WO2021101441A1

WO2021101441A1 - Electrode design for the delivery of electrical stimuli

Info

Publication number: WO2021101441A1
Application number: PCT/SG2020/050651
Authority: WO
Inventors: Pravar JAIN; Wai Tung CHOW; Ching-Chiuan YEN
Original assignee: National University Of Singapore
Priority date: 2019-11-21
Filing date: 2020-11-12
Publication date: 2021-05-27

Abstract

This invention relates to a sensory stimulation system comprising a surface comprising a stimulation area, and a plurality of electrodes distributed across the stimulation area, the plurality of electrodes comprising a plurality of first electrodes and a plurality of second electrodes having opposite polarity to the first electrodes.

Description

ELECTRODE DESIGN FOR THE DELIVERY OF ELECTRICAL STIMULI

TECHNICAL FIELD

The present invention relates to an electrode design for the delivery of electrical stimuli to elicit gustatory perception.

BACKGROUND

In recent years, there has been a growing interest in the potential benefits and new applications that may be afforded by incorporating digital flavor augmentation technologies into traditional eating and drinking experiences. The sense of taste is a core mechanism that directly affects all flavor experiences. The sensation of taste is considered as the final frontier of virtual reality technologies. Using digital taste technology, a whole new set of interactions can be introduced to the virtual reality domain, that are based on the sensation of taste.

Digital Taste Interface is a system that aims to simulate primary taste sensations by applying electrical and thermal stimulation to the human tongue. Based on the proposed experimental results, participants were able to perceive sour, salty, bitter, and sweet tastes whilst using the system. Similarly, work has been proceeding on creating virtual lemonade present interactive platforms that aim to enhance drinking experiences by combining techniques for superimposing colors onto beverages and stimulating the user's taste buds via electrical pulses controlled by a Pulse Width Modulation (PWM) based technique.

It has also been demonstrated that the use of electricity for augmented gustation can be achieved by applying an electric current through isotonic drinks (containing electrolytes) and food (vegetables, fruits, and cheese) in order to change their taste characteristics. One potential issue here is that unwanted reduction-oxidation reactions may occur as a consequence of applying an electric current through different liquids (through electrolysis). Despite the intriguing results that have been produced from these methods of electrical and thermal stimulation, many of these studies also outline key challenges associated with this approach, including unwanted sour and metallic tastes produced by electric taste stimulation and the general inconsistency of effects between users.

It is generally desirable to overcome or ameliorate one or more of the above described difficulties, or to at least provide a suitable alternative. SUMMARY OF THE INVENTION

Presently disclosed herein is a sensory stimulation system, comprising: a surface comprising a stimulation area; and a plurality of electrodes distributed across the stimulation area, the plurality of electrodes comprising a plurality of first electrodes and a plurality of second electrodes having opposite polarity to the first electrodes.

The plurality of first electrodes and the plurality of second electrodes may alternate across the stimulation area. The plurality of electrodes may be distributed evenly across the stimulation area. The electrodes may be distributed across the stimulation area such that stimulation travels between electrodes in at least two directions.

The sensory stimulation may comprise at least one first trace along which two or more said first electrodes are disposed and at least one second trace along which two or more said second electrodes are disposed. The first electrodes may be offset, along the at least one first trace, relative to the second electrodes.

The electrodes may have a tessellating shape. Edges of the electrodes may be straight. The electrodes may be diamond-shaped. A distance between the edges of neighbouring ones of said first electrodes and second electrodes may be consistent.

The plurality of electrodes may be arranged so that the traces do not intersect over the stimulation area. Each first electrode may be an anode, and each second electrode may be a cathode. The electrodes may be spaced across the stimulation area to vary a concentration of stimulation across the stimulation area. An electrical charge applied through at least one said electrode may be controllable independently of an electrical charge applied through another said electrode. An electrical charge of each electrode of the plurality of electrodes may be independently controllable.

Disclosed herein is also a sensory stimulation bowl comprising a rim region on an external surface of the bowl, the rim region comprising the disclosed sensory stimulation system. The first electrodes and second electrodes may be arranged circumferentially around the bowl. The plurality of electrodes may alternate along an axis of the bowl.

Disclosed herein is also a sensory stimulation cutlery comprising a rear, convex surface, the rear, convex surface comprising the disclosed sensory stimulation system. The cutlery may be one of a spoon, fork, spork and chopsticks. The cutlery being one of a spoon and fork, may comprise a plurality of tines, and a sensory stimulation system according to any one of 1 to 15 disposed at least partially along the tines. Neighboring tines may support electrodes of opposite polarity.

Disclosed herein is also a sensory stimulation crockery, comprising the disclosed sensory stimulation system.

Disclosed herein is also a sensory stimulation drinking vessel, comprising the disclosed sensory stimulation system.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments will now be described, byway of non-limiting example only, with reference to the accompanying drawings in which:

Figure 1A illustrates one embodiment of the sensor stimulation system for the delivery of electrical stimuli;

Figure 1 B illustrates a stimuli field stimulation of the sensor stimulation system in Figure 1 A; Figure 2 illustrates a usage scenario of the sensor stimulation system;

Figure 3 illustrates one example user interface of a mobile application; and

Figure 4A illustrates embodiment of eating utensils/cutlery with the sensor stimulation system.

DETAILED DESCRIPTION

Sensory stimulation systems disclosed herein facilitate the delivery of electrical stimuli to elicit gustatory perception. The sensory stimulation system is applied to stimulate particular sensory receptors in the mouth, for example, to simulate a salty or sweet taste. The sensory stimulation system may be used to treat xerostomia, impaired taste (cancer patients/low sodium or acidic diets/elderly etc.), alcohol addiction, obesity and weight-loss, diabetes and prediabetes, and in general consumer experience/entertainment and flavor development.

A sensory stimulation system 100 is described with reference to Figure 1A. The sensory stimulation system 100 can be inserted into the mouth of the user and used to stimulate part of the user's mouth - e.g. the tongue or a predetermined portion of the tongue. The sensory stimulation system 100 broadly comprises a surface 102 and a plurality of electrodes 104. The surface 102 comprises a stimulation area - the stimulation area is the area over which stimulation occurs when that area is brought into with the user, e.g. with the user's tongue. The surface 102 may a be curved or flat surface. The electrodes 104 are distributed across the stimulation area. When in use, the electrodes can be incorporated on flat as well as curved surfaces based on the fabrication feasibility, chosen materials and the design of the body the user will place in their mouth - e.g. a spoon, bottle neck, fork etc. By distributing the electrodes across the stimulation area, the present design enables a large effective contact surface area to be created for stimulation.

Figure 2 shows a usage scenario of the sensor stimulation system. The sensor stimulation system 100 herein simulates beverage flavors based on the digital taste stimulation on the tongue. To deliver digital taste, said electrodes 104 are incorporated into or mounted on/around the rim of a beverage container 202. The rim will contact the user's tongue during consumption of the beverage. The electrodes 104 are attached to the rim or mouthpiece (i.e. in each case, the portion of the body that comes into contact with the user's mouth, and through which the user's mouth is desired to be stimulated) to simulate sourness/saltiness/bitterness by electrically stimulating the user’s tongue. Users simply touch the electrodes using their tongues while drinking to simulate the sourness/saltiness/bitterness or other desired taste sensation.

The sensor stimulation system may be similarly implemented in mugs and drinking glasses. In each case, by electrically stimulating taste, the foods and drinks being consumed can be modified - e.g. made healthier. For example, by electrically stimulating a sweet taste, rather than adding sugar to food or drink, the present stimulation system could make low-sugar drinks taste sweeter and thereby help people reduce sugar intake.

Once a user places their tongue on the electrodes 104, the circuit completes or closes. Electric waves from anodal current are then applied to taste buds as the current travels between anodes and cathodes. In some embodiments, the waves may contain two voltage values: 2V (on) and 0 (off), and the corresponding frequency is fixed at 490Flz. Different duty cycles can be applied for pulse-width modulation (PWM) wave, resulting in different taste modes. Following example settings can be used to deliver three different electric tastes:

• Sour: magnitude of current: 180mA, PWM duty cycle: 67%;

• Salty: magnitude of current: 40mA, PWM duty cycle: 20%;

• Bitter: magnitude of current: 80mA, PWM duty cycle: 43%.

The sensor stimulation system 100 can work together with a control system 204 placed at the base of the beverage container 202 - in other embodiments, the control system forms part of the sensor stimulation system. The sensor stimulation system 100 acts as an interface between the control system and the tongue. Said control system has several submodules for electrical stimulation, communication, and the power management. A constant current source is implemented to maintain constant current levels for all the participants in the electrical stimulation submodule - this type of electrical architecture will be understood by the skilled person in view of present teachings. As shown in Figure 3, the control system communicates with a mobile application 300 used to enable users to control stimulation to modify taste sensation provided by the stimulation system. In particular, the app may be used to craft virtual flavors by remotely controlling the system’s relative intensity levels. Play and stop buttons on the left and right sides of the user interface are used to “play” and “stop” the stimulation in the system. The interface includes buttons 302, 304 and 306, for controlling at least one of taste, colour and scent of a food product, during creation of an experience - e.g. drinking a cocktail with virtual stimulation overlaid onto the drinking experience - with buttons 308, 310 and 312 enabling control of at least one of sour, salty and bitter taste stimulation. Each parameter may be simply Boolean - e.g. ON or OFF - or may be amplitude controllable using, e.g., a slider. Figure 3 also shows an app interface 314 for control of stimulation itself. There may be any number of buttons for controlling respective ones of taste, colour, scent, sour, salty, bitter, aroma combinations etc, and all such variations, from one button to any necessary number, are encapsulated by the present disclosure. In addition, there may be parameters other than taste, colour and aroma that are provided for, including combinations of parameters - e.g. a single button may create the experience of a particular drink, including predefined taste stimulation, colour and aroma.

The interface 314 includes a channel selector, enabling the electrodes to be grouped into one or more channels, of which there are presently two (316, 318). Each channel can accept different stimulation parameters and therefore stimulate different areas of the tongue in different ways. Thus, the stimulation area can comprise a plurality of stimulation sub-areas. The stimulation for each sub-area is separately controllable. For each channel 316, 318, there is a stimulation waveform selector (e.g. square wave, sinusoidal wave and other waveform profiles as desired or created for a particular application). For each channel 316, 318 there is also at least one of, and presently each of, a waveform amplitude field, frequency field and duty cycle field. Each said field can be controlled separately - e.g. by a slider.

As shown in Figure 1 A, the plurality of electrodes 104 comprises a plurality of first electrodes 106 and a plurality of second electrodes 108. The second electrodes 108 have opposite polarity to the first electrodes 106. In some examples, each first electrodes 106 is an anode and each second electrode 108 is a cathode. Stimuli can be applied by attaching or touching the electrodes to the tongue. The tongue makes contact between the first and second electrodes and thus electricity passing between those electrodes passes through, and stimulates, the tongue.

The dimensions for the electrodes are selected to fit onto the user’s tongue effortlessly and comfortably. In some embodiments, pure silver electrodes are chosen to be used since silver has high electrical conductivity.

Although it may be enough to use only one pair of parallel strips (traces) of electrodes (i.e. a cathode and an anode) to deliver the electrical stimuli and evoke the perception of certain tastes, increasing the number of traces, and thus electrodes, can provide distinct advantages. The more electrodes there are, the larger the effective contact area for stimuli delivery will be. In fact, it has been scientifically demonstrated that all taste sensations come from all regions of the tongue, and different parts are more sensitive to certain taste. Higher resolution can be achieved by delivering stimuli at multiple points, using multiple electrodes simultaneously. By using a larger number of smaller traces the electrode density increases and the stimulation area is more consistently or uniformly stimulated.

The plurality of first electrodes 106 and the plurality of second electrodes 108 may alternate across the stimulation area. As shown in Figure 1A, the electrodes 106 and 108 are organized such that the electrodes with opposing polarity (i.e. the anodes and cathodes) are alternated along both the horizontal and vertical axis. This provides a relatively consistent stimulation pattern as shown in Figure 1 B - the electrode layout design provides a radiating distribution of electrical stimulation. This also ensure stimulation applies relatively evenly in multiple directions on the tongue, which can make the stimulation feel more realistic since food and drink tend to stimulate areas of the tongue, rather than parallel lines along the tongue.

One of the functions of said digital taste technology with the proposed stimulation system is to afford delivery of stimuli of higher intensity. In some occasions, the intensity of the virtual stimulation produced by the simulator can be much weaker than the real sensations including sourness/saltiness/bitterness. There are two reasons for this phenomenon. First, the perception of the sour/salty/bitter taste and their intensity through electrical stimulation on the tongue may be weakened by water or saliva. Second, participants may perceive mixed sensations, for example, higher sweetness or saltiness due to the color change and other cross-modal effects. The traditional approach to increase the intensity of virtual taste is to utilize a stronger electrical pulse, for instance. However, simply using stronger electrical pulses can cause unnecessary tingling, thus reducing the user’s comfort. Moreover, such an effect would not be caused by the food or drink the user is consuming, and therefore makes the taste sensation less realistic. Through the above electrode layout design of the present stimulation systems, a radiating distribution of stimuli density can not only afford delivery of stimuli of higher intensity, but also ensure the user’s comfort brought by stimuli diffusion across an area. This is particularly the case for tessellating electrode shapes as discussed below.

The plurality of electrodes may be distributed evenly across the stimulation area. For example, the distance between neighboring electrodes may be consistent such as is shown in Figure 1 . Such uniform distribution allows different parts of the tongue to be equally stimulated, and also makes it easier to control and estimate the intensity level of the stimuli applied to a specific position on the tongue. For example, as shown in Figure 1 B, when the electrodes are evenly distributed, it is easy to determine that the stimuli intensity is highest at the midpoint of the two neighboring electrodes with the same polarity, and is weakest at the point of each electrode. It is important to accurately control the intensity level. When in use, the stimuli should not exceed a certain limit since it may cause a faradaic reaction between electrodes. In some occasions, higher stimuli intensity levels may even cause a tingling sensation or metallic taste on the tongue.

The electrode traces (e.g. traces 11 , 114) may instead be non-uniformly distributed across the sensory stimulation area. This can be useful when endeavouring to stimulate a specific taste sensation that is strongest at a particular region of the tongue. For example, the front of the tongue is particularly sensitive to sweet tastes. A spoon incorporating the present sensory stimulation system, may have a higher concentration of traces and electrodes towards the handle of the spoon when compared with the tip of the spoon, such that stimulation provided across the electrodes is concentrated on the front of the tongue, in use.

The plurality of electrodes are distributed across the stimulation area such that the sensory stimulation travels between electrodes in at least two directions. The electrodes 106 and 108 are segmented into horizontal rows/vertical columns. Figure 1A shows that neighbouring electrodes with the same polarity in each horizontal row are connected together by strips (herein interchangeably referred to as 'traces") 110. The strips are made of conductive material, and form relatively narrow rectangles. In some examples, the strips 110 are separated from the first/second electrodes by a dielectric material. In Figure 1A, the sensory stimulation travels through said strips horizontally. In particular, the sensory stimulation comprises at least one first trace 112 along which two or more said first electrodes 106 are disposed and at least one second trace 114 along which two or more said second electrodes 108 are disposed. The electrodes 106 and 108 are segmented into rows/columns such that the anodes and cathodes are offset with respect to each other. As shown in Figure 1A, the first electrodes 106 are offset, along the at least one first trace 112, relative to the second electrodes 108. It can be desirable that the electrodes with same polarity that are arranged in vertical columns do not come into direct electrical contact with each other, and the electrodes in each vertical column are not connected together by strips 110. Although not shown in Figure 1A, it will be appreciated that the electrodes in each vertical column may also be connected together by strips of the conductive material. In that occasion, the sensory stimulation may also travel vertically between neighboring electrodes with the same polarity in each vertical column. Each electrode may also be connected with its neighboring electrodes with the same polarity in both horizontal row and vertical column such that sensory stimulation can travel between electrodes horizontally and vertically, simultaneously.

An electrode design (refer Figure 1A) is used for the delivery of digital taste stimuli characterized by recurring two-dimensional (2D) electrodes. Each electrode has a tessellating shape - each edge of each electrode has the same profile as an edge of a neighbouring electrode. This ensure a distance between the edge of one electrode and the edge of a neighbouring electrode of opposite polarity is consistent along the length of those edges. Edges of the electrodes may be straight. The present design uses a diamond electrode pattern - if the diamonds were brought together, they would be tessellating or interlocking. The electrodes include a single layer of transparent conductive material arranged in a pattern of diamond-shaped electrodes 106 and 108. It will be appreciated that the electrodes may also have a triangle shape or a rectangular shape or other shape as needed.

The features of such 2D diamond shaped electrodes design described herein provide several advantages. First, providing a plurality of electrodes with only a single layer of conductive material may reduce the cost and complexity of the manufacturing process. Second, such design enables a large projection of stimuli field. In some embodiments, such design permits variation in electrode size and pitch, thus enables optimization for different applications. Third, the use of the diamond shaped electrodes reduce pin point intensity of stimuli. Fourth, such diamond shaped electrodes can bring in widespread taste perception by spreading across the surface of the tongue. Last but not least, such design also reduces tingling sensations and metallic taste by avoiding the requirement for large stimulation currents to make stimulated taste perceivable.

As shown in Figure 1A, the distance between the edges of neighboring ones of said first diamond shaped electrodes 106 and second diamond shaped electrodes 108 is consistent. Figure 1 B shows that such design allows different parts of the tongue to be equally stimulated, and also makes it easier to control and estimate the intensity level of the stimuli applied to a specific position on the tongue. For example, as shown in Figure 1 B where the distance between the edges of neighboring ones of said first diamond shaped electrodes 106 and second diamond shaped electrodes 108 is consistent, it is easy to estimate the stimuli intensity at the point between two neighboring electrodes with opposing polarity. It is important to accurately estimate and control the intensity level. If the stimuli intensity exceeds a certain limit, may cause faradaic reaction between electrodes. In some occasions, higher stimuli intensity levels may even cause a tingling sensation or metallic taste on the tongue.

The plurality of electrodes may be arranged so that the traces 112 and 114 do not intersect over the stimulation area. The electrodes may be spaced across the stimulation area to vary a concentration of stimulation across the stimulation area - for example, the electrodes or traces may be sparse at some areas and dense at other areas. Electrodes may also be non- uniformly distributed along a trace. Alternatively, or in addition, an electrical charge applied through at least one said electrode may be controllable independently of an electrical charge applied through another said electrode. An electrical charge of each electrode of the plurality of electrodes may be independently controllable. This enables some traces or electrodes to produce greater stimulation than others, to change the taste effect when compared with uniform stimulation across the stimulation area.

Based on the fabrication feasibility with chosen materials, the proposed electrode design can be incorporated on flat as well as curved surface. Figure 4A shows an example sensory stimulation bowl 402 comprising a rim region on an external surface of the bowl, the rim region comprising the disclosed sensory stimulation system. The bowl 402 may also be a sensory stimulation drinking vessel. The first electrodes and second electrodes 106 and 108 may be arranged circumferentially around the bowl. The plurality of electrodes may alternate along an axis of the bowl. To deliver digital taste, said electrodes 106 and 108 are mounted to the rim of the bowl 402, where users are instructed to place their tongue when drinking the beverage. For bottles and other vessels or crockery, electrodes may be attached to the mouthpiece or rim to simulate sourness/saltiness/bitterness by electrically stimulating the user’s tongue. Users may simply touch the electrodes using their tongues while drinking to simulate the sourness/saltiness/bitterness.

Figure 4B shows sensory stimulation cutlery 407 comprising a rear, convex surface, the rear, convex surface comprising the disclosed sensory stimulation system. The cutlery 407 may be one of a spoon, fork, spork or chopsticks. The cutlery 407 being one of a spork and a fork may comprise a plurality of tines 406, and the sensory stimulation system 100 may be disposed at least partially along the tines as shown. The plurality of electrodes may alternate along an axis or length of the tines. However, as shown in Figure 4A, neighbouring tines 406 support electrodes 106 and 108 of opposite polarity. It will be appreciated that many further modifications and permutations of various aspects of the described embodiments are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this specification relates.

Claims

1. A sensory stimulation system comprising: a surface comprising a stimulation area; and a plurality of electrodes distributed across the stimulation area, the plurality of electrodes comprising a plurality of first electrodes and a plurality of second electrodes having opposite polarity to the first electrodes.

2. The sensory stimulation system of claim 1 , wherein the plurality of first electrodes and the plurality of second electrodes alternate across the stimulation area.

3. The sensory stimulation system of claim 1 or 2, wherein the electrodes are distributed across the stimulation area such that stimulation travels between electrodes in at least two directions.

4. The sensory stimulation system of claim 3, comprising at least one first trace along which two or more said first electrodes are disposed and at least one second trace along which two or more said second electrodes are disposed.

5. The sensory stimulation system of claim 4, wherein the first electrodes are offset, along the at least one first trace, relative to the second electrodes.

6. The sensory stimulation system of any one of claims 1 to 5, wherein the electrodes have a tessellating shape.

7. The sensory stimulation system of claim 6, wherein edges of the electrodes are straight.

8. The sensory stimulation system of claim 7, wherein the electrodes are diamond-shaped.

9. The sensory stimulation system of claim 7 or 8, wherein a distance between the edges of neighbouring ones of said first electrodes and second electrodes is consistent.

10. The sensory stimulation system of claim 4, wherein the plurality of electrodes are arranged so that the traces do not intersect over the stimulation area.

11 . The sensory stimulation system of any one of claims 1 to 10, wherein each first electrode is an anode and each second electrode is a cathode.

12. The sensory stimulation system of any one of claims 1 to 11 , wherein the electrodes are spaced across the stimulation area to vary a concentration of stimulation across the stimulation area.

13. The sensory stimulation system of any one of claims 1 to 12, wherein an electrical charge applied through at least one said electrode is controllable independently of an electrical charge applied through another said electrode.

14. The sensory stimulation system of any one of claims 1 to 13, wherein an electrical charge of each electrode of the plurality of electrodes is independently controllable.

15. A sensory stimulation bowl comprising a rim region on an external surface of the bowl, the rim region comprising a sensory stimulation system according to any one of claims 1 to 14.

16. The bowl of claim 15, wherein the first electrodes and second electrodes are arranged circumferentially around the bowl.

17. The bowl of claim 15 or 16, wherein the plurality of electrodes alternate along an axis of the bowl.

18. A sensory stimulation cutlery comprising a rear, convex surface, the rear, convex surface comprising a sensory stimulation system according to any one of claims 1 to 14.

19. The cutlery of claim 18, being one of a spoon, fork, spork and chopsticks.

20. The cutlery of claim 19, being one of a spoon and fork, comprising a plurality of tines, and a sensory stimulation system according to any one of claims 1 to 14 disposed at least partially along the tines.

21. A sensory stimulation fork of claim 19, wherein neighboring tines support electrodes of opposite polarity.

22. A sensory stimulation crockery, comprising a sensory stimulation system according to any one of claims 1 to 14.

23. A sensory stimulation drinking vessel, comprising a sensory stimulation system according to any one of claims 1 to 14.