Feedback-Control Wearable Upper-Limb Electrical Stimulation Device

[0001] 1. Field of Invention

[0002] This invention generally relates to an electrical stimulation device, and more particularly to an electrical stimulation device that can be used on the upper limbs of human and provides a feedback control function.

[0003] 2. Description of the Related Art

[0004] People may lose the ability to control their limbs entirely or partially, which is caused by a stroke, certain diseases or trauma. In order to prevent the atrophy of affected limbs and recover the ability of controlling the limbs that are paralyzed or partially disabled, the physical treatment and rehabilitation should be given to the patient after diagnosed.

[0005] For example, the stroke usually causes the hemiparesis or hemiplegia on the patient with different degrees and may be partial-ataxia or losing control on local neuromuscular system, which results in muscle weakness. So far, to give how much rehabilitation to the patient depends on the different degree of paralysis, for example, asking a patient to hold a rehabilitation cup and then move it from a position to another repeatedly for training the paralysis or affected limb. For the patient who is in serious paralysis, a stretching exercise or an electrical stimulation can be given to the patient to stimulate the neuromuscular system of the patient's affected limbs and to assist the patient to do some rehabilitation movements such as stretching, retracting, opening the palm and clenching.

[0006] However, the conventional electrical stimulation is always given by the patient or a third person (for example, the rehab therapist) to stimulate the neuromuscular system of the affected limbs of the paralysis side via a controller, in order to achieve some assigning motions. Although the above-mentioned conventional electrical stimulation can make the affected limbs do the assigning motions and process the rehabilitation, the patient cannot control their limbs volitionally. The conventional electrical stimulation only can achieve a limited result and cannot train the patient to control the affected limbs of paralyzed body side self-consciously.

[0007] Therefore, the conventional electrical stimulation of rehabilitation still has some inconvenience and defection, which needs to be further improved. In order to solve the above-mentioned problems, all the related manufacturers are eager to find the solutions. However, they still don't have any appropriate designs, and there are no products having appropriate designs that solve the above-mentioned problems.

[0008] The purpose of the invention is to overcome the limitation of a conventional electrical stimulation rehabilitation method or device that only can provide limb movement that is similar to physical treatment, but cannot provides a training to the limb that is controlled by patients self-consciously, and cannot integrates an electrical stimulation and an electromyography signal. As the result, the efficiency of the conventional electrical stimulation of rehabilitation is ineffective. The objective of the present invention is to provide a wearable upper limb electrical stimulation device with feedback control function. This invention provides an integration of the electrical stimulation and an analysis of a volitional electromyography signal and a stimulus electromyography signal that cause a muscle contraction. This invention provides the appropriate assisting electrical stimulation for an affected limb according to the analyzed result of a volitional electromyography signal, which is able to get a fulfill rehabilitation achievement.

[0009] The present invention provides a wearable upper limb electrical stimulation device with feedback control function comprising multiple electrical stimulation electrodes, multiple electromyography signal sensors, an electrical stimulation output unit, an electromyography signal acquisition unit, an electromyography signal operation unit and a control module, wherein each one of the electrical stimulation electrodes is pasted or attached to a human's limb, and the electrical stimulation is given to a neuromuscular system of the human's limb by each one of the electrical stimulation electrodes; in order to sense and receive the electromyography signal being generated by the human's limb, each one of the electromyography signal sensors is pasted or attached to the human's limb corresponding to a position of the neuromuscular system of human's limb where the electrical stimulation electrode is pasted, wherein the electromyography signal thereof comprises the volitional electromyography signal, the stimulus electromyography signal and the interference signal; an electrical stimulation output unit is connected to each one of the electrical stimulation electrodes and provides the electrical stimulation. An electromyography signal acquisition unit is connected to each one of the electromyography signal sensors and successively receives, filters and amplifies the electromyography signal. The electromyography signal operation unit is connected to the electromyography signal acquisition unit and receives the electromyography signal been filtered and amplified. The control module is connected to the electrical stimulation output unit and the electromyography signal operation unit. The control module receives the electromyography signal via the electromyography signal operation unit and controls the electrical stimulation output unit according to the position and strength of the electromyography signal. The electrical stimulation output unit provides electricity to at least one electrical stimulation electrode for outputting the electrical stimulation to human's body.

[0010] This invention's purpose and the technical problem which it solves can realize by the technology below.

[0011] The above-mentioned wearable upper limb electrical stimulation device with feedback control function, wherein the electromyography signal acquisition unit thereof comprises an electrical stimulation signal blocking circuit, a instrumentation amplifier, an amplifier circuit, a high-pass and low-pass filter and a voltage level shifter or clamp circuit. The electrical stimulation signal blocking circuit filters the electromyography signal from the interference by the electrical stimulation. The instrumentation amplifier performs a front-end amplification to the electromyography signal. The amplifier circuit increases an amplification ratio of the electromyography signal. The high-pass and low-pass filter filters the electromyography signal except for a setting range of the electromyography. The voltage level shifter or clamp circuit increases the voltage level of the electromyography signal. The above-mentioned wearable upper limb electrical stimulation device with feedback control function further comprises an analog-to-digital converter connected between the voltage level shifter or clamper circuit and the electromyography signal operation unit. The analog-to-digital converter transfers the electromyography signal outputted from the voltage level shifter or clamper circuit, and the electromyography signal operation unit receives the digitized electromyography signal, wherein the electromyography signal operation unit thereof comprises an interference operation unit, a comb filter and a subtraction circuit. After the interference operation unit filters pulses of the electrical stimulation in the electromyography signal, the comb filter gets the volitional electromyography signal from the electromyography signal. The subtraction circuit generates the stimulus electromyography signal by subtracting the volitional electromyography signal from the electromyography signal.

[0012] The front-end signal of each electromyography signal is filtered by the interference operation unit with a predefined time range between 100 μs and 5 ms.

[0013] The above-mentioned wearable upper limb electrical stimulation device with feedback control function further comprises a fixed brace being shaped corresponding to human's limb, the fixed brace connects each one of the electrical stimulation electrodes, each one of the electromyography signal sensors, the electrical stimulation output unit, the electromyography signal operation unit and the control module respectively, the electrical stimulation electrode and the electromyography signal sensor are mounted on an inner surface of the fixed brace.

[0014] The above-mentioned wearable upper limb electrical stimulation device with feedback control function, wherein the fixed brace thereof comprises an upper arm fixed portion, a forearm fixed portion and a palm fixed portion being shaped respectively corresponding to an upper arm, a forearm and a palm of human, and is detachably mounted separately on the upper arm, the forearm and the palm.

[0015] The control module controls the corresponding electrical stimulation electrodes to generate the electrical stimulation according to the position and status of the received electromyography signal. The position of the electrical stimulation electrode is corresponding to the neuromuscular system.

[0016] The control module may be a micro-processor module or a programmable chip.

[0017] The control module adjusts the electrical stimulation by using the electromyography signal. The control module defines the intensity of the electrical stimulation by using a comparison method or a look-up table method. The comparison method or the look-up table method is to compare the reading electromyography signal and a stored standard of electromyography signal, then outputting an appropriate electrical stimulation according to the result of the comparison, wherein the stored standard of the electromyography signal is an electromyography signal value of a healthy limb or an average electromyography signal value of human.

[0018] The wearable upper limb electrical stimulation device with feedback control function further comprises multiple flex/band sensors being connected to the fixed brace corresponding to joints of the upper arm, the forearm and the palm of human respectively, the flex/band sensors sense the curvature of the joints, and transfers the curvature to the control module. The control module controls the electrical stimulation output unit through a specific electrical stimulation electrode according to the curvature of the flex/band sensors and the electromyography signal.

[0019] The present invention has advantages and benefits as follows.

[0020] First, the present invention provides a suitable intensity of the electrical stimulation for a patient's limb to execute a specific movement or action, and provides an appropriate assist to the patient according to the received strength of the electromyography signal of the limb. Thus, the present invention not only activates the patient's partially disabled limb, but also can train the patient to have the ability to control the affected limb effectively.

[0021] In summary, the present invention relates to a wearable upper limb electrical stimulation device with feedback control function having multiple electrical stimulation electrodes, multiple electromyography signal sensors, an electrical stimulation output unit, an electromyography signal operation unit and a control module. The present invention identifies the intensity of the electrical stimulation so as to provide an appropriate assist to the patient's limb to execute a specific movement according to the strength of the electromyography signal of the limb.

[0022] Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

[0030] With reference to FIGS. 1 and 2, a preferred embodiment of a wearable upper limb electrical stimulation device with feedback control function in accordance with the present invention comprises multiple electrical stimulation electrodes 10, multiple electromyography signal sensors 20, an electrical stimulation output unit 30, an electromyography signal acquisition unit 35, an analog-to-digital converter 37, an electromyography signal operation unit 40, a control module 50 and a fixed brace 60.

[0031] With reference to FIGS. 3 to 5, FIG. 3 is an operational perspective view of the preferred embodiment of the present invention. FIG. 4 is an operational perspective view of the pasted position of the electrical stimulation electrode 10 and the electromyography signal sensor 20 of the preferred embodiment of the present invention. FIG. 5 is another operational perspective view of the pasted position of the electromyography signal sensor 20 in the preferred embodiment. Each one of the electrical stimulation electrodes 10 is detachably attached or pasted to a human's limb 70. The human's limb 70 is an arm. Each one of the electrical stimulation electrodes 10 is controlled to provide an electrical stimulation to a neuromuscular system of the arm in an appropriate time. For example, each one of the electrical stimulation electrodes 10 is attached to an extensor muscle, a flexor muscle, a triceps brachii, or an extensor digitorum muscle, and provides an appropriate intensity of the electrical stimulation to stimulate the muscles of the neuromuscular system to perform corresponding movements.

[0032] The appropriate time is a time to output the electrical stimulation to different muscle group so as to make an arm move forward, a palm open or grip and do other similar actions. The said appropriate intensity is to provide suitable intensity of the electrical stimulation to assist relevant muscles based on characteristics of the neuromuscular system or the muscle groups. The appropriate intensity may be decided by pretesting or recording the intensity of the electrical stimulation that each muscle group of a hemiparesis or hemiplegia limb requires to generate a same or similar movement of a normal limb. Thus, the present embodiment may have intensity of the electrical stimulation for different muscle group to execute different movements. Therefore, each electrical stimulation electrode 10 may be controlled to output electrical stimulation with suitable intensity for a specific movement that relevant muscle group requires.

[0033] Each one of the electromyography signal sensors 20 is attached or pasted to the human's limb 70 and is correspondingly located on each muscle group of the neuromuscular system of the human's limb 70. The electromyography signal sensor 20 detects and continuously receives an electromyography signal from the human's limb 70, and the electromyography signal comprises a volitional electromyography signal, a stimulus signal and an interference signal.

[0034] The electromyography signal is a potential signal generated by the muscle relative to a movement of the muscle. The electromyography signal is proportional to an activation state of the muscle of the human's limb 70. Therefore, the activation states of the neuromuscular system of the human's limb 70 may be quantized through analyzing the electromyography signal. Since the electromyography signal is relative to information about the activation state of the muscle, when the human's limb 70 of the embodiment receives the electrical stimulation from the electrical stimulation electrodes 10, the muscle of the human's limb 70 responses a voluntary contraction accordingly, which is a source of the volitional electromyography signal. Furthermore, the electromyography signal is directly evoked by giving the electrical stimulation to the muscle and is known as a stimulus electromyography signal in the above-mentioned. The electrical stimulation causes interference to the electromyography signal.

[0035] The electrical stimulation output unit 30 is connected to each one of the electrical stimulation electrodes 10. The electrical stimulation output unit 30 generates the electrical stimulation to each one of the electrical stimulation electrodes 10 for the human's limb 70.

[0036] With reference to FIGS. 6A and 6B, the electromyography signal acquisition unit 35 is connected with each one of the electromyography signal sensors 20, which receives electromyography signals from the electromyography signal sensors 20, and the electromyography signal acquisition unit 35 has an electrical stimulation signal block circuit 351, a instrumentation amplifier 355, a high-pass and low-pass filter 357 and a voltage level shifter or clamper circuit 359. In the preferred embodiment, the electrical stimulation signal block circuit 351 eliminates the electrical stimulation from the raw electromyography signal. The electrical stimulation signal block circuit 351 may have an OP amplifier circuit that is used to preliminarily eliminate the electrical stimulation from the electromyography signal to reduce interference.

[0037] As the raw electromyography signal is very weak, it needs to be amplified before being processed. First, the electromyography signal is processed by a front-end amplification through the instrumentation amplifier 353. Secondly, an amplification ratio of the electromyography signal is enhanced by amplifier circuit 355. Thirdly, the electromyography signal is then filtered by the high-pass and low-pass filter 357. The high-pass and low-pass filter 357 filters frequencies outside a defined range of 1 Hz to 1000 Hz and also filters a noise frequency. Finally, the electromyography signal is inputted to the voltage level shifter or the clamp circuit 359 to boost voltage levels of the electromyography signal.

[0038] The analog-to-digital converter 37 is connected to the electromyography signal acquisition unit 35. After receiving the electromyography signal outputted from the voltage level shifter or clamp circuit 359, the analog-to-digital converter 37 transfers the electromyography signal to a digital signal.

[0039] The electromyography signal operation unit 40 is connected to the electromyography signal acquisition unit 35, which receives the electromyography signal and outputs the electromyography signal after a signal processing (for example, filtering or clamping). In order to separate the volitional electromyography signal of the electromyography signal, the stimulus electromyography signal and the interference signal, with reference to FIG. 6B, the electromyography signal operation unit 40 comprises a serial interference operation unit 41, a comb filter 43 and a subtraction circuit 45. The interference operation unit 41 may filters a partial or predefined section of each electromyography signal, wherein the interference operation unit 41 may eliminate or give a fixed value or a mean value, or it can use an algorithm to process the front section of each electromyography signal.

[0040] The interference signal of the electromyography signal is mainly caused by the electrical stimulation that is provided to the human's limb 70, the electrical stimulation is normally a big pulse signal comparing to the electromyography signal. Therefore, the interference operation unit 41 eliminates a section having the electrical stimulation in time domain of the electromyography signal, for example, 100 μs to 5 ms in the time domain of each electromyography signal.

[0041] The comb filter 43 then separates the volitional electromyography signal from the electromyography signal and transmits the volitional electromyography signal to the subtraction circuit 45. The subtraction circuit 45 uses the electromyography signal which is processed by the interference operation unit 41 to substrate the volitional electromyography signal generated from the comb filter 43 to receive the stimulus electromyography signal afterward.

[0042] The control module 50 is connected to the electrical stimulation output unit 30 and the electromyography signal operation unit 40. The control module 50 controls the electrical stimulation output unit 30 to provide electrical stimulation according to a position and strength of the electromyography signal to selected specific electrical stimulation electrodes 10 in an appropriate time to stimulate the human's limb 70 for designated movements. The control module 50 controls the corresponding electrical stimulation electrodes to generate the electrical stimulation according to the position and status of the received electromyography signal. The electrical stimulation electrodes 10 are pasted to the corresponding muscle.

[0043] For example, a patient that has hemiparesis or hemiplegia in the upper limb receives an instruction from a rehab therapist to move a rehabilitation cup from a position to another for training the paralysis or affected limb. The control module 50 detects the upper arm of the patient having no ability to raise volitionally by the electromyography signal and the volitional electromyography signal. When the strength of the volitional electromyography signal is lower than the required strength to raise the upper arm, the control module 50 controls the electrical stimulation output unit 30 to provide the electrical stimulation to proper electrical stimulation electrodes 10. The electromyography signal sensor 20 then detects the electromyography signals instantly and transfers the electromyography signals to the control module 50. The control module 50 may instantly adjust the electrical stimulation output to the upper arm, making the patient move the upper limb smoothly.

[0044] Thus, the required electrical stimulation corresponding to designated movements in the rehabilitation courses may be provided or predefined during training, for example, pushing out the upper arm and opening the palm. Practically, the control module 50 may be a microprocessor circuit module or a programmable chip. The control module 50 defines intensities of the electrical stimulation by using the electromyography signal. The control module 50 defines the intensity of the electrical stimulation by a comparison method or a look-up table method. The comparison method or the look-up table method is to compare the reading electromyography signal and a stored standard of the electromyography signal, then outputting an appropriate electrical stimulation according to the result of the comparison, wherein the stored standard of the electromyography signal is an electromyography signal value of a healthy limb of the patient with hemiparesis or hemiplegia or an average electromyography signal value of human.

[0045] Furthermore, the comparison method or the look-up table method has at least one adjustable parameter. The adjustable parameter may be defined by the medical professional or the user. The mode for carrying out of the adjustable parameter setting is based on the maximum voluntary contraction of user, and then the system outputs an appropriate intensity of the electrical stimulation or increases the intensity of the electrical stimulation by each output according to the differences between each electromyography signal analyzed result and the maximum voluntary contraction. The other mode for carrying out of the adjustable parameter setting is to separate the electromyography signal into several layers and decide an appropriate intensity of the electrical stimulation or the increase intensity of the electrical stimulation by each output according to which layer the electromyography signal lies in.

[0046] The fixed brace 60 is used to connect each one of the electrical stimulation electrodes 10, each one of the electromyography signal sensors 20, the electrical stimulation output 30, the electromyography signal operation unit 40 and the control module 50 respectively. The fixed brace 60 is designed to attach to the human's limb 70 and is shaped according to the different position of the human's limb 70. In the present embodiment, the fixed brace 60 is suitable for the upper limb, which comprises an upper arm fixed portion 62, a forearm fixed portion 64 and a palm fixed portion 66. The upper arm fixed portion 62, the forearm fixed portion 64 and the palm fixed portion 66 are shaped respectively corresponding to the upper arm, the forearm and the palm of human and are separately attached to the upper arm, the forearm and the palm. Each one of the electrical stimulation electrodes 10 and each one of the electromyography signal sensors 20 are located inside the fixed brace 60. Therefore, when the patient wears the fixed brace 60, each one of the electrical stimulation electrodes 10 and each one of the electromyography signal sensors 20 can attach to the surface of the skin of the patient.

[0047] Furthermore, to judge the condition of paralysis of the patient's upper arm's movement more precisely, the control module 50 may analyze each one of the electromyography signal sensors according to the above-mentioned description or detect curvature of partial or each one of limb joints with the flex/band sensors on the fixed brace 60 according to the corresponding position of the joints of wrists, fingers, elbows and arms. Through detecting results of each one of the flex/band sensors, the control module 50 is able to define the condition of the upper arm of the patient and to control each one of the electrical stimulation electrodes 10 through the electrical stimulation output unit 30 to output the electrical stimulation to patient for suitable assistance.

[0048] The shape of the flex/band sensor is usually rod-shaped or bar-shaped. The flex/band sensor generates different resistance according to the curvature thereof. For example, the flex/band sensor of the embodiment is a product by Spectra Symbol Company. Resistance of the flex/band sensor is 10KΩ under a non-curvature. The resistance increases from 30Ω to 40Ω as curvature increases, which is shown in Table 1.

TABLE 1
	Approximately	Approximately	Approximately
Resistance	equal to 9KΩ	equal to 14KΩ	equal to 22KΩ
Degree of	Straight line	90 degree	180 degree
curvature

[0049] Thus, the present embodiment may automatically define the required intensity of the electrical stimulation for the human's limb 70 to perform designated movements according to the detected strength of the electromyography signal of the human's limb 70. The present embodiment can give appropriate assistance to the patient, and it not only activates the patient's partially disabled limb effectively, but also is helpful for training the ability of controlling the affected limb of the patient.

[0050] The above mentioned is the embodiment of the present invention only, and not a limitation of the present invention in anyway. Although the present invention discloses the embodiment as above, it's not used to limit the present invention. Every technician familiar with this profession can use the technical content to make some changes or modify it achieve an equivalent embodiment.