the movement / reciprocation of the brush head.

[0023] In some embodiments, one or both of the electrodes are mechanically coupled to the actuator, such that movement of the actuator causes movement of the electrode.

[0024] In such embodiments, movement of the actuator can result in an increase in the effective area, in other words the footprint, in which the electrochemical treatment provided by the electrode is realized.

[0025] Alternatively or additionally, the oral care device can include at least one cleaning element for mechanically cleaning the interior of the subject's oral cavity.

[0026] In some embodiments, the at least one cleaning element is mechanically coupled to the actuator, such that movement of the actuator causes movement of the at least one cleaning element. As a result, a combination of mechanical calculus disruption and calculus dissolution by pH assist is particularly effective and also provides the advantage that it can be achieved, for example, when the subject uses the oral care device at home.

[0027] The at least one cleaning element can have bristles for brushing the interior of the subject's oral cavity. Alternatively or additionally, the at least one cleaning element can have a cup formed from an elastic material for rubbing the surfaces within the subject's oral cavity. Such a cup is, for example, a so-called profi-cup.

[0028] Alternatively or additionally, the oral care device can include at least one cleaning element for fluidly cleaning the interior of the subject's oral cavity.

[0029] In such an embodiment, at least one cleaning element may be configured such that the movement of the actuator provides a fluid supply from the at least one cleaning element.

[0030] In such an embodiment, the actuator control signal may be, for example, an electrical switch signal of a pump of an oral irrigator.

[0031] In some embodiments, the electrical signal has periodic variations in at least one of amplitude, polarity, and frequency. This can assist in controlling the accumulation of hydrogen ions and thus assist in controlling the local pH.

[0032] Alternatively or additionally, the electrical signal has a bidirectional waveform. Altering the polarity of the electrodes via such a bidirectional waveform can limit the progression of the low-pH "front line" emitted from the electrodes and assist in stabilizing the pH. This is because, following the change in polarity, hydrogen ions previously generated at one electrode can be neutralized by hydroxide ions currently generated at the same electrode.

[0033] In some embodiments, the positive peak amplitude of the bidirectional waveform is different from the negative peak amplitude of the bidirectional waveform. This can cause a continuous but controlled increase or decrease in the pH at a particular location.

[0034] In some embodiments, one of the positive and negative peak amplitudes is at least 1.1 times, for example about 1.5 times, the other of the positive and negative peak amplitudes.

[0035] In one set of embodiments, the electrical signal is a continuous waveform, such as a sine wave or a rectangular wave. Such a continuous waveform can be considered to provide a continuously varying electrical signal.

[0036] In another embodiment, the electrical signal is a pulsed electrical signal. Such a pulsed electrical signal can provide a more gentle and controlled change in pH, for example, compared to the case of a non-varying voltage between a pair of electrodes.

[0037] In some embodiments, the duty cycle of the pulsed electrical signal is 90% or less, preferably 75% or less, and most preferably 50% or less.

[0038] The duty cycle is the percentage of the ratio of the pulse duration or pulse width to the total period of the waveform. A shorter total current "on" time associated with the pulsed electrical signal compared to the non-varying voltage between a pair of electrodes can help limit the progression of the above-described low pH "front".

[0039] In some embodiments, the electrical (current or voltage) signal is both pulsed and bipolar. In such embodiments, the duty cycle associated with the positive component of the bipolar electrical signal may be the same as or different from the duty cycle associated with the negative component of the bipolar electrical signal.

[0040] In at least some embodiments, the control unit is configured to provide an electrical signal to the pair of electrodes for a predetermined time period before ending the provision of the electrical signal to the pair of electrodes. The combination of such a predetermined time period and the variation of the electrical signal can help control the accumulation of hydrogen ions generated at the electrodes.

[0041] This predetermined time period may be the same as or different from a (further) predetermined time during which the actuator moves based on the electrical signal.

[0042] For example, the further predetermined time period during which the actuator moves based on the electrical signal may be longer than the predetermined time period during which the electrical signal is provided to the pair of electrodes.

[0043] For example, mechanical cleaning via the movement of the actuator can continue even after the generation of hydrogen ions stops due to the end of the predetermined time period.

[0044] In some embodiments, a pair of electrodes is insertable into the subject's oral cavity, and the aqueous solution has the subject's saliva and / or one or more oral care agents. This can provide a relatively physically simple way to provide a low pH near the subject's teeth.

[0045] Such oral care agents are at least one selected from toothpastes, mouth rinses, and whitening agents.

[0046] More generally, it should be noted that the aqueous solution may contain one or more ions, as well as water.

[0047] In some embodiments, the oral care device has a cleaning unit, such as a cup, for insertion into the subject's oral cavity. The cleaning unit can have a recess to which one or both of the pair of electrodes are attached. In this manner, the cleaning unit can assist in protecting the pair of electrodes and minimize the risk of the pair of electrodes unintentionally contacting the tissues within the subject's oral cavity.

[0048] In some embodiments, a pair of electrodes is arranged such that one electrode defines an outer electrode, and the outer electrode at least partially surrounds the other electrode that defines an inner electrode.

[0049] Instead of or in addition to the one electrode that defines the outer electrode that at least partially surrounds the inner electrode, the pair of electrodes may be interconnected.

[0050] The term "interconnected" in this context can mean that each electrode has a plurality of electrode members spaced from each other, and one electrode member of the pair of electrodes is disposed in the space between the other electrode members of the pair of electrodes.

[0051] This can provide a particularly spatially efficient arrangement of a pair of electrodes, especially when the pair of electrodes are included in the brush head and / or when space may be limited, such as when mounted within a cup, for example in a cleaning unit. The interconnected electrodes assist in simplifying the structure of the oral care device and limit the electrical contacts required to drive the electrodes.

[0052] Furthermore, in combination with the electrical signals described above, such an interconnected arrangement of electrodes may serve to define the electrolytic footprint provided by the device.

[0053] In some embodiments, the cleaning unit, such as a cup, is formed from an elastic material for rubbing the surfaces within the oral cavity of interest. Such a cup is, for example, a so-called profiler cup.

[0054] In embodiments where the oral care device has at least one cleaning element mechanically coupled to an actuator such that the movement of the actuator results in the movement of the at least one cleaning element, the at least one cleaning element may include a cup.

[0055] For example, the at least one cleaning element can include a cup in addition to bristles.

[0056] More generally, the oral care device can be or can have a toothbrush, a mouthpiece, an irrigator, or a dental professional instrument operable by a dentist or dental hygienist. In particular, an oral care device in the form of a toothbrush is referred to.

[0057] According to another aspect, a method of operating an oral care device having a pair of electrodes in contact with an aqueous solution is provided, the method comprising providing an electrical signal to the pair of electrodes to generate hydrogen ions from water in the aqueous solution for supply into the oral cavity of interest, wherein the variation of the electrical signal controls the generation of the hydrogen ions.

[0058] The device employed in this method may be according to any of the embodiments described in this document. In particular, the electrical signal can be provided by a control unit included in the device.

[0059] More generally, the embodiments described in this document in relation to the method are applicable to the device, and the embodiments described in this document in relation to the device are applicable to the method.

Brief Description of the Drawings

[0060]

Figure 1

Figure 2

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Figure 4

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Figure 6A

Figure 6B

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Figure 10

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Figure 12A

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Figure 14A

Figure 14B

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Figure 16

[0061] Hereinafter, examples of the present invention will be described in detail with reference to the accompanying drawings.

[0062] The present invention will be described with reference to the figures.

[0063] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, system and method, are for the purpose of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the apparatus, system and method of the present invention will be better understood from the following description, the appended claims and the accompanying drawings. It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numbers are used throughout the figures to indicate the same or similar parts.

[0064] An oral care device for removing dental calculus is provided. The oral care device has a control unit configured to provide an electrical signal, such as an electrical signal that varies over time. The oral care device also has a pair of electrodes that contact an aqueous solution. Each of the pair of electrodes is connected to the control unit and is configured to generate hydrogen ions from water in the aqueous solution based on the electrical signal and supply them to the target oral cavity, particularly to the target teeth. The change in the electrical signal controls the generation of hydrogen ions. The hydrogen ions thus generated lower the local pH of the target teeth and assist in dissolving the dental calculus thereon. The change in the electrical signal, such as a change over time, can provide control over the generation of hydrogen ions, as opposed to the uncontrolled generation of hydrogen ions via a non-varying voltage across a pair of electrodes provided by a DC power source, for example. Further, a method of operating such an oral care device is provided.

[0065] FIG. 1 schematically shows the enamel layer 10 of a tooth and the pellicle layer 12 on the enamel layer 10. FIG. 1 also shows dental calculi 14A, 14B, 14C, 14D laminated on the pellicle layer 12.

[0066] The dental calculi 14A - D shown in FIG. 1 include a plurality of different calcium phosphate crystal phases having different water solubilities. The calculus layer 14A farthest from the pellicle layer 12 has dicalcium phosphate dihydrate (DCPD), the layer 14B adjacent to the calculus layer 14A has octacalcium phosphate (OCP), and the layer 14D closest to the pellicle layer 12 and the layer 14C between the layer 14B and the layer 14D can have a relatively small amount of hydroxyapatite (HAp). HAp is a main component of the enamel layer 10.

[0067] HAp has lower water solubility than OCP, and OCP has lower water solubility than DCPD. As a result, the relative and / or absolute water solubility decreases in the direction of arrow 16. However, the absolute solubility of OCP and DCPD in water is low, and their proximity to the enamel layer 10 can prevent the target from removing dental calculus, particularly at home.

[0068] It has been found that the water solubility of the above crystal phase depends on pH. In particular, dissolution in an aqueous solution can be assisted by lowering the pH. Figure 2 provides graphs 18, 20 showing the solubility of the crystal phase containing calcium phosphate calculus as a function of pH. Figure 2 generally shows that for OCP (graph 18) and HAp (graph 20), as the pH decreases, the concentration of calcium ions dissolved in the solution increases. At pH 5.5, the solubility of OCP is approximately two orders of magnitude higher than that of HAp.

[0069] The pH at which the tooth enamel 10 begins to dissolve is indicated by the dotted line 22 in Figure 2. This pH can be considered the critical intraoral pH at which the tooth enamel dissolves (recognized as a threshold) and approximately pH 5.5, which is clinically relevant.

[0070] The present disclosure is based in part on the recognition that by controlling the local pH of the tooth to be less than 7 but 5.5 or more, the OCP and DCPD of the calculus 14, particularly in the initial stage of calculus, can be dissolved with minimal or no damage to the tooth enamel 10. This is because such a pH range can minimize the dissolution of HAp into the tooth enamel 10, as shown in Figure 2.

[0071] Figure 3 schematically shows an example of an apparatus 100. The apparatus 100 has a control unit 102 configured to provide an electrical signal. The apparatus 100 also has a pair of electrodes 104A, 104B that contact an aqueous solution. Each of the pair of electrodes 104A, 104B is connected to the control unit 102 and is configured to generate hydrogen ions from water in the aqueous solution based on the electrical signal.

[0072] Generating hydrogen ions, that is, H+ ions, from water in the aqueous solution means that the potential difference between the electrodes 104A, 104B resulting from the electrical signal is sufficient for the electrolysis of water to occur.

[0073] The electrodes 104A and 104B can be made of any suitable conductive material that enables the electrochemical generation of hydrogen ions via the electrolysis of water. For example, the electrodes 104A and 104B can be selected from platinum electrodes, platinum-clad electrodes such as platinum-clad titanium electrodes, gold electrodes, gold-clad electrodes, carbon electrodes such as graphite electrodes, and polymer-based electrodes in which a conductive material is embedded in the polymer. This conductive material can be selected from, for example, platinum, gold, or carbon such as graphite.

[0074] In some embodiments, each of the pair of electrodes 104A and 104B is a non-sacrificial electrode.

[0075] The term "non-sacrificial electrode" can mean that the electrodes 104A and 104B are each formed of a conductive material that does not dissociate into ions or dissociates only to a negligible extent based on an electrical signal.

[0076] In at least some embodiments, the pair of electrodes 104A and 104B is insertable into a subject's oral cavity, the aqueous solution has the subject's saliva and / or one or more oral care agents, and the oral care agents include, for example, dentifrices, mouth rinses, and / or whitening agents. This can provide a relatively physically simple way to provide a low pH near the subject's teeth.

[0077] Referring again to FIG. 3, when this electrode is operated as a cathode, at electrode 104A, TIFF2025519332000002.tif25114 occurs.

[0078] This generation of hydroxide ions (or consumption of hydrogen ions) can increase the pH in the vicinity of electrode 104A. Such a local increase in pH shown in region 106A around electrode 104A in FIG. 3 may have a smaller effect on the solubility of tartar 14 than the local decrease in pH proximal to electrode 104B shown in region 106B around electrode 104B when electrode 104B is operated as an anode. It becomes TIFF2025519332000003.tif30106. This is because, as represented by the calculus dissolution spot 108 proximal to the electrode 104B in FIG. 3, the dissolution of dental calculus can be assisted, as described above, by lowering the pH, in other words, by increasing the hydrogen ion concentration.

[0079] The pair of electrodes 104A and 104B may be spaced apart from each other by any suitable distance 110, for example, a distance 110 greater than 50 μm, for example, a distance 110 between 50 μm and 1 mm.

[0080] A distance 110 greater than 50 μm is thought to help prevent the hydrogen ions generated at the anode from being immediately neutralized by the hydroxide ions generated at the cathode.

[0081] For example, 25 μm which is half the distance (L / 2) is covered by the pH front in ~0.07 seconds (L 2 / 4D, where D = 9*10 -9 m 2 / s, the diffusion coefficient of H+ ions). This lower limit of 50 μm means that the total processing time exceeds 0.07 seconds. This total processing time is the time period during which an electrical signal is provided to the pair of electrodes 104A and 104B, for example, a predetermined time period (and thus not the on / off current time in the pulses in embodiments where the electrical signal is pulsed).

[0082] More generally, it has been found that using a non-varying voltage between a pair of electrodes provided by a DC power supply can provide a relatively uncontrolled generation of hydrogen ions. In contrast, an electrical signal, for example, a time-varying electrical signal, helps to enhance the control that can be exerted on the generation of hydrogen ions and thus on the local pH to which the target tooth is exposed. This is described in detail below.

[0083] The device 100 is, or can have, a toothbrush, a mouthpiece, an irrigator, or a dental professional instrument operable by a dentist or a dental hygienist. In particular, an oral care device 100 in the form of a toothbrush is referred to.

[0084] It should be noted that a toothbrush, a mouthpiece, and an irrigator can be regarded as examples of the personal care oral device 100. Such a personal care oral device 100 can be used at home by the subject himself / herself.

[0085] In some embodiments as shown in FIG. 4, the device 100 has an actuator 112 connected to a control unit 102. In such an embodiment, the actuator 112 can be configured to move based on an electrical signal generated by the control unit 102.

[0086] In this context, the term "move based on an electrical signal" can mean that the actuator control signal provided by the control unit 102 to control the movement of the actuator 112 is the same as the electrical signal, or one of the actuator control signal and the electrical signal is based on the other of the actuator control signal and the electrical signal.

[0087] The actuator control signal may, for example, be in phase with the electrical signal, or a phase difference may be defined between the actuator control signal and the electrical signal.

[0088] For example, the movement of the actuator 112 that causes the movement of the brush head of the device 100 in the form of the oral care device 100 can thus be provided in parallel with hydrogen ion generation, enhancing calculus removal.

[0089] In certain embodiments, the movement of the actuator based on the electrical signals provided to the electrodes 104A, 104B can facilitate, in addition to assisting in controlling hydrogen ion generation at the pair of electrodes 104A, 104B, the provision of a specific cleaning movement, such as a reciprocating movement, by the actuator.

[0090] Any suitable type of actuator 112 is contemplated and includes, for example, a motor such as a reciprocating motor (not visible in the figures).

[0091] In some embodiments, such as those shown in FIG. 4, the device 100 has at least one cleaning element 114 for mechanically cleaning the oral cavity, and the at least one cleaning element 114 is mechanically coupled to the actuator 112, such that movement of the actuator 112 results in movement of the at least one cleaning element 114.

[0092] Any suitable type of cleaning element is contemplated. In the non-limiting example shown in FIG. 4, the at least one cleaning element 114 has bristles for brushing the oral cavity of interest. In such embodiments, calculus removal facilitated by hydrogen ion generation can be enhanced by the movement of the bristles resulting from movement of the actuator 114 based on an electrical signal.

[0093] The reciprocating motion of the actuator 112, such as that of the reciprocating motor described above, may be provided based on an electrical signal that varies periodically.

[0094] In such embodiments, the reciprocating motion of the actuator 112 results in movement such that the cleaning element 114, such as the bristles, move in a corresponding reciprocating manner.

[0095] Such a periodic electrical signal can also assist in controlling the local pH, particularly to help reduce the risk that the local pH at one or both of the electrodes 104A, 104B will drop below a certain pH level, as will be described in more detail below.

[0096] This combination of mechanical calculus disruption and calculus dissolution assisted by low local pH is particularly effective and also offers the advantage of being achievable, for example, by a subject using the device 100 at home.

[0097] In some non-limiting examples, at least one cleaning element 114 has a cup formed of an elastic material for rubbing the surface in the target oral cavity instead of or in addition to bristles. Such a cup is, for example, a so-called profi cup.

[0098] In an embodiment in which a cup formed of an elastic material is included in the oral treatment device 100, whether or not such a cup is configured to be moved by the actuator 114, one or both of the pair of electrodes 104A, 104B are attached inside the cup. This example will be described below with reference to FIG. 9.

[0099] In a specific embodiment as shown in FIG. 4, the control unit 102 includes a drive train circuit 116 configured to provide an actuator control signal for controlling the actuator 112 and to provide an electrical signal to the pair of electrodes 104A, 104B.

[0100] In such an embodiment, the actuator control signal may be the same as the electrical signal so as to advantageously provide a simple and cost-effective electrical design.

[0101] In an alternative embodiment as shown in FIG. 5, the control unit 102 has an electrode control circuit 118 configured to convert a drive train control signal into an electrical signal for providing to the pair of electrodes 104A, 104B in addition to a drive train circuit 116 configured to provide an actuator control signal.

[0102] The electrode control circuit 118 can include only passive electronic elements such as, for example, diodes, resistors and / or capacitors configured to convert the drive train control signal into an electrical signal.

[0103] An example of such an electrode control circuit 118 is shown in FIG. 6A. In this example, the diode converts the alternating current signal shown in the upper diagram of FIG. 6B into a rectified output waveform without a negative half cycle as shown in the lower diagram of FIG. 6B.

[0104] The drive train circuit 116 can be implemented in any suitable manner, such as a drive train circuit 116 having a microcontroller configured to generate an actuator control signal, for example, a motor microcontroller.

[0105] Note that the AC signals in the examples shown in FIGS. 6A and 6B need not be provided via the drive train circuit 116, and in other examples, they may be provided by a power source configured to supply power to the apparatus 100, for example, a main power source (not visible in the figure).

[0106] In such an example, the control unit 102 can include an electrode control circuit 118 for providing a unipolar pulse-like signal (such as that shown in the lower diagram of FIG. 6B) from the AC signal provided by the power source. Here, the drive train control circuit 116 is omitted.

[0107] In some embodiments as shown in FIG. 7, one or both of the electrodes 104A, 104B are mechanically coupled to the actuator 112. As a result, the movement of the actuator 112 causes the movement of the electrodes 104A, 104B.

[0108] In the non-limiting example shown in FIG. 7, the electrical signal 120 is a periodic bipolar electrical signal that changes with time t.

[0109] During the positive-polarity half-cycle 120A of the electrical signal 120 shown in FIG. 7, the actuator 112, and thus the electrodes 104A, 104B, exhibit a first movement. During the negative-polarity half-cycle 120B of the electrical signal 120, the actuator 112, and thus the electrodes 104A, 104B, exhibit a second movement that mirrors the first movement. The gradient / slope of the electrical signal 120 is represented by the dotted line 122 in FIG. 7.

[0110] This can be achieved by the control unit 102 providing an actuator control signal for controlling the actuator 112 that is in the same phase as the electrical signal provided to the electrodes 104A, 104B.

[0111] The movement of the actuator can result in an increase in the effective area, in other words, the footprint, where the electrochemical process provided by electrodes 104A, 104B is realized. Further, the alternating polarities mean that hydrogen ion generation is realized at both electrodes 104A, 104B, but is carried out sequentially, which further aids in increasing the effective area where the electrochemical process is provided. Additionally, the periodic electrical signal can also help control the local pH, particularly to reduce the risk that the local pH at electrodes 104A, 104B drops below a certain pH level. This will be explained in more detail below.

[0112] In an alternative embodiment, the control unit 102 may be configured to provide an actuator control signal to control the actuator 112, and a phase difference is defined between the actuator control signal and the electrical signals provided to the electrodes 104A, 104B.

[0113] Accordingly, the electrical signal is desynchronized from the actuator control signal, and thus can be desynchronized from the movement of the actuator 112, such as the reciprocating movement of the brush head.

[0114] Such a phase difference can be introduced in any suitable manner, such as via one or more capacitors, inductors, etc. Accordingly, relatively few electrical elements may be required (in addition to the electrical elements for providing the actuator control signal) to provide the phase difference.

[0115] In some embodiments, the control unit 102 has an electrode control circuit 118 configured to convert the actuator control signal into the electrical signals provided to the electrodes 104A, 104B, in addition to a drive train circuit 116 configured to provide the actuator control signal. As a result, a phase difference is intentionally defined between the actuator control signal and the electrical signal.

[0116] In some embodiments, such as those shown in FIG. 8, the device 100 in the form of an oral care device 100 has a plurality of pairs of electrodes 104A, 104B; 104C, 104D. In such embodiments, the control unit 102 may be configured to provide an electrical signal to each of the plurality of pairs of electrodes 104A, 104B; 104C, 104D.

[0117] The oral care device 100 can be powered in any suitable manner, such as via the main power supply of the circuit and / or by one or more batteries 124. In embodiments where the oral care device 100 is powered by one or more batteries 124, the control unit 102 may be configured to generate an electrical signal, such as a current or voltage signal, from the direct current generated by the one or more batteries 124.

[0118] The first electrical connection 126A can connect the control unit 102 to one of the electrodes 104A of a pair of electrodes 104A, 104B, and the second electrical connection 126B can connect the control unit 102 to the other electrode 104B of the pair of electrodes 104A, 104B.

[0119] In the non-limiting example shown in FIG. 8 where the oral care device 100 includes two pairs of electrodes 104A, 104B; 104C, 104D, the first electrical connection 126A connects the control unit 102 to electrodes 104A and 104C, and the second electrical connection 126B connects the control unit 102 to electrodes 104B and 104D.

[0120] In some embodiments, such as those shown in FIG. 9, the oral care device 100 has a toothbrush including a brush head 128 attached to a handle 130. In such embodiments, a pair of electrodes 104A, 104B is preferably included in the brush head 128, and the control unit 102 is included in the handle 130.

[0121] In the non-limiting example shown in FIG. 8, one or more batteries 124 are housed within the handle 130 together with the control unit 102.

[0122] In some embodiments, a brush head 128 including a pair of electrodes 104A, 104B is detachably coupled to a handle 130, enabling the replacement of the brush head 128 without replacing the control unit 102 included in the handle 130. In such embodiments, the first and second electrical connections 126A, 126B between the control unit 102 included in the handle 130 and the pair of electrodes 104A, 104B included in the (replaceable) brush head 128 can be established simultaneously when the brush head 128 is attached to the handle 130, for example, by snap - fitting or press - fitting.

[0123] In the non - limiting example shown in FIG. 8, each of a plurality of pairs of electrodes 104A, 104B; 104C, 104D is included in the brush head 128.

[0124] In embodiments where the oral care device 100 is a toothbrush or has a toothbrush, the brush head 128 can have at least one cleaning element 114, such as bristles as described above and / or a cup formed from an elastic material for rubbing against the surfaces within the target oral cavity.

[0125] In some embodiments as shown in FIG. 8, at least one cleaning element 114 has bristles, and the bristles extend further from the brush head 128 than each of the pair of electrodes 104A, 104B, such that the pair of electrodes 104A, 104B are recessed with respect to the bristles.

[0126] At least one cleaning element 114, and in some cases the entire brush head 128, can be moved by the actuator 112 as described above.

[0127] In embodiments where at least one cleaning element 114 has a cup formed from an elastic material, one or both of the pair of electrodes 104A, 104B may be mounted inside the cup.

[0128] In an embodiment where a plurality of pairs of electrodes 104A, 104B; 104C, 104D are included in the oral care device 100 as shown in FIG. 8, the oral care device 100 may include a plurality of cups. In such an embodiment, one or both of each pair of electrodes 104A, 104B; 104C, 104D may be mounted within an individual cup of the plurality of cups.

[0129] The electrodes 104A, 104B can be arranged relative to each other in any suitable manner. In some embodiments, the electrodes 104A, 104B are arranged such that one of the electrodes 104B defines an outer electrode 104B that at least partially surrounds the other of the electrodes 104A that defines an inner electrode 104A. This example is shown in FIG. 8.

[0130] FIG. 8 also shows a region 106A around the electrode 104A and a region 106B around the electrode 104B. In one of these regions 106A, 106B, the local pH can be increased by the generation of hydroxide ions based on an electrical signal, and in the other of these regions 106B, 106A, the local pH can be decreased by the generation of hydrogen ions as previously described in connection with FIG. 3.

[0131] Instead of or in addition to one of the electrodes 104B that defines an outer electrode 104B that at least partially surrounds the inner electrode 104A, the pair of electrodes 104A, 104B may be interconnected.

[0132] The term "interconnected" in this context can mean that each of the electrodes 104A, 104B has a plurality of electrode members spaced apart from each other, and one electrode member of the pair of electrodes 104A, 104B is disposed in the space between the other electrode members of the pair of electrodes 104B, 104A.

[0133] This can provide a particularly space - efficient arrangement of the pair of electrodes 104A, 104B, especially when the pair of electrodes 104A, 104B are included in the brush head 128 and / or when mounted within a cup where space is limited.

[0134] A non - limiting example of such an interconnected arrangement of the pair of electrodes 104A, 104B is depicted in FIG. 9.

[0135] Similar to the non - limiting example shown in FIG. 8, a cleaning element 114 having bristles is included in the oral care device 100 shown in FIG. 9. In this latter non - limiting example, a plurality of peripheral bristle bundles are disposed around a pair of interconnected electrodes 104A, 104B disposed centrally.

[0136] In some embodiments as shown in FIG. 8, the oral care device 100 has a cup 132 for insertion into the oral cavity of a subject, and the cup 132 has a recess 134 to which one or both of the pair of electrodes 104A, 104B are attached. In this manner, the cup 132 can protect the pair of electrodes 104A, 104B and help minimize the risk of the pair of electrodes 104A, 104B coming into unintended contact with the tissues within the oral cavity of the subject.

[0137] The cup 132 can be formed of any suitable material, for example, an electrically insulating material. In some embodiments, the cup 132 is formed of an elastic material for rubbing against the surface within the oral cavity of the subject as previously described.

[0138] The cup 132 formed of an elastic material can sway and flex to conform to the contour of the teeth of the subject to assist in selective stain removal and interdental cleaning.

[0139] For the cup 132, any suitable elastic material such as silicone rubber can be considered.

[0140] In some embodiments as shown in FIGS. 8 and 9, the brush head 128 is attached, for example detachably, via a neck 136 to a handle 130 of the oral care device 100, which in this example is in the form of a toothbrush. Such a neck 136 can extend between the upper end of the handle 130 and the lower end of the brush head 128.

[0141] FIG. 10 provides a graph 138 of the calculus dissolution depth over 30 seconds for a continuous DC voltage across a pair of electrodes 104A, 104B. As the voltage increases, the associated local pH decrease caused by the generation of hydrogen ions results in dissolution to a greater depth of the calculus. However, FIG. 10 also provides a graph 140 of the enamel dissolution depth of the tooth over 30 seconds for a continuous DC voltage across a pair of electrodes 104A, 104B, indicating that relatively low pH conditions caused by relatively high voltages may cause dissolution of the tooth enamel.

[0142] FIG. 11 schematically shows a 2D simulation setup including two electrolysis electrodes 104A, 104B in a 0.1M KCl solution (corresponding to the experimental measurements shown in FIG. 10. A mixture of saliva and toothpaste has a comparable conductivity.), where d = 145 μm and w = 500 μm. L1 and L2 represent the boundaries of the domain. This 2D simulation setup was used to evaluate various electrical signals in an exemplary embodiment.

[0143] FIG. 12A provides a graph of a non - varying voltage (step signal) across a pair of electrodes provided by a DC power supply, and FIG. 12B provides graphs 142B, 144B, 146B of pH versus time at individual points 142A, 144A, 146A proximate to the electrodes 104A, 104B shown in FIG. 11 when the electrical signal shown in FIG. 12A is provided to the electrodes 104A, 104B.

[0144] While the application of the DC signal results in a relatively large change and strong drift in pH, in graph 146B (corresponding to point 146A in FIG. 11), a relatively rapid / uncontrolled decrease towards a pH of less than 5.5 (see region 148 in FIG. 12B) is observed.

[0145] FIG. 13A provides a graph of an electrical signal according to a first example where the electrical signal is periodic and bipolar, and FIG. 13B provides graphs 142C, 144C, 146C of pH versus time at individual points 142A, 144A, 146A proximate to electrodes 104A, 104B shown in FIG. 11 when the electrical signal shown in FIG. 13A is provided to electrodes 104A, 104B.

[0146] Note that in order to enable comparison with FIGS. 13A and 13B, the intensity of the non-varying voltage shown in FIG. 12A is normalized.

[0147] The electrical signals shown in FIGS. 13A and 13B induce a relatively rapid stabilization of pH, indicating that the overall change in pH is small and stabilizes at approximately pH 5. Thus, changing the electrical signal can enhance the control that can be exerted on the generation of hydrogen ions and thus on the local pH to which the target tooth is exposed.

[0148] In some embodiments such as those shown in FIGS. 13A and 13B, the electrical signal has periodic variations in amplitude. This can assist in controlling the accumulation of hydrogen ions and thus assist in controlling the local pH.

[0149] Alternatively or additionally, the electrical signal has or is a bidirectional waveform. An example of this is shown in FIG. 13A. Alternating the polarities of electrodes 104A, 104B via such a bidirectional waveform can suppress the progression of the low pH "front" emitted from electrodes 104A, 104B and assist in stabilizing the pH. This is because after the change in polarity, hydrogen ions previously generated at one of electrodes 104A, 104B can be neutralized by hydroxide ions currently generated at the same electrodes 104A, 104B.

[0150] In some embodiments such as those shown in FIGS. 13A and 13B, the electrical signal has or is a continuous waveform. In particular, FIG. 13A shows a continuous waveform in the form of a sine wave.

[0151] In an alternative embodiment, the electrical signal has, or is, a pulsed electrical signal. Such a pulsed electrical signal can be generated, for example, in the manner described above in connection with FIGS. 6A and 6B.

[0152] FIG. 14A provides a graph of an electrical signal according to a second example where the electrical signal is periodic, pulsed (10 Hz, duty cycle 10%) and unipolar, and FIG. 14B provides graphs 142D, 144D, 146D of pH versus time at individual points 142A, 144A, 146A proximal to electrodes 104A, 104B shown in FIG. 11 when the electrical signal shown in FIG. 14A is provided to electrodes 104A, 104B.

[0153] In contrast to the non-varying voltages of FIGS. 12A and 12B where the pH reaches the relatively rapidly unsafe value of pH 4, the pulsed signals of FIGS. 14A and 14B result in a much gentler and controlled change in pH that reaches pH 4.8 after about 0.5 seconds.

[0154] In some embodiments, referring to FIG. 15, the duty cycle of the pulsed electrical signal is 90% or less, preferably 75% or less, and most preferably 50% or less. The duty cycle is the percentage of the ratio of the pulse duration or pulse width to the total period 150 of the waveform. The shorter total current "on" time associated with the pulsed electrical signal compared to the non-varying voltages of FIGS. 12A and 12B can assist in suppressing the progression of the low pH "front".

[0155] In some embodiments as shown in FIG. 15, the electrical (current or voltage) signal is pulsed and bipolar. The signal for each half cycle can be applied with a given duty cycle. In the non-limiting example shown in FIG. 15, the duty cycle is 50%.

[0156] The duty cycle associated with the positive component of the bipolar electrical signal may be the same as or different from the duty cycle associated with the negative component of the bipolar electrical signal.

[0157] Note that in some embodiments, a duty cycle may not be employed.

[0158] In some embodiments, the electrical signal can be defined by an asymmetric pulse. Such an asymmetric electrical signal may help to induce a preferential pH change at a particular location.

[0159] In some embodiments, such as those shown in FIG. 16, the electrical signal is a bidirectional waveform, and the positive peak amplitude 152 of the bidirectional waveform is different from the negative peak amplitude 154 of the bidirectional waveform. This can cause a continuous but controlled increase or decrease in pH at a particular location. Thus, the greater control provided by pulsing the electrical signal relative to the application of a non-varying voltage can be combined with the limitation of the generation of an "extreme" pH zone near the electrodes 104A, 104B by periodic neutralization provided by the changing polarity.

[0160] In some embodiments, one of the positive and negative peak amplitudes 152, 154 is at least 1.1 times the other of the positive and negative peak amplitudes 154, 152.

[0161] In the non-limiting example shown in FIG. 16, the negative peak amplitude 154 is 1.5 times the positive peak amplitude 152. The average signal is represented by the dotted line 156 in FIG. 16.

[0162] In at least some embodiments, the control unit 102 is configured to provide an electrical signal to the pair of electrodes 104A, 104B for a predetermined time before ending the provision of the electrical signal to the pair of electrodes 104A, 104B. The combination of such a predetermined time period and the variation of the electrical signal can help to control the accumulation of hydrogen ions generated by the electrodes 104A, 104B.

[0163] This predetermined time period may be the same as or different from the (further) predetermined time period during which the actuator 112 moves based on the electrical signal. For example, the further predetermined time period during which the actuator 112 moves based on the electrical signal may be longer than the predetermined time period during which the electrical signal is provided to the pair of electrodes 104A, 104B.

[0164] A method of operating an apparatus having a pair of electrodes 104A, 104B in contact with an aqueous solution is also provided. The apparatus can be based on any of the embodiments described herein. The method includes providing an electrical signal to the pair of electrodes 104A, 104B to cause the generation of hydrogen ions from water in the aqueous solution. The change in the electrical signal controls the generation of hydrogen ions.

[0165] The electrical signal can be provided by the control unit 102 included in the apparatus 100 described herein.

[0166] The above-described control unit 102 (and / or drive train circuit 116) can be implemented in a plurality of ways using software and / or hardware to perform the various required functions. An example of the control unit 102 / drive train circuit 116 employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform functions. However, the control unit 102 / drive train circuit 116 can be implemented with or without employing a processor and can be implemented as a combination of dedicated hardware for performing some functions and a processor, e.g., one or more programmed microprocessors and associated circuitry, for performing other functions.

[0167] Examples of controller elements that can be employed in various embodiments of the present application include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0168] In some examples, the control unit 102 / drive train circuit 116 is associated with one or more storage media such as volatile and non-volatile computer memories such as RAM, PROM, EPROM, EEPROM. The storage media may be encoded with one or more programs that perform the required functions when executed by one or more processors and / or controllers. The various storage media may be fixed within the control unit 102 / drive train circuit 116 or may be transportable such that one or more programs stored therein can be loaded into the control unit 102 / drive train circuit 116.

[0169] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in light of the drawings, description, and appended claims. In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

1. A personal oral care device for use by a subject at home, comprising: a control unit that provides an electrical signal; and a pair of electrodes that contact an aqueous solution, the pair of electrodes being connected to the control unit, and based on the electrical signal, at least one of the electrodes generating hydrogen ions from water in the aqueous solution and supplying them into the subject's oral cavity, the electrical signal and the pair of electrodes being configured such that fluctuations in the electrical signal control the generation of the hydrogen ions, and the electrical signal being a pulsed electrical signal.

2. The oral care device according to claim 1, wherein the fluctuations in the electrical signal limit the rate of change of the generation of the hydrogen ions and / or promote the neutralization of the hydrogen ions.

3. The oral care device according to claim 1 or 2, further comprising an actuator that moves based on the electrical signal.

4. The oral care device according to claim 3, wherein the control unit generates an actuator control signal for controlling the movement of the actuator, and the actuator control signal is in phase with the electrical signal or a phase difference is defined between the actuator control signal and the electrical signal.

5. The oral care device according to claim 3 or 4, further comprising at least one cleaning element for mechanically or fluidly cleaning the subject's oral cavity, the at least one cleaning element being arranged such that the movement of the actuator results in the movement of the at least one cleaning element and / or the supply of fluid from the at least one cleaning element.

6. The oral care device according to any one of claims 1 to 5, wherein the electrical signal has periodic fluctuations in at least one of amplitude, polarity, and frequency.

7. The oral care device according to any one of claims 1 to 6, wherein the duty cycle of the pulsed electrical signal is 90% or less.

8. The oral care device according to any one of claims 1 to 7, wherein the electrical signal has a bidirectional waveform supplied to the electrodes.

9. The oral care device according to claim 8, wherein the positive peak amplitude of the bidirectional waveform is different from the negative peak amplitude of the bidirectional waveform.

10. The oral care device according to claim 9, wherein one of the positive and negative peak amplitudes is at least 1.1 times the other of the positive and negative peak amplitudes.

11. The oral care device according to any one of claims 1 to 10, wherein the control unit provides an electrical signal to the pair of electrodes for a predetermined time period before ending the provision of the electrical signal to the pair of electrodes.

12. The oral care device according to any one of claims 1 to 11, wherein the pair of electrodes is insertable into the oral cavity of the subject, and the aqueous solution contains the saliva of the subject and / or one or more oral care agents.

13. The oral care device according to any one of claims 1 to 12, further comprising a cleaning unit for insertion into the oral cavity of the subject, the cleaning unit having a recess to which one or both of the pair of electrodes are attached.

14. The pair of electrodes are arranged such that one of the electrodes defines an outer electrode that at least partially surrounds the other electrode that defines the inner electrode, and / or the pair of electrodes are interconnected. The oral care device according to any one of claims 1 to 13.

15. The oral care device according to any one of claims 1 to 14, wherein the personal oral care device is a toothbrush, a mouthpiece, or an irrigator.

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