Patent Publication Number: US-11654045-B2

Title: Methods and devices for treating sleep apnea

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is directed generally to methods and devices for treating sleep apnea. 
     Description of the Related Art 
     All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. 
     Obstructive sleep apnea (“OSA”) is a chronic disease of upper airway collapse during sleep. Prevalence is estimated from as low as 1-4% of adults, to 15% of women and 30% of men, an enormous health burden, costing at least $25 B/yr today. See Virk et al., “When Continuous Positive Airway Pressure (CPAP) Fails,”  J Thorac Dis;  8(10):E1112-21 (2016), Young et al., “Burden of Sleep Apnea: Rationale, Design, and Major Findings of the Wisconsin Sleep Cohort Study,”  WMJ;  108:246 (2009), and Peppard et al., “Increased Prevalence of Sleep-Disordered Breathing in Adults,”  Am J Epidemiol;  177:1006 (2013). With an increasingly obese population, prevalence of OSA is increasing in parallel, including in children, contributing to pediatric metabolic syndrome. See Van Eyck et al., “Sleep-Disordered Breathing, Systemic Adipokine Secretion, and Metabolic Dysregulation in Overweight and Obese Children and Adolescents,”  Sleep Med;  30:52-56 (2017), and Li et al., “Pediatric Sleep Apnea Syndrome: An Update.”  J Allergy Clin Immunolol Pract;  4(5):852-861 (September/October 2016). 
     Major risk factors include advanced age, male sex, obesity, craniofacial or upper airway soft tissue abnormalities. Pathophysiology of intermittent upper airway (“UA”) obstruction, or collapse of the pharyngeal airway, despite ongoing respiratory effort, is a function of both the physiology of sleep and UA mechanics. See Danny J. Eckert, “Phenotypic Approaches to Obstructive Sleep Apnoea—New Pathways for Targeted Therapy,”  Sleep Med Rev, pii: S 1087-0792(16)30154-X, Epub ahead of print, &lt;http://dx.doi.org/10.1016/j.smrv.2016.12.003&gt; (Dec. 18, 2016). UA factors include the effectiveness of genioglossus muscle function. See Subramani et al., “Understanding Phenotypes of Obstructive Sleep Apnea: Applications in Anesthesia, Surgery, and Perioperative Medicine,”  Anesth Analg;  124(1):179-191 (2017). 
     Diagnosis of OSA is made by documenting hypopneas or apneas during sleep with polysomnography testing, and a history of daytime symptoms. See Young et al., “The Occurrence of Sleepdisordered Breathing Among Middle-Aged Adults,”  N Engl J Med,  328(17):1230-5 (1993). Increasingly, due to cost, portable monitors are used for diagnosis and wearables are entering this space. See Kundel et al., “Impact of Portable Sleep Testing,”  Sleep Med Clin;  12(1):137-147 (2017), Garde et al., “Identifying Individual Sleep Apnea/Hypoapnea Epochs Using Smartphone-Based Pulse Oximetry,”  Conf Proc IEEE Eng Med Biol Soc,  3195-3198 (2016), and Puri et al., “Design and Preliminary Evaluation of a Wearable Device for Mass-Screening of Sleep Apnea,”  Conf Proc IEEE Eng Med Biol Soc,  1870-1873 (2016). 
     Most OSA is considered mild to moderate. The American Academy of Sleep Medicine (AASM) defines mild OSA as an apnea-hypopnea index (“AHI”) of 6-14 events per hour; moderate OSA as an AHI of 15-30 events per hour; and severe OSA as an AHI of greater than 30 events per hour. See American Academy of Sleep Medicine,  International Classification of Sleep Disorders,  3rd ed, American Academy of Sleep Medicine, Darien, Ill. 2014. 
     Nevertheless, OSA results in daytime somnolence, poor cognitive performance, depression, sympathetic activation, and increased morbidity from cardiac disease including heart failure, arrhythmias, and stroke. See Lang et al., “Associations of Undiagnosed Obstructive Sleep Apnea and Excessive Daytime Sleepiness with Depression: An Australian Population Study,”  J Clin Sleep Med , pii: jc-00336-16, Epub ahead of print (Jan. 11, 2017), Ljunggren et al., “Increased Risk of Heart Failure in Women with Symptoms of Sleep-Disordered Breathing,”  Sleep Med,  17:32-37 (January 2016), and Javaheri et al., “Sleep Apnea: Types, Mechanisms, and Clinical Cardiovascular Consequences,”  J Am Coll Cardiol,  69(7):841-858 (Feb. 21, 2017). 
     While OSA is common, its treatment options are limited and currently available treatment options for OSA are sub-optimal. For example, continuous positive airway pressure (“CPAP”), including nasal CPAP, is the standard therapy and overall the best non-surgical treatment, but does not cure OSA. CPAP works by forcing sufficient pressure into the airway to stent it open. CPAP is often not well-tolerated leading to poor compliance. For example, CPAP complications include dry nose, dry mouth, dry throat, eye irritation, face irritation, and abdominal bloating. Further, meta-analyses show that while CPAP positively affects quality of life, CPAP does not significantly reduce OSA-related mortality. See Jonas et al., “Screening for Obstructive Sleep Apnea in Adults: Evidence Report and Systematic Review for the US Preventive Services Task Force,”  JAMA,  317(4):415-433 (2017). Improved CPAP modes with customized masks, humidified air, and/or automatic pressure adjustment can help with compliance. See Tomasz J. Kuzniar, “New Approaches to Positive Airway Pressure Treatment in Obstructive Sleep Apnea,”  Sleep Med Clin,  11:153-159 (2016). 
     Another example includes mandibular advancement devices (“MADs”), which are useful in some OSA patients with milder disease who do not tolerate CPAP. See Kuhn et al., “Effects of CPAP and MADs on Healthrelated Quality of Life in OSA: A Systematic Review and Meta-Analysis,” Chest, pii:S0012-3692(17)30038-7, doi: 10.1016/j.chest.2017.01.020, [Epub ahead of print] (2017), and Lim et al., “Oral Appliances for Obstructive Sleep Apnoea,”  Cochrane Database Syst Rev,  1:CD004435 (2006). However, MADs overall clinical and cost-effectiveness have been questioned in meta-analyses. See McDaid et al., “Continuous Positive Airway Pressure Devices for the Treatment of Obstructive Sleep Apnoea—Hypopnoea Syndrome: A Systematic Review and Economic Analysis,” Health Technol Assess, 13(4), http://dx.doi.org.3310/hta13040 (2009). Unfortunately, MADs can cause jaw discomfort, gum discomfort, mouth discomfort, tooth damage, and mouth ulcers. See Sharples et al., “Clinical Effectiveness and Cost-Effectiveness Results from the Randomized Controlled Trial of Oral Mandibular Advancement Devices for Obstructive Sleep Apnoea-Hypopnoea (TOMADO) and Long-Term Economic Analysis of Oral Devices and Continuous Positive Airway Pressure,”  Health Technology Assessment,  18(67), DOI 10.3310/hta18670 (2014). 
     Considerably less experience is available for upper airway electrical stimulation devices which require a surgical procedure to implant the device. Notably these electrical stimulation devices are proving effective in moderate to severe OSA. See Eastwood et al., “Treating Obstructive Sleep Apnea with Hypoglossal Nerve Stimulation,”  Sleep,  34(11):1479-86 (Nov. 1, 2011) and Gillespie et al., “Upper Airway Stimulation for Obstructive Sleep Apnea: Patient-Reported Outcomes after 48 Months of Follow-up,”  Otolaryngol Head Neck Surg,  156(4):765-771 (2017). 
     Weight loss and exercise training are adjunctive therapies for OSA, but difficult to sustain. See Iftikhar et al., “Comparative Efficacy of CPAP, MADs, Exercise-Training, and Dietary Weight Loss for Sleep Apnea: A Network Meta-Analysis,”  Sleep Med,  30:7-14 (2017). Patient positioning during sleep can also be helpful. Less commonly, surgical procedures correcting nasal or airway anatomic features can treat OSA. See Dizdar et al., “Comparative Analysis of Lateral Pharyngoplasty and Uvulopalatopharyngoplasty Techniques with Polisomnography and Epworth Sleepiness Scales,”  J Craniofac Surg,  26(7):e647-e651 (October 2015). 
     However, each of the currently available treatment options mentioned above has its drawbacks. Thus, a need exists for methods and devices for treating OSA. The present application provides these and other advantages as will be apparent from the following detailed description and accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
         FIG.  1    is a block diagram of a system for treating sleep apnea in a patient. 
         FIG.  2    is a top view of an exemplary wired embodiment of an upper bite block that includes stimulating electrodes and a tongue position sensor and is configured to fit over the patient&#39;s maxillary teeth. 
         FIG.  3    is a bottom view of the upper bite block of  FIG.  2   . 
         FIG.  4    is a side cross-sectional view of an exemplary wireless embodiment of an upper bite block illustrated in the patient&#39;s mouth. 
         FIG.  5    is a bottom view of the upper bite block of  FIG.  4    illustrated in the patient&#39;s mouth. 
         FIG.  6    is a side view of an exemplary wired embodiment of a lower bite block illustrated in the patient&#39;s mouth. 
         FIG.  7    is a bottom view of an exemplary wireless embodiment of a lower bite block illustrated in the patient&#39;s mouth. 
         FIG.  8    is a perspective view of the patient wearing a headband that include a control unit and intraoral stimulation device(s) of the system of  FIG.  1   . 
         FIG.  9 A  is a side view of an exemplary electrode pivotally connected to one of the intraoral stimulation device(s) of the system of  FIG.  1   . 
         FIG.  9 B  is a cross-sectional view of the electrode of  FIG.  9 A . 
         FIG.  10    is a block diagram of an exemplary computing system of  FIG.  1   . 
         FIG.  11    is an illustration of an exemplary user interface generated by the computing system of  FIG.  10   . 
         FIG.  12    illustrates traces of a signal received by the control unit from one or more sensors of the intraoral stimulation device(s) and an electrical stimulation sent by the control unit to one or more electrodes of the intraoral stimulation device(s) and delivered to the patient thereby. 
         FIG.  13    is a flow diagram of a method that may be performed by the system of  FIG.  1   . 
         FIG.  14    illustrates traces of a signal received by the control unit from one or more sensors of the intraoral stimulation device(s) and an electrical stimulation sent by the control unit to one or more electrodes of the intraoral stimulation device(s) and delivered to the patient thereby. 
     
    
    
     Like reference numerals have been used in the figures to identify like components. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As used herein, the terms “treatment” and “treating” refer to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent or decrease (lessen) the targeted condition or disorder even if the treatment or prevention is ultimately unsuccessful. Those in need of treatment include those already afflicted with the disorder as well as those prone to have the disorder or those in whom the disorder is to be prevented or treated. For example, in obstructive sleep apnea (“OSA”) treatment, a therapeutic apparatus may decrease the number of apneic and/or hypoxic episodes, which may decrease the symptoms and/or sequelae associated with OSA. 
       FIG.  1    illustrates a system  100  for treating sleep apnea in a patient  102  (see  FIGS.  4  and  8   ). Referring to  FIG.  4   , obstruction of the upper airway (“UA”)  104  that occurs in OSA is caused by a reduction in the tone of the muscles of the UA  104  during sleep, accompanied by prolapse of the base of the tongue  106  into the UA  104 . Fortunately, this may be prevented by activating the muscles that extend the tongue  106 . These muscles may be activated by direct electrical stimulation of the nerves effecting tongue extension. As explained below, these muscles may also be activated by an acquired tongue extension reflex that is acquired and maintained by electrical stimulation of the hard palate  108 . 
     Referring to  FIG.  1   , the system  100  may be characterized as being a biofeedback training system. The system  100  includes one or more intraoral stimulation devices  110  operated by a control unit  130 . The control unit  130  is powered by a power source  132  (e.g., a battery). Depending upon the implementation details, the intraoral stimulation device(s)  110  may also be powered by the power source  132 . The intraoral stimulation device(s)  110  may be connected by one or more wired and/or wireless connections  122  to the control unit  130 . The control unit  130  may be connected by one or more wired and/or wireless connections  124  to an external computing device  120  (e.g., a cellular telephone, tablet computing device, laptop computer, and the like). 
     The intraoral stimulation device(s)  110  are configured to deliver electrical stimulation to the hard palate  108  (see  FIGS.  4  and  9 B ) of the patient  102  (see  FIGS.  4  and  8   ) when the tongue  106  (see  FIGS.  4  and  5   ) is in an undesirable position in which the tongue  106  may obstruct the UA  104  (see  FIG.  4   ). The electrical stimulation delivered to the tongue  106  (see  FIGS.  4  and  5   ) causes the tongue  106  to move forwardly to a desirable position whereat the tongue  106  no longer obstructs the UA  104  (see  FIG.  4   ). 
     A brief discussion of the electrophysiology of sensory nerves of the skin and integument of the mouth may be helpful. A range of somatosensory percepts is served by various types of sensory nerve fibers which originate in the skin and lining of the mouth. The sensations of touch and pressure are mediated by large nerve fibers with specialized endings. Pricking pain is mediated by smaller delta fibers, and burning pain is mediated by the smallest nerve fibers (C-Fibers). See Vernon M., “Chapter 10: Mechanisms in Somaesthesia and Pain in Sensory Sensibilities,”  Mountcastle Medical Physiology , Volume 1 (1974). 
     While nerve fibers are normally activated by touch, pressure, or injury, they also can be activated by electrical stimulation. For example, a train of electrical pulses, each pulse having a current amplitude (I) and a duration (D), may be used. The following Hill equation may be used to determine values for the current amplitude I and the duration D that will generate an electrical stimulus pulse that is just adequate to activate a nerve fiber, and thus elicit the percepts served by that class of fibers:
 
 I   th   =I   r /(1− e   −D/T ).
 
In the Hill equation, I th  is the threshold current just sufficient to activate the fiber, I r  is the nerve fiber&#39;s rheobase current, T is the fiber&#39;s chronaxie, and D is the duration of the stimulus pulse that is just adequate to activate the fiber. It is well established that I r  and T are greater for smaller nerve fibers. Thus, when a train of electrical pulses is applied to the skin or to the lining of the mouth, and the current amplitude I is small and/or the pulse duration D is short, only the larger nerve fibers that mediate the sensation of touch or pressure will be activated. As duration D and/or current amplitude I are progressively increased, the A-delta nerve fibers mediating pricking pain will be recruited and the percept will transition from that of touch or tapping to pricking pain, and finally, to burning pain as the current amplitude I and/or duration D of the stimulus pulses becomes sufficient to activate C-fibers.
 
     Referring to  FIG.  4   , the tongue  106  moves forwardly and reflexively in response to electrical stimulation. While stronger electrical stimuli may be needed initially to cause the tongue  106  to move, the stimuli may be reduced as the tongue  106  is trained by the system  100  (see  FIG.  1   ). Thus, the system  100  may lower a threshold of the conditioned tongue-forward reflex in response to electrical stimulation, independently increase UA muscle tone, and/or improve OSA. See Robbins J., “Upper Aerodigestive Tract Neurofunctional Mechanisms: Lifelong Evolution and Exercise,”  Head Neck,  33 Suppl 1:S30-6 (2011), Chwieśko-Minarowska et al., “Rehabilitation of Patients with Obstructive Sleep Apnea Syndrome,”  Int J Rehabil Res,  36(4):291-297 (2013), Rousseau et al., “Effects of One-Week Tongue Task Training on Sleep Apnea Severity: A Pilot Study,”  Can Respir J,  22(3):176-8 (May-June 2015), Svensson et al., “Pleasticity in Corticomotor Control of the Human Tongue Musculature Induced by Tongue-Task Training,”  Exp Brain Res,  152(1):42-51 (2003), Verma et al., “Oropharyngeal Exercises in the Treatment of Obstructive Sleep Apnoea: Our Experience,”  Sleep Breath,  20(4):1193-1201 (December 2016), and Guimaraes et al., “Effects of Oropharyngeal Exercises on Patients with Moderate Obstructive Sleep Apnea Syndrome,”  Am J Resp Crit Care Med,  179:962-966 (2009). It is possible that extended training with the system  100  could reduce OSA symptoms (and reduce the need for therapy). 
     Intraoral Stimulation Device(s) 
     Referring to  FIG.  1   , the intraoral stimulation device(s)  110  may be characterized as being a patient interface that includes one or more sensors  112  and one or more electrodes  114 . The intraoral stimulation device(s)  110  may include an upper (maxillary) bite block  110 U (see  FIGS.  2 - 5   ) configured to be positioned on the patient&#39;s upper teeth  116  (see  FIGS.  4  and  5   ) of a patient&#39;s maxilla (upper jaw)  117  (see  FIG.  4   ) and/or a lower (mandibular) bite block  110 L (see  FIGS.  6  and  7   ) configured to be positioned on the patient&#39;s lower teeth  118  (see  FIGS.  6  and  7   ) of a patient&#39;s mandible (lower jaw)  119  (see  FIG.  4   ). 
     Referring to  FIG.  8   , the upper and lower bite blocks  110 U and  110 L may each be implemented as a dental fixture, a maxillary dental mouthpiece, and the like. By way of a non-limiting example, the upper and lower bite blocks  110 U and  110 L may be substantially similar to bite blocks used for teeth whitening and may be custom-fitted by a dentist. The upper and lower bite blocks  110 U and  110 L may be constructed from a flexible material (such as a silicone) that is custom molded to a patient&#39;s teeth and jaw. For example, the upper (maxillary) bite block  110 U may be fabricated using a tooth tray that fits the patient&#39;s upper palate arch and is adapted to the patient&#39;s individual upper teeth  116  (see FIGS.  4  and  5 ). The lower bite block  110 L may substantially cover the entire mandibular arch. Alternatively, the lower bite block  110 L may be made smaller so that it sits only on front ones of the lower teeth  118  and not on the entire mandibular arch. 
     The upper and lower bite blocks  110 U and  110 L may be constructed from a flexible material that may be transparent at least in the vicinity of the sensor(s)  112  (see  FIG.  1   ). However, this is not a requirement. In alternate embodiments, the material may be translucent or opaque. 
     Referring to  FIG.  4   , to keep the UA  104  open, the tongue  106  should be positioned just behind the teeth  116  and  118 . Referring to  FIG.  1   , the sensor(s)  112  are configured to sense the position of the tongue  106  (see  FIGS.  4  and  5   ) inside the patient&#39;s mouth. Each of the sensor(s)  112  may be configured to monitor the position of the tongue  106  (see  FIG.  4   ) and/or the force exerted by the tongue  106  (particularly, the tip of the tongue  106 ) against the sensor. The sensor(s)  112  may be implemented as sensing electrodes. Examples of suitable tongue position sensors are provided in U.S. Pat. No. 8,249,723, which is incorporated herein by reference in its entirety. By way of non-limiting examples, each of the sensor(s)  112  may have an emitter and a detector in a transparent encapsulant separated by an opaque partition. The emitter may be an infrared emitter and the detector may be an infrared detector. 
     Referring to  FIG.  1   , if the patient  102  (see  FIGS.  4  and  8   ) breathes primarily through the patient&#39;s nose (instead of through the patient&#39;s mouth) during sleep, the sensor(s)  112  of the upper bite block  110 U (see  FIGS.  2 - 5   ) may be use to sense the position of the tongue  106  (see  FIGS.  4  and  5   ) inside the patient&#39;s mouth. On the other hand, if the patient  102  breaths primarily through the patient&#39;s mouth (instead of through the patient&#39;s nose, which is commonly referred to as “mouth breathing”) during sleep, the sensor(s)  112  of the lower bite block  110 L (see  FIGS.  6  and  7   ) may be used to sense the position of the tongue  106  (see  FIGS.  4  and  5   ) inside the patient&#39;s mouth. Thus, the lower bite block  110 L (see  FIGS.  6  and  7   ) may only be needed by mouth breathing patients. In other words, the patient  102  may use the upper bite block  110 U (see  FIGS.  2 - 5   ) or both the upper and lower bite blocks  110 U and  110 L (see  FIGS.  6  and  7   ) depending upon how the patient  102  breathes during sleep. 
     The electrode(s)  114  are configured to deliver electrical stimulation to a structure in the patient&#39;s mouth (e.g., the hard palate  108  illustrated in  FIG.  4   ). By way of a non-limiting example, the electrode(s)  114  may be configured to deliver direct electrical stimulation to the integument of the hard palate  108  (see  FIGS.  4  and  9 B ). The direct electrical stimulation applied by the electrode(s)  114  of the intraoral stimulation device(s)  110  cause the tongue  106  (see  FIGS.  4  and  5   ) to move forwardly (or protrude to an anterior position), maintain the tongue  106  in an anterior position, and/or maintain an increased tone in the tongue extensor muscles during sleep, thereby avoiding obstruction of the UA  104  (see  FIG.  4   ) during sleep. As explained below, the intensity of the simulation delivered by the electrode(s)  114  may increase over a predetermined time period (e.g., about 5 seconds to about 7 seconds). Thus, when the tongue  106  does not move, the intensity increases until the tongue  106  moves forwardly. 
       FIG.  2    is a top view of an exemplary embodiment of the upper (maxillary) bite block  110 U. Referring to  FIG.  2   , the sensor(s)  112  (see  FIG.  1   ) of the upper bite block  110 U include a tongue position sensor  160  and the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ) of the upper bite block  110 U include a pair of stimulating electrodes  162  and  164 . When the upper bite block  110 U is positioned inside the patient&#39;s mouth, the tongue position sensor  160  is positioned close to the front of the patient&#39;s tongue  106  and the stimulating electrodes  162  and  164  are positioned close to and contact the hard palate  108  (see  FIGS.  4  and  9 B ). The stimulating electrodes  162  and  164  are maintained in a reliable but comfortable contact with the hard palate  108  (see  FIGS.  4  and  9 B ). The tongue position sensor  160  and the stimulating electrodes  162  and  164  may be embedded in the upper (maxillary) bite block  110 U. Referring to  FIG.  4   , the stimulating electrodes  162  and  164  (see  FIGS.  2  and  5   ) are configured to deliver stimulation to the anterior hard palate  108  when the tongue position sensor  160  detects the tongue  106  is positioned away from the upper teeth  116 , which means the tongue  106  is in the patient&#39;s UA  104 . 
     Referring to  FIG.  2   , the upper bite block  110 U has an upper surface  166  that may include a palate region  168  configured to contact the patient&#39;s hard palate  108  (see  FIGS.  4  and  9 B ). In the embodiment illustrated, the palate region  168  includes the stimulating electrodes  162  and  164  positioned to contact the patient&#39;s hard palate  108  (see  FIGS.  4  and  9 B ). The stimulating electrodes  162  and  164  may be connected to electrical leads  170  and  172 , respectively, which supply power to the stimulating electrodes  162  and  164 . By way of a non-limiting example, the stimulating electrodes  162  and  164  may be constructed from platinum. 
       FIG.  3    is a bottom view of the upper (maxillary) bite block  110 U. Referring to  FIG.  3   , the tongue position sensor  160  is located near a front portion  174  of the upper bite block  110 U in a generally upwardly concave contoured portion  176 . The tongue position sensor  160  may detect or monitor the position of the tongue  106  or the force exerted by the tongue  106  against the tongue position sensor  160 . The tongue position sensor  160  may be connected to an electrical lead  173 , which supplies power to the tongue position sensor  160 . 
       FIGS.  2  and  3    illustrate a wired implementation of the upper (maxillary) bite block  110 U. In such an embodiment, referring to  FIG.  1   , the control unit  130  and the power source  132  may both be external to the upper bite block  110 U (see  FIGS.  2  and  3   ) and the connection(s)  122  may include control and power wiring  169  (see  FIGS.  2  and  3   ). Referring to  FIG.  2   , the wiring  169  extends from the upper bite block  110 U and is connected to the external control unit  130  (see  FIGS.  1 ,  4 ,  5 , and  7   ) and the power source  132  (see  FIG.  1   ). The wiring  169  carries tongue position information from the tongue position sensor  160  (via the electrical lead  173 ) to the external control unit  130 . The wiring  169  also conducts electrical power from the power source  132  to the tongue position sensor  160  via the electrical lead  173 . The wiring  169  carries a stimulation signal from the external control unit  130  to the stimulating electrodes  162  and  164  (via the electrical leads  170  and  172 ). 
     Alternatively,  FIGS.  4  and  5    illustrate a wireless implementation of the upper (maxillary) bite block  110 U. Referring to  FIG.  5   , in such an embodiment, the upper bite block  110 U includes onboard wireless transponder  177  and an onboard battery  178  that may be molded into the upper bite block  110 U. In this embodiment, the connection(s)  122  may be implemented as a wireless connection between the onboard wireless transponder  177  and the control unit  130 . The onboard battery  178  is configured to provide power to the tongue position sensor  160 , the stimulating electrodes  162  and  164 , and the onboard wireless transponder  177 . The battery  178  may be charged wirelessly, such as by inductive charging or by other technology. The tongue position sensor  160  is configured to detect and/or monitor tongue position information and transmit this information to the onboard wireless transponder  177 . The onboard wireless transponder  177 , which is wirelessly connected to the control unit  130 , is configured to wirelessly communicate the tongue position information to the control unit  130 . The control unit  130  receives this information and wirelessly sends stimulation instructions to the onboard wireless transponder  177 . The onboard wireless transponder  177  may be connected to a signal-generating device  179  that is configured to generate a stimulation signal based on the stimulation instructions. The stimulation signal is powered by the battery  178  and delivered to the stimulating electrodes  162  and  164 , which deliver the stimulation signal to the hard palate  108  (see  FIG.  4   ). Thus, the control unit  130  is configured to receive the tongue position information (directly or wirelessly) and determine whether to deliver the stimulation signal to the patient  102 . 
     Referring to  FIG.  9 A , each of the electrode(s)  114  (e.g., the stimulating electrodes  162  and  164  illustrated in  FIGS.  2  and  5   ) may be attached to one of the intraoral stimulation device(s)  110  (e.g., the upper bite block  110 U illustrated in  FIGS.  2 - 5  and  8   ) in a manner that allows them to maintain stable and reliable but comfortable contact with the patient&#39;s hard palate  108  (see FIGS.  4  and  9 B).  FIGS.  9 A and  9 B  illustrate an exemplary implementation of one of the electrode(s)  114  (e.g., the electrode  162  illustrated in  FIG.  2   ) pivotally connected to one of the intraoral stimulation device(s)  110 . Each of the electrode(s)  114  may be pivotally connected to a different pivot member  186  that allows each of the electrode(s)  114  to pitch and pivot to lie flat against the integument of the hard palate  108  (see  FIGS.  4  and  9 B ). By way of a non-limiting example, the pivot member  186  may be implemented as a flexible silicone supporting tube (e.g., constructed of medical grade silicone rubber) or other mechanism(s) (e.g., springs, ball joints, silicon arms, and the like) configured to allow the electrode  114  to pivot relative to the intraoral stimulation device  110 . 
     In the embodiment illustrated, the pivot member  186  is connected to a backing plate  188  that is connected to the intraoral stimulation device  110 . A pivot space  189  is defined between the electrode  114  and the backing plate  188 . The pivot space  189  allows the electrode  114  to pivot to position the top of the electrode  114  generally flush with the upper surface (e.g., the upper surface  166  illustrated in  FIG.  2   ) of the intraoral stimulation device  110  in its palate region  168  (see  FIG.  2   ). The pivot space  189  also allows the electrode  114  to pivot to lie flat against the hard palate  108  (see  FIGS.  4  and  9 B ). Referring to  FIG.  9 B , the pivot member  186  allows the electrode  114  to maintain uniform contact with the hard palate  108 , even when the patient  102  bites or sucks against the intraoral stimulation device  110  (e.g., a night guard). The intraoral stimulation device  110  may be implemented as a night guard of the type used widely to treat bruxism. Such a night guard may be custom fitted to the patient  102  by a qualified dentist with experience fitting these devices. Referring to  FIG.  7   , as mentioned above, the lower (mandibular) bite block  110 L may be used in conjunction with the upper (maxillary) bite block  110 U (see  FIGS.  2 - 5   ) and is particularly useful for a mouth breather, whose tongue  106  (see  FIGS.  4  and  5   ) may be closer to the lower teeth  118  than the upper teeth  116  (and the tongue position sensor  160  of the upper bite block  110 U). The sensor(s)  112  (see  FIG.  1   ) of the lower bite block  110 L include a tongue position sensor  180  (e.g., a sensing electrode) and the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ) of the lower bite block  110 L may include one or more stimulating electrodes  182 . The tongue position sensor  180  and the stimulating electrode(s)  182  may be embedded in or otherwise attached to the lower bite block  110 L. The tongue position sensor  180  is positioned behind front ones of the lower teeth  118  and configured to detect whether the tongue  106  (see  FIGS.  4  and  5   ) is in the desired (forward) position, or is retracted back towards the UA  104  (see  FIG.  4   ). 
     In the embodiment illustrated, the stimulating electrode(s)  182  have been implemented as sublingual electrodes that are configured to excite the tongue extensor muscle directly, as described in U.S. Pat. Nos. 8,249,723, 8,359,108, and 8,774,943, each of which is incorporated herein by reference in its entirety. By way of non-limiting examples, the sublingual electrodes may be substantially identical to electrodes 403 of U.S. Pat. Nos. 8,249,723, 8,359,108, and 8,774,943 that are configured to deliver electrical stimulation to the tongue extensor muscles. 
     Alternatively and/or additionally, the stimulating electrodes  162  and  164  (see  FIGS.  2  and  5   ) may deliver stimulation to the anterior hard palate  108  (see  FIGS.  4  and  9 B ) when the tongue position sensor  180  detects the tongue  106  (see  FIGS.  4  and  5   ) is positioned away from the lower teeth  118  (see  FIG.  6   ). In such embodiments, the stimulating electrode(s)  182  may be omitted. 
       FIG.  6    illustrates a wired implementation of the lower bite block  110 L. In such an embodiment, the control unit  130  (see  FIGS.  1 ,  4 ,  5 , and  7   ) and the power source  132  (see  FIG.  1   ) may both be external to the lower bite block  110 L and the connection(s)  122  (see  FIG.  1   ) may include control and power wiring  184  (see  FIG.  8   ). The wiring  184  (see  FIG.  8   ) extends from the lower bite block  110 L and is connected to the external control unit  130  (see  FIGS.  1 ,  4 ,  5 , and  7   ) and the power source  132  (see  FIG.  1   ). The wiring  184  (see  FIG.  8   ) carries tongue position information from the tongue position sensor  180  to the external control unit  130  and conducts electrical power to the tongue position sensor  180  from the power source  132 . The wiring  184  (see  FIG.  8   ) may carry a stimulation signal from the external control unit  130  to the stimulating electrode(s)  182  (see  FIG.  7   ), when present. Referring to  FIG.  2   , alternatively and/or additionally, the wiring  169  may carry the stimulation signal to the stimulating electrodes  162  and  164 , which deliver the stimulation to the anterior hard palate  108 . The stimulation signal is also powered by the power source  132 . 
       FIG.  7    illustrates a wireless implementation of the lower bite block  110 L. In such an embodiment, the lower bite block  110 L may include an onboard wireless transponder  190  and an onboard battery  192  that may be molded into the lower bite block  110 L. In this embodiment, the connection(s)  122  may be implemented as a wireless connection between the onboard wireless transponder  190  and the control unit  130 . The onboard battery  192  is configured to provide power to the mandibular tongue position sensor  180 , the stimulating electrode  182 , the onboard wireless transponder  190 , and, when present, the stimulating (sublingual) electrode(s)  182 . The onboard battery  192  may be charged wirelessly, such as by inductive charging or by other technology. The tongue position sensor  180  is configured to detect and/or monitor tongue position information. The tongue position sensor  180  transmits this information to the onboard wireless transponder  190 . The onboard wireless transponder  190  is configured to wirelessly communicate the tongue position information to the control unit  130 . The control unit  130  receives this information and wirelessly sends stimulation instructions to the onboard wireless transponder  190 . The onboard wireless transponder  190  may be connected to signal generating device  191  that is configured to generate a stimulation signal based on the stimulation instructions. The stimulation signal is powered by the battery  192  and delivered to the stimulating electrode(s)  182 , which deliver the stimulation signal to the tongue extensor muscle. 
     Referring to  FIG.  5   , alternatively and/or additionally, the control unit  130  may send instructions to the onboard wireless transponder  177 , which is connected to the signal-generating device  179 . The signal-generating device  179  is configured to generate a stimulation signal based on the stimulation instructions, and sends the stimulation signal to the stimulating electrodes  162  and  164 , which deliver the stimulation to the anterior hard palate  108 . 
     Thus, referring to  FIG.  7   , the control unit  130  is configured to receive the tongue position information (directly or wirelessly) from the lower bite block  110 L and determine whether to deliver the stimulation signal to the patient  102  (see  FIGS.  4  and  8   ). 
     The mandibular tongue position sensor  180  and the maxillary tongue position sensor  160  (see  FIGS.  2 - 5   ) may both be connected to the control unit  130  at the same time. In such embodiments, the control unit  130  may determine based on the tongue position information received from the sensors  180  and  160  whether the tongue  106  is closer to the mandibular tongue position sensor  180  or the maxillary tongue position sensor  160 . In this way, the control unit  130  may use the greater (or stronger) of the two signals (including the tongue position information) received from the two tongue position sensors  180  and  160  to determine whether to deliver electrical stimulation to the patient  102  (see  FIGS.  4  and  8   ). 
     Control Unit 
     The control unit  130  may be implemented using a circuit board (e.g., a custom signal interface board) with components implementing a wired or wireless control unit. While in the embodiment illustrated, the control unit  130  is illustrated as being a separate component, in alternate embodiments, the control unit  130  may be a component of either the computing device  120  and/or the intraoral stimulation device(s)  110 . For example, referring to  FIGS.  4  and  5   , in a wireless implementation illustrated, the control unit  130  may be a component of the upper bite block  110 U. Referring to  FIG.  7   , by way of another non-limiting example, the control unit  130  may be a component of the lower bite block  110 L. 
     Referring to  FIG.  1   , the control unit  130  is connected to the intraoral stimulation device(s)  110  and may both receive signals from the sensor(s)  112  and send electrical stimulation to the electrode(s)  114 . As mentioned above, the control unit  130  is powered by the power source  132  (e.g., by a battery). The power source  132  may be a component of the control unit  130  and/or a separate component. 
     The control unit  130  may include one or more processors  200 , which may be implemented by any suitable technology, such as a microprocessor, microcontroller, application-specific integrated circuit (ASIC), digital signal processor (“DSP”), or the like. The processor(s)  200  may be integrated into an electrical circuit, similar to a “motherboard” of a general-purpose computer that supplies power to the processor(s)  200  and otherwise supports its function. 
     The processor(s)  200  may include internal memory or have memory  210  coupled thereto. The memory  210  may be coupled to the processor(s)  200  by an internal bus  212 . The memory  210  is a computer readable medium that includes instructions  214  or computer executable components that are executed by the processor(s)  200 . The memory  210  may also store data  216 . The memory  210  may include random access memory (RAM) and read-only memory (ROM). The instructions  214  and the data  216  may control the operation of the processor(s)  200 . The instructions  214  may include software and/or firmware configured to operate a tongue sensor/stimulation feedback loop. The memory  210  may also include a basic input/output system (BIOS), which contains the basic routines that help transfer information between elements within the control unit  130 . The control unit  130  is not limited by the specific hardware component(s) used to implement the processor(s)  200  or the memory  210  components of the control unit  130 . 
     The instructions  214  are executable by the processor(s)  200  and instruct the processor(s)  200  to process and/or analyze the signals received by the sensor(s)  112 . The instructions  214  may instruct the processor(s)  200  to generate electrical stimulus and deliver that stimulus to the electrode(s)  114 , which deliver the stimulus to the patient  102  (see  FIGS.  4  and  8   ). The instructions  214  executed by the control unit  130  may monitor and record tongue force applied to the sensor(s)  112  as well as tongue position. These instructions may include computer readable software components or modules stored in the memory  210 . 
     The control unit  130  may also include an external device interface  220  permitting a user (e.g., the patient  102 , and/or a medical professional) to enter control commands, such as a command triggering the delivery of the electrical pulses, commands providing new instructions to be executed by the processor(s)  200 , commands changing parameters related to electrical pulses delivered by the control unit  130 , and the like, into the control unit  130 . The external device interface  220  may include a wireless user input device. The external device interface  220  may include an antenna (not shown) for receiving and transmitting a signal, such as a radio frequency (RF) signal, to and from the control unit  130 . The control unit  130  may also include software components for interpreting the commands and executing control commands included in a command signal. These software components may be stored in the memory  210 . The connection  124  may be implemented using WiFi, Bluetooth, or similar wireless communication standards. In such embodiments, the control unit  130  is configured to communicate with the computing device  120  (e.g., a cellular telephone) using at least one of these standards. 
     The control unit  130  includes a signal interface  230  coupled the sensor(s)  112  (e.g., the tongue position sensor  160  illustrated in  FIGS.  2 - 5   , and/or the tongue position sensor  180  illustrated in  FIGS.  6  and  7   ) configured to receive signals regarding the position of the tongue  106  (see  FIGS.  4  and  5   ) or the force exerted by the tongue  106  onto the sensor(s)  112 . The signal interface  230  may include any standard electrical interface known in the art for connecting a signal carrying wire to a conventional circuit board as well as any components capable of communicating a low voltage time varying signal received from the sensor(s)  112  through an internal bus  240  to the processor(s)  200 . The signal interface  230  may include hardware components such as memory as well as standard signal processing components such as an analog to digital converter, amplifiers, filters, and the like. 
     The control unit  130  may include an electrical stimulation interface  250  connected to the electrode(s)  114  (e.g., the electrode(s)  162  and  164  illustrated in  FIGS.  2  and  5   , and/or the electrode(s)  182  illustrated in  FIG.  7   ). In wired embodiments, the electrical stimulation interface  250  is configured to deliver electrical stimulation pulses (e.g., charge-balanced pulses) to the electrode(s)  114 . In such embodiments, the electrical stimulation interface  250  may include any standard electrical interface known in the art for connecting a signal-carrying wire to a conventional circuit board as well as any components capable of communicating a low voltage time-varying signal generated by the processor(s)  200  or a signal generating device (e.g., like the signal generating device  179  illustrated in  FIG.  5   ) controlled by the processor(s)  200  to the electrode(s)  114  through the internal bus  240 . The control unit  130  is configured to generate voltage waveforms that are delivered to the electrode(s)  114  and applied thereby as the stimulation to the hard palate  108  (see  FIGS.  4  and  9 B ). The electrical stimulation interface  250  may include hardware components such as memory as well as standard signal processing components such as a digital to analog converter, amplifiers, filters, and the like. Alternatively, in wireless embodiments, the electrical stimulation interface  250  may include a communication interface configured to communicate commands or instructions from the processor(s)  200  to the intraoral stimulation device(s)  110 , which generates the electrical stimulation delivered by the electrode(s)  114  based on the commands or instructions. 
     The various components of the control unit  130  may be coupled together by the internal buses  240 , which may include a single bus or multiple buses connected together and configured to communicate with one another. The internal bus  240  may be constructed using a data bus, control bus, power bus, I/O bus, and the like. The internal bus  240  may be wireless. 
     The control unit  130  may be fabricated using a combination of computer hardware, an interface board, and custom electronics configured to interface directly or indirectly with the sensor(s)  112  and/or the stimulating electrode(s)  114 . For example, the control unit  130  may be fabricated using discrete logic components and/or analog circuit elements. 
     The control unit  130  may log or store data locally (e.g., in the data  216  stored in the memory  210 ) and communicate (e.g., upon request) at least a portion of the data  216  to the computing device  120 . 
     The control unit  130  may provide analog to digital (“A/D”) conversion as well as digital to analog (“D/A”) conversion. For example, the signal interface  230  may convert analog tongue position information received from the sensor(s)  112  into a digital signal for use by the processor(s)  200 . Similarly, the electrical stimulation interface  250  may convert a digital stimulation signal received from the processor(s)  200  into an analog stimulation signal that is delivered to the electrode(s)  114 . 
     Optionally, the control unit  130  may include one or more audible alarms  260 . 
     Optionally, the control unit  130  may be used to calibrate the upper bite block  110 U and/or its software, if present. 
     Referring to  FIG.  8   , optionally, the control unit  130  may be configured to be attached to a wristband  278  or a headband  280 . Together the control unit  130  and the headband  280  may form a headband assembly  282 . The headband assembly  282  may be worn on the head  284  of the patient  102  overnight. The headband assembly  282  may be configured to be comfortable to wear as well as easy to wear and clean. The headband assembly  282  may be stable and remain in position overnight. When present, the wiring  169  (see  FIGS.  2  and  3   ) and/or the wiring  184 , may be routed to the control unit  130  (see  FIGS.  1 ,  4 ,  5 , and  7   ) attached to the headband  280 , which helps reduce the likelihood of the patient  102  becoming entangled in the wiring  169  and/or the wiring  184  and thereby placing tension on the upper bite block  110 U and/or the lower bite block  110 L, respectively. 
     Power Source 
     Referring to  FIG.  1   , during operation of a wired embodiment, the power source  132  is not required to provide a lot of power to the control unit  130  and the intraoral stimulation device(s)  110 . For example, both the control unit  130  and the intraoral stimulation device(s)  110  may be powered by four  9 V transistor batteries providing a total of 2000 milliamp hours. Thus, the power source  132  may be implemented as a typical thin format rechargeable cellphone battery configured to deliver about 2000 mAHr to about 2400 mAHr and may be attached to the headband  280  (see  FIG.  8   ) and form part of the headband assembly  282  (see  FIG.  8   ). By way of another non-limiting example, the power source  132  may be a battery configured to provide ±18 Volts. 
     Computing System 
       FIG.  10    is a functional block diagram illustrating a mobile communication device  300  that may be used to implement the computing device  120  (see  FIGS.  1  and  8   ). By way of non-limiting examples, the mobile communication device  300  map be implemented as a laptop computer, a tablet computer, a smartphone, a cellular telephone, any computing device, and the like. 
     The mobile communication device  300  includes a central processing unit (CPU)  302 . Those skilled in the art will appreciate that the CPU  302  may be implemented as a conventional microprocessor, application specific integrated circuit (ASIC), digital signal processor (DSP), programmable gate array (PGA), or the like. The mobile communication device  300  is not limited by the specific form of the CPU  302 . The mobile communication device  300  also contains a memory  304 . 
     The memory  304  may store instructions and data to control operation of the CPU  302 . The memory  304  may include random access memory, ready-only memory, programmable memory, flash memory, and the like. The memory  304  may include external storage, such as cloud storage. The mobile communication device  300  is not limited by any specific form of hardware used to implement the memory  304 . The memory  304  may also be integrally formed in whole or in part with the CPU  302 . 
     The mobile communication device  300  also includes conventional components, such as a display  306  and keyboard or keypad  308 . The display  306  may be implemented as a touchscreen user interface. In such embodiments, the keypad  308  may be omitted from the mobile communication device  300 . The display  306  and the keypad  308  are conventional components that operate in a known manner and need not be described in greater detail. Other conventional components found in wireless communication devices, such as a USB interface, Bluetooth interface, camera/video device, infrared device, and the like, may also be included in the mobile communication device  300 . For the sake of clarity, these conventional elements are not illustrated in the functional block diagram of  FIG.  10   . 
     The mobile communication device  300  also includes a network transmitter  310  such as may be used by the mobile communication device  300  for normal network wireless communication with a base station (not shown).  FIG.  10    also illustrates a network receiver  312  that operates in conjunction with the network transmitter  310  to communicate with the base station (not shown). In a typical embodiment, the network transmitter  310  and network receiver  312  are implemented as a network transceiver  320 . The network transceiver  320  is connected to an antenna  330 . Referring to  FIG.  1   , the antenna  330  (see  FIG.  10   ) is configured to communicate wirelessly with the external device interface  220  over the connection  124 . Returning to  FIG.  10   , operation of the network transceiver  320  and the antenna  330  for communication with a wireless network (not shown) is well-known in the art and need not be described in greater detail herein. 
     In alternate embodiments, referring to  FIG.  1   , the connection  124  between the control unit  130  and the computing device  120  may include a wired connection that includes isolation modules (not shown), such as high voltage isolation modules. In such embodiments, the computing device  120  may include a wired interface (not shown) configured to communicate with the control unit  130  over the wired connection. 
     Referring to  FIG.  1   , the mobile communication device  300  may also include a conventional geolocation module (not shown) operable to determine the current location of the mobile communication device  300 . 
     The various components illustrated in  FIG.  10    are coupled together by a bus system  345 . The bus system  345  may include an address bus, data bus, power bus, control bus, and the like. For the sake of convenience, the various busses in  FIG.  10    are illustrated as the bus system  345 . The memory  304  may store instructions executable by the CPU  302 . 
     Such instructions may be stored on one or more non-transitory computer or processor readable media. The instructions may include a control application  340  and a biofeedback training application  350  stored in the memory  304 . The control application  340  and/or the biofeedback training application  350  may be configured to track apnea episodes, log tongue position, and log stimulation profiles. In this manner, the computing device  120  may track disease progression or treatment efficacy over time. 
     Referring to  FIG.  1   , while the computing device  120  is illustrated as being a separate component from the control unit  130 , in an alternate embodiment, the functionality of the computing device  120  and the control unit  130  may be combined into a single component. This single component may be configured to be attached to the headband  280  (see  FIG.  8   ) and worn on the head of the patient  102  (see  FIGS.  4  and  8   ) overnight. 
     Control Application 
     Referring to  FIG.  1   , the control unit  130  and the intraoral stimulation device(s)  110  may be managed by the control application  340  (see  FIG.  10   ) executing on the computing device  120  (e.g., the mobile communication device  300  illustrated in  FIG.  10   ). The control application  340  (see  FIG.  10   ) provides an interface between a user (e.g., the patient  102  illustrated in  FIGS.  4    and  8 ) and the control unit  130  and/or the intraoral stimulation device(s)  110 . The control application  340  may be used to manage the control unit  130  and/or the intraoral stimulation device(s)  110  as well as monitor status of these components. For example, the user may use the computing device  120  to set operating parameters through a touchscreen user interface (e.g., the display  306  illustrated in  FIG.  10   ). By way of non-limiting examples, the control application  340  (see  FIG.  10   ) may upload a preferred stimulation profile (e.g., derived from the biofeedback training), record and log data (tongue position/stimulation events) received from the control unit  130  during use, and activate the audible alarms  260  (see  FIG.  1   ). 
       FIG.  11    illustrates an optional user interface  400  that may be generated by the control application  340  (see  FIG.  10   ). The user interface  400  includes pull-down menus  402  for selecting parameters positioned at or near the top of the user interface  400 . The parameters (described below) each have a range from which values can be selected from one of the pull-down menus  402 . An upper screen portion  404  shows a signal Sa(V) received from the sensor(s)  112  (see  FIG.  1   ). Progressively higher values indicate extension of the tongue  106  (see  FIGS.  4  and  5   ) towards the sensor(s)  112 , the tongue  106  contacting with the sensor(s)  112 , and an amount of force exerted by the tongue  106  against the sensor(s)  112 . A lower screen portion  406  shows the amplitude of the electrical stimuli that is applied to the integument of the hard palate  108  (see  FIGS.  4  and  9 B ). 
     When the user interface  400  is first launched (or started), the parameters are assigned initial values (e.g., specified in an initiation file, which may also specify ranges for the two screen portions  404  and  406 ). A sample initiation file (e.g., named “apnea.ini”) is provided below. The initiation file may be implemented as an asci text file and may be customized for a particular patient, in which case, the user does not need to change any of the parameter values after the user interface  400  is started. However, the user can change these parameter values, but in most cases this should not be necessary. The initiation file may be changed by the user using the pull-down menus  402  so when the user interface  400  is re-started, the initial parameter values are those last selected by the user. The parameter values for a particular patient can be restored by copying their personal parameter values (e.g., stored in a personal initiation file) to initiation file. 
     The following are sample parameters stored by the initiation file (e.g., apnea.ini):
         [Setup]   SaveDir=d:\data   FileName=a0131   AOFreq=10   RContact=18   XScale=20   YLimit=20   AO0PIsWidth=5   AO0RampTime=10   AO0MaxAmp=8   AO0ResetAmp=2       

     The parameters may include a Width parameter, an AOFreq parameter, an Amp(V) parameter, a Ramp(s) parameter, and a Reset parameter. In the example file above, the Width parameter is identified as “AO0PIsWidth” and assigned an initial value of 5, the Amp(V) parameter is identified as “AO0MaxAmp” and assigned an initial value of 8, the Ramp(s) parameter is identified as “AO0RampTime” and assigned an initial value of 10, and the Reset parameter is identified as “AO0ResetAmp” and assigned an initial value of 2. 
     The Width parameter is the duration (e.g., in msec) of each phase of the biphasic, controlled-voltage stimulus pulses that are applied to the patient&#39;s mouth. The pull-down menus  402  include a width menu  410  that may be used to provide the value of the Width parameter. By way of non-limiting examples, the width menu  410  may include the following selectable parameter values: 5 msec per phase, 10 msec per phase, 15 msec per phase, and 20 msec per phase. First and second phases of the electronic stimulation may have opposite polarities and may be automatically set to the same duration. The initial parameter value specified for the Width parameter may be 5 msec per phase. However, this is not a requirement. 
     The AOFreq parameter is a stimulus pulse rate (e.g., specified in pulses per second (“pps”) or hertz) of the controlled-voltage stimulus. The pull-down menus  402  include a AOFreq menu  412  that may be used to provide the value of the AOFreq parameter. By way of non-limiting examples, the AOFreq menu  412  may include the following selectable parameter values: 5 pps, 10 pps, and 20 pps. The initial parameter value specified for the AOFreq parameter may be 10 pps (or 10 Hz). However, this is not a requirement. The Amp(V) parameter is the maximum amplitude (e.g., in volts) of the stimulus pulses. The pull-down menus  402  include an Amp(V) menu  414  that may be used to provide the value of the Amp(V) parameter. By way of non-limiting examples, the Amp(V) menu  414  may include the following selectable parameter values: 1 V, 2 V, 3 V, 4 V, 5 V, 6 V, 7 V, 8 V, 9 V, 10 V, 11 V, and 12 V. The initial parameter value specified for the Amp(V) parameter may be 8 V. However, this is not a requirement. 
     The Ramp(s) parameter is the number of seconds required for the electrical stimulus to increase from 0 to the value of the Amp(V) parameter. The pull-down menus  402  include a Ramp(s) menu  416  that may be used to provide the value of the Ramp(s) parameter. By way of non-limiting examples, the Ramp(s) menu  416  may include the following selectable parameter values: 1 sec, 2 sec, 3 sec, 4 sec, 5 sec, 6 sec, 7 sec, 8 sec, 9 sec, 10 sec, 11 sec, 12 sec, 13 sec, 14 sec, 15 sec, 16 sec, 17 sec, 18 sec, 19 sec, and 20 sec. The initial parameter value specified for the Ramp(s) parameter may be 10 seconds. However, this is not a requirement. 
     The Reset parameter is the amplitude of the signal Sa(V) received from the sensor(s)  112  that causes the stimulus amplitude to reset to 0 volts. The signal Sa(V) is displayed as a continuous trace  420  in the upper screen portion  404  of the user interface  400 . The pull-down menus  402  include a Reset menu  418  that may be used to provide the value of the Reset parameter. By way of non-limiting examples, the Reset menu  418  may include selectable parameter values ranging from 1 V to 10 V in steps of 0.1 V. The value of the Reset parameter may be pre-set for each patient. For example, the Amp(V) parameter may be set to a low value (e.g., 2 volts or less), so that the Reset parameter may be adjusted without the patient receiving a perceptible electrical stimulus. Next, the patient  102  (see  FIGS.  4  and  8   ) may place the intraoral stimulation device(s)  110  (see  FIGS.  1 ,  9 A, and  9 B ) into their mouth and the user sets the Reset parameter to 0.1 V below a value indicated by the trace  420  when the patient&#39;s tongue  106  (see  FIGS.  4  and  5   ) is extended over the sensor(s)  112  (see  FIG.  1   ). The trace  420  should start to decrease when the patient&#39;s tongue retracts from the sensor(s)  112 . After the appropriate value of the Reset parameter has been determined, this can be entered into the patient&#39;s personal initiation file. 
       FIG.  12    illustrates the control application  340  using the parameter values to deliver stimulus. In  FIG.  12   , a line  430  illustrates the amplitude of the signal Sa(V) received from the sensor(s)  112  (see  FIG.  1   ) and a line  432  illustrates the amplitude of the stimulation signal delivered by the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ) to the hard palate  108  (see  FIGS.  4  and  9 B ). In  FIG.  12   , the stimulation signal is delivered as a series of biphasic pulses. By way of a non-limiting example, the biphasic pulses may have a pulse rate of 5 pulses per second and a duration of each phase may be about 5 milliseconds. The amplitude of the pulses in the series steady increases. The amplitude may return to zero after each biphasic pulse pair, and remain at zero (e.g., for about 190 msec) until the next pulse pair begins 
     A dashed line  434  illustrates the value of the Reset parameter and a dashed line  436  illustrates the value of the Amp(V) parameter. A vertical dashed line  440  illustrates when the line  430  has fallen below the dashed line  434 , which means that the amplitude of the signal Sa(V) has fallen below the value of the Reset parameter. A vertical dashed line  442  illustrates when the line  430  has risen above the dashed line  434 , which means that the amplitude of the signal Sa(V) is equal to or greater than the value of the Reset parameter. 
     When the amplitude of the signal Sa(V) (represented by the line  430 ) falls below the value of the Reset parameter (represented by the dashed line  434 ), indicating that the tongue  106  (see  FIGS.  4  and  5   ) is retracting from the sensor(s)  112  (see  FIG.  1   ), the pulsatile stimulation is applied to mucosal lining of the hard palate  108  (see  FIGS.  4  and  9 B ) through the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ). The ramp-up of the stimulus amplitude from zero volts toward the value of the Amp(V) parameter (represented by the dashed line  436 ) may begin after a delay  444  (e.g., 1 second) that may be hard-coded in the control application  340  (see  FIG.  10   ). Initially, the stimulus amplitude (represented by the line  432 ) is zero volts, but increases to the value of the Amp(V) parameter (represented by the dashed line  436 ), where it remains until the patient  102  moves their tongue  106  forward and causes the amplitude of the signal Sa(V) to fall below the value of the Reset parameter, whereupon the stimulus amplitude is immediately reset to zero volts. As mentioned above, the stimulus amplitude may increase over the predetermined time period (e.g., about 5 seconds to about 7 seconds). 
     The value of the Reset parameter may greater than the amplitude of the signal Sa(V) (represented by the line  430 ) when the tongue  106  just contacts the sensor(s)  112 , so that the tongue  106  must exert at least a prescribed amount of force against the sensor(s)  112 , thereby increasing the tone in the tongue extensor muscles above what would be required to simply contact the sensor(s)  112 . 
     The control application  340  (see  FIG.  10   ) continuously records (e.g., at interval of about one second) the output (represented by the line  430 ) of the sensor(s)  112 , and the voltage of the amplitude (represented by the line  432 ) of the electrical stimulus (e.g., delivered in pulses). By way of a non-limiting example, this data saving may be initiated by the user selecting a START SAVING option  450 . By way of a non-limiting example, the data may be saved in Microsoft Excel (“xl”) format. The control application  340  (see  FIG.  10   ) may also record the patient&#39;s hemoglobin saturation, as monitored by a finger clip pulse oximeter. 
     Biofeedback Training Application 
     Referring to  FIG.  4   , maintaining the tongue  106  in a desired (forward) position requires that the patient  102  maintain a small tone in the tongue extensor muscles. This behavior may be induced in the patient  102  and maintained by induction of a new reflex (or conditioned response), using biofeedback to induce and maintain the reflex. Prior investigators who have researched treating obstructive sleep apnea have not considered biofeedback-based training systems that function to generate and/or reinforce a conditioned reflex whereby the tongue  106  is moved forward and into contact with the lower incisors in response to weak electrical stimulation delivered to the surface of the anterior hard palate  108 . Referring to  FIG.  10   , the biofeedback training application  350  implements such biofeedback-based training. 
     The biofeedback training application  350  may upgrade and/or program the control application  340  depending on data collected from the sensor(s)  112  (see  FIG.  1   ) and action of the stimulating electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ). As the patient&#39;s tongue  106  (see  FIGS.  4  and  5   ) becomes trained to move forward in response to weak electrical stimulation, it is expected that lower stimulus voltages will be required. Data collected from the sensor(s)  112  may be used to calibrate the control unit  130  and/or its software (e.g., the instructions  214  illustrated in  FIG.  1   ). 
     The user (e.g., the patient  102  illustrated in  FIGS.  4  and  8   ) may use a touchscreen user interface (e.g., the display  306  illustrated in  FIG.  10   ) of the computing device  120  (see  FIGS.  1  and  8   ) to implement the biofeedback training. Referring to  FIG.  10   , the biofeedback training application  350  may be gamified to improve training and engage the user (e.g., the patient  102 ) in the training process. The biofeedback training application  350  provides an interface between the user and the control unit  130  and the intraoral stimulation device(s)  110 . This interface provides visual feedback regarding both tongue position and stimulation that is used to implement a training protocol (and later for airway rehabilitation training). 
     Biofeedback based training is based at least in part on conditioned responses and conditioned protective/avoidance reflexes. The phenomenon of conditioned (or conditional) reflexes first was investigated systematically by the Russian physician and physiologist Ivan Pavlov (1874-1936). Behavior that is not innate can be “conditioned” and thus becomes automatic and “unconscious” by repeated pairing of a conditioned stimulus with a (non-conditioned) stimulus to which the behavior is innately linked. A related phenomenon is the conditioned protective reflex, in which an individual becomes conditioned to automatically initiate an action that will preclude pain or injury in response to a non-injurious, non-noxious percept that is paired with the onset of the noxious stimulus. 
     For example, referring to  FIG.  4   , the patient  102  will reflexive withdraw the tongue  106  from between the patient&#39;s incisors upon perception of dental pressure against the tongue  106 . This occurs because the patient  102  has been conditioned to associate the percept of moderate (bite) pressure against the tongue  106  with the probability of subsequent pain and injury to the tongue  106 , unless an appropriate protective response is initiated (e.g., withdrawal of the tongue  106  from between the incisors). 
     The biofeedback training application  350  (see  FIG.  10   ) may be used to provide biofeedback based training that trains the patient  102  to position the patient&#39;s tongue  106  such that the patient&#39;s tongue  106  does not obstruct the patient&#39;s UA  104 . The upper bite block  110 U and/or the lower bite block  110 L (see  FIGS.  6  and  7   ) may be used to perform a biofeedback-based method, which may generate (or induce) and maintain, in the patient  102 , a conditioned reflex whereby the tongue  106  is moved anteriorly and/or dorsally in response to very weak electrical stimulation delivered to the hard palate  108 . In other words, the conditioned reflex means lower amplitude stimulation is needed to induce the tongue  106  to move from an undesired to a desired position. The biofeedback-based mode may be used alone or in combination with a mode wherein the movement of the tongue  106  is produced directly by electrical stimulation applied through the (sublingual) electrode(s)  182  (see  FIG.  7   ) to branches of the hypoglossal nerve. The biofeedback training application  350  (see  FIG.  10   ) may apply the conditioning electrical stimulus through the electrode(s)  114  (see  FIG.  1   ) that contact the hard palate  108 , and/or through the (sublingual) electrode(s)  182  (see  FIG.  7   ). The (sublingual) electrode(s)  182  (see  FIG.  7   ) may also directly stimulate the nerves that extend the tongue  106 . 
     Referring to  FIG.  1   , the biofeedback training application  350  (see  FIG.  10   ) implements a training phase during which the patient  102  (see  FIGS.  4  and  8   ) is trained to have the conditioned response (or reflex) in response to the electrical stimuli delivered by the electrode(s)  114 . During the training phase, the patient  102  experiences a number of substantially identical sessions.  FIG.  13    is a flow diagram of a method  500  that may be performed during a session of the training phase. In first block  510 , the patient  102  inserts the intraoral stimulation device(s)  110 . Then, in block  520 , while awake, the patient  102  places the patient&#39;s tongue  106  in an undesired position (e.g., retracted from the sensor(s)  112 ). At this point, the stimulation parameters are assigned their initial values (discussed above) by the control unit  130 , which are configured to deliver weak electrical stimulation. In block  530 , the sensor(s)  112  send signal(s) encoding tongue position information to the control unit  130 . 
     In decision block  540 , the control unit  130  determines whether to send the stimulation signal to the electrode(s)  114  based on the tongue position information. The decision in decision block  540  is “YES” when the control unit  130  determines that the patient&#39;s tongue  106  is in the undesired position. Otherwise, the decision in decision block  540  is “NO.” When the decision in decision block  540  is “NO,” in block  545 , the control unit  130  resets the amplitude of the stimulation back to its initial value. Then, the method  500  returns to block  530 . 
     On the other hand, when the decision in decision block  540  is “YES,” in block  550 , the control unit  130  configures the electrical stimulation and sends it to the stimulating electrode(s)  114 . In block  560 , the stimulating electrode(s)  114  deliver the electrical stimulation to the hard palate  108 . Then, the method  500  returns to block  530 . 
     The first time the block  550  is performed, the electrical stimulation configured by the control unit  130  is based on the initial stimulation parameter values. Thus, the electrical stimulation is relatively weak, having a low amplitude that is barely perceptible to the patient  102 . Each successive time block  550  is performed without the amplitude being reset in block  545 , the control unit  130  increases the amplitude of the electrical stimulation until the tongue  106  moves to the desired position (e.g., touching or pressing upon the tongue position sensor  160  and/or the tongue position sensor  180 ), which results in the decision in decision block  540  being “NO.” In some cases, the electrical stimulation may become uncomfortable to the patient  102 , which will encourage the patient  102  to develop the conditioned reflex. 
     After the training phase is complete, the patient  102  has acquired the conditioned response (or reflex). Thus, the method  500  may be used to treat OSA when the patient  102  is asleep. In such embodiments, the block  520  is omitted after block  510 . In block  530 , the sensor(s)  112  send signal(s) encoding tongue position information to the control unit  130 . When the control unit  130  determines the patient&#39;s tongue  106  in an undesired position in decision block  540 , the tongue  106  may be moved to the desired position by electrical stimulation delivered to the hard palate  108  by the stimulating electrode(s)  114  (in blocks  550  and  560 ). As occurred during each of the sessions, the electrical stimulation delivered to the sleeping patient  102  may start out as weak electrical stimulation. If the tongue  106  does not move to the desired position in response to the weak electrical stimulation, the control unit  130  may continuously increase the amplitude of the electrical stimulation until the tongue  106  moves to the desired position. 
     Maintaining the tongue  106  in a desired (forward) position requires that the patient  102  maintain a small tone in the tongue extensor muscles. This behavior by the patient  102  may be induced and maintained by induction of this new reflex (or conditioned response), using biofeedback to induce and maintain the reflex. 
       FIG.  14    is a graph showing a 90-second snippet of data captured from the upper bite block  110 U (see  FIGS.  2 - 5   ) during use in the patient&#39;s mouth during sleep. In  FIG.  14   , a line  600  illustrates the amplitude of the signal Sa(V), which represents tongue position as determined by the tongue position sensor  160  (see  FIGS.  2 - 5   ). A line  602  illustrates the amplitude of the electrical stimulation delivered to the patient&#39;s hard palate  108  (see  FIGS.  4  and  9 B ).  FIG.  14    illustrates the position of the tongue  106  (represented by the line  600 ) of the patient  102  (see  FIGS.  4  and  8   ) who has developed a tongue extension reflex in response to the sessions of stimulation of the hard palate  108  with the graded stimulus while awake. The letters A-D in  FIG.  14    correspond to the following:
         A. The tongue  106  (see  FIGS.  4  and  5   ) moves forward in patient&#39;s mouth, close to the tongue position sensor  160     B. The tongue  106  retracting from the tongue position sensor  160 ;   C. Electrical stimulus to patient&#39;s hard palate  108  (see  FIGS.  4  and  9 B ) begins, in response to retracting of the tongue  106 ; amplitude of stimulus increases continuously during the next 15 seconds, until the tongue  106  moves forward; and   D. Patient&#39;s tongue  106  moves forward and electrical stimulus to the hard palate  108  stops (represented by line segments “C”).       

     As shown in  FIG.  14   , the electrical stimulus (represented by the line  602 ) begins (represented by line segments “C”) when the tongue  106  is retracted from the tongue position sensor  160  (see  FIGS.  2 - 5   ). As shown by the line portions “C,” the amplitude of the electrical stimulus increased continuously while the tongue  106  (see  FIGS.  4  and  5   ) remained retracted from the tongue position sensor  160 . As shown by the line portions “C′,” the electrical stimulus ceases when the tongue  106  moved forward. 
     The method  500  may be characterized as being a biofeedback-based method, in which an invariant sequence of events is performed. Referring to  FIG.  13   , when the control unit  130  first detects the tongue  106  is retracted from the tongue position sensor  160  and the decision in decision block  540  is “YES,” in block  550 , the control unit  130  initiates an onset of low-amplitude stimulation that is barely perceptible to the patient  102 . This stimulation is delivered by the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ) in block  560 . Then, if the control unit  130  again detects that the tongue  106  is retracted from the tongue position sensor  160  and the decision in decision block  540  is “YES,” in block  550 , the control unit  130  increases the amplitude of the stimulus sent to the electrode(s)  114  (see  FIGS.  1 ,  9 A, and  9 B ), which is delivered thereby in block  560 . As long as the control unit  130  continues to detect that the tongue  106  is retracted from the tongue position sensor  160 , the control unit  130  continuously increases the amplitude of the stimulation, which may become uncomfortable to the patient  102  (see  FIGS.  4  and  8   ). 
     In other words, initially, the amplitude of the stimulus pulses is very low and imperceptible to the patient  102 , but if the tongue  106  (see  FIGS.  4  and  5   ) remains retracted from the tongue position sensor  160  (e.g., in a posterior position) or if the tongue  106  does not exert the prescribed force upon the tongue position sensor  160 , the stimulus amplitude increases steadily (e.g., over an interval of 10 seconds to 20 seconds) becoming perceptible as a tactile sensation, and, if continued, becoming mildly uncomfortable as the stimulus amplitude increases and delivers strong (or high-amplitude) stimulation to the hard palate  108 . 
     Finally, when the control unit  130  detects the tongue  106  is in the desired position and the decision in decision block  540  is “NO,” meaning no stimulation is delivered. Thus, the stimulation immediately terminates when the tongue  106  ( FIG.  6   ) moves anteriorly and into contact with the tongue position sensor  160 . 
     The patient  102  (see  FIGS.  4  and  8   ) must experience the above sequence of events many times, first while awake, for the repositioning of the tongue  106  (see  FIGS.  4  and  5   ) to become automatic, or “conditioned,” so that the tongue  106  move will move forward in response to the onset of barely perceptible low-level (e.g., low amplitude) stimulation. This training of the conditioned response may first be administered when the subject is awake, but later it may be maintained and reinforced when the subject is asleep by the action of the control unit  130  (see  FIGS.  1 ,  4 ,  5 , and  7   ). The control unit  130  continues to administer the sequence of events described above whenever the patient&#39;s tongue  106  retracts from the tongue position sensor  160 . 
     As shown in  FIG.  14   , at line segment C 3 , the patient&#39;s tongue  106  moved forward as soon as the stimulus began and remained forward near the tongue position sensor  160 , which indicates that training has taken place and the conditioned reflex has been acquired by the patient  102 . 
     The conditioned reflex persists during sleep in response to a level of electrical stimulation that will not disturb sleep. Thus, this conditioned reflex is like other acquired protective and/or defensive oral reflexes, including opening of the jaw and retraction of the tongue  106  (see  FIGS.  4  and  5   ) in response to light (but non-painful) bite pressure against the tongue  106 . The amplitude and pulse rate of the electrical stimulus can be adjusted (e.g., using the control application  340 ) so that the most intense electrical stimulation experienced by the patient  102  will be an unpleasant “prickling” sensation. 
     In  FIG.  14   , the electrical stimulus applied to the patient&#39;s hard palate  108  (see  FIGS.  4  and  9 B ) was a train of biphasic voltage pulses. As discussed above, the phase duration, pulse rate, and maximum amplitude (voltage) may be set by the user using the user interface  400  (see  FIG.  11   ). In  FIG.  14   , the pulse rate was 5 pulses per second and duration of each phase was 5 milliseconds. The line  602  shows the amplitude of each 5 msec pulse, as the pulse amplitude steady increases. In actuality, the stimulus amplitude returned to 0 V after each biphasic pulse pair, and remained at 0 V for about 190 msec, until the next pulse pair began. 
     Referring to  FIG.  1   , the control unit  130  may decide to deliver stimulation in decision block  540  (see  FIG.  13   ) when the sensor(s)  112  detect that the tongue  106  (see  FIGS.  4  and  5   ) is not in an anterior position and particularly in its most anterior position. Alternatively, the control unit  130  may be adjusted to begin the electrical stimulation whenever the tongue  106  (see  FIGS.  4  and  5   ) is not exerting a prescribed amount of force upon the sensor(s)  112  (e.g., the tongue position sensor  160  illustrated in  FIGS.  2 - 5   ). For example, referring to  FIG.  4   , the prescribed amount of force against the tongue position sensor  160  needed to terminate stimulation may be about zero grams to about 150 grams. The lower force value (zero grams) allows the tongue&#39;s position alone (i.e., merely contacting the tongue position sensor  160 ) to terminate stimulation, which in some patients may be adequate to maintain an open airway. In other embodiments, the prescribed amount of force required to terminate stimulation may be about 20 grams to about 100 grams. Such embodiments, the method  500  may be performed when it is determined that additional muscle tone in the muscles of the tongue  106  is required to prevent obstruction of the UA  104 . 
     In various embodiments, the voltage amplitude of the electrical stimulation may be about 5 volts to about 15 volts and the rate may be about 3 pulses per second to about 50 pulses per second. In other embodiments, the voltage amplitude of the electrical stimulation may be about 10 volts to about 25 volts and the rate may be about 5 pulses per second to about 50 pulses per second. It is expected that this will encourage (reinforce) development of a protective reflex whereupon the tongue  106  (see  FIGS.  4  and  5   ) is moved into contact with the sensor(s)  112  and/or exerts a prescribed force upon the sensor(s)  112  in response to the onset of the electrical stimulus, when the amplitude of the electrical stimulus is very low. The movement of the tongue  106  (see  FIGS.  4  and  5   ) may be effected by the acquired or conditioned reflex that is initiated by direct electrical stimulation applied to the hard palate  108 , direct electrical stimulation of the motor nerve that extends the tongue  106 , or a combination thereof. The stimulus amplitude remains below the charge density that can cause tissue injury. When the tongue  106  is moved anteriorly and makes contact with the sensor(s)  112  or exerts a prescribed force against the sensor(s)  112 , the electrical stimulation may cease. 
     As described above, referring to  FIG.  2   , the upper bite block  110 U (e.g., an individually-fitted maxillary dental fixture or night guard) may maintain extension of the tongue  106  by a conditioned reflex, rather than by direct stimulation of the innervation to the tongue extensor muscles. The upper bite block  110 U positions the stimulating electrodes  162  and  164  (see  FIGS.  2  and  5   ) in contact with the stable integument surface of the hard palate  108 . The tongue position sensor  160  senses when to deliver the directed stimulation (via the stimulating electrodes  162  and  164 ). Referring to  FIG.  7   , the lower bite block  110 L may be used in combination with the upper bite block  110 U (see  FIGS.  2 - 5   ) for mouth breathers. Furthermore, training provided by the biofeedback training application  350  is designed so that it is likely that many patients will eventually require less electrical stimulation and some patients may be able to retrain so that use of the upper and/or lower bite blocks  110 U and  110 L is not required on a regular basis or perhaps, at all. 
     Referring to  FIG.  1   , the system  100  may offer advantages over currently available therapies for treating OSA. For example, the system  100  does not include a mask placed on the face of the patient  102  (see  FIGS.  4  and  8   ). The system  100  does not disrupt the position of the patient&#39;s temporomandibular joint. The system  100  does not require surgery and the patient&#39;s body position during sleep is flexible. Additionally, the patient  102  is not tethered to a hose. Therefore, the patient  102  may be more willing to use the system  100 . Thus, the system  100  may have much higher compliance than CPAP or even MDA. The intraoral stimulation device(s)  110  may be configured to fit easily into one or more small cases for traveling. For example, referring to  FIG.  8   , the upper bite block  110 U may be stored in a first case  194  and the lower bite block  110 L may be stored in a second case  196 . 
     The foregoing described embodiments depict different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. Furthermore, it is to be understood that the invention is solely defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). 
     Conjunctive language, such as phrases of the form “at least one of A, B, and C,” or “at least one of A, B and C,” (i.e., the same phrase with or without the Oxford comma) unless specifically stated otherwise or otherwise clearly contradicted by context, is otherwise understood with the context as used in general to present that an item, term, etc., may be either A or B or C, any nonempty subset of the set of A and B and C, or any set not contradicted by context or otherwise excluded that contains at least one A, at least one B, or at least one C. For instance, in the illustrative example of a set having three members, the conjunctive phrases “at least one of A, B, and C” and “at least one of A, B and C” refer to any of the following sets: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, {A, B, C}, and, if not contradicted explicitly or by context, any set having {A}, {B}, and/or {C} as a subset (e.g., sets with multiple “A”). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of A, at least one of B, and at least one of C each to be present. Similarly, phrases such as “at least one of A, B, or C” and “at least one of A, B or C” refer to the same as “at least one of A, B, and C” and “at least one of A, B and C” refer to any of the following sets: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, {A, B, C}, unless differing meaning is explicitly stated or clear from context. 
     Accordingly, the invention is not limited except as by the appended claims.