Related Applications

This application claims priority from United States provisional patent filing serial no. 62/088806, filed 08 Dec. 2014, the contents of which are here incorporated by reference.

Government Interest

None.

Technical Field

Our invention relates to a non-invasive way to prevent the noise of snoring or related obstructive sleep apnoea episodes in humans. We do this by using magnetic induction for nerve activation and muscle activation. Our invention appears particularly suitable for mild to moderate snoring, or for obstructive sleep apnoea, or for quickly identifying a potential occurrence of sudden infant death syndrome.

Background

It is well known that if a time-varying current is sent through a coil, a time-varying magnetic field will be generated. This magnetic field is able to induce an electric field, which can in turn activate human nerves located some distance from the coil. Thus, time-varying magnetic fields can stimulate peripheral muscles without the need for direct electrical stimulation of nerves or a surgically-invasive direct application of electrodes to nerves.

This means that nerve stimulation can be done non-invasively, and indeed can be done trans-cutaneously. If the electric field so induced is of sufficient amplitude (from about one to about ten Teslas) and duration (up to a few milliseconds), then neuromuscular tissue will be stimulated as with direct electrical stimulation of nerves using an invasive electrode.

Magnetic stimulation can pass through clothing and bone and other tissue. We believe that this makes stimulation of electrically-excitable tissues (nerve tissue or muscle tissue) with a time-varying magnetic field highly attractive, because the technique can be applied non-invasively and is virtually painless. According to Faraday's law of induction, time-varying magnetic fields generated by alternating current through a coil can activate nerves via induction of extracellular electrical fields and neuronal activation and later studies showed alternating power sources applied to a coil external to the skull could activate neurons within the brain by electromagnetic induction. See Park Hyun-Joo et al., Activation of the Central Nervous System 2013 NAT. COMMUN. (13 March 2014). However, this technology was not widely utilized until the 1980's when electronic and power source advances led to the development of more reliable systems. One is able to generate a muscle twitch response of the contralateral limbs by magnetic activation of cerebral cortex. See Barker AT et al., Non-Invasive Magnetic Stimulation Of Human Motor Cortex, 11 LANCET 1106 (1985).

Activation of nerves by the use of micro-coils is a development of magnetic induction. Transcranial magnetic stimulation is a stimulation method in which a magnetic coil generates a magnetic field in an area of interest in the brain. See Pashut T., et al, Mechanisms of Magnetic Stimulation of Central Nervous System Neurons, 7 PLoS COMPUT. BIOL. el002022 (2011). The magnetic field induces an electric field that modulates neuronal activity. Transcutaneous magnetic stimulation (TCMS) can also be used to activate nerves in other parts of the body. For example, time-varying magnetic fields can activate myelinated axons in peripheral nerves. An electrical current is most effective in depolarizing an axon to treshhold when the current is oriented along the longitudinal axis of the axon; a transversely- oriented current is much less effective. Thus, the most efficient use of electric power is to have the edge of a circular coil placed as near the nerve as possible and oriented longitudinally along the course of the nerve.

The basic design and mechanisms of magnetic peripheral nerve stimulators are well known. See e.g., Barker AT: An Introduction To The Basic Principles Of Magnetic Nerve Stimulation, J CLIN NEUROPHYSIOL 1991 , 8(l):26-37; Evans BA: Magnetic Stimulation Of The Peripheral Nervous System, J CLIN NEUROPHYSIOL 1991, 8(l):77-84; Jalinous R: Technical And Practical Aspects Of Magnetic Nerve Stimulation, J CLIN NEUROPHYSIOL 1991 , 8(1): 10-25, Amassian VE, Cracco RQ, Maccabee PJ: Basic Mechanisms Of Magnetic Coil Excitation Of Nervous System In Humans And Monkeys And Their Applications, IEEE SPECIAL SYMPOSIUM ON MATURING TECHNOLOGIES AND EMERGING HORIZONS (1988) 10-17.

The art teaches implantable electrical stimulation devices for relief of sleep apnea. See e.g., Douglas M. Mechlenburg et ah, US7367935 at Claim 1 ("A method of treating obstructive sleep apnea comprising: implanting a passive probe into target tissue").

Alternatively, non-implanted trans-cutaneous electrical nerve stimulation ("TENS") is used as a method of pain relief involving the use of a mild electrical current. A TENS machine is a small, battery-operated device that has leads connected to stick pads containing electrodes. The patient attaches the pads directly to the skin. When the machine is switched on, small electrical impulses are delivered to the affected area of the body, creating a tingling sensation. These electrical impulses are intended to reduce the pain signals going to the spinal cord and the brain, and thus help relieve pain and relax muscles. They may also stimulate the production of endorphins, which act as pain reducing neurotransmitters. There isn't enough good-quality scientific evidence to say for sure whether TENS is a reliable method of pain relief. More research is needed and clinical trials for TENS are ongoing. Healthcare professionals have reported that it seems to help some people, although how well it works depends on the individual and the condition being treated. TENS isn't a cure for pain and often only provides short-term relief while the TENS machine is being used. However, the treatment is generally very safe and patients may feel it's worth trying instead of, or in addition to, the usual medical treatments. The art, however, teaches to avoid using TENS on the neck. See e.g., www.nhs.uk/conditions/tens/Pages/Introduction.aspx ("Never 76 place the pads over: the front or sides of your neck"); www.shopcompex.com/user-

77 manual/warnings ("Stimulation should not be applied on the neck. Severe spasm of the

78 muscles may occur and the contractions may be strong enough to close the airway or cause

79 difficulty in breathing. Stimulation on the neck could also have adverse effects on the heart

80 rhythm or blood pressure."); www.livestrong.com/article/356315-what-is-the-effectiveness-

81 of-electric-muscle-stimulation-on-injuries/ ("There are many contraindications or reasons to

82 not use electrical stimulation. You should not use electrical stimulation if you have a

83 pacemaker or heart arrhythmias. This treatment also shouldn't be used over the throat and

84 side of the neck").

85 There remains, however, need for device which does not require insertion of an

86 electrode through the skin, i.e., one that is non- invasive, and which is, unlike TENS, suitable

87 for placement on the neck. The use of magnetic induction of nerve activation and muscle

88 activation as a therapeutic technique when applied to the neck and mouth region to treat

89 snoring and partial upper airway obstruction is unknown and forms part of the invention

90 hereby disclosed.

91 Brief Description of the Figures

92 Figure 1 provides a general schematic of our system.

93 Figure 2 provides a general schematic of the control circuitry our system.

94 Figure 3 illustrates exemplary signal decay from the circuit of Figure 2.

95 Figures 4 and 5 measure magnetic field strength vs distance.

96 In Figure 6 the components of an entire example of our system are described.

97 Figure 7 illustrates an embodiment of the invention miniaturised.

98 Figure 8 is an embodiment of Figure 6.

99 Figure 9 provides photographs of single and double coil configurations.

100 Figures 10 and 1 1 provide schematics of double and single coil configurations. 101 Figures 12 and 13 show possible placement configurations the user.

102 Detailed Description

103 One aspect of our invention is a device that includes a coil or micro-coil through

104 which electric current is passed to generate an electromagnetic field. The coil is placed

105 adjacent to (or adherent to) the skin of the face, jaw or neck, whereby the electromagnetic

106 field affects the tissues beneath the skin, and in so doing activates electrically-sensitive

107 nerves or muscles of the neck and mouth region. This has the effect of stimulating the

108 muscles controlling the tongue, soft palate or back of the throat, moving the muscle to

109 thereby open up the upper airway of the user of the device. This is schematically illustrated

110 in Figure 1 , where a battery (or equivalent electrical power source such as a capacitor or

111 transformer) feeds electrical current through a coil placed along the skin surface of the neck

112 or jaw. The coil induces a magnetic field oriented perpendicular to the skin surface, thus

113 penetrating the skin surface to stimulate a muscle (such as the palatoglossus) or nerve (such

114 as the hypoglossal nerve).

115 The voltage induced around a coil of any geometry placed in a magnetic field is

116 proportional to the rate of change of magnetic flux in that loop. If the magnetic field is

117 uniform accross the loop, this can be expressed as

118 V = -(AdB) / dt

119 where A is the area of the loop and B is the uniform magnetic flux density passing through it.

120 The total flux passing through the loop is the product of the magnetic flux density and the

121 loop area, where the magnetic flux density is measured in Teslas. The induced electric field

122 to which the induced current in a homogenous conducting object will be proportional, is

123 given by the total voltage around the loop, divided by the length of the loop. Thus, for a

124 circular loop, electric field is

125 E = -Α/2ΠΓ * dB/dt = -dB/dt * r/2 126 where r is the radius of the loop.

127 For a circular coil, the maximum induced electric field occurs in a loop of radius

128 approximately equal to that of the coil. The exact position of the maximum depends on the

129 geometry of the coil winding, and the distance from the coil plane. In the body, the

130 maximum also depends on non-homogeneous conductivity caused by various anatomical

131 structures and their various electrical anisotropy.

132 During discharge of the magnetic pulse, the coil may be subject to high voltage and

133 current, producing a large physical force acting on the coil. For example, the physically

134 larger prior art coils used to stimulate the brain used 3kV and lOkA, producing a 1,500 to

135 15,000 pounds per square inch force on the coil. Thus, not only must the coil be designed

136 carefully, but the requisite electrical insulation coating must also be suitable. For example, a

137 0.1mm thick polyester coating might suffice to insulate 3kV due to its high dielectric

138 strength, but during normal use could become damaged due to physical force.

139 To generate an electric field of amplitude large enough to cause neural stimulation in

140 vivo, one needs to generate a large magnetic field pulse. Power adequate to do this may be

141 obtained from a conventional alternating current power source. We prefer, however, to store

142 the electric power in a capacitor in a switched discharge circuit. A simplified exemplary

143 circuit is shown in Figure 2. With switch SI closed and switch S2 open, the energy storage

144 capacitor C is charged by applying voltage from a voltage source V. The voltage source may

145 be an external power source, or may be a power generator which transforms the patient's heat

146 energy or mechanical energy (from, e.g., the normal movement during sleep) into electric

147 power. The device is triggered by an appropriate signal; for example, a microphone or

148 vibration sensor which detects snoring sound or vibration. In response to this triggering

149 signal, switch S 1 is opened and switch S2 closed. Current then discharges from the capacitor

150 C to the stimulating coil LC, creating a magnetic field. 151 Diode D and resistor R may be used to modulate the magnetic field's subsequent

152 decay rate. Modulation is important because the electrical charge required to stimulate a

153 nerve is a function of the duration of the stimulus: short pulse durations lose less of their

154 energy through leakage via membrane resistance, so provide more efficient nerve stimulation.

155 Thus, a more rapid decay rate (as shown in Figure 3 [c]) is preferable to a slower decay rate

156 (as shown in Figure 3 [d]).

157 The two variables which can be readily controlled in the capacitor discharge circuit

158 are the rise in time to peak magnetic field and the subsequent rate of decay to zero. The

159 former is approximately proportional to the square root of the product of storage capacitance

160 times coil inductance, while the latter is approximately proportional to the square root of the

161 product of coil inductance times resistance.

162 In one embodiment the device may be placed on the skin beneath the jawbone to

163 activate the hypoglossal nerve. This may be achieved by using a circular coil, the most-

164 common and least expensive type of coil. A circular coil, however, produces circular

165 induced current loops with a maximum amplitude occurring at approximately the mean

166 diameter of the coil. Thus, all structures lying tangential to this mean diameter are all equally

167 stimulated.

168 To enable a more focused stimulation of the hypoglossal nerve while minimizing

169 stimulation of extraneous tissues, one may use a pair of coils arrayed in a figure-eight

170 configuration, wired such that the current in the first coil passes in an opposite direction to

171 that in the second coil. This configuration produces current loops which in vitro tend to add

172 below the position where the two coils approach each other. This induces currents two- to

173 three-times greater under the center of the double coil than under the outside edges of the

174 double coil, making stimulation more likely to occur in the center of the configuration than

175 elsewhere. This is illustrated in Figure 4. 176 The specific size of the coil will affect the depth of its effective magnetic field

177 strength. For example, a coil just large enough to stimulate the brain produces a magnetic

178 field which loses strength rapidly as depth increases. This is illustrated in Figure 5.

179 A larger coil diameter will produce a stronger magnetic field more deeply in the

180 patitne, yet suffers from being less comfortable, an important consideration in a sleep-apnea

181 or snoring prevention device.

182 In another embodiment the device may be placed on the skin near the upper end of the

183 neck to activate directly the muscles of the soft palate and the back of the throat to open up

184 the upper airway, increasing patency.

185 In another embodiment the device can incorporate a sensing device that detects

186 abnormal breathing: the sound of noisy breathing or snoring, for example, or the unexpected

187 absence of breathing sound (potentially indicative of the onset of sudden infant death

188 syndrome). If abnormal breathing is detected, then device activates the electrical current

189 through the coil, creating an electrical field which corrects the snoring, or which prompts

190 regular breathing.

191 In another embodiment the device incorporates a sensing device that picks up the

192 vibrations of snoring as the upper airway partially collapses with each breath.

193 In Figure 6 the components of an entire example of our system are described. Not all

194 components are essential for correct working of the invention. The essential elements are a

195 coil able to carry electrical current to generate a magnetic field having a South pole and a

196 North pole, a snore sensor [1] such as a nano microphone or snoring vibration sensor

197 powered by a power source [3], a switch [2] controlled by the snore sensor [1] and able to

198 turn current to the coil on or off, an electric power source [3] such as a battery (e.g., a nano-

199 battery), capacitor or transformer, and optionally a wifi chip [4] or equivalent communication

200 device powered by the power source [3] and capable of transmitting data on the use of the 201 system. The sensor could be, for example, a vibration sensor, a noise senor or a respiratory

202 effort sensor. In normal operation, the switch [2] rests in the open position, preventing

203 electric current fro passing through the coil. When the snore sensor [ 1 ] senses the vibration

204 or sound characteristic of snoring or sleep apnea, the sensor signals the switch [2], which

205 closes, providing electrical power to the coils adequate to generate a magnetic field adequate

206 activate nerves or muscles when applied to the area of the jaw or neck.

207 Figure 7 illustrates an embodiment of the invention miniaturised such that it is able to

208 be placed on the user's neck using a large size adhesive bandage. One variant of the

209 invention is that the entire system could be 3-D printed on a single flexible sheet.

210 Figure 8 is an embodiment of Figure 6 with the switch [2] disposed in a different

211 location.

212 Figure 9 provides photographs of single and double coil configurations. Figures 10

213 and 1 1 provide schematics showing how double and single coil configurations work,

214 optionally including a heat sink (e.g., a tube carrying water or air) or temperature cooler.

215 Figures 12 and 13 show the possible placement of the single and double coil

216 configurations on the user. The apparatus may be contained in, or held in place with, a

217 standard C-form neck pillow [5]. Alternatively the pillow could be thinner than a standard

218 pillow to make it more comfortable.

219 The skilled person will be able readily to identify possible alternative configurations

220 for the battery and/or power source for this invention. In one very simple alternative

221 configuration, the battery is a simple pre-charged power source.

222 The presence of a programmable chip enables more sophisticated monitoring to

223 include not only the timings of activation and the severity of the sensed signal that triggered

224 activation, but also documentation of the extent and severity of the snoring or obstructive

225 sleep apnoea, to enable medical professionals to monitor whether the patient is regularly 226 suffering. It could go further and set off a reminder or an alarm if a pre-programmed

227 threshold is reached, for example. The alarm can be local to the patient, or remote at control

228 centre, a medical centre or hospital. The chip can be programed to run different patterns,

229 frequencies or strengths of activation of the nerves or muscle. The signal can be sent

230 wirelessly to the cloud for computer storage by a variety of devices, as is known to one

231 skilled in the art.

232 It can be seen that the device is easy to use for people who are aware they snore or

233 people diagnosed as suffering from a variety of sleep disordered breathing patterns including

234 but not limited to obstructive sleep apnoea.

235 Some aspects of our invention are therefore:

236 1. A device comprising a sensor, a switch, a battery to generate an electrical current

237 and a metal coil or micro-coil through which an alternating or direct electrical current can be

238 passed, where the coil or micro-coil can be applied on or adjacent to the skin of the jaw, neck

239 or face of a human and left in place as he or she sleeps.

240 2. A device according to Paragraph #1 wherein the sensor is a microphone which

241 detects the noise of snoring.

242 3. A device according to Paragraph #1 wherein the sensor is a vibration sensor which

243 detects the vibrations in the throat as a result of partial, complete or intermittent obstruction

244 of the upper airway.

245 4. A device according to Paragraph #1 wherein the electrical current in the coil is

246 varying.

247 5. A device according to Paragraph #1 wherein the electrical current in the coil is

248 alternating current.

249 6. A device according to Paragraph #1 wherein the electrical current in the coil

250 generates an electromagnetic field. 251 7. A method wherein a device described according to any one of Paragraphs 1 to 6 is

252 placed on or near the skin of the neck or face region, either on one side or both, of a person to

253 generate a time varying magnetic field penetrating the neck and mouth region and thereby

254 activating the nerves and/or muscles around the neck, mouth and tongue with the effect of

255 activating the muscle of the tongue and palate to open up the upper airway of the person.

256 8. A method wherein a device described according to any one of Paragraphs 1 to 6 is

257 used to treat a person with sleep-related noisy breathing occasioned by obstruction or partial

258 obstruction of the upper airway.

259 9. A method wherein a device described according to any one of Paragraphs 1 to 6 is

260 used to activate the muscles of the tongue and/or soft palate and and/or throat to stop or

261 reduce the noisy breathing or snoring.

262 10. A method wherein a device described according to any one of Paragraphs 1 to 6

263 is used to treat a person with sleep-related obstructive sleep apnoea as would recognized by

264 one skilled on the art such as a physician or primary care doctor.

265 11. A method wherein a device described according to any one of Paragraphs 1 to 6

266 can be purchased by a person or a relative of a person so affected to treat him or herself of the

267 basis of being told they snore whilst asleep.

268 12. The method of Paragraph 8 wherein the noisy breathing is related to obstructive

269 sleep apnoea (OSA).

270 13. The method of Paragraph 8 wherein the battery is switched on by a device which

271 detects a noise characteristic of snoring in the patient.

272 14. The method of Paragraph 8 further comprising providing at least one sensor

273 which detects snoring or vibrations related to OSA and/or snoring providing the trigger to

274 switch on the battery to activate electrical current through the coil. 275 15. The method of Paragraph 8 wherein the battery and coil are placed in a device

276 placed adjacent to skin of the neck region.

277 16. The method of Paragraph ί wherein the battery and coil are printed on a flexible

278 3-D printed material.

279 17. The method of Paragraph 8 wherein material is adhesive and can be attached to

280 the skin of the neck or face.

281 18. The method of Paragraph 8 wherein the battery is rechargeable.

282 19. The method of Paragraph 8 wherein the battery is pre-charged.

283 20. The method of Paragraph 8 wherein the battery is charged by movement of the

284 neck.

285 21. The method of Paragraph ί > wherein the battery is charged by the heat of the skin

286 surface.

287 22. The method of Paragraph 8 wherein some of the components are 3-D printed on a

288 flexible sheet.

289 23. The method of Paragraph 8 wherein all of the components are 3-D printed on a

290 single flexible sheet.

291

292