Oral care devices and methods

Abstract

The oral care device has a field generator adapted to generate an electric field in the oral cavity of a user in response to an input control signal. The electric field is used to apply a force to particles forming a biofilm to be removed by the oral care device or to particles of a cleaning agent. A cyclic control signal is generated for intermittently generating the electric field at a first RF frequency. Intermittent generation using an RF electric field means that the force applied by the electric field to the particles (particularly polarized particles) is itself cyclic. The cyclic nature of the applied force has been found to be more effective in decomposing the biofilm to be removed, and therefore makes subsequent mechanical removal (e.g., by brushing) easier.

Description

Technical Field

[0001] The present invention relates to oral care devices and methods, and in particular to devices for removing biofilm from the oral cavity. Background Art

[0002] It is known that radio frequency (RF) electromagnetic radiation can be used to provide a cleaning function in the oral cavity. In particular, an oral cleaning device may include a cleaning unit (such as a head or mouthpiece portion), for example, for insertion into the oral cavity of a user, the cleaning unit portion including two or more electrodes coupled to an RF signal generator. The signal generator drives the electrodes with an RF signal, which causes RF radiation to be emitted around and between the electrodes.

[0003] It is also known to deliver oral cleansers to the oral cavity as part of an oral care regimen.

[0004] US 10 / 201701B2 describes a prior art electric toothbrush. The toothbrush comprises a pressure plate, an RF generator, two RF electrodes and a dielectric barrier in the form of a silicone strip located between the two RF electrodes. The toothbrush also comprises bristles. The dielectric barrier has a height extending upward to the distal end of the bristles. The barrier forces the RF waves transmitted between the electrodes to travel on top of the barrier, thereby reaching the area where the bristles engage with the surface of the teeth and gums during use.

[0005] When the RF field interacts with the surfaces of the teeth and gums, it provides a cleaning function by loosening the bonds between impurities and surfaces in the oral cavity. In particular, the RF field generated in this way can remove dental plaque as well as calculus. Tooth staining can also be reduced.

[0006] It is known that biological particles in biofilms to be removed (e.g., plaque and calculus), and indeed other polarizable particles (such as detergent particles as described above), can be moved under the influence of dielectrophoretic forces. A given RF drive frequency will generate a force acting on the particles in a particular direction. However, that direction may not be optimal for removing plaque, for example if it is toward the teeth, or it may not result in the desired movement of the detergent particles.

[0007] Dental plaque is usually composed of bacterial microcolonies embedded in an exopolysaccharide (EPS) matrix. In addition, it is known that dental biofilms (such as dental plaque) can show different degrees of toughness, making the biofilm difficult to remove. For example, the toughness of dental plaque varies significantly depending on the location. In areas that are easily reached by toothbrush bristles, such as oral and lingual tooth surfaces, dental plaque is difficult to remove, and the bristles need to apply enough work to be able to destroy and erode the dental plaque layer. Between and under the gums, such as in periodontal pockets, dental plaque is softer, but bristles cannot reach these areas, and therefore cannot clean these areas. Therefore, this so-called difficult-to-reach area requires the application of additional physical tools and principles. To destroy and remove dental plaque.

[0008] Therefore, there is a need to find methods to more effectively break up formed biofilms and / or deliver cleaning agents to the biofilms, thereby facilitating the mechanical removal of the biofilms.

[0009] EP 3 104 807 discloses a teeth whitening device in which an AC activation signal is applied to a conventional toothpaste. An AC field is applied, for example, in the range of 300 kHz to 40 MHz. The AC field may be continuous or pulsed. Summary of the invention

[0010] The invention is defined by the claims.

[0011] According to an example according to one aspect of the present invention, there is provided an oral care device, the oral care device comprising:

[0012] a field generator adapted to generate an electric field in a user's mouth in response to an input control signal;

[0013] a controller adapted to generate an input control signal to control the generation of an electric field, wherein the electric field is used to apply a force to particles forming a biofilm to be removed by the oral care device or to particles of a cleaning agent,

[0014] The controller is suitable for:

[0015] A cyclic control signal is generated for intermittently generating an electric field at a first RF frequency.

[0016] The device utilizes intermittent generation of an RF electric field. In this way, the force applied by the electric field to the particles (particularly polarized particles) is itself cyclical. The cyclical nature of this force is more effective in decomposing the biofilm to be removed, either through direct interaction with the biofilm particles, or through controlled delivery of detergent particles or controlled interaction of detergent particles with the biofilm. This makes subsequent mechanical removal (e.g., by brushing) easier.

[0017] The detergent particles may include polarizable particles, or one or more non-polarizable detergent particles may be carried by a polarizable delivery medium, such as a capsule.

[0018] The cyclic control signal controls the timing of the RF field generation. Therefore, the frequency of the cyclic control signal is much lower than the RF frequency itself.

[0019] The field generator creates a field in the space in the oral cavity with a certain field pattern that depends on the control signal and the geometry of the field generator (e.g. the geometry or arrangement of the electrodes or coils). The field pattern encompasses field intensity gradients or field lines that define a pattern of force paths through space when acting on polarizable particles. Particles of the biofilm or detergent particles are electrically polarizable particles and forces are exerted on them according to these field lines and gradients.

[0020] The controller is adapted to generate a cyclic control signal for generating an electric field alternately at a first RF frequency and a second RF frequency.

[0021] Different RF frequencies result in different forces. The selection of these forces can be used to create effective disintegration, or controlled motion, or oscillation of detergent particles.

[0022] There may be a switch between the first and second frequencies.Conversely, the controller may be adapted to generate a cyclic control signal for generating a frequency sweep between the first RF frequency and the second RF frequency.

[0023] Therefore, a switch or sweep of the resultant force, and a switch or sweep of the force direction can be generated.

[0024] The first RF frequency is, for example, below a threshold frequency and the second RF frequency is above a threshold frequency, thereby generating dielectrophoretic forces on the particles in opposite directions. The dielectrophoretic effect is frequency dependent and in this way forces in opposite directions can be applied alternately. This provides an efficient decomposition solution.

[0025] The threshold frequency is, for example, 1 MHz, so that at least one frequency is below 1 MHz and at least one frequency is above 1 MHz.

[0026] The frequency of the cyclic control signal is, for example, in the range of 0.1 Hz to 1 kHz, for example in the range of 1 Hz to 100 Hz.

[0027] In an alternative set of examples (not within the scope of the claims), the controller may be adapted to generate a cyclic control signal for switching the generation of the electric field at the first RF frequency on and off. In this way, only a single frequency is used, but it is cyclically applied over alternating periods of force application using the RF electric field and periods of no force application.

[0028] In all examples, the oral care device may also include:

[0029] Brush heads; and

[0030] A motor is used to drive the brush head in a vibrating motion having a vibrating frequency.

[0031] This combines the breakdown of biofilm (eg, plaque) and / or delivery of cleaning agents with mechanical dislodging and removal.

[0032] The frequency of the cyclic control signal is for example equal to the vibration frequency or a subharmonic of the vibration frequency.In this way, by combining the effects of mechanical vibration and electromagnetic forces from the RF field, forces are exerted on the particles of the biofilm in opposite directions.

[0033] When cyclic control involves on-off cycles for a single RF frequency, when the RF field is on, a force can be generated in one direction that supplements the force applied by the mechanical vibrations. When the RF field is off, a force is still generated in the opposite direction by mechanical vibrations alone. In this way, even at a single RF frequency, forces with alternating directions are applied to the particles.

[0034] The method can also be used to generate a net force in one preferred direction. This can be used to direct detergent particles to a desired location or desired pattern of locations.

[0035] When cyclic control involves two RF frequencies or sweeps of RF frequencies, the positive and negative forces induced by the RF field can be enhanced by synchronization with the brush head vibration. For example, the force generated by the RF field changes from positive to negative (i.e., changes direction) at the same moment that the brush head motion changes direction. With proper synchronization, the force generated by the RF field and the force transmitted to the particles by the brush motion is always in the direction of the brush head motion.

[0036] Therefore, this driving scheme is more effective in vibrating and loosening particles in the biofilm.

[0037] The vibration frequency is, for example, in the range of 50 Hz to 1 kHz.

[0038] The field generator may be coupled to the brush head to move with the brush head. Particles subjected to the force generated by the RF field will, for example, be effectively captured by the force and move with the movement of the brush head.

[0039] The field generator is, for example, configured to generate a non-uniform electric field having a field intensity gradient in one or more directions for generating a force on the polarizable particles along the direction of the gradient.

[0040] Inhomogeneous fields such as these can be used to move electrically polarized particles. Due to the non-uniform forces experienced at each pole of the electric dipole of the particle, the polarized or polarizable particles will move in the direction of the field strength gradient. Thus, the field can be configured to present a field strength gradient that defines one or more gradient paths corresponding to the direction of the force desired to be applied. Inhomogeneous electric fields can be used to move electrically polarizable or polarizable particles by means of the dielectrophoresis (DEP) effect.

[0041] Forces may be exerted in this way on particles of the biofilm to be removed, but forces may also be exerted on particles of the detergent being delivered to the oral cavity. Thus, the field may be configured to present a field strength gradient that defines one or more gradient paths leading to locations where the detergent particles are desired to be delivered.

[0042] In this case, the system can use electrically polarizable capsules containing oral treatment agents therein, which constitute cleanser particles that are sensitive to electric fields. These capsules can be moved to desired locations in the oral cavity by means of a non-uniform electric field. The active agent therein can then be deployed at these locations. This can occur without additional interaction from the device, for example, the capsule is water-soluble and breaks down due to interaction with saliva, or it can be triggered by an activation stimulus generated by the device.

[0043] The field generator, for example, comprises one or more conductive elements electrically coupled to the controller, and the control signal is an electrical drive signal for energizing the one or more conductive elements.

[0044] The oral care device is for example controlled by a method comprising the following steps:

[0045] generating a control signal to control the generation of an electric field in the oral cavity of a user, wherein the electric field is used to apply a force to particles forming a biofilm to be removed by the oral care device, or to particles of a cleaning agent,

[0046] The control signal includes a cyclic control signal for generating an electric field alternately at a first RF frequency and a second RF frequency, wherein the cyclic control signal is used to:

[0047] generating a frequency switch between the first RF frequency and the second RF frequency; or

[0048] A frequency sweep is generated between the first RF frequency and the second RF frequency.

[0049] The invention also provides a computer program product comprising computer program code executable on a processor or a computer. When the processor or the computer is operatively coupled to the field generator, the code is configured to cause the processor to perform the method defined above.

[0050] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the invention, and in order to more clearly show how the invention may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0052] Figure 1 Schematically illustrating components of a first example apparatus;

[0053] Figure 2 An example electrode pair is shown for inducing an electric field between the electrode pair to achieve a dielectrophoresis (DEP) effect;

[0054] Figure 3 The relationship between the force in a specific direction and the logarithmic frequency is shown;

[0055] Figure 4 A first example of an oral care device is shown in more detail;

[0056] Figure 5 A second example of an oral care device is shown in more detail;

[0057] Figure 6 A third example of an oral care device is shown in more detail;

[0058] Figure 7 Another example drive system for an oral care device is shown;

[0059] Figure 8 A cyclic control signal for synchronizing with the vibrating brush head motion is shown;

[0060] Fig. 9 The synchronized DEP force and motion direction are shown;

[0061] Fig.10 Shown is a Figure 6 A brush head having a set of bristles for lifting particles in the manner shown; and

[0062] Fig.11 Shows the Figure 7 Modification of the system to achieve synchronization with the brush head vibration. DETAILED DESCRIPTION

[0063] The present invention will be described with reference to the accompanying drawings.

[0064] It should be understood that the detailed description and specific examples, although indicating exemplary embodiments of the apparatus, system and method, are intended to be used for illustrative purposes 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 become better understood from the following description, the appended claims and the accompanying drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to represent the same or similar components.

[0065] The present invention provides an oral care device having a field generator for generating an electric field in the oral cavity of a user in response to an input control signal. The electric field is used to apply a force on particles (which form a biofilm to be removed by the oral care device) or cleaning particles. A cyclic control signal is generated, which is used to intermittently generate an electric field at a first RF frequency (i.e., the first frequency is applied with a duty cycle, which has a period when the RF field is generated at this frequency, and a period when there is an RF field of a different frequency or no RF field). This means that the force applied to the particles is itself cyclic, and thereby more effectively breaks down the biofilm to be removed.

[0066] Therefore, the present invention relates to the use of forces induced by RF fields to directly assist in loosening of biofilms in the oral cavity, or to assist in loosening of biofilms in the oral cavity by means of detergent particles, thereby assisting in removing biofilms. This application of RF fields can be used alone by an oral care device (e.g., it can be a pure RF treatment device, or the RF treatment device can be followed by conventional brushing), or the oral care device can be implemented in combination with physical brushing. For example, an RF-based oral care device can be integrated into an electric toothbrush or an oral brushing device. The oral care device can also be used in combination with the delivery of oral treatment substances (e.g., active agents such as fluoride, whitening solutions, mouthwashes, and special toothpastes or gels).

[0067] The invention relates in particular to the control of forces acting on biofilm particles, or the control of the movement of detergent particles, generated by the use of RF fields.Other functions of the oral care device, such as an electric toothbrush, will therefore not be described in detail.

[0068] Figure 1 Components of a first example apparatus are schematically illustrated in accordance with one or more embodiments.

[0069] The device 8 comprises a field generator 16 adapted to generate a first electric field 20 in space in response to an input control signal.

[0070] The device further comprises a controller 10 adapted to generate control signals to control the generation of an electric field 20 in the space. The field is used to exert a force on particles of the biofilm or other polarizable particles sensitive to the field, such as detergent particles.

[0071] The field generator 16 is adapted to operate in the oral cavity of a user. When the field applies a force to the biofilm particles themselves, the direction of the force applied to the biofilm particles preferably includes at least one component that is non-perpendicular to the tooth surface, thereby providing a lateral force.

[0072] In this example, the field generator comprises two field generating devices or parts 16a, 16b, each field generating device or part 16a, 16b comprises a first electrical conductor 18a and a second electrical conductor 18b, the first electrical conductor 18a and the second electrical conductor 18b being arranged to receive control signals from the controller 10. Each field generating device or part generates a corresponding local field 20 between corresponding conductors for applying force to particles in a local area. However, this is not required, and in other examples, a single field generating device may be provided, which is arranged to generate a field over a single area.

[0073] In this example, the device 8 includes a support 12 that carries or integrates field generators 16a, 16b. For example, the field generators are carried on a support surface 13 of the support or integrated below the support surface. The controller 10 may also be carried by the support 12 or integrated in the support 12, or the controller 10 may be separated from the support and electrically coupled to or couplable with the field generator 16 of the support. For example, in some cases, the device 8 may also include a handle or main body portion, the support 12 is coupled or attached to the handle or main body portion, and the handle or main body portion integrates the controller 10.

[0074] exist Figure 1 In the example shown, each field generating device 16a, 16b of the field generator 16 comprises a respective pair of electrodes 18a, 18b separated by space and arranged to receive a voltage source from the controller 10 to charge the electrodes. This induces an electric field 20 between the electrodes.

[0075] When the electric field 20 is generated by the field generator 16, the field-sensitive particles have a force exerted on them.

[0076] Depending on the application, there are different choices for the form and structure of the device 8. For example, the present invention may be implemented in a range of different oral care devices, such as mouthpiece devices, toothbrushes, interdental cleaning devices, dental floss devices and oral irrigator devices.

[0077] Figure 1One example of a mouthpiece device form is shown having an arcuate support body 12 with a support surface 13. The arcuate shape allows the mouthpiece to be received in the mouth of a user. It can be shaped to conform to the geometry or contour of the user's mouth (e.g., a particular user or a typical user). It can have an upper surface and a lower surface. The conductive elements of the field generator 16 can be carried by the support surface 13 of the support body 12.

[0078] As explained in more detail below, the control signal generated by the controller 10 varies dynamically as a function of time to dynamically control the force applied to the sensitive particles. The control signal can vary over time to dynamically control the manner in which the particles are polarized in the generated electric field. Specifically, the polarization depends on the frequency. For example, the frequency can be controlled so that the force varies in magnitude and sign. The field generator 16 is thus configured to generate a non-uniform field 20 (non-uniform field strength) having a field strength gradient in one or more directions for applying a force to the particles along the gradient direction.

[0079] Inhomogeneous fields such as these can exert forces on electrically polarizable or polarizable particles. Due to the inhomogeneous forces experienced at each pole of the particle's electric dipole, a polarized particle will have a force applied in the direction of the field strength gradient. In this way, inhomogeneous electric fields can be used to exert forces on electrically polarizable or polarizable particles by virtue of the dielectrophoresis (DEP) effect.

[0080] exist Figure 1 In the example of , in order to promote the non-uniform electric field 20, the electrodes 18 of each pair are different in corresponding size. This is just one way to generate a non-uniform field pattern. For example, Figure 1 The first electrode 18a in the embodiment is longer than the second electrode. For example, it may be longer in a dimension perpendicular to the separation direction between the electrode pair.

[0081] Thus, an asymmetric electrode pair is provided. By providing one electrode 18a which spans a greater distance in a direction perpendicular to the separation of the electrode pair than the other electrode 18b, this causes the field to be more spatially extended on one side of the separation space than the other, with the result that there is a net force towards the smaller electrode.

[0082] More generally, each electrode 18a, 18b of the electrode pair may have a corresponding chargeable or active area for generating an electric field 20 in the space between the electrode pair when charged, and wherein the chargeable or active areas of the two electrodes may differ in size. Thus, the portions of the electrodes 18a, 18b that are charged and contribute to the field may differ in area between the electrodes. They may additionally or alternatively differ in dimensional extension along a direction perpendicular to the separation direction between the electrodes.

[0083] Note that providing electrodes of different lengths or areas is not the only way to generate a spatially non-uniform field. For example, an alternative approach is to provide pairs of electrodes of the same length, spaced apart from each other, but arranged at an oblique angle with respect to each other. More generally, any electrode arrangement can be used in which the potential gradient between the electrodes varies spatially, rather than a simple parallel plate arrangement that generates a uniform field.

[0084] The electrodes may be plate electrodes, but equally one of the electrodes in each pair may be a flat plate electrode and the other electrode may have a different, rounded end shape so that the electrically active area of ​​the electrode extends around the side surface of the electrode.

[0085] The DEP effect Figure 2 is shown in Figure 2 An example pair of electrodes 18a, 18b separated by a space D is shown. One electrode 18a is negatively charged and the other 18b is positively charged, thereby inducing an electric field between them. The first electrode 18a is longer than the second electrode 18b in a dimension perpendicular to the separation direction D between the electrodes. This has the effect that for a polarized or polarizable particle 22 located within the field, there is a net force on the particle towards the smaller electrode 18b along the separation direction between the electrodes. This is because in a non-uniform field, the particle is not uniformly polarized because different parts of the particle are in field regions of different field strengths.

[0086] In case the particles are electrically polarizable particles and the electrode pairs are driven by an alternating potential to generate an alternating field, this effect is called the dielectrophoresis (DEP) effect.

[0087] In this effect, the electric field 20 polarizes the particle 22 so that the poles experience a force along the field lines, which can be attractive or repulsive depending on the orientation on the dipole. Since the field 20 is inhomogeneous, and at this frequency the particle is polarized in phase with the RF field (positive DEP), the pole experiencing the largest electric field will dominate the other pole, and the particle will move in that direction. At other frequencies where there is a negative DEP, the particle will of course move in the opposite direction.

[0088] Bioparticles or other polarizable particles in the biofilm (such as detergent particles) can have a force applied to them and therefore move under the influence of this dielectrophoretic force (if and when they are free to move). However, if a single RF drive frequency is used, the force on the particles is always in the same direction. If that direction is, for example, towards the teeth, it will not remove plaque optimally.

[0089] Dental plaque is typically composed of bacterial microcolonies embedded in an exopolysaccharide (EPS) matrix. In addition, it is known that dental biofilm or dental plaque can display varying degrees of toughness, making the biofilm difficult to remove. Therefore, there is a need to find methods to more effectively break down the formed biofilm to aid in mechanical removal of the biofilm.

[0090] Plaque toughness varies significantly depending on location. In areas that are easily reached by toothbrush bristles (e.g., oral and lingual tooth surfaces), plaque is difficult to remove, and the bristles need to apply sufficient work to be able to disrupt and erode the plaque layer. In the intergingival and subgingival areas (e.g., in periodontal pockets), plaque is softer, but bristles cannot reach these areas and therefore cannot clean these areas. Therefore, such so-called hard-to-reach areas require the application of additional physical tools and principles to disrupt and remove plaque.

[0091] It is known that the direction of the net dielectrophoretic force can be changed depending on the frequency. Figure 3 , which shows the force along a particular direction (y-axis, arbitrary units) versus logarithmic frequency (x-axis, Hz). For typical biological cell-like particles, switching occurs in the RF frequency range of, for example, about 1 MHz.

[0092] With reference to " Dielectrophoresis as a Tool to Characterizeand differentiate isogenic mutants of Escherichia coli ", Biophysical Journal, Vol. 91, No. 10, November 15, 2006, pp. 3937-3945. This article shows that for the bacterium studied, there may in fact be two intersections of the dielectric force direction relative to the frequency, and this can also be applied to biofilms that similarly comprise bacterial substances. These intersections are referred to as transition frequencies, and they are different for different particle types (e.g., different bacteria).

[0093] The present invention is based on the recognition that these properties of dielectrophoretic forces can be exploited in an oral care device with RF field generation, such as a toothbrush, to improve the movement of particles or the breakdown of biofilms for cleaning teeth or improving oral health.

[0094] The present invention utilizes intermittent generation of an electric field at least at a first RF frequency. There may also be a combination of RF frequencies, and these may optionally and additionally be synchronized with the frequency and amplitude of motion of the electrically vibrating toothbrush head. One possible purpose is to promote the removal of dental plaque by destroying the connection between particles (cells or colonies) and EPS. Particles (cells or colonies) may additionally be removed from hard-to-reach areas (e.g., removed from periodontal pockets). The movement of detergent particles may also be controlled.

[0095] The controller 10 provides, for example, an alternating drive signal between the electrodes 18a, 18b of each pair of electrodes to thereby induce a (non-uniform) alternating field between each pair of electrodes.The RF field may be used to perform an oral cleaning function and / or may be used to perform a function of directing particle movement.

[0096] The RF field may be used at any frequency in the range of, for example, 10 kHz-100 MHz. A preferred frequency range may be 500 kHz-30 MHz. It has been found that RF fields having frequencies in the order of 1 MHz (e.g., between 0.5 MHz and 1.5 MHz) are particularly effective in inducing motion of polarizable particles using the dielectrophoresis (DEP) effect.

[0097] Figure 4 Compare Figure 1 The schematic example of shows an example device in the form of a mouthpiece unit in more detail.

[0098] The device also includes a support 12 having a support surface 13, the support being intended to be received in the oral cavity of a user. The support is coupled to a handle portion 34 that houses the controller 10. In this example, the handle portion is shown as having an optional additional feature of a local reservoir 32 for holding detergent particles including an active agent or substance for delivery in the oral cavity. It is fluidly connected to the development surface of the device, for example via one or more fluid channels, so that in use the particles can be received on the surface in preparation for delivery.

[0099] Additionally or alternatively, the device may be adapted to releasably couple or dock an external container 36 (such as a bottle or other container). When docked, particles may be loaded from the container onto the support surface 13 to be ready for release in the mouth.

[0100] exist Figure 4 In the example of the invention, the device comprises a first arcuate electrode 18a and a second arcuate electrode 18b, which are radially spaced from each other (along the radial dimension of the arcuate or semi-annular support). The first electrode 18a extends close to and along the contour of the outer circumferential edge of the body 12. The second electrode 18b extends close to and along the contour of the inner circumferential edge of the body 12.

[0101] The two electrodes are connected to a voltage source 11 and are provided with voltages of opposite polarity. An alternating voltage is used to generate the RF field.

[0102] Figure 4 A separate voltage source 11 and controller 10 are shown in FIG. 1 . For example, the controller controls a driving scheme of the voltage source. However, in other examples, the controller 10 may provide the voltage source. The electrode pair 18a, 18b provides a field generator 16 in combination with the voltage source.

[0103] When the electrodes 18a, 18b are driven by an AC voltage source to generate an RF field in a manner explained in more detail below, the electrically polarizable particles 22 can be driven to migrate along the field gradient line (e.g., toward the smaller inner electrode 18b). In this case, the field gradient direction is a radial direction toward the second electrode, and the gradient is uniform along the circumferential direction. Therefore, the force is directed to the second electrode. Alternatively, the force can be applied to static particles in the biofilm to be removed, thereby decomposing the biofilm.

[0104] Figure 5 A further example oral cleaning device 8 is shown. This embodiment can be compared in all respects with the first and second electrodes 18a, 18b except that radially protruding electrode nodes 21 are additionally provided for each of the first and second electrodes 18a, 18b. Figure 4 The first electrode 18a includes a first set of nodes 21a that are spaced apart along the length of the electrode facing the second electrode 18b, and the second electrode 18b includes a second set of nodes 21b that are spaced apart and face the first electrode. The first and second sets of nodes are circumferentially offset from each other so that each node radially faces a node-free space on the other opposing electrode.

[0105] This pattern results in a non-uniform field, but where the field strength gradient guides the particles towards the locations of the nodes 21a, 21b. The nodes thus allow different force directions to be defined (e.g. including a lateral component). Alternatively, more localized particle collection points may be defined on the support surface 13, allowing the particles to be directed to more specific locations in the oral cavity when in use.

[0106] Figure 6 A further example oral cleaning device 8 is shown which is similar in all respects to the embodiment of the present invention except for the configuration of the first and second electrodes. Figure 4 and 5 In this example, the first electrode 18a and the second electrode 18b are provided in the form of arcuate cross electrodes. Each of the first electrode 18a and the second electrode 18b includes a set of protruding electrode fingers 19a, 19b. These effectively perform the same as in providing more spatially defined particle collection points. Figure 5 The node 21 of FIG. 1 has the same function as the node 21 of FIG. 1. When the electrodes 18a and 18b are driven with an alternating drive signal to generate an alternating field, the field intensity gradient is directed toward the electrode fingers 19a and 19b.

[0107] and Figure 5 Like the nodes of the first electrode 18a, the first electrode 18a includes a first set of fingers 19a which are spaced apart along the length of the electrode facing the second electrode 18b, and the second electrode 18b includes a second set of fingers 19b which are spaced apart and facing the first electrode. The first set of electrode fingers and the second set of electrode fingers are circumferentially offset from each other so that each finger radially faces the free space on the other opposing electrode.

[0108] The advantage of electrode fingers over nodes is that the field strength gradient is directed towards their distal (free) ends and the finger elements 19 can be made as long as required (in radial direction). Thus, the force pattern (and e.g. the location of particle collection) can be defined more flexibly.

[0109] Figure 7 An oral care device 8 is shown in the form of a toothbrush and shows an RF field generator 16 and its controller 10 for generating an input control signal "control" to control the generation of an electric field by application to electrodes 18. The electric field exerts a force on particles forming a biofilm to be removed by the oral care device or on particles of a cleaning agent.

[0110] The oral care device in this example comprises an electric toothbrush having a brush head 72 and a motor and drive train 74 for driving the brush head with a vibratory motion having a vibratory frequency. The controller 16 has suitable control electronics (such as a Schmitt trigger) to be able to switch between at least two different frequencies or apply a duty cycle to a single frequency. In all cases, there will be a cyclic control signal for intermittently generating an electric field having a first RF frequency, and the control signal may additionally control the generation at one or more additional frequencies.

[0111] In a first example, the controller 16 applies two RF fields of different frequencies on either side of the above-mentioned DEP switching point.Therefore, a conventional RF drive scheme (with a single frequency RF drive) is adapted to better exploit DEP.

[0112] The RF electrodes in this example are driven using two RF frequencies, one on each side of a threshold, which is the transition point between attraction and repulsion of polarized or polarizable particles.

[0113] For example, Figure 3 The DEP driving force shown above is explained as having a transition frequency of about 1 MHz. Suitable driving frequencies may then be 0.5 MHz and 5 MHz, or 100 kHz and 10 MHz, etc.

[0114] In addition to discrete frequencies, a frequency sweep can also be performed between two extreme frequencies if these extremes again span the switching frequency between positive and negative DEP.

[0115] Switching between frequencies should occur fairly quickly, for example once every few seconds or several times per second, or even hundreds of times per second, thus having a frequency between 0.1 Hz and 1 kHz.

[0116] This force direction reversal is particularly meaningful for applying force directly to biofilm particles. Thus, the force on the biological particles of the biofilm in the oral cavity will be reversed at this switching frequency. The particles will thereby be vibrated and loosened more effectively than if the force was maintained in the same direction.

[0117] Since there are many different bacteria mixed in dental plaque with different sizes and properties, the transition frequencies between bacteria will be different, as explained in "Dielectrophoresis as a Tool to Characterize anddifferentiate isogenic mutants of Escherichia coli" cited above. When using a frequency sweep as described above, there are many occasions, especially at frequencies near the transition frequency of a particular bacterial species present, where one bacterium will be attracted and the next will be repelled, thereby locally pulling the dental plaque apart.

[0118] In a second example, the controller 16 applies an RF field of only one frequency, but applies the field intermittently. Furthermore, the frequency of the cyclic control signal providing such intermittent field generation is preferably correlated to the vibrations in the toothbrush to better exploit DEP.

[0119] Specifically, a single RF frequency may be used, but switched on and off in a cycle that is synchronized with the frequency (or sub-harmonics of the frequency) of the brush head motion.

[0120] Figure 8 A cyclic control signal with a 50% duty cycle is shown (as one possible example, other duty cycles may be used), and one cycle corresponds to one oscillation cycle of the vibrating brush head motion. When the RF field is activated, there is a force on the polarizable particles (DEP force), and when the duty cycle is such that the RF field is deactivated, the force is zero.

[0121] For systems that deploy detergent particles, this can be used to control the movement of the particles. For example, when a toothbrush vibrates, the RF field is displaced in space (following the toothbrush movement because the electrodes are mounted on the brush head). Therefore, particles that are subjected to forces (e.g., from DEP) will be effectively captured by the force and move as the brush head moves.

[0122] If the RF is activated continuously, this will cause some vibration (in the direction of the brush motion) but will not cause any net movement of the particles. However, by applying this intermittent drive scheme, particles can be captured and moved during one part of the duty cycle (where the brush head moves in one direction), but released during another part of the duty cycle (where the brush head moves in the opposite direction). Thus, particles can be repeatedly moved in the same direction, rather than back and forth.

[0123] This situation is Fig. 9 . The DEP force generated by the RF electric field is shown as arrow 90 and the direction of motion is shown as arrow 92, where the DEP force acts in the same direction as the direction of the brushing motion imposed by the vibrating system. The bristles undergo bending and sliding motions. Reaction forces and friction forces are shown, which are in the order of mN.

[0124] Fig.10 A brush head 72 having a set of bristles 100 is shown for use with Fig. 9 Move the particles in the manner shown.

[0125] Since the vibration frequency can be quite high (on the order of several hundred Hz), this results in very fast movement of particles in one direction. This is particularly useful for removing bacteria from the subgingival area, especially from deeper periodontal pockets. Such periodontal pockets can be, for example, 5 mm deep, and bacteria are often loosely attached or even floating in the periodontal pocket fluid. In a specific pocket cleaning embodiment, the DEP force can be used to pull bacterial cells out of the pocket when synchronized with the brushing.

[0126] Depending on the position and orientation of the toothbrush (eg, upper or lower jaw), the DEP force may alternatively be synchronized with the downward sweep or with the upward sweep.

[0127] In a third example, the controller may implement the drive scheme by switching between two RF frequencies (as explained above for the first example), or applying a frequency sweep but in sync with the vibration frequency of the toothbrush (as explained above for the second example).

[0128] Thus, known RF drive schemes are suitable for providing cyclic control, but also better exploiting DEP in a manner that provides synchronization with vibrations in the toothbrush.The drive switches between at least two RF frequencies to induce positive and negative DEP at the frequency (or subharmonics of the frequency) of the brush head motion.

[0129] At the same time as the brush head motion changes direction, the DEP force on the particles thereby changes from positive to negative. If this is correctly synchronized, the force of the DEP and the force transmitted from the brush motion to the captured particles is always in the direction of the brush head motion.

[0130] Fig.11 Shows the Figure 7 The drive train current or voltage or amplitude signal is used as the synchronization and control signal 110 of the controller 10.

[0131] As mentioned above, the present invention is particularly concerned with the control of RF fields and the forces they generate, and these forces can be used to act directly on particles of biofilm to break up the biofilm, or they can be used to control the delivery of detergent particles.

[0132] Cleaner particles include, for example, oral cleaning treatments or treatment agents (such as fluoride, whitening agents, mouthwashes, or antimicrobial effective particles). The delivered reagents may also include catalytic antibacterial robots (CARs) in polarizable carrier capsules. These utilize iron oxide nanoparticles with catalytic functions to: (i) generate bactericidal free radicals, (ii) decompose biofilm exopolysaccharide (EPS) matrix, and (iii) remove broken biofilm fragments in a controlled manner via an electric field gradient driven robotic assembly to prevent biofilm regrowth. Any other substance for oral cleaning or treatment purposes may also be considered.

[0133] In order to most effectively utilize these agents, the agents need to be delivered evenly across the areas of the mouth where they are needed. For example, whitening agents need to be evenly dispersed on the surface of the teeth, and antimicrobial particles need to be evenly dispersed on portions of the gums. However, delivering agents to the portions of the mouth where they are needed is difficult and inefficient, which reduces their efficacy and causes inconvenience to the user.

[0134] Thus, the electric field may additionally be used to manipulate the distribution of particles comprising the oral treatment agent in the oral cavity.

[0135] The particles manipulated by the field can themselves be particles of an oral treatment agent, or can be carrier particles that contain the treatment agent to be deployed. For example, the particles can be capsules for containing the treatment agent. The particles can then be guided to move due to the force induced by the field on the particles. For example, in some cases, the particles can be guided to move along or across the surface 13 of the support 12 so as to deliver them to a desired location in the oral cavity.

[0136] The present invention may be used in systems using only RF for controlling the delivery of detergent particles.The present invention may alternatively be used in systems using only RF fields to apply force directly to biofilm particles.

[0137] In a system that uses RF fields to effectuate the delivery of detergent particles and uses RF fields to apply forces to the biofilm itself, the controller may then be selectively controllable between at least two different modes as follows:

[0138] a particle delivery mode in which the controller provides control signals to the field generator to generate a field for directing field-sensitive particles to a desired location in space; and

[0139] Cleaning mode, in which the controller provides the intermittent control signal as described above to the field generator to generate an RF field in the space for performing an oral cleaning function. This can be done simultaneously with the vibrating brushing function.

[0140] The device can be configured to have a function of triggering activation of the delivered particles. The activation can be a chemical or physical reaction process, or a process of decomposing the particles to trigger the release of their contents. For example, this step can be performed after moving the particles to the desired location in the oral cavity. Therefore, the device may also include a particle activator suitable for generating physical stimulation for stimulating activation events of the reagent particles. The particle activator is composed of the same or different components of the field generator. Therefore, in some examples, the particle activator can be provided by the field generator, or can be formed by a separate set of one or more components.

[0141] As non-limiting examples, the stimulation may include at least one of: a generated field (electrical and / or magnetic stimulation), thermal stimulation, and acoustic stimulation.

[0142] The examples of a toothbrush mouthpiece and an electric toothbrush are given above. However, the present invention can also be applied to other oral cleaning devices (such as irrigators or dental floss devices).

[0143] As described above, embodiments utilize a controller. A controller may be implemented in a variety of ways using software and / or hardware to perform the various functions desired. A processor is an example of a controller that employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform the desired functions. However, a controller may be implemented with or without a processor, and may also be implemented as a combination of dedicated hardware that performs certain functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) that performs other functions.

[0144] Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0145] In various embodiments, a processor or controller may be associated with one or more storage media, such as volatile and non-volatile computer memory (such as RAM, PROM, EPROM, and EEPROM). The storage media may be encoded with one or more programs that, when executed on one or more processors and / or controllers, perform the desired functions. The various storage media may be fixed within the processor or controller, or may be transportable so that one or more programs stored thereon may be loaded into the processor or controller.

[0146] Variations of the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0147] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0148] The computer program may be stored / distributed on appropriate media such as optical storage media or solid-state media provided together with or as part of other hardware, but may also be distributed in other forms such as via the Internet or other wired or wireless telecommunications systems.

[0149] If the term "suitable for" is used in the claims or the specification, it should be noted that the term "suitable for" is intended to be equivalent to the term "configured to".

[0150] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An oral care device (8), comprising: a field generator (16) adapted to generate an electric field (20) in the oral cavity of a user in response to an input control signal; a controller (10) adapted to generate the input control signal to control the generation of the electric field, wherein the electric field is used to apply a force to particles (22) forming a biofilm to be removed by the oral care device or to particles of a cleaning agent, wherein the controller is adapted to generate a cyclic control signal for alternately generating the electric field at a first RF frequency and a second RF frequency, wherein the first RF frequency is below a threshold frequency and the second RF frequency is above the threshold frequency, thereby generating dielectrophoretic forces on the particles in opposite directions, wherein the cyclic control signal is used to: generating a frequency switch between the first RF frequency and the second RF frequency; or A frequency sweep is generated between the first RF frequency and the second RF frequency.

2. The oral care device of claim 1, wherein the threshold frequency is 1 MHz.

3. An oral care device according to claim 1 or 2, wherein the frequency of the cyclic control signal is in the range of 0.1 Hz to 1 kHz.

4. The oral care device of claim 3, wherein the frequency of the cyclic control signal is in the range of 1 Hz to 100 Hz.

5. The oral care device of claim 1, further comprising: Brush head; as well as A motor is used to drive the brush head with a vibrating motion having a vibration frequency synchronized with the cyclic control signal.

6. The oral care device of claim 5, wherein the frequency of the cyclic control signal is equal to the vibration frequency, or a subharmonic of the vibration frequency.

7. The oral care device of claim 6, wherein the vibration frequency is in the range of 50 Hz to 1 kHz.

8. The oral care device of claim 5, 6 or 7, wherein the field generator (16) is coupled to the brush head to move with the brush head.

9. The oral care device according to claim 1 or 2, wherein the field generator is configured to generate a non-uniform electric field having a field intensity gradient in one or more directions for generating a force along the direction of the gradient.

10. An oral care device according to claim 1 or 2, wherein the field generator (16) includes one or more conductive elements (18) electrically coupled to the controller (10), and wherein the control signal is an electrical drive signal for energizing the one or more conductive elements.

11. A computer program product comprising computer program code, the computer program code being executable on a processor or a computer, wherein: When the processor or computer is operatively coupled to the field generator of the oral care device according to claim 1, the code is configured to cause the processor to perform a method of controlling the oral care device, the method comprising: generating a control signal to control the generation of an electric field in the oral cavity of a user, wherein the electric field is used to apply a force to particles (22) forming a biofilm to be removed by the oral care device or to particles of a cleaning agent, wherein the control signal comprises a cyclic control signal for alternately generating the electric field at a first RF frequency and a second RF frequency, wherein the first RF frequency is lower than a threshold frequency and the second RF frequency is higher than the threshold frequency, thereby generating dielectrophoretic forces on the particles in opposite directions, wherein the cyclic control signal is used to: generating a frequency switch between the first RF frequency and the second RF frequency; or A frequency sweep is generated between the first RF frequency and the second RF frequency.

Images