Implantable stimulation devices deliver electrical stimuli to nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators (DBS) to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227. However, the present invention may find applicability with any implantable medical device (IMD) or in any implantable medical device system.
As shown in FIG. 1, a SCS system includes an implantable pulse generator 10 (hereinafter, and more generically, IMD 10), which includes a biocompatible device case 12 formed of titanium for example. The case 12 typically holds the circuitry and battery 14 necessary for the IMD 10 to function. The IMD 10 is coupled to electrodes 16 via one or more electrode leads 18 (two of which are shown). The proximal ends of the leads 18 are coupled to the IMD 10 at one or more lead connectors 20 fixed in a header 22, which can comprise an epoxy for example. In the illustrated embodiment, there are sixteen electrodes, although the number of leads and electrodes is application specific and therefore can vary. In an SCS application, two electrode leads 18 are typically implanted on the right and left side of the dura within the patient's spinal column. The proximal ends of the leads 18 are then tunneled through the patient's flesh to a distant location, such as the buttocks, where the IMD case 12 is implanted, at which point they are coupled to the lead connectors 20.
Cross sections of two examples of IMD 10, 10a and 10b, are shown in FIGS. 2A and 2B. Both contain a charging coil 26 for wirelessly charging the IMD's battery 14 using an external charging device (not shown). (If battery 14 is not rechargeable, charging coil 26 can be dispensed with). Both IMDs 10a and 10b also contain control circuitry such as a microcontroller 21, telemetry circuitry 23 (discussed further below), and various components 25 necessary for IMD operation, such as stimulation circuitry for forming therapeutic pulses at the electrodes 16. The charging coil 26, battery 14, microcontroller 21, telemetry circuitry 23, and other components 25 are electrically coupled to a printed circuit board (PCB) 19.
Different in the two IMDs 10a and 10b are the telemetry antennas 24a and 24b used to transcutaneously communicate data through the patient's tissue 80 with devices external to the patient (not shown in FIGS. 2A and 2B). In IMD 10a (FIG. 2A), the antenna comprises a coil 24a, which can bi-directionally communicate with an external device along a magnetic induction communication link 75a. Telemetry circuitry 23a is electrically coupled to the antenna coil 24a to enable it to communicate via magnetic induction link 75a, which comprises a magnetic field of typically less than 10 MHz operable in its near-field to communicate at a distance of 12 inches or less for example. Telemetry circuitry 23a generally includes driver circuitry for energizing the antenna coil 24a to transmit data and amplifier/filter circuitry for resolving data received at the coil 24a. Telemetry circuitry 23a generally also operates in accordance with a modulation scheme (defining how data to be transmitted is modulated on the link 75a and will be demodulated when received) and a communication protocol (defining the manner in which the data is formatted). Telemetry circuitry 23a receives the data to be transmitted in digital form from the microcontroller 21, and provides received digital data to the microcontroller 21 for interpretation. A typical modulation scheme used by telemetry circuitry 23a is Frequency Shift Keying (FSK), although other modulation schemes could also be used. In FIG. 2A, the external device would also contain communication means (e.g., a coil antenna; telemetry circuitry) compatible with the magnetic induction link 75a and the protocol used by the IMD 10a. 
In IMD 10b (FIG. 2B), short-range Radio Frequency (RF) communication means—including short-range RF antenna 24b and compliant short-range RF telemetry circuitry 23b—are provided that operate in accordance with a short-range RF communication standard and its underlying protocols to bi-directionally communicate with an external device along a short-range RF communication link 75b. RF communication link 75b typically operates using far-field electromagnetic waves ranging from 10 MHz to 10 GHz or so. Short-range RF standards supported by short-range RF telemetry circuitry 23b and antenna 24b include, for example, Bluetooth, BLE, NFC, Zigbee, WiFi, and the Medical Implant Communication Service (MICS). Short-range RF antenna 24b can take any number of well-known forms for an electromagnetic antenna, such as patches, slots, wires, etc., and can operate as a dipole or a monopole. The external device in FIG. 2B would also contain short-range RF communication means compatible with RF link 75b and the standard/protocol used in IMD 10b. As used herein, “short-range” RF telemetry may allow communications between devices (e.g., an external device and IMD 10b) at distances of about 50 feet or less.
Although both of antennas 24a and 24b in IMDs 10a and 10b are shown in FIGS. 2A and 2B inside of case 12, they may also be placed within the IMD's header 22, or on the outside of the case 12.
Different configurations for external devices used to communicate with IMDs such as 10a and 10b exist in the prior art. Such external devices are typically used to send or adjust the therapy settings the IMD 10a or 10b will provide to the patient (such as which electrodes 16 are active to issue pulses; whether such electrodes sink or source current (i.e., polarity); the duration, frequency, and amplitude of pulses, etc.), which settings together comprise a stimulation program for the patient. External devices can also act as receivers of data from the IMD 10a or 10b, such as various data reporting on the IMD's status and the level of the IMD's battery 14.
An external device having such functionality is shown in FIG. 3 in the form of a patient remote control (external controller) 50. External controller 50 is typically hand-held, portable, and powered by a battery. The external controller 50 includes a user interface similar to that used for a cell phone, including buttons 54 and a display 58, and may have other interface aspects as well, such as a speaker. Although not shown, the external controller 50 would also include within its housing communication means (including a coil antenna or a short-range RF antenna) compatible with the link 75a or 75b and the communication means in the IMD 10a or 10b. 
External devices such as the external controller 50 of FIG. 3 were historically built by the manufacturer of the IMDs, and thus were generally dedicated to communicate only with such IMDs. However, there are many commercial mobile devices, such as cell phones, that have user interfaces and built-in communication means suitable for functioning as a wireless external controller for an IMD. Using such mobile devices as external controllers for IMDs would benefit both manufacturers and patients: manufacturers would not need to design, build, and test dedicated external controllers, and patients could control and communicate with their IMDs without the inconvenience of having to carry and purchase additional custom external controllers.
FIGS. 4A and 4B show an example of a mobile device 100 configured for use as an external controller for an IMD, as described in commonly-owned U.S. Provisional Patent Application Ser. No. 61/874,863, filed Sep. 6, 2013, which is incorporated herein by reference. The mobile device 100 may be a commercial, multipurpose, consumer device, such as a cell phone, tablet, personal data assistant, laptop or notebook computer, or like device—essentially any mobile, hand-holdable device capable of functioning as a wireless external controller for an IMD. Examples include the Apple iPhone or iPad, Microsoft Surface, Nokia Lumia devices, Samsung Galaxy devices, and Google Android devices for example.
As shown in FIG. 4A, the mobile device 100 includes a user interface with a display 102, which may also receive input if it is a touch screen. The mobile device 100 may also have buttons 104 (e.g., a keyboard) for receiving input from the patient, a speaker 106, and a microphone 108. Shown on the display 102 is a typical home screen graphical user interface provided by the mobile device 100 when first booted or reset. A number of applications (“apps”) 110 may be present and displayed as icons on the mobile device home screen, which the patient can select and execute.
One of the applications (icons) displayed in FIG. 4A is a Medical Device Application (MDA) 120, which when executed by the patient will configure the mobile device 100 for use as an external controller to communicate with an IMD. FIG. 4B shows the home screen of the MDA 120 after it is executed, which includes options selectable by a patient to control his stimulation program or monitor his IMD. For example, the MDA 120 may present options to: start or stop stimulation; increase or decrease the amplitude of the stimulation pulses (or adjust other pulse parameters and electrode settings); check the battery and operating status of the IMD; review data telemetered from the IMD; exit the MDA 120 and return to the mobile device's home screen (FIG. 4A), etc. The MDA 120, like other applications 110 selectable in the mobile device 100, may have been downloaded using traditional techniques, such as from an Internet server or an “app store.”
When the MDA 120 is first selected and executed, or when an appropriate selection is made in the MDA (FIG. 4B), wireless communications with the IMD can be established using a communication means in the mobile device 100 and enabled by the MDA 120. The above-incorporated '863 Application discloses different examples in which such communication can occur, illustrated here in FIGS. 5A-5C.
In FIG. 5A, the MDA 120 establishes wireless communication directly with the mobile device 100 along RF link 75b using short-range RF communication means supported by the mobile device 100 (e.g., Bluetooth). In this instance, the IMD 10b would include short-range communication means compatible with RF link 75b, such as shown earlier with respect to FIG. 2B.
In FIG. 5B, a communication coil 112 in a communication head 113 is coupled by a cable 114 to a port on the mobile device 100, such as a USB port. In this instance, the communication coil 112 can be placed proximate to the IMD 10a to establish a magnetic induction link 75a, perhaps as modulated via FSK as mentioned earlier. The IMD 10a would include communication means compatible with magnetic induction link 75a (e.g., a coil antenna 24a), such as shown earlier with respect to FIG. 2A. The MDA 120 in this example would program the mobile device 100 to issue and receive data at its USB port, which data may be modulated or digital depending whether the modulation/demodulation circuitry resides in the mobile device 100 or the communication head 113.
In FIG. 5C, the mobile device 100 communicates with the IMD 10a via an intermediary bridge 90. The bridge 90 contains first communication means (including an RF antenna 118) for wirelessly communicating with the mobile device 100 via short-range RF link 75b, and second communication means (including a coil antenna 116) for wirelessly communicating with the IMD 10a via magnetic induction link 75b. The bridge 90, which is preferably battery powered, essentially “translates” short-range RF data on link 75b into magnetic-induction data on link 75a, and vice versa. The MDA 120 can thus program the mobile device 100 to use its short-range RF communication means (e.g., Bluetooth) even if the IMD is not compatible with such means, because the bridge 90 can translate and communicate with both.
The '863 Application further teaches that the MDA 120 can secure the mobile device 100 by controlling hardware and software in the mobile device that could affect, or worse corrupt, its use as an IMD external controller. For example, the '863 Application discloses that the MDA 120 upon execution can temporarily configure the mobile device 100 to prevent operation of the mobile device inconsistent with external controller functionality. In particular, the MDA 120 may disable or reconfigure hardware modules in the mobile device 100 that are either unnecessary or could potentially interfere with operation of the MDA 120, such as short-range communication means not used to communicate with the IMD, the camera, the cellular modem, GPS, the accelerometer, etc.
The MDA 120 can also terminate or temporarily suspend software tasks that might interfere with secure operation of the mobile device 100 as an external controller, such as other apps 110 displayable and executable from the mobile device home screen (FIG. 4A), or other software tasks that may run in the background of the mobile device in manners not immediately noticeable to the patient. Examples include e-mail and e-mail synchronization programs, software updates, alarm clocks, telephony functions, e-mail programs, music players, video games, mapping programs, Internet browsing applications, push service applications requiring Internet access, and other software tasks not essential to IMD communications.
The '863 Application additionally discloses that hardware and software security of these sorts can also be incorporated into the mobile device 100's booting process after it is powered on or restarted, or can modify the booting process to allow a patient to select how the mobile device 100 should be configured—either as a less-secure normal mobile device 100 or as a secure external controller for IMD communications.
While a mobile device 100 can function as an external controller for an IMD, the inventor sees certain problems that need to be overcome. For one, a mobile device 100 should be rendered operational to communicate with an IMD quickly. Assume for example that a patient's IMD is causing discomfort. It would be desirable for the patient to use the mobile device 100/MDA 120 (FIG. 4B) to quickly decrease the intensity of IMD stimulation, or to shut down operation of the IMD altogether. Mobile devices 100 may contain features preventing such quick operation, such as lock screens or other password protection mechanisms that require user input before the mobile device 100 can be operated as an external controller or otherwise. Additionally, the mobile device may have a series of menus or steps that must be navigated prior to running the MDA 120, even if the mobile device 100 is unlocked. If a patient is experiencing discomfort, having to take time to unlock the mobile device 100 or to navigate through menus would be aggravating at least, or at worst could injure the patient.
The inventor further recognizes that it is desirable to provide physical security regarding mobile device 100/IMD communications that is not wholly reliant on software. Even if an MDA 120 in a mobile device 100 is paired to a particular patient's IMD, another user of the patient's mobile device 100 could access the MDA 120 and potentially tamper with the patient's therapy. Alternatively, another user could download the MDA 120 to his mobile device 100 (even if not himself an IMD patient), and attempt to “hack” into a patient's IMD or the MDA 120 on the patient's phone. A physical security measure akin to a physical key for rendering a mobile device 100 useable as an IMD external controller is therefore desired.
Finally, while mobile devices 100 typically contain different types of communication means to enable various types of short-range wireless communications, the inventor realizes that it cannot be guaranteed that a patient's IMD will be compatible with such means. For example, if a patient has an IMD 10a containing an antenna coil 24a (FIG. 2A) operable in accordance with FSK, attempting to establish IMD communications using the mobile device 100's Bluetooth communication means would be ineffective, because the IMD is not compatible with Bluetooth. Conversely, it may be the mobile device 100 that is lacking in its communication ability. For example, while mobile devices 100 typically include common, commercially-used communication means (supporting Bluetooth, BLE, NFC, and WiFi for example), they may not be compatible with communication means used more-uniquely in implantable medical devices (such as Zigbee and MICS). This limits the utility of the mobile device 100 as an external controller for an IMD, particularly if it is desired to allow such devices to communicate directly (e.g., FIG. 5A).