Patent Application
20250161678
This application claims the benefit of European patent application 23383170.0, filed on 16 Nov. 2023, the disclosure of which is incorporated herein by reference in its entirety.
The present disclosure relates to the field of functional electrical stimulation and, in particular, to apparatuses, systems and methods for rehabilitation of paralyzed or impaired body parts, such as hands and/or arms, by electrostimulation of peripheral nerves.
Neurological injuries or disorders, such as stroke, spinal cord injury or cerebral palsy, among others, usually cause complete or partial paralysis or severe weakness in certain body parts. This often results in impaired or lost function in one or more limbs. It is well-known that people affected by these traumas can rehabilitate significantly by executing familiar and/or functional tasks. Assistance for performing this rehabilitation is usually required, since after neurological injuries the patient is usually diminished in his/her capacity to control or to strength the afflicted limb or limbs. Wearable devices have been proven to be of effective assistance in such rehabilitation tasks.
There exist electro-mechanical wearable rehabilitation devices. For example, EP3199136B1 discloses a portable device for hand rehabilitation designed to be grasped by a hand to be trained. This device enables independent flexion/extension movement for the thumb, index fingers and three remaining fingers. In turn, U.S. Pat. No. 9,398,994B2 discloses an orthotic system for limb rehabilitation including a brace having two pivotably sections, an electrically powered actuator assembly and an electroencephalographic (EEG) sensor. The actuator assembly applies a force that moves the brace sections in flexion/extension direction. The applied force is based on signals from the EEG sensor.
Functional electrical stimulation (FES) is a technique that uses low energy electrical pulses to artificially generate muscle contractions to produce body segment movements and motor functions such as grasping or walking. There exist wearable rehabilitation devices for external activation of paralyzed or impaired body parts by stimulation of peripheral nerves based on FES. For example, EP2519312B1 discloses a sleeve designed to be worn by a user having a stimulation layer having multi-pad electrodes designed to be in contact with the user's skin, and an activation layer opposite the stimulation layer and overlapping it, composed of pressure-driven sensors for activating/deactivating corresponding pads of the stimulation layer.
A challenge of FES devices for the upper-limb is to determine the proper activation means so that they can be integrated in the daily activities as currently do FES devices for the lower-limb. Current FES devices require the use of external sensors to control the application of stimulating signals.
For example, the MindMaze group provides (https://www.intento.ch/movement-therapy/, last access of Oct. 11, 2023) a FES device having electrodes to be placed on specific areas of the patient's arm to stimulate muscular contractions and induce the desired movements. The patient controls the stimulation by an external device activated with the other hand. Bioness (https://www.bioness.com/, last access of Nov. 8, 2023) also offers the H200® wireless system, which uses FES to activate the nerves that control the muscles in the hand and forearm and is controlled from a hand-held control unit.
A drawback with the former proposals is that they require the impaired person to hold a control device in his/her hand different from the hand or arm being rehabilitated. However, depending on the condition of the user, this requirement can become an insurmountable obstacle for the patient.
Devices have been developed, which do not rely on a hand-held device portable with the hand not being under rehabilitation. For example, EP3650077A1 discloses a FES device for limb rehabilitation which includes a garment mountable on a user's body part. The garment holds an electrode and a socket in turn housing a stimulator. The stimulator adapts the stimulating electrical signals to be provided to the electrode from sensor signals provided by an external sensor that measures the movement resultant from the stimulation; however, the trigger for that stimulation is sent from an external control means as a tablet or smartphone.
In turn, EP1555968B1 discloses a detector disposed on the user's head to control signals applicable to electrodes to stimulate muscles to open and/or close thumbs and fingers of the hand. The detector detects mechanical vibrations elicited by sudden contact of upper and lower teeth and these vibrations are used to control the operation of the electrodes.
Despite the efforts to accommodate current devices to the condition of the user, there is still a need to reduce complexity in terms of the equipment the patient must wear or carry, with the aim to simplify as much as possible the rehabilitation process and to enable the patient to perform the daily activities in total autonomy.
The drawbacks of conventional FES devices are addressed by the present disclosure, which provides a functional electrical stimulation device which is very easy to use in an autonomous way, even for a person having suffered a neurological injury. The device detects a user's intention to perform an action with the upper limb and stimulates the muscles required to do so. The upper limb may include the hand, forearm, elbow, arm and/or shoulder.
The device improves upper limb function and active range of motion in adults and pediatric individuals with injury or pediatric-related motor dysfunction related to injuries or diseases affecting the physiological functioning of the upper limb (e.g., stroke, paralysis of the upper limb, etc.).
Particularly, the device electrically stimulates the muscles and nerves of the affected upper limb to provide joint flexion and extension. It also facilitates muscle re-education, it prevents or retards atrophy of said muscles, it helps to maintain or increase joint range of motion and it increases local blood flow.
The device for functional electrical stimulation of the present disclosure is intended to be positioned on an upper limb of a user for stimulation of the user's upper limb, such as its hand and/or arm.
In a first aspect of the disclosure, a device for functional electrical stimulation intended to be positioned on an upper limb of a user for stimulation of the user's upper limb, is provided. The device comprising:
As previously explained, the embedded sensor continuously measures the presence or lack of movement of the stimulator. In the context of the present disclosure, the term “continuously” means that the measurements captured by the sensor are captured at a frequency above a certain value, such as above 20 Hz, or above 60 Hz, or above 120 Hz. This means that the sensor obtains measurements, and it sends them to the control means in a high enough frequency, e.g., 125 Hz, to permit fine movement detection.
As a skilled person in the art knows, the stimulating electrical signals generated on the upper limb of the user by the electrode are stimulation patterns, such as pulse patterns with certain characteristics or parameters, such as frequency, pulse width, amplitude, compensation, time duration, etc., which cause the contraction or relaxations of the muscles.
In affected users, when they want to perform an action, the stimulus generated by the brain does not reach the muscle, which does not move as it should. Thanks to the device of the disclosure the muscle contracts by the stimulation. Thus, the brain receives information about the movement and strives to control it, creating new connections as another area of the brain controls the movement, recovering autonomy.
Both the sensor and the control means are embedded in the stimulator. Communication between the embedded sensor and the control means is preferably via a wired connection. The device also has the advantage, compared to the devices of the state of the art, that it eliminates external elements, allowing bimanual tasks (cannot be done with a remote control in the other hand), avoiding the loss of said external elements, and also for aesthetic reasons.
In embodiments of the disclosure, the stimulator is intended to be attached to the user's arm.
In embodiments of the disclosure, the movement of the stimulator associated with an intention of the user to perform an action with his/her upper limb is a sharp or abrupt movement of the stimulator followed and preceded by a rest period. A rest period is a period where the control means of the stimulator have not detected any movement or the movement detected is below a predefined threshold. A sharp or abrupt movement is therefore a short movement preceded and followed by a rest period. For example, in embodiments of the disclosure, a short movement could last a couple of milliseconds and the rest period a couple of seconds.
That type of movement is key to the use of the device in the daily life of a user. The device must be easy enough to be used so that users are able to perform the movement freely by themselves, but at the same time it must be a movement that is only performed intentionally to allow it to be differentiated from normal upper limb use and to avoid false positives in the detection of movement intention.
This type of movement can be generated at least in three ways:
In embodiments of the disclosure the movement of the stimulator is generated by at least one of:
These kinds of movements (in particular, those in the first and second lists above) encourage the use of the affected arm to trigger stimulation and hand opening/closing. Specifically, forearm prosupinantion, abduction with hand in a fixed position and adduction with hand in a fixed position are movements that can be performed while grasping and carrying objects. These movements require stricter rest periods before and after the movement, to avoid false detections and accidentally drop the objects, for example. All the described movements, but particularly the ones that can be performed while grasping objects, enable activities of daily living.
In embodiments of the disclosure, the embedded sensor is an IMU (inertial measurement unit). This sensor is very precise and obtains very accurate measurements, allowing optimum calibration of the device to ensure detection of movement without giving false positives. In embodiments of the disclosure the IMU is a three axis IMU. In other embodiments of the disclosure the IMU is a six axis IMU. In embodiments of the disclosure the embedded sensor is a 6-axis IMU, comprising a 3-axis gyroscope and a 3-axis accelerometer sensor. In embodiments of the disclosure, the embedded sensor is an EMG sensor (electromyography), which records the electrical activity generated by the user's muscles when trying to perform a movement with the upper limb even if they are not able to complete it; therefore, providing information about the movement intention of the user. In embodiments of the disclosure, the embedded sensor can comprise both, an IMU and an EMG.
In embodiments of the disclosure, the measurements that the embedded sensor sends to the control means include one or more of the positions of the three axis of the gyroscope and the acceleration measured by the accelerometer. In embodiments of the disclosure, after the embedded sensor sends its measurements to the control means, the last obtains the modulus of the three axes of the gyroscopes and the modulus of the three axes of the accelerometer. In embodiments of the disclosure the control means calculate one or more of the Quaternion, Euler angles and rotation vector.
In a second aspect of the disclosure, a method for rehabilitation of upper limb function by functional electrical stimulation is provided. The method comprising the steps of:
As with the device previously described, the method of the disclosure allows a user to perform an upper limb action through electrical stimulation of the upper limb muscles in a simple and comfortable way.
In embodiments of the disclosure the stimulator having the embedded sensor is attached to a user's arm.
As with the device of the disclosure, in an embodiment of the disclosure the movement is generated in one of the following ways:
In an embodiment of the disclosure, the movement associated with an intention of the user to perform an action with his/her hand or arm (upper limb) is detected when the control means detect, in the sensor measurements, a value above a predefined threshold preceded by a first rest period and followed by a second rest period.
In embodiments of the disclosure, an additional period, referred to as waiting period, is defined. This waiting period is aimed at turning the device to an active mode. For example, the waiting period can follow the second rest period, or the waiting period can precede the first rest period. This waiting mode is very important to avoid false positives, for example if the user has poor control over his/her impaired limb, or, following a rest period, the user can still experience some residual movements after having performed an action. It also helps the patient's rehabilitation by requiring finer control of the arm or hand. During this waiting mode the control means remain inactive. Inactive meaning that the control means do not send any signal to the electrode to activate or deactivate the electrode pads.
The sensor may measure different parameters. In embodiments of the disclosure, the measurements that the embedded sensor measures and sends to the control means include one or more of the positions of the three axis of the gyroscopes and the acceleration measured by the accelerometers. In embodiments of the disclosure, after the embedded sensor sends its measurements to the control means, the control means obtains the modulus of the three axes of the gyroscope and the modulus of the three axes of the accelerometer. In embodiments of the disclosure the control means calculate one or more of the Quaternion, Euler angles and rotation vector.
In an embodiment of the disclosure, the control means determine that there is an intention to perform a movement if the following conditions are met:
In preferred embodiments of the disclosure, the control means determine that there is an intention to perform a movement if all the conditions are met.
An additional moderated rest period can be used between the movement period and the second rest period.
For example, when the sensor is an IMU including a gyroscope, the first value is between 0 and 12 dps (degrees per second), preferably between 0 and 6 dps and more preferably between 0 and 3 dps.
For example, when the sensor is an IMU including a gyroscope, the second value is above 15 dps, provided that the second value is at least twice the first value.
In embodiments of the disclosure, when the sensor is an accelerometer, the control module identifies an intention to perform an action if the module of the acceleration changes, which may be directly related to hit or fast speed change of the stimulator.
For example, the first rest period is between 100 and 250 ms, the movement period is between 250 and 1000 ms and the second rest period is between 150 and 750 ms.
The exemplary values described above ensure an optimum operation of the device.
Additional advantages and features of the disclosure will become apparent from the detail description that follows and will be particularly pointed out in the appended claims.
To complete the description and in order to provide for a better understanding of the disclosure, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the disclosure, which should not be interpreted as restricting the scope of the disclosure, but just as an example of how the disclosure can be carried out. The drawings comprise the following figures:
The following description is not to be taken in a limiting sense but is given solely for the purpose of describing the broad principles of the disclosure. Next embodiments of the disclosure will be described by way of example, with reference to the above-mentioned drawings, showing apparatuses and results according to the disclosure.
As presented in
The electrode pads 3 can be activated independently or in combination, allowing it to be adapted to the anatomy of different users. Also, intensity can be controlled. The generated pulse can be symmetric biphasic or compensated biphasic, for example with a 0-60 mA intensity, 150 us-300 us width and 1-40 Hz frequency.
As illustrated in
The movement of the stimulator 4 that causes the control means 6 to determine that the user wants to perform an action is a sharp or abrupt movement of the stimulator 4 followed and preceded by a rest period. As an example,
Moreover, an additional period, referred to as waiting period, can be defined. This waiting period is aimed at turning the device 1 to an active mode. The waiting period can follow the second rest period, or it can precede the first rest period. In the case of the flow diagram of
These steps are only an example of the actions that can be performed when the electrodes 2 are activated by the control means 6, when the device identifies a movement as an intention to perform an action. These actions depend on the location and number of electrode pads 3 that are activated.
Examples of the types of movement which can make the control means 6 detect an intention to perform an action are depicted in
The arm movements are depicted on the upper portion of
The forearm movements are depicted on the lower portion of
Finally,
As previously explained, the sensor 5 continuously measures the presence or absence of the movement of the stimulator 4. The sensor sends its measurements to the control means 6, which determine, based on values of the sensor measurements, if there is an intention to perform an action. An intention to perform an action is inferred when the detected measurements are over a predetermined threshold, therefore only when a sharp movement is detected, which must be preceded and followed by a rest period. This configuration prevents false positives, which could occur with nonintentional movements that could activate the device 1.
The processing unit 28 of the exemplary electronics of the stimulator 4 further comprise, as presented in
The exemplary electronics of the stimulator 4 also comprise a pulse generator 16, which is the one in charge of generating the electrical signals that, by means of the electrode 2, will activate the muscles of the user. The pulse generator 16 is connected to the output module 29 and, in particular, it is connected to anode and cathode selection modules 24 and 25, connected to a control unit 26 and to electrode connectors 27.
In this embodiment shown in
In a first case (WAIT_QUIET) 103 the control means 6 wait for a resting period. If during said resting period no movement has been detected 104, the control means 6 start a timeout for trigger detection 105. Then 107, the device 1 goes to the second case (WAIT_TRIGGER) 108.
In this second case (WAIT_TRIGGER) 108, if the timeout for trigger detection ends 109, the device 1 goes back 110 to the first case (WAIT_QUIET) 103.
In this second case (WAIT_TRIGGER) 108 if a trigger (a sharp movement) is detected 111, a stimulation step (STIMULATION) is activated 112, which is described below. In this case, the conditions to detect a trigger are the following:
In this second case (WAIT_TRIGGER) 108 if an intention trigger is detected 113, the stimulation step (STIMULATION) is activated, and the timeout for trigger detection is increased, if required 114.
The previously mentioned STIMULATION 115 step goes as follows:
All the previous steps start a timer to separate triggers 120, after which, the device 1 goes to a state of (WAIT_BETWEEN_TRIGGERS) 121.
In the case (WAIT_BETWEEN_TRIGGERS) 132, if the timer to separate triggers is ended 133, it goes to WAIT_TRIGGER 134.
In this text, the term “comprises” and its derivations (such as “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.
The disclosure is obviously not limited to the specific embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the disclosure as defined in the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23383170.0 | Nov 2023 | EP | regional |
