System and method for performing blood flow monitoring and neuromuscular electrical stimulation

Abstract

According to embodiments, a system for performing blood flow monitoring and neuromuscular electrical stimulation is provided. The system includes a non-invasive contact sensor configured to perform measurement of blood flow in a blood vessel to obtain blood flow data; a control module in communication with the non-invasive contact sensor; and a neuromuscular electrical stimulation module in communication with the control module. The control module is configured to determine at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data. The control module is further configured to send a control signal to the neuromuscular electrical stimulation module, the control signal being based on the at least one of arterial flow data, venous flow data, or tissue perfusion data. According to further embodiments, a method and a computer implemented method for performing blood flow monitoring and neuromuscular electrical stimulation are also provided.

Description

SYSTEM AND METHOD FOR PERFORMING BLOOD FLOW MONITORING AND NEUROMUSCULAR ELECTRICAL STIMULATIONCross-Reference To Related Application

[0001] This application claims the benefit of priority of Singapore patent application No. 10202500625V, filed 12 March 2025, the content of it being hereby incorporated by reference in its entirety for all purposes.Technical Field

[0002] Various embodiments relate to a system and a method for monitoring blood flow and performing neuromuscular electrical stimulation (NMES).Background

[0003] Chronic venous insufficiency (CVI) affects about 30% of the population in Singapore, among which more than 50% have symptoms such as pain, swelling, unsightly varicose-veins, and venous ulcers. In the United States, it has been estimated that CVI affects more than 25 million adults, and around 6 million of these adults have advanced stages of venous disease. Venous ulcers cause the loss of approximately 2 million working days and incur treatment costs of approximately $3 billion per year in the United States.

[0004] The current gold-standard diagnosis is a Duplex Ultrasound of the venous system which takes about 2 hours and cannot be easily accessed by patients. As such, most patients with suspected CVT are referred to a tertiary hospital for assessment and treatment, which increases the workload of the hospital significantly. There is currently no fast-screening tool to facilitate risk stratification of CVI in large populations. Patients are unable to know their status at home or clinics after they were diagnosed with CVI, and thus they have to visit hospitals frequently to monitor the treatment efficacy.

[0005] Therefore, a point of care testing (POCT) device for quick screening of CVI, and for self-assessment of conservative treatment effects at home, is in great demand.

[0006] As an effective therapeutic tool to manage CVI, neuromuscular electrical stimulation has been used to improve the blood flow / blood circulation of human subjects. However, most stimulation tools do not provide blood flow monitoring functionality to give real time feedback to the patients. While some of these tools offer only stimulation function without the capability to monitor the blood flow in arteries or veins, others may only monitor the capillary flow through photoplethysmography (PPG) without being able to measure the blood flow in deep vascular tissue.

[0007] Thus, there is a need for an integrated apparatus or system that addresses at least the problems mentioned above, while promising comprehensive care and improved outcomes for CVI patients.Summary

[0008] According to an embodiment, a system is provided. The system includes a non-invasive contact sensor configured to perform measurement of blood flow in a blood vessel to obtain blood flow data; a control module in communication with the non-invasive contact sensor, the control module configured to determine at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data; and a neuromuscular electrical stimulation module in communication with the control module. The control module is further configured to send a control signal to the neuromuscular electrical stimulation module, the control signal being based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

[0009] According to an embodiment, a computer implemented method is provided. The computer implemented method includes receiving blood flow data from a non-invasive contact sensor, wherein the blood flow data is based on a blood flow in a blood vessel; determining at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data; and sending a control signal to a neuromuscular electrical stimulation module, wherein the control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

[0010] According to an embodiment, a method is provided. The method includes measuring, with a non-invasive contact sensor, blood flow data of a blood flow in a blood vessel; determining at least one of arterial flow data, venous flow data, or tissue perfusiondata from the blood flow data; sending a control signal to a neuromuscular electrical stimulation module, wherein the control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data; and operating the neuromuscular electrical stimulation based on the control signal

[0011] According to an embodiment, a data processing apparatus including means for carrying out the method described herein, is provided.

[0012] According to an embodiment, a computer-readable medium including instructions which, when executed by a computer, cause the computer to carry out the method described herein, is provided.Brief Description of the Drawings

[0013] In the drawings, like reference characters generally refer to like parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which:

[0014] FIG. 1 A shows a schematic cross-sectional view of a system for monitoring blood flow and performing neuromuscular electrical stimulation (NMES), according to various embodiments.

[0015] FIG. IB shows a flow chart illustrating a computer implemented method for monitoring blood flow and performing NMES, according to various embodiments.

[0016] FIG. 1C shows a flow chart illustrating a method for monitoring blood flow and performing NMES, according to various embodiments.

[0017] FIG 2A shows a schematic representative view of diffuse speckle pulsatile flowmetry DSPF illustrating the optical method for flow measurement, according to an example.

[0018] FIG. 2B shows a plot depicting simultaneous measurement results of photoplethysmography PPG waveform and blood flow index (or rate) BFI waveform, according to an example.

[0019] FIG. 3 shows a schematic representative view of a proposed wearable platform that is combined by two sub-modules, namely an integrated sensor and a neuromuscular electrical stimulation device, according to an example.

[0020] FIG. 4A and FIG 4B show a perspective view of the integrated sensor, and a bottom view of the same, respectively, according to an example.

[0021] FIG. 5 shows a plot illustrating the arterial signal and the venous signal measured by the integrated sensor, according to one example.

[0022] FIG. 6 shows a schematic representative view illustrating a closed-loop control of the neuromuscular electrical stimulation device by the integrated sensor, according to an example.

[0023] FIGS. 7A to 7K respectively show panels of representative results (in terms of scores) for a selection of tests carried out by the proposed wearable platform, where each panel corresponding to one session with the left trace depicting pre-stimulation flow and the right trace showing post-stimulation flow, according to an example.Detailed Description

[0024] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0025] Embodiments described in the context of one of the methods or devices are analogously valid for the other methods or devices. Similarly, embodiments described in the context of a method are analogously valid for a device, and vice versa.

[0026] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore,additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0027] Tn the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0028] In the context of various embodiments, the phrase “at least substantially” may include “exactly” and a reasonable variance.

[0029] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance.

[0030] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0031] As used herein, the phrase of the form of “at least one of A or B” may include A or B or both A and B. Correspondingly, the phrase of the form of “at least one of A or B or C”, or including further listed items, may include any and all combinations of one or more of the associated listed items.

[0032] As used herein, the expression “configured to” may mean “constructed to” or “arranged to”.

[0033] Various embodiments provide a wearable platform for neuromuscular electrical stimulation (NMES) and arterial / venous blood flow monitoring.

[0034] FIG. 1A shows a schematic cross-sectional view of a system 100 for monitoring blood flow and performing NMES, according to various embodiments. As shown in FIG.1A, the system 100 includes a non- invasive contact sensor 102 configured to perform measurement of blood flow in a blood vessel to obtain blood flow data; a control module 104 in communication with the non- invasive contact sensor 102 (as denoted by a line 108); and a neuromuscular electrical stimulation module 106 in communication with the control module 104 (as denoted by a line 110). The control module 104 is configured to determine at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data. The control module 104 is further configured to send a control signal to the neuromuscular electrical stimulation module 106, the control signal being based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

[0035] In other words, the system 100 is a wearable platform with 2 sub-modules that provide both neuromuscular electrical stimulation and blood flow monitoring functions in arteries and veins nonmvasively. This is in contrast to existing devices that can only achieve either stimulation or blood flow measurement, and not both. The integration of stimulation and real time monitoring in a closed feedback loop requires synchronization between the neuromuscular electrical stimulation module 106 and blood flow monitoring module, and application of signal processing techniques to extract arterial blood flow and venous blood flow patterns, and clinical inputs to design the most optimized threshold for stimulation and monitoring. Designing such a platform involves mter-disciplinary fields of wearable device design and development, signal processing, algorithm development for blood flow analysis, optical design, and clinical know-hows in venous diseases

[0036] In various embodiments, if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be below a minimum threshold value, the control signal may be a start signal to commence neuromuscular electrical stimulation by the neuromuscular electrical stimulation module 106.

[0037] On the other hand, if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be above a maximum threshold value, the control signal may be a stop signal to cease ongoing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module 106.

[0038] However, if the neuromuscular electrical simulation is ongoing and if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be decreasing over a period of time, the control module 104 may be configured to send the control signal to increase an intensity of the neuromuscular electrical simulation.

[0039] The neuromuscular electrical stimulation module 106 may be configured with a safety operation period and / or a safety operation interval. The neuromuscular electrical stimulation module 106 may be configured to operate for a maximum of the safety operation period and each operation of the neuromuscular electrical stimulation module 106 may be separated by at least the safety operation interval.

[0040] In various embodiments, the non-invasive contact sensor 102 may include one or more laser diodes configured to emit light at the blood vessel; one or more laser drivers configured to supply power to the one or more laser diodes; an image sensor configured toreceive the light reflected and / or scattered from the blood vessel; and a controller configured to process a signal from the image sensor. The signal may be associated with the light reflected and / or scattered from the blood vessel.

[0041] The non-invasive contact sensor 102 may be configured to measure the blood flow using diffuse speckle pulsatile flowmetry measurement.

[0042] In various embodiments, in determining the at least one of arterial flow data, venous flow data or tissue perfusion data from the blood flow data, the control module 104 may be configured to identify an arterial signal of an arterial blood flow in the blood vessel and / or a venous signal of a venous blood flow in the blood vessel; and determine a plurality of parameters including at least one of an amplitude of the arterial signal, an average value of the arterial signal, an average peak value of the arterial signal, an average value of the venous signal, a standard deviation of the venous signal, an average peak value of the tissue perfusion data, an average value of the tissue perfusion data, an amplitude of the tissue perfusion data, or a standard deviation of the tissue perfusion data.

[0043] The control module 104 and the non-invasive contact sensor 102 may be in wireless communication with each other. The control module 104 and the neuromuscular electrical stimulation module 106 may be in wireless communication with each other.

[0044] The non-invasive contact sensor 102 may be configured to perform real-time measurement of the blood flow in the blood vessel to obtain the blood flow data.

[0045] The non-invasive contact sensor 102 and the neuromuscular electrical stimulation module 106 may be configured to be externally applied to a skin of a subject, the blood flow data being obtainable from the blood vessel of the subject. The neuromuscular electrical stimulation module 106 may be configured to perform neuromuscular electrical stimulation on muscles of the subject to improve the blood flow of the subject.

[0046] In various embodiments, the system 100 may further include a device including the control module 104 and a display unit configured to display the measurement of the blood flow, and optionally a remote unit in communication with the control module 104. The remote unit may be configured for display and storage of the blood flow data.

[0047] The system 100 may further include a housing to contain the non-mvasive contact sensor 102 and the control module 104.

[0048] FIG. IB shows a flow chart illustrating a computer implemented method 120 for monitoring blood flow and performing NMES, according to various embodiments. In FIG. IB, at Step 122, blood flow data is received from a non-invasive contact sensor (e.g. 102 of FIG 1 A). The blood flow data is based on a blood flow in a blood vessel In Step 124, at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data is determined. In Step 126, a control signal is sent to a neuromuscular electrical stimulation module (e.g. 106 of FIG. 1A). The control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

[0049] Receiving the blood flow data from the non-invasive contact sensor 102 at Step 122 may include receiving, from the non-invasive contact sensor 102, real-time measurement data of the blood flow in the blood vessel.

[0050] FIG. 1C shows a flow chart illustrating a method 140 for monitoring blood flow and performing NMES, according to various embodiments. In FIG. 1C, at Step 142, blood flow data of a blood flow in a blood vessel is measured with a non-invasive contact sensor (e.g. 102 of FIG. 1A). In Step 144, at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data is determined. In Step 146, a control signal is sent to a neuromuscular electrical stimulation module (e g. 106 of FIG. 1A). The control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data. In Step 148, the neuromuscular electrical stimulation module 106 is operated based on the control signal.

[0051] In various embodiments, if the at least one of arterial flow data, venous flow data, or tissue perfusion data is below a minimum threshold value, in response to the control signal being a start signal, the method 140 may further include commencing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module 106.

[0052] On the other hand, if the at least one of arterial flow data, venous flow data, or tissue perfusion data is above a maximum threshold value, in response to the control signal being a stop signal, the method 140 may further include ceasing ongoing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module 106.

[0053] However, if the neuromuscular electrical simulation is ongoing and if the at least one of arterial flow data, venous flow data, or tissue perfusion data is decreasing over atime period, the method 140 may further include increasing, by the control signal, an intensity of the neuromuscular electrical simulation.

[0054] The method 140 may further include setting a safety operation period and / or safety operation interval for the neuromuscular electrical stimulation module 106; and operating the neuromuscular electrical stimulation module 106 for a maximum of the safety operation period. Each operation of the neuromuscular electrical stimulation module 106 may be separated by at least the safety operation interval.

[0055] In various embodiments, the method 140 may further include obtaining the blood flow data using diffuse speckle pulsatile flowmetry measurement, prior to measuring the blood flow data.

[0056] Determining the at least one of arterial flow data or venous flow data from the blood flow data at Step 144 may include identifying an arterial signal of an arterial blood flow in the blood vessel and a venous signal of a venous blood flow in the blood vessel; and determining a plurality of parameters including an amplitude of the arterial signal, an average value of the arterial signal, an average peak value of the arterial signal, an average value of the venous signal, and a standard deviation of the venous signal.

[0057] In one embodiment, the blood flow data may include the arterial flow data and the venous flow data measured from a blood vessel in an arm or a leg of a subject.

[0058] In another embodiment, the blood flow data may include the tissue perfusion data measured from a blood vessel in a palm, a finger, or a toe of a subject.

[0059] While each of the methods described above is illustrated and described as a series of steps or events, it will be appreciated that any ordering of such steps or events are not to be interpreted in a limiting sense. For example, some steps may occur in different orders and / or concurrently with other steps or events apart from those illustrated and / or described herein. In addition, not all illustrated steps may be required to implement one or more aspects or embodiments described herein. Also, one or more of the steps depicted herein may be carried out in one or more separate acts and / or phases.

[0060] Various embodiments may provide a data processing apparatus including means for carrying out the computer implemented method 120 of FIG. IB, or the method 140 of

[0061] Various embodiments may also provide a computer-readable medium including instructions which, when executed by a computer, cause the computer to carry out the computer implemented method 120 of FIG. IB, or the method 140 of FIG. 1C.

[0062] Examples of the system 100 and the methods 120, 140 will be described in more details, while taking reference to a wearable platform that includes two sub-modules: an electrical pulsing module for stimulation and an optical module for monitoring deep tissue blood flow.

[0063] The wearable platform may include the same or like elements or components as those of the system 100 of FIG. 1 A, and as such, the like elements may be as described in the context of the system 100 of FIG. 1 A.

[0064] The two sub-modules may be placed on different parts of the body, e g. the electrical pulsing module near the muscle requiring stimulation, and the optical module on top of the targeted artery or vein. The two sub-modules may be either connected by wires or through a single wireless control device (such as a smartphone or a laptop), so that the readings from the optical module may be used to regulate the stimulation intensity and duration of the electrical pulsing module. An analysis method to separate the artery signal and vein signal may also be provided.

[0065] The major contributions and significant advantages of such a wearable platform, as described herein according to various embodiments, are:• how to synchronize the blood flow monitoring and electrical stimulation to assess pre- and post- stimulation blood flow levels, as well as the blood flow response during the stimulation;• how to analyse the blood flow signals quantitatively in real-time to provide feedback for the stimulation intensity;• the design of the wearable platform to provide a seamless user experience when using the two sub-modules.

[0066] The integration of the two sub-modules may be in a form realting to chronic venous insufficiency (CVI) as follow.

[0067] For example, a wearable blood flow monitoring device A, e g. the HaloFlow, may be provided. The wearable blood flow monitoring device A has the capability of differentiating between arterial flow and venous flow for fast CVI screening at clinics, andfor self-monitoring of CVI by patients at home. Thus, patients only need to do the diagnostic at hospital in one time, and if they are diagnosed with CVI, doctors would suggest these patients to use wearable blood flow monitoring device A at home and monitoring the treatment efficiency. Such proposed treatment monitoring solution offers an affordable alternative, usable in both clinical and home environments, with a cost per device of several hundred dollars. By providing patients with real-time feedback on their CVI status to monitor treatment efficacy, the wearable blood flow monitoring device A not only reduces the financial and time burdens on patients but also markedly enhances treatment efficiency. The wearable blood flow monitoring device A empowers a patient to utilize it conveniently on any part of their body, whether at clinics or home environments. Through cloud connectivity, clinicians gain access to real-time patient health data, enabling prompt medical guidance and intervention.

[0068] However, in absence of an effective therapeutic tool to manage CVI in the wearable blood flow monitoring device A, a Device B, e.g. Revene, is introduced to complement this protocol by offering a CVI treatment solution for both clinics and home use. Clinicians may perform specific monitoring so they may adjust the dose accordingly, while patients may independently monitor treatment effectiveness using the HaloFlow, enhancing their engagement in the therapeutic process, thereby enriching the proposed protocol, promising comprehensive care and improved outcomes for CVI patients.

[0069] The proposed protocol serves both clinicians and patients seamlessly. Clinicians may monitor patient health status via cloud access, while patients gain real-time insights into their blood flow health e g. via smartphone connectivity. With the Device B Revene designed to enhance blood flow, patients may determine optimal usage with the HaloFlow. Such closed-loop stimulation and monitoring is achieved by precise synchronization of the two sub-modules.

[0070] A smartphone app may offer intuitive prompts (or feedbacks), guiding patients on when to initiate or cease Revene usage, ensuring effective treatment management.

[0071] The wearable blood flow monitoring device A, HaloFlow, may be described in similar context to the non- invasive contact sensor 102 (in FIG. 1 A). The Device B Revene may be described in similar context to the neuromuscular electrical stimulation module 106 (in FIG. 1 A).[0072J Working Principle

[0073] The HaloFlow is capable of measuring blood flow velocities at a rate of more than 300 Hz, which is the fastest non-invasive deep tissue blood flow measurement modality, known to date. The working principle involves a non-invasive deep tissue blood flow measurement method referred to as diffuse speckle pulsatile flowmetry (DSPF). FIG. 2A shows a schematic representative view of DSPF illustrating the optical method for flow measurement, according to an example. As seen in FIG. 2A, light from a laser 201 is directed on a skin surface 203 and propagated through to a deep tissue blood vein 205. The light is scattered by the blood flowing through the deep tissue blood vein 205, and is detected by a charged coupled device (CCD) 207 via a multimode detection fiber 209. The dynamics of the scattering liquid may be extracted from corrected speckle image 211. The index is defined as dynamics index = (L'stdf3, where I is the mean intensity of all the pixels within a stipulated region of interest, std is the standard deviation of all the pixels within the same region. The power of 2.3 is an optimal value obtained from theory simulations. However, it should be noted that the power at a range of 1.8 to 2.6 would also work for the dynamics index.

[0074] FIG. 2B shows a plot 221 depicting simultanous measurement results of photoplethysmography PPG (or blood volume) waveform 223 and blood flow index (or rate) BFI waveform 225, according to an example. Because of the relatively fast measurement rate (i.e. high measurement speed), millisecond-scale detailed changes within each cardiac cycle may be captured clearly, as shown in FIG. 2B where At denotes the time delay between the peak of BFI and the peak of PPG signal for each cardiac cycle. The unit of At may be in milliseconds. Since arterial blood flow always follows a regular pattern that is regulated by heart beating, venous flow may be recovered by removing the arterial flow pattern.

[0075] System Design

[0076] A wearable platform is provided to implement the DSPF method and neuromuscular electrical stimulation, which may be used anywhere on the human body for and real-time monitoring of deep tissue blood flow and stimulation.

[0077] FIG. 3 shows a schematic representative view of the proposed wearable platform 300 that is combined by two sub-modules, namely an integrated sensor 302 and a neuromuscular electrical stimulation device 306.

[0078] The wearable platform 300 may be include the same or like elements or components as those of the system 100 of FIG. 1 A, respectively, and as such, the same ending numerals are assigned and the like elements may be as described in the context of the system 100 of FIG. 1 A, respectively, and therefore the corresponding descriptions are omitted here.

[0079] More specifically, the integrated sensor 302 and the neuromuscular electrical stimulation device 306 may include the same or like elements or components as those of the non- invasive contact sensor 102 and the neuromuscular electrical stimulation module 106 of FIG 1A, respectively, and as such, the like elements may be as described in the context of the non-invasive contact sensor 102 and the neuromuscular electrical stimulation module 106 of FIG. 1A, respectively, and therefore the corresponding descriptions are omitted here.

[0080] FIG. 4 A and FIG. 4B show a perspective view of the integrated sensor 302, and a bottom view of the same, respectively, according to an example.

[0081] The integrated sensor 302 may be a single-channel device that includes a low-power laser diode 401 , a laser diode driver circuit (not shown in the figures), a high speed CMOS sensor 407, and a CMOS sensor driver circuit in a single printed circuit board (PCB) (not shown in the figures). As an example, the integrated sensor 302 may have a length of about 10 cm, a width of about 6 cm and a height of about 3 cm. It should appreciated that other dimensions of the integrated sensor 302 may be possible as long as the integrated sensor 302 can be effectively and comfortably applied to the skin surface of a patient, without causing hindrance to the patient.

[0082] The PCB of the low-power laser diode 401 may potentially be made into soft and flexible PCB. One advantage is that the integrated sensor 302 does not require any optical fibers to deliver or collect light. The integrated sensor 302 does not need a dedicated console for operation but may be directly connected to a laptop or other mini-computers to function. A microprocessor may also be integrated in this PCB to calculate the dynamics index and transmit the index value through wireless means e.g. Bluetooth and Wi-Fi.

[0083] The integrated sensor 302 may implement the DSPF method with the low-power (<10 mW) 785 nm mini laser diode (e.g 401 of FIG. 4B) as the light source, and the highspeed CMOS ARX340 as the photodetector (e.g 407 of FIG. 4B), arranged at the base or bottom of the integrated sensor 302. The data processing code is built-in with a board device, e.g. a CompuLab UCM-iMXM-Plus. The entire setup is intended to be directly attached on the skin surface of a human body with a disposable sticky patch, where the base of of the integrated sensor 302 is facing toward the skin surface. The integrated sensor 302 may also be provided with a power switch button 441 for turning the integrated sensor 302 on or off, a power light indicator 443 for indicating the on / off status of the integrated sensor 302, a USB port 445 for USD cable conntection to an external device and a Bluetooth light indicator 447 for indication of Bluetooth connectivity status of the integrated sensor 302. These components may be disposed on parts of the integrated sensor 302 which are accessible and / or visible to a user when the integrated sensor 302 is placed on the skin surface.

[0084] The neuromuscular electrical stimulation device 306 may be attached to a separate location of the human body because of its wireless design. It works with a mobile app and connects to the app by Bluetooth or Wi-Fi 327.

[0085] The neuromuscular electrical stimulation device 306 has at least the following two strengths over the existing system(s):- • the neuromuscular electrical stimulation device 306 involves a built-in data time synchronization method and apparatus for real-time communication between multiple devices, and• the neuromuscular electrical stimulation device 306 has a smart processor and algorithm to control the stimulation intensity based on the blood flow signal to implement a closed feedback loop.

[0086] As shown in FIG 3, the integrated sensor 302 and the neuromuscular electrical stimulation device 306 may be attached on the human body and connected as clients with a server on a smartphone 331 or computer. The server creates a session, and a plurality of clients are Bluetooth paired with the server through the session. The server places the information to be output to each client into an output buffer corresponding to each client respectively, and each client obtains the information from its corresponding output bufferthrough the Bluetooth object exchange specification in accordance with the preset time interval. The wireless connection 327 facilitates seamless data synchronization and processing between the integrated sensor 302, the neuromuscular electrical stimulation device 306 and the smartphone(s) 331.

[0087] The smartphone 331 may include the same or like elements or components as those of the control module 104 of FIG. 1 A, and as such, the like elements may be as described in the context of the control module 104 of FIG. 1A, and therefore the corresponding descriptions are omitted here.

[0088] Blood flow analysis occurs in real-time, achieving a speed of 300 frames per second (fps). Trigger thresholds are dynamically (and substantially simultaneously) calculated based on the blood flow signal / curve 335 using a proprietary algorithm, ensuring accurate and timely response.

[0089] The small size and low power consumption make the integrated sensor 302 and the neuromuscular electrical stimulation device 306 suitable as a wearable on human body for long-term real-time (continuous) monitoring 333, and has the potential to be integrated into other systems and medical devices. With the combination of big data and cloud computing technology, both doctors and patients may monitor and record their blood flow condition on their remote devices that display the arterial and venous blood flow changes. This advantageously increases the efficiency and feasibility of CVI monitoring.

[0090] To assess the operational status of the wearable platform 300 and facilitate closed-loop control 329 of the treatment process, a protocol was developed for the quantitative analysis of blood flow signals 335. FIG. 5 shows a plot illustrating the arterial signal 501 and the venous signal 503 measured by the integrated sensor 302, according to one example. This protocol enables the extraction of key parameters from two distinct components of the acquired blood flow data 501, 503. The arterial blood flow signal 501 has a more pronounced pulsed signal characteristic, compared to the smoother venous blood flow signal 503. The identified parameters include the amplitude of the arterial signal ('AA'), the average value of the arterial signal ('AV A'), the standard deviation of the arterial signal ('SDA'), the average peak value of the arterial signal ('APVA'), the average value of the venous signal ('AVV'), and the standard deviation of the venous signal ('SDV'). TheSDV stand for the venous blood flow vibration which may be used to determine the degree of change in the blood flow rate.

[0091] In a different example (not shown in the figures), the integrated sensor 302 may also measure the tissue perfusion data The blood flow data may include the arterial flow data, arterial flow data, and tissue perfusion data.

[0092] The operator or user needs to find the position of a target artery or vein on the subject’s body to perform the measurement. Generally, a sharp pulsatile signal may be observed when the sensor was placed on the top of the artery, while a broader pulsatile signal may be observed when the sensor was placed on the vein or tissue perfusion. The venous flow signal may be acquired by fit a lower envelope line of the pulsatile signal. This lower envelope line may be considered as the venous flow signal at the measurement position.

[0093] The tissue perfusion signal is broader than the arterial data. The difference between tissue perfusion data and arterial flow data may be distinguished by the shape of the pulsatile signal. Meanwhile, the measurement position of the tissue perfusion data is mainly on palm, finger, and toe, while the arterial and venous flow data is mainly measured on arms and legs. Thus, the signal of tissue perfusion and arterial flow may be separated by the measurement position. The integrated sensor 302 may detect the measurement of the tissue perfusion data based on the shape of the pulsatile signal and / or based on user input of the measurement position.

[0094] The evaluation of blood flow conditions involves the integrated sensor 302 conducting blood flow evaluations, with the neuromuscular electrical stimulation device 306 treating CVI through neuromuscular electrical stimulation, e.g. via the following steps:(i) conduct a 5 -minute measurement of arterial and venous signals using the integrated sensor 302, without stimulation at the target position;(ii) perform a 5-minute measurement of arterial and venous signals using the integrated sensor 302, with stimulation at the target position by the neuromuscular electrical stimulation device 306;(hi) repeat a 5-minute measurement of arterial and venous signals using the integrated sensor 302, without stimulation at the target position;(iv) compare the vibration characteristics of signals 'AA,' 'AV A,' 'SDA,' 'APVA,' 'AVV,' and 'SDV during procedures (i) to (hi);(v) an increase in 'AA,' 'AV A,' and 'APVA' suggests an enhancement in arterial blood flow, whereas an increase in 'AW and 'SDV indicates improved venous blood flow.

[0095] These parameters collectively serve as indicators for evaluating the efficacy of the treatment process. The tissue perfusion data may be measured by the similar parameters of at least one of amplitude, average value, average peak value, or standard deviation, in particular the average peak value and average value of the tissue perfusion data.

[0096] FIG. 6 shows a schematic representative view illustrating the closed-loop control of the neuromuscular electrical stimulation device 306 by the integrated sensor 302, according to an example.

[0097] The neuromuscular electrical stimulation device 306 and the integrated sensor 302 are placed on different parts of a limb 603 of a patient (subject).

[0098] The integrated sensor 302 provides real-time monitoring of both arterial signals 501 and venous signals 503 and the tissue perfusion data, wirelessly transmitting the data to the smartphone 331. The integrated sensor 302 monitors the blood flow signals 501, 503 (see O and © in FIG. 6) that are used to determine if the neuromuscular electrical stimulation device 306 starts or stops 503 (see © and 0 in FIG. 6). Both the integrated sensor 302 and the neuromuscular electrical stimulation device 306 connect to the smartphone 331 (or a mobile device), so the smartphone 331 receives the blood flow signals 501, 503 and the working signal of the neuromuscular electrical stimulation device 306 simultaneously. If the blood flow parameters fall below the designated threshold (see © in FIG. 6), the smartphone 331 activates the neuromuscular electrical stimulation device 306 to initiate neuromuscular electrical stimulation until the parameters reach the target level. Subsequently, the integrated sensor 302 continues monitoring the blood flow signals to ensure that the parameters remain within the desired range until the next stimulation cycle begins. Real-time measurement results are concurrently displayed on the smartphone 331 and may be uploaded to the cloud. This allows healthcare providers to promptly assess the patient's health status, offering the capability to contact the patient through the dedicated app when needed

[0099] The neuromuscular electrical stimulation device 306 may be configured with a safety operation period and / or a safety operation interval. The safety operation period may set a maximum operating time for the device (e.g. about 10 minutes) and each operation of the neuromuscular electrical stimulation device 06 may be separated by at least the safety operation interval (e.g. about 30 minutes). This allows the user to use the neuromuscular electrical stimulation device 306 in a safe manner and avoid over stimulation. The safety operation period and interval may be set as appropriate or required.

[0100] Preliminary Experiments

[0101] Preliminary experiments were conducted using the proposed wearable platform 300 in combination with neuromuscular electrical stimulation (NMES) to record changes in arterial blood flow before and after stimulation. The protocol was as follow:• place the integrated sensor 302 of the wearable platform 300 over the radial artery at the wrist of a subject and neuromuscular electrical stimulation device 306 on the forearm;• acquire 1 minute of resting blood-flow signals;• apply 5 minutes of NMES; and• record 4 minutes of post- stimulation signals.

[0102] FIGS. 7 A, 7B, 7C, 7D, 7E, 7F, 7G, 7H, 71, 7J and 7K respectively show panels 701, 703, 705, 707, 709, 711, 713, 715, 717, 719 and 721 of representative results (in terms of scores) for a selection of tests. Each panel 701, 703, 705, 707, 709, 711, 713, 715, 717, 719 and 721 corresponds to one session, with the left trace depicting pre -stimulation flow and the right trace showing post-stimulation flow. The data demonstrate that the wearable platform reliably captures blood-flow changes induced by NMES, and that stimulation produces a significant increase in flow, supporting the feasibility of the proposed wearable platform for NMES-coupled arterial / venous blood-flow monitoring

[0103] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

Claims

CLAIMS1. A system comprising:a non-invasive contact sensor configured to perform measurement of blood flow in a blood vessel to obtain blood flow data;a control module in communication with the non-invasive contact sensor, the control module configured to determine at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data; anda neuromuscular electrical stimulation module in communication with the control module,wherein the control module is further configured to send a control signal to the neuromuscular electrical stimulation module, the control signal being based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

2. The system as claimed in claim 1,wherein if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be below a minimum threshold value, the control signal is a start signal to commence neuromuscular electrical stimulation by the neuromuscular electrical stimulation module; andwherein if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be above a maximum threshold value, the control signal is a stop signal to cease ongoing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module.

3. The system as claimed in claim 2, wherein if the neuromuscular electrical simulation is ongoing and if the at least one of arterial flow data, venous flow data, or tissue perfusion data is determined to be decreasing over a period of time, the control module is configured to send the control signal to increase an intensity of the neuromuscular electrical simulation.

4. The system as claimed in any one of claims 1 to 3, wherein the neuromuscular electrical stimulation module is configured with a safety operation period and / or a safety operation interval, the neuromuscular electrical stimulation module is configured to operate for a maximum of the safety operation period and each operation of the neuromuscular electrical stimulation module is separated by at least the safety operation interval.

5. The system as claimed in any one of claims 1 to 4, wherein the non-invasive contact sensor comprises:one or more laser diodes configured to emit light at the blood vessel;one or more laser drivers configured to supply power to the one or more laser diodes;an image sensor configured to receive the light reflected and / or scattered from the blood vessel; anda controller configured to process a signal from the image sensor.

6. The system as claimed in claim 5 wherein the non-invasive contact sensor is configured to measure the blood flow using diffuse speckle pulsatile flowmetry measurement.

7. The system as claimed in any one of claims 1 to 6, wherein in determining the at least one of arterial flow data, venous flow data or tissue perfusion data from the blood flow data, the control module is configured to identify an arterial signal of an arterial blood flow in the blood vessel and / or a venous signal of a venous blood flow in the blood vessel; and determine a plurality of parameters including at least one of an amplitude of the arterial signal, an average value of the arterial signal, an average peak value of the arterial signal, an average value of the venous signal, a standard deviation of the venous signal, an average peak value of the tissue perfusion data, an average value of the tissue perfusion data, an amplitude of the tissue perfusion data, or a standard deviation of the tissue perfusion data.

8. The system as claimed in any one of claims 1 to 7, whereinthe control module and the non-invasive contact sensor are in wireless communication with each other, andthe control module and the neuromuscular electrical stimulation module are in wireless communication with each other9. The system as claimed in any one of claims 1 to 8, wherein the non-invasive contact sensor is configured to perform real-time measurement of the blood flow in the blood vessel to obtain the blood flow data.

10. The system as claimed in any one of claims 1 to 9, wherein the non-invasive contact sensor and the neuromuscular electrical stimulation module are configured to be externally applied to a skin of a subject, the blood flow data being obtainable from the blood vessel of the subject.

11. The system as claimed in any one of claims 1 to 10 further comprising:a device comprising the control module and a display unit configured to display the measurement of the blood flow; andoptionally a remote unit in communication with the control module, the remote unit configured for display and storage of the blood flow data.12 The system as claimed in any one of claims 1 to 11 further comprising a housing to contain the non-invasive contact sensor and the control module.

13. A computer implemented method comprising:receiving blood flow data from a non-mvasive contact sensor, wherein the blood flow data is based on a blood flow in a blood vessel;determining at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data; andsending a control signal to a neuromuscular electrical stimulation module, wherein the control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data.

14. The method as claimed in claim 13, wherein receiving the blood flow data from the non-invasive contact sensor comprises receiving, from the non-invasive contact sensor, real-time measurement data of the blood flow in the blood vessel15. A method comprising:measuring, with a non-invasive contact sensor, blood flow data of a blood flow in a blood vessel;determining at least one of arterial flow data, venous flow data, or tissue perfusion data from the blood flow data;sending a control signal to a neuromuscular electrical stimulation module, wherein the control signal is based on the at least one of arterial flow data, venous flow data, or tissue perfusion data; andoperating the neuromuscular electrical stimulation module based on the control signal.

16. The method as claimed in any one of claims 13 to 15,wherein if the at least one of arterial flow data, venous flow data, or tissue perfusion data is below a minimum threshold value, in response to the control signal being a start signal, the method further comprises commencing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module; andwherein if the at least one of arterial flow data, venous flow data, or tissue perfusion data is above a maximum threshold value, in response to the control signal being a stop signal, the method further comprises ceasing ongoing neuromuscular electrical stimulation by the neuromuscular electrical stimulation module17. The method as claimed in claim 16, wherein if the neuromuscular electrical simulation is ongoing and if the at least one of arterial flow data, venous flow data, or tissue perfusion data is decreasing over a time period, the method further comprises increasing, by the control signal, an intensity of the neuromuscular electrical simulation.

18. The method as claimed in claim 16 or 17, further comprising:setting a safety operation period and / or safety operation interval for the neuromuscular electrical stimulation module; andoperating the neuromuscular electrical stimulation module for a maximum of the safety operation period,wherein each operation of the neuromuscular electrical stimulation module is separated by at least the safety operation interval.

19. The method as claimed in any one of claims 13 to 18, further comprising:prior to measuring the blood flow data, obtaining the blood flow data using diffuse speckle pulsatile flowmetry measurement.

20. The method as claimed in any one of claims 13 to 19, wherein determining the at least one of arterial flow data or venous flow data from the blood flow data comprises identifying an arterial signal of an arterial blood flow in the blood vessel and a venous signal of a venous blood flow in the blood vessel; and determining a plurality of parameters including an amplitude of the arterial signal, an average value of the arterial signal, an average peak value of the arterial signal, an average value of the venous signal, and a standard deviation of the venous signal.

21. The method as claimed in any one of claims 13 to 20, wherein the blood flow data includes the arterial flow data and the venous flow data measured from a blood vessel in an arm or a leg of a subject.

22. The method as claimed in any one of claims 13 to 20, wherein the blood flow data includes the tissue perfusion data measured from a blood vessel in a palm, a finger, or a toe of a subject.

23. A data processing apparatus comprising means for carrying out the method as claimed in claim 13, or claim 14, or any one of claims 16 to 22 when depending on claim 13 or 14.

24. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method as claimed in claim 13, or claim 14, or any one of claims 16 to 22 when depending on claim 13 or 14

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