Sensor, sensor system and method of determining neuropathy

Abstract

Various embodiments may relate to a sensor for determining neuropathy. The sensor comprises: a flexible substrate defining a measurement axis; a plurality of stimulating electrode pairs coupled to the substrate, the plurality of stimulating electrode pairs defining a stimulating zone; and a plurality of sensing electrode pairs coupled to the substrate, the plurality of sensing electrode pairs defining a sensing zone, the sensing zone and the stimulating zone being spaced apart by a predetermined measurement gap along the measurement axis, wherein the plurality of stimulating electrode pairs are distributed in the stimulating zone along the measurement axis, wherein the plurality of sensing electrode pairs are distributed in the sensing zone along the measurement axis.

Description

SENSOR, SENSOR SYSTEM AND METHOD OF DETERMINING NEUROPATHYTECHNICAL FIELD

[0001] Various embodiments of this disclosure relate to a sensor for determining neuropathy, a sensor system for determining neuropathy, and a method of determining neuropathy.BACKGROUND

[0002] There is an unmet clinical need for a more sensitive screening test for neuropathy. In examples of diabetic peripheral neuropathy (DPN), early intervention results in significant reduction in the long-term neuropathic complications of diabetes mellitus such as diabetic foot ulcers and lower limb amputation. Conventional screening tests have relatively poor sensitivity in identifying early-stage DPN. Further, some conventional methods for determining neuropathy are invasive in nature, or are time-consuming, operator dependent, non-repeatable, and / or require specialists to perform and interpret, hence making the conventional methods difficult to implement as a screening tool.SUMMARY

[0003] Various embodiments of the present disclosure relate to a sensor for determining neuropathy. The sensor includes: a flexible substrate defining a measurement axis; a plurality of stimulating electrode pairs coupled to the substrate, the plurality of stimulating electrode pairs defining a stimulating zone; and a plurality of sensing electrode pairs coupled to the substrate, the plurality of sensing electrode pairs defining a sensing zone, the sensing zone and the stimulating zone being spaced apart by a predetermined measurement gap along the measurement axis, wherein the plurality of stimulating electrode pairs are distributed in the stimulating zone along the measurement axis, wherein the plurality of sensing electrode pairs are distributed in the sensing zone along the measurement axis.

[0004] According to another aspect, a sensor system is disclosed. The sensor system includes the sensor as described above, and a processor in signal communication with the sensor. The processor is configured to: receive at least one sensing signal from at least one of the plurality of sensing electrode pairs, and determine a degree of neuropathy based on the at least one sensing signal.

[0005] According to another aspect, a method of determining neuropathy. The method includes: receiving at least one sensing signal from the sensor as described above; and determining a degree of neuropathy based on the at least one sensing signal.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments. In the following description, various embodiments of the invention are described with reference to the following drawings.

[0007] FIG. 1 shows a schematic illustrating a sensor system according to various embodiments.

[0008] FIG. 2 shows a parametric view of a first side of a sensor according to various embodiments.

[0009] FIG. 3A shows a parametric view of a second side of the sensor of FIG. 2.

[0010] FIG. 3B shows a top view of FIG. 3A.

[0011] FIG. 4A shows a sectional view of A-A according to various embodiments.

[0012] FIG. 4B shows a sectional view of A-A according to various embodiments.

[0013] FIG. 4C shows a sectional view of A-A according to various embodiments.

[0014] FIG. 5 shows a stimulating signal, a sensing signal, and a post-processed sensing signal according to various embodiments.

[0015] FIG. 6 shows a parametric view of a sensor according to various embodiments.

[0016] FIG. 7 shows a top view of a sensor according to various embodiments.

[0017] FIG. 8 shows a schematic view of a sensor system for assessing carpel tunnel syndrome according to various embodiments.

[0018] FIGs. 9A to 9H each show a top view of a sensor according to various embodiments.

[0019] FIG. 10A shows a parametric view of a sensor including a connecting pad according to various embodiments.

[0020] FIG. 10B shows a bottom view of FIG. 10A.

[0021] FIG. 11 A shows a parametric view of a sensor including a connecting pad according to various embodiments.

[0022] FIG. 1 1 B shows a bottom view of FIG. 1 1 A.

[0023] FIG. 12 is a flowchart illustrating a method of determining neuropathy according to various embodiments.

[0024] FIGs. 13 A to 13C show an experimental setup of a sensor system and a sensor according to various embodiments.

[0025] FIG. 14 shows the nerve conduction results from a sensor system according to an example.

[0026] FIG. 15 shows the nerve conduction results from the Powerlab 15T system.

[0027] FIG. 16 shows the nerve conduction results from the Natus VikingQucst system.DESCRIPTION

[0028] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details, and embodiments in which the proposed technical solution may be practiced. These embodiments are described in sufficient detail to enable those skilled in the ail to practice the proposed technical solution. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present disclosure. The various embodiments are not necessa ily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0029] 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.

[0030] 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.

[0031] 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, e.g., within 10% of the specified value.

[0032] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0033] For the sake of brevity, the term "neuropathy" may be used to refer to any one or more of the terms "peripheral neuropathy", "diabetic peripheral neuropathy", “nervous-related damages”, “nerve damage”, etc., as will be understood from the context.

[0034] As used herein, the terms “attach”, “attachment”, “contact” or “abut" generally refer to the context of a non-invasive form of coupling, connecting, or fixing an object to a target surface (e.g., skin). For avoidance of doubt, in the present context, “non-invasive” coupling does not involve penetrating the target surface.

[0035] Embodiments described in the context of one stimulating signal arc analogously valid for multiple concurrent or sequential stimulating signals. Similarly, embodiments described in the context of one sensing signal are analogously valid for multiple concurrent or sequential sensing signals.

[0036] Peripheral neuropathy occurs when the nerves (peripheral nerves) that branch out from the brain and spinal cord are damaged. This condition often causes weakness, numbness, and / or pain, usually in the hands and feet. It may also affect other body parts / areas and body functions including digestion and urination.

[0037] Diabetes is the leading cause of peripheral neuropathy, accounting for 30% of cases globally. Peripheral neuropathy is also prevalent in prc-diabctic patients. Diabetic peripheral neuropathy (DPN) or diabetic-related peripheral neuropathy may broadly be separated into generalised symmetrical polyneuropathy, and asymmetrical (focal and multifocal) neuropathy. Other conditions causing peripheral neuropathy include trauma, autoimmune diseases (e.g., Guillain-Bane syndrome), drugs (e.g., neurotoxic agents), critical illness neuropathy, end stage disease (e.g., Uremic polyneuropathy), cndocrinopathics (e.g., Hypothyroidism), vitamin B 12 and folate deficiencies, infection (e.g., HIV, Lyme disease), amyloidosis and hereditary causes (e.g., Charcot-Marie Tooth disease, Krabbe disease etc.). Chemotherapy -induced peripheral neuropathy (CIPN) is a common side effect experienced by patients receiving neurotoxic chemotherapy for cancer, with 30 40% developing CIPN. There is variability in its severity between patients where it is sensory-predominant with pain and can predispose to long-term morbidity in survivors.

[0038] Diabetic polyneuropathy, in which nerves in different parts of the body arc affected, is predominantly axonal, however variable degrees of demyelination are often present. The pathophysiology of DPN is complex and likely relates to metabolic, inflammatory, and ischaemic effects. 50% of diabetic patients suffer from polyneuropathy, which is the mostcommon cause of hospitalisation and a leading cause of non-traumatic lower extremity amputation (LEA). DPN Patients have a 10 times higher chance for LEA compared to the general population, with a global incidence of 60-70% of diabetic patients being affected by DPN related complications. The early detection of patients with DPN is crucial because up to 50% of patients may be asymptomatic. This places patients at risk for developing unnoticed foot injuries, leading to ulcers. Foot ulceration could result in LEA and neuropathic pain that can cause significant morbidity. LEA results in poorer quality of life and places a heavy burden on the healthcare system. Hence, if patients with early DPN can be identified in advance, early intervention measures can be taken, including closer diabetic clinic, podiatry reviews, and patient education on identifying trauma and ulceration of their feet, etc., to delay the progression to severe lower limb complications, reducing the need for amputations.

[0039] Conventional screening protocols such as pinprick, temperature, ankle reflex, and vibration perception (128 - Hz tuning fork) or pressure sensation (10 g monofilament test), are often highly subjective and, in that sense, non-rcpcatablc. For example, a monofilament test often results in varying outcomes as patients may differ in terms of their baseline sense of touch as well as the patient’s attention to the stimulus. Further, the monofilament test has poor sensitivity and specificity for identifying DPN, e.g., due to differences in the application of the monofilament (number and site), interpretation of the monofilament test (definition of thresholds), and differences in study populations, etc.

[0040] The present disclosure describes various embodiments of a comparatively high- fidelity sensor for detecting peripheral neuropathy and a sensor system suitable for detecting peripheral neuropathy amongst other conditions. The sensor may be used for early detection of peripheral neuropathy, such as diabetic peripheral neuropathy (DPN), during diabetic screening in primary care settings, or for monitoring of established DPN during outpatient visits. This allows risk stratification of patients with early DPN which may benefit from early aggressive glycaemic control and early podiatric intervention. Early detection of DPN allows for an early intervention thereby reducing risk of diabetic limb threatening complications.

[0041] FIG. 1 illustrates a sensor system 100 according to various embodiments of the present disclosure. The sensor system 100 may be used for determining neuropathy in a subject’s lower limb 70. The sensor system 100 may include a flexible sensor 200 attachable to a skin surface or attachment surface of the subject’s lower limb 70. The sensor system 100 may also include a processor 300 in signal communication with the sensor 200 and a displaymodule 400 for displaying an outcome indicative of a degree of neuropathy in the subject’s lower limb 70. In various embodiments, the processor 300 and the display module 400 may be integrated into a single system 320. As an example, the processor 300 and the display module 400 may be housed within a single portable device 320 to provide a portable / mobile assessment system.

[0042] As shown in FIG. 1, according to various embodiments, the sensor 200 may include multiple stimulating electrode pairs defining a stimulating zone 210; and multiple sensing electrode pairs defining a sensing zone 220. The stimulating zone 210 and the sensing zone 220 may be spaced apart from each other. In some examples, the stimulating zone 210 and the sensing zone 220 of the sensor 200 may be attached in alignment with a target nerve of the patient. In an example, the target nerve may be the superficial peroneal nerves of the lower left limb 70 of the patient. The stimulating zone 210 may be attached to the shin 70a of the patient in alignment with an upper / superior portion of the superficial peroneal nerves, and the sensing zone 220 may be attached to the foot 70b of the patient in alignment with a lower / inferior portion of the superficial peroneal nerves. Therefore, the sensor 200 may be attached extending from a first body part of the patient to a second body part of the patient.

[0043] In various embodiments, to determine neuropathy in the subject’s lower limb 70, the electrodes in the stimulating zone 210 or stimulating electrode pair(s) of the sensor 200 may provide one or more stimulating signals to the first body part, i.e., upper / superior portion of the superficial peroneal nerves, of the patient. In some embodiments, each stimulating electrode pair may include two electrodes disposed within the stimulating zone 210 but spaced apart from one another. The stimulating signal may be an electrical signal such as an impulse or step signal. The stimulating signal may travel down the superficial peroneal nerves from the upper / superior portion towards the lower / inferior portion of the superficial peroneal nerves. Thereafter, the electrodes in the sensing zone 220 or sensing electrode pair(s), adjacent to or neighbouring the lower / inferior portion of the superficial peroneal nerves, pick up the signal as one or more sensing signal. In some embodiments, each sensing electrode pair may include two electrodes disposed within the sensing zone 220 but spaced apart from one another. The processor 300 then receives the sensing signal(s) and determine a degree of neuropathy based on the sensing signal(s). In some embodiments, the processor 300 may determine a degree of neuropathy based on a time duration between the stimulating signal and the sensing signal. For example, a time duration between respective peaks of the stimulating signal and the sensingsignal. In other words, the processor 300 may determine the degree of neuropathy based on a travel time of the stimulating signal from the stimulating zone 210 to the sensing zone 220.

[0044] In some embodiments, the stimulating zone 210 and the sensing zone 220 may be spaced apart by a measurement gap (G). The measurement gap may be defined by a gap or spacing between the stimulating zone 210 and the sensing zone 220 along a length of the sensor 200. In some embodiments, the measurement gap may correspond to an electrode distance between any one stimulating electrode in a stimulating electrode pair in the stimulating zone 210 and any one sensing electrode of a sensing electrode pair in the sensing zone 220. In some embodiments, the measurement gap may be a minimum distance or nearest distance between one of the stimulating electrode in the stimulating zone 210 and one of the sensing electrode in the sensing zone 220. In other words, the measurement gap may correspond to a minimum distance between a location for applying the stimulating signal and a location for receiving the sensing signal. In some embodiments, the measurement gap may be configured to correspond to the anatomy of the human body. For example, the measurement gap may be determined based on the length of a target body part or the length of a target ncrvc(s). In the example as shown in FIG. 1, the measurement gap may correspond to a length of the superficial peroneal nerves of the lower limb 70. In other examples, the measurement gap may correspond to a distance between selected portions of the superficial peroneal nerves of the lower limb 70, such as portions of the superficial peroneal nerves which are located closer or nearer to the skin surface of the lower limb 70.

[0045] In some embodiments, apart from corresponding to the anatomy of the human body, the measurement gap (G) of the sensor 200 may be between a maximum gap length and a minimum gap length. The reason is that a smaller measurement gap corresponds to a shorter travel distance for the stimulating signal, thus increasing the difficulty in differentiating between a sensing signal for a healthy patient and a sensing signal for a neuropathy patient. In other words, the sensitivity of the sensor 200 is reduced with a small measurement gap. On the other hand, a larger measurement gap may cause the sensing signal to pick up noise or be overly noisy, thus similarly increasing the difficulty in measurements. Further, a larger measurement gap may also cause the stimulating signal to be diminished over the measurement gap. Therefore, the measurement gap may be predetermined or decided based on the sensor’s and sensor system’s particular application or purpose. For example, for a sensor suitable for the superficial peroneal nerves of the lower limb 70, the measurement gap between the stimulatingzone 210 and the sensing zone 220 may be in the range of 11 centimetres to 12 centimetres, which forms a balance between good sensitivity and low noise. It may be appreciated that the measurement gap may be standardized over in some scenarios where there is less anatomy variation between patients, such as measuring lower limb neuropathy for adult diabetic patients. However, the measurement gap may also be customized or be patient-specific for specific scenarios, such as for use in pediatrics.

[0046] FIGs. 2 to 3B illustrate a sensor 200 according to various embodiments of the disclosure. The sensor 200 may include a flexible substrate 202 or a flexible film. The substrate 202 may be in the form of a relatively thin film which defines a film plane 80. The substrate 202 may include a contact surface 202a which is intended to be a skin-facing surface when in use, and an exterior surface 202b opposing the contact surface 202a. In some examples, the substrate 202 may be an elongated member defining a proximal end 2021 and a distal end 2022. Further, the substrate 202 may define a measurement axis 82 through the proximal end 2021 and the distal end 2022, and a lateral axis 84 which is transverse to the measurement axis 82. Both the measurement axis 82 and the lateral axis 84 may be coplanar with the film plane 80. In some examples, the measurement axis 82 extends along a length of the substrate 82. The substrate 200 may be flexible or bendable along a thickness axis 86 which is orthogonal or transverse to the film plane 80. However, the substrate 200 may be relatively rigid along the measurement axis 82 and the lateral axis 84. In other words, the substrate 200 is substantially non-stretchable. As an example, the substrate 200 may be formed from Teflon.

[0047] Referring to FIGs. 3 A and 3B, the sensor 200 may include a plurality of stimulating electrode pairs 211 / 213 coupled to the substrate 202. The stimulating electrode pairs 211 / 213 may form a stimulating electrode array. The stimulating electrode pairs 211 / 213 may collectively define a stimulating zone 210 adjacent to the proximal end 2021. The stimulating zone 210 may define a length (LI ) along the measurement axi 82 and a width (W 1 ) along the lateral axis 84. In some examples, first stimulating electrode pair 211 may define a first stimulating electrode distance (DI) therebetween. Similarly, second stimulating electrode pair 213 may define a second stimulating electrode distance (D2). The stimulating electrode pairs 211 / 213 may be elongated electrodes arranged in parallel to each other. In some embodiments, the stimulating electrode pairs 211 / 213 may be distributed in the stimulating zone 210 along the measurement axis 82. In other words, the stimulating electrode pairs 211 / 213 may be positioned spaced apart from each other along the measurement axis 82. In some examples asshown in FIG. 1, the stimulating electrode pair 211 may be positioned spaced away yet overlapping the stimulating electrode pair 213 along the measurement axis, therefore minimizing the length (LI) of the stimulating zone 210. In other examples, stimulating electrode pairs 211 / 213 may be spaced apart such that they do not overlap each other.

[0048] The sensor 200 may further include a plurality of sensing electrode pairs 221 / 223 / 225 coupled to the substrate 202. The sensing electrode pairs 221 / 223 / 225 may form a sensing electrode array. The plurality of sensing electrode pairs 221 / 223 / 225 may collectively define a sensing zone 220 adjacent to the distal end 2022. The sensing zone 220 may define a length (L2) along the measurement axis 82 and a width (W2) along the lateral axis 84. In some examples, first sensing electrode pair 221 may define a first sensing electrode distance (D3) therebetween. Similarly, second sensing electrode pair 223 may define a second sensing electrode distance (D4). Similarly, third sensing electrode pair 225 may also define a third sensing electrode distance (D5) therebetween. In the example as shown in FIG. 3B, the first sensing electrode distance (D3) and the third sensing electrode distance (D5) are equal in length. In some examples, the number of stimulating electrode pairs 211 / 213 may be different from the number of sensing electode pairs 221 / 223 / 225.

[0049] In various embodiments, the sensing electrode pairs 221 / 213 may be square or rectangular electrodes arranged staggered to each other. In an example, each electrode is a 1cm by 1cm square electrode. In some embodiments, the sensing electrode pairs 221 / 223 may be distributed in the sensing zone 220 along the measurement axis 82. In other words, the sensing electrode pairs 221 / 223 may be positioned spaced apart from each other along the measurement axis 82. In some examples as shown in FIG. 3B, the sensing electrode pair 221 may be positioned spaced away yet overlapping the sensing electrode pair 223 along the measurement axis 82, therefore minimizing the length (L2) of the sensing zone 220. In other examples, sensing electrode pairs 221 / 223 may be spaced apart such that they do not overlap each other. Further, in some embodiments, the sensing electrode pahs 221 / 223 / 225 may be distributed in the sensing zone 220 along the lateral axis 84. Similarly, the sensing electrode pair 221 may be positioned spaced away yet overlapping the sensing electrode pair 223 along the lateral axis 84, therefore minimizing the width (W2) of the sensing zone 220.

[0050] In some embodiments, the sensor 200 may further include a ground electrode 230 coupled to the substrate 202. The ground electrode 202 may be disposed or positioned between the plurality of stimulating electrode pairs 21 1 / 213 and the plurality of sensing electrode pairs221 / 223 along the measurement axis 82. In various embodiments, the sensor 200 may also include an electrical connector 240 in electrical connection with the stimulating electrode pairs 211 / 213, the plurality of sensing electrode pairs 221 / 223 / 225, and the ground electrode 230.

[0051] In various embodiments, the stimulating zone 210 and the sensing zone 220 may form a predetermined measurement gap (G) along the measurement axis 82. The measurement gap (G) may be defined as a minimum distance between the stimulating electrode pairs 211 / 213 and the sensing electrode pairs 221 / 223 / 225. In some embodiments, the measurement gap (G) may correspond to the anatomy of the human body, such as the superficial peroneal nerves.

[0052] In various embodiments, the first stimulating electrode pair 211 and the first sensing electrode pair 221 are spaced apart by a first electrode spacing (ESI) along the measurement axis 82. Similarly, the second stimulating electrode pair 213 and the second sensing electrode pair 223 are spaced apart by a second electrode spacing (ES2) along the measurement axis 82. Likewise, the first stimulating electrode pair 211 and the second sensing electrode pair 223 are spaced apart by a third electrode spacing (ES3) along the measurement axis 82. Similarly, the second stimulating electrode pair 213 and the first sensing electrode pair 221 are spaced apart by a fourth electrode spacing (ES4). The various electrode spacings (ES1 / ES2 / ES3 / ES4) allow flexibility in adjusting or varying the distance between a location of applying the stimulating signal and a location for sensing / receiving the sensing signal. Further, the various electrode pairs (211 / 213 / 221 / 223 / 225) may be distributed along the measurement axis 82 and / or the lateral axis 84. This provides flexibility in varying the location of applying the stimulating signal and the location for receiving the sensing signal. During actual mcasurcmcnts / asscssmcnts, by varying the distance between the stimulating signal and sensing signal enables a finetuning or balance between the sensor 200 sensitivity and noise parameters (e.g., Signal-to-Noise Ratio) as mentioned in previous sections. Further, varying the respective locations of the stimulating signal and sensing signal overcomes the individual anatomy variation, allowing a robust placement of the sensor 200 adjacent to the target nerve(s). It may be appreciated that in some instances, a combination of varying both the distance and location of the stimulating and sensing signals may be performed.

[0053] In an example shown in FIG. 3B, the first electrode spacing (ESI) and / or the second electrode spacing (ES2) may be larger than the measurement gap (G). In some examples, the first electrode spacing (ESI) and the second electrode spacing (ES2) may have a common length, therefore allowing a relatively constant electrode spacing (e.g., ESI equal to ES2, orES 1 substantially equal to ES2) with varying respective positions of the electrode pairs 211 / 221 and 213 / 223. Therefore, a variation of electrode position may be achieved by varying between the first stimulating and sensing electrode pairs 211 / 221 and the second stimulating and sensing electrode pairs 213 / 223, while concurrently preserving the distance between the distance between the respective stimulating and sensing electrodes. In some examples, the third electrode spacing (ES3) may be larger / longer than the first electrode spacing (ESI) and / or the second electrode spacing (ES2), therefore allowing a variable electrode spacing (e.g., ES3 greater than ESI). It may be noted that the third electrode spacing (ES3) also defines a maximum electrode spacing for the device. In some examples, the fourth electrode spacing (ES4) may be equal to the measurement gap (G), which therefore defines a minimum electrode spacing for the device 200.

[0054] Still referring to FIG. 3B, in various embodiments, the sensor 200 may include a first attachment pad 219 coupling the stimulating electrode pairs 211 / 213 to the contact surface 202a of the substrate 202. The first attachment pad 219 may hold the stimulating electrode pairs 211 / 213 relative to the contact surface 202a of the substrate 202. In some examples, the first attachment pad 219 may have a surface area larger than the stimulating zone 210, therefore overlapping the stimulating zone 210. The first attachment pad 219 may be attachable to a target surface, such as the skin surface of a patient. In some embodiments, the first attachment pad 219 may also be detachable from the target surface, hence allowing easy removal of the sensor 200 from the target surface. In some embodiments, responsive to attaching the first attachment pad 219 to the target surface, the stimulating electrode pairs 211 / 213 are held in contact with the target surface.

[0055] Similarly, the sensor 200 may also include a second attachment pad 229 coupling the sensing electrode pairs 221 / 223 / 225 to the contact surface 202a of the substrate 202. The second attachment pad 229 may hold the sensing electrode pairs 221 / 223 / 225 relative to the contact surface 202a of the substrate 202. In some examples, the second attachment pad 229 may have a surface area larger than the sensing zone 220, therefore overlapping the sensing zone 220. The second attachment pad 229 may be attachable to a target surface, such as the skin surface of a patient. In some embodiments, the second attachment pad 229 may also be detachable from the target surface, hence allowing easy removal of the sensor 200 from the target surface. In some embodiments, responsive to attaching the second attachment pad 229to the target surface, the sensing electrode pairs 221 / 223 arc held in contact with the target surface.

[0056] In various embodiments, one or both of the first attachment pad 219 and the second attachment pad 229 may be adhesive pads. In some examples, the respective stimulating electrode pairs 211 / 213 and sensing electrode pairs 221 / 223 / 225 (see FIG. 4A) may adhere to the respective surfaces of the adhesive pads 219 / 229. The adhesive pad 219 may have a surface area larger than the stimulating zone 210 and the adhesive pad 229 may have a surface area larger than the sensing zone 220. Therefore, the adhesive pads 219 / 229 may overlap the respective stimulating zone 210 and sensing zone. The surfaces (e.g. 229a in FIG. 4A) of the adhesive pads 219 / 229 not covered by the electrode pairs 211 / 213 / 221 / 223 / 225 may allow the adhesive pads 219 / 229 to adhere to the target surface. This allows the adhesive pads 219 / 229 to hold the respective stimulating electrode pairs 211 / 213 and sensing electrode pairs 221 / 223 / 225 in contact with the target surface.

[0057] In some embodiments, the adhesive pads 219 / 229 may be electrically conductive adhesive formed in a pad. For example, the electrically conductive adhesive may be formed from electrolyte gel with adhesive properties. In other examples, the adhesive pads 219 / 229 or electrically conductive adhesive may be in a form of a solid-based or a semi-solid electrolyte gel. In some embodiments, the electrolyte gel layer does not flow. In an example, the solidbased electrolyte gel layer may be a conductive tape. The solid-based electrolyte gel may allow a controlled or predetermined amount of electrolyte gel to be used at each measurement instance. The solid-based electrolyte gel may avoid instances of excessive use or insufficient use of electrolyte gel during measurement, which may contribute to measurement errors, such as noise and signal saturation. In various embodiments, each of the adhesive pads may include a predetermined amount of electrically conductive adhesive. The predetermined amount of electrically conductive adhesive is configured to ensure electrical contact / conductivity between the respective electrode pairs 211 / 213 / 221 / 223 / 225 and the target surface. In some examples, the electrode pairs 211 / 213 / 221 / 223 / 225 may be fully covered by the respective adhesive pads 219 / 229 (see FIG. 4B) to enhance electrical conductivity between the electrode pairs 211 / 213 / 221 / 223 / 225 and the target surface. Therefore, the surfaces of the adhesive pads 219 contact and adhere to the target surface.

[0058] In various embodiments, one or both the first attachment pad 219 and the second attachment pad 229 may be compressible elastic pads. For example, the elastic pads 219 / 229arc at least compressible along the thickness axis 86. Upon attaching the sensor 200 or the elastic pads 219 / 229 to the target surface, the elastic pads 219 / 229 may be compressed and thus apply a contact force or contact pressure on the respective electrode pairs 211 / 213 / 221 / 223 / 225, thereby ensuring good electrical contact between the respective electrode pairs 211 / 213 / 221 / 223 / 225 and the target surface.

[0059] Referring to FIG. 4C, in some embodiments, the contact surface 202b of the substrate 202 may be coated with or coupled with an adhesive layer 207 extending across the substrate 202. In this way, the clastic pads 219 / 229 may be attached to a portion of the adhesive layer 207 with the remaining portion 207a of the adhesive layer 207 (not overlapping with the elastic pads 219 / 229) attachable to the target surface.

[0060] Referring to FIGs. 3A and 3B, one or more flexible fingers 203 may be coupled to the substrate 202 for conforming to the target surface. In some embodiments, the substrate 202 may be integrally formed with the flexible fingers 203. The flexible fingers 203 may be formed symmetrically about the measurement axis 82, e.g., the flexible fingers 203 may be disposed in mirror symmetry relative to the measurement axis 82. In an example shown in FIG. 1, the fingers 203 may be foldable fingers 203 with slots 205 formed adjacent to the fingers 203, such that the finders 203 arc foldable along the thickness axis 86.

[0061] In various embodiments, one or more locating portions 204 may be coupled to the substrate 202 for positioning the sensor 200 relative to a reference part of the target surface. The locating portions 204 may be disposed laterally from the sensing zone 220. In some embodiments, the substrate 202 may be integrally formed with the locating portions 204. For example, the locating portion 204 may be used for positioning the sensor 200 relative to a reference body part of a patient, such as an ankle 70c of the patient (see FIG. 1). In some embodiments, the locating portion 204 may be formed as an aperture sized according to the reference body part. Each of the locating portion 204 may be sized to at least partially receive the reference body part. In some examples, the reference body part may be defined by a lateral malleolus or ankle 70c of the subject. In some embodiments, each of the locating portion 204 may include a laterally extending flange defining the aperture. In some embodiments, the locating portion 204 may be formed on respective foldable fingers 203 such that the locating portion 204 may be displaceable towards the reference part / ankle 70c.

[0062] In some embodiments, the locating portions 204 may facilitate with the placing and / or locating of a specific nerve, such as the superficial peroneal nerves (SPN) in the lowerlimb of a patient. In some embodiments, a pair of locating portions 204 may be coupled to or formed on opposing sides of the substrate 202. The pair of locating portions 204 may be disposed in mirror symmetry relative to the measurement axis 82. The symmetrical arrangement of the pair of locating portions 204 allows the sensor 200 to be usable on both the left and right limbs for determining peripheral neuropathy. For example, when the sensor 200 is attached to the lower left limb, one of the locating portions 204 may be used to locate the outer ankle surface on the lower left limb (see FIG. 1). Alternatively, when the sensor 200 is attached to the lower right limb, another of the locating portions 204 may be used to locate the outer ankle surface of the lower right limb. In other embodiments, both the locating portions 204 may be used concurrently to locate the opposing sides / surfaces of one ankle.

[0063] Referring to FIGs. 1 to 5, the operation of the sensor system 100 and sensor 200 for assessing the risk of diabetic peripheral neuropathy in the lower limb of a patient is described in the following example. In the example, the sensor system 100 may be configured to perform a nerve conduction study / assessment on the superficial peroneal nerves (SPN) in the lower limb. During the assessment, the sensor 200 may first be attached to the left lower limb (or right lower limb in other examples) of a patient by way of the attachment pads 219 / 229 (or adhesive pads) and / or the adhesive layer 207 of the substrate 202. Before attaching the sensor 200, the locating portion 204 of the sensor 200 may first be used to locate the ankle 70c of the patient. Thereafter, with the flexing and / or bending of the substrate 202 and the flexible fingers 203, the sensor 200 conforms to and is attached to the lower limb of the patient. The locating portion 204 allows the substrate 202 and the respective electrode pairs 211 / 213 / 221 / 223 / 225 to be generally aligned and positioned adjacent to the SPN in the lower limb. As the substrate 202 is relatively rigid along the measurement axis 82 and the lateral axis 84, the relative positions of the respective electrode pairs 211 / 213 / 221 / 223 / 225 remain relatively unchanged during the attachment of the sensor 200 to the lower limb. Further, the attachment pads 219 ensure good physical contact and electrical contact between the electrode pairs 211 / 213 / 221 / 223 / 225 and the lower limb. In some embodiments, a solid-based or semi-solid electrolyte gel layer may be used to enable good physical contact and electrical contact between the electrode pairs 211 / 213 / 221 / 223 / 225 and the lower limb. In some embodiments, the electrolyte gel layer does not flow. In an example, the solid-based electrolyte gel layer may be a conductive tape. In some instances, an excess amount of electrolyte gel may contribute to signal saturation. In other instances, an insufficient amount of electrolyte gel may contribute tonoise in the captured signal. Hence, the solid-based electrolyte gel enables more consistent results during measurements. This completes the attachment process of the sensor 200 which is fast, accurate and reliable. It may be noted that the process is simple and docs not require high precision and / or expertise from the user or medical practitioner. Further, the sensor 200 may even be attached by a non-medical practitioner such that the assessment may be performed in a remote location from the medical facility, such as at home.

[0064] Referring to FIG. 5. upon attaching the sensor 200 to the patient, the processor 300 may be activated to begin the assessment process. During assessment, the processor 300 may send one or more stimulating signals 610 to the stimulating zone 210 and receive one or more sensing signals 620 from the sensing zone 220. In an example, the processor 300 may be configured to send an impulse signal to the stimulating electrode pair 21 1. The impulse signal causes an electrical / nervous signal to form and travel in the SPN of the lower limb, to be picked up as a sensing signal 620 by one of the sensing electrode pairs 221. The sensing signal 620 may then be processed by the processor 300 to obtain a risk of diabetic peripheral neuropathy in the patient’s lower limb. In some applications, the processor 300 is configured to compare the present sensing signal 620 with previously obtained sensing signal(s) from previous assessment sessions in determining an improvement or deterioration of the patient’s diabetic peripheral neuropathy. In other applications, the processor is configured to compare the present sensing signal 620 with a database of sensing signals for determining a risk of the patient’s diabetic peripheral neuropathy.

[0065] In some embodiments, the processor 300 may also perform signal conditioning or processing to the sensing signal 620. For example, the processor 300 may be configured to remove noise from the sensing signal 620 to obtain a processed sensing signal 630. In another example, the processor 300 may be configured to amplify the sensing signal 620.

[0066] In some embodiments, the processor 300 may be configured to determine the degree of neuropathy in the patient’s lower limb based on the sensing signals 620 / 630. For example, the processor 300 may be configured to determine the degree of neuropathy based on a time duration (Tl) between a peak 632 and another peak 634 of the sensing signal 630. In other example, the processor 300 may be configured to determine the degree of neuropathy based on a voltage value or potential difference of the sensing signal 630.

[0067] In other embodiments, the processor 300 may be configured to determine the degree of neuropathy based on the stimulating signal 610 and the sensing signals 620 / 630. Forexample, the processor 300 may be configured to determine the degree of neuropathy based on a time duration (T2) between a peak 612 of the stimulating signal 610 and a peak 632 of the sensing signal 630.

[0068] In various embodiments, at the stimulating zone 210, the processor 300 may be configured to send a stimulating signal 610 to each of the stimulating electrode pairs 211 / 213 sequentially or one after another. This may be done for sensory nerve conduction studies. In other embodiments, the processor 300 may be configured to send a stimulating signal 610 to each of the stimulating electrode pairs 211 / 213 concurrently. This may be done for motor nerve conduction studies. In some embodiments, the processor 300 may be configured to send the stimulating signal 610 to selected stimulating electrode pairs. This enables the sensor 200 to controllably vary or change the position of the stimulating signals 610 and / or alter an electrode distance between the respective stimulating and sensing electrode pairs.

[0069] At the sensing zone 220, in some embodiments, the processor 300 may be configured to receive respective sensing signals from each of the sensing electrode pairs 221 / 223 / 225. In some embodiments, the processor 300 may be configured to determine the degree of neuropathy based on selected ones of the sensing signals. In some embodiments, the sensing signals which meet one or more predetermined criteria, may be selected for determining the degree of neuropathy. For example, sensing signals which meet a voltage threshold or a Signal- to-Noise ratio (SNR) threshold may be deemed to be satisfactory and meet the predetermined criteria to be further used for neuropathy assessment.

[0070] In other embodiments, the processor 300 may be configured to determine one or more selected sensing electrode pairs based on the corresponding sensing signals. The selected sensing electrode pairs may correspond to the sensing signals which fulfil the predetermined criteria. The selected sensing electrode pairs may be used for determining the degree of neuropathy in subsequent assessments.

[0071] FIG. 6 illustrates the sensor 200 according to various other embodiments of the present disclosure. Similar to previous embodiments, the sensor 200 may include a substrate 202 with electrode pairs defining a stimulating zone 210 and a sensing zone 220. Further, a ground electrode 230 may be provided disposed between the stimulating zone 210 and the sensing zone 220. Flexible fingers 203 may be coupled to the substrate 202 for conforming to the target surface. Each locating portion 204 may be formed on two adjacent fingers 203 suchthat the locating portions 204 define an aperture which is both flexible and expandable. This allows the locating portion 204 to account for variations in ankle sizes for different patients.

[0072] In some embodiments, the processor 300 may be configured as a printed circuit board (PCB) attached to and integrated with the sensor 200. The PCB 300 may include computing units such that the processing of the sensing signals may be performed in the PCB 300. Therefore, the relevant computations for peripheral neuropathy assessment may be performed on the PCB 300 without requiring a further processing / computing unit. The PCB 300 may then provide a processed output directly to an end node, such as a display unit or a mobile device, through the electrical connector 240 mounted to the PCB 300. This provides a compact solution for neuropathy assessment which may be brought off-site away from medical facilities for performing remote assessments.

[0073] Referring to FIG. 7, in various embodiments of the present disclosure, the stimulating electrode pairs in the stimulating zone 210 may be distributed along both the measurement axis 82 and the lateral axis 84. Similarly, the sensing electrode pairs in the sensing zone 220 may be distributed along both the measurement axis 82 and the lateral axis 84. Therefore, the sensing electrode pairs and the stimulating electrode pairs may each be in a respective staggered arrangement. The stimulating electrode pairs and the sensing electrode pairs may be square electrodes with a constant electrode area. This enables a similar physical contact area and hence a consistent surface resistance between the respective stimulating and sensing electrode pairs and the attachment surface.

[0074] In some embodiments, one or more first slots 206 may be coupled to or formed on the substrate 202 neighbouring the stimulating zone 210. Similarly, one or more second slots 208 may be coupled to or formed on the substrate 202 neighbouring the sensing zone 220. The slots 206 / 208 may be formed on the periphery of the substrate 202. The first slots 206 may be configured for anchoring a first brace relative to the substrate 202, such that the first brace holds the sensor 200 in contact with a first body part (such as the wrist) of the patient. Similarly, the second slots may be configured for anchoring a second brace relative to the substrate, such that the second brace holds the sensor 200 in contact with a second body part (such as the aim) of the patient. By using the braces for holding the sensor 200, there is minimal adhesion between the sensor 200 and the respective skin surface of the patient, thus alleviating any difficulties in detaching or removing the sensor 200 upon completion of the assessment.

[0075] As illustrated in FIG. 8, the sensor system 100 and sensor 200 may be used for assessing nervous-related conditions or a risk of such conditions, such as carpel tunnel syndrome in a patient’ s hand 74. In various embodiments, the sensor 200 may include slots and braces for attaching the sensor 200 to the patient’ s hand 74. In some examples, a first brace 76a may assist in securing a stimulating zone 210 and the respective stimulating electrode pairs to a wrist portion 74a of the patient’ s hand 74, and a second brace may assist in securing a sensing zone 220 and the respective sensing electrode pairs to a dorsal side 74b of the hand 74. In some embodiments, the processor 300 may be configured as a portable device which allows the assessment of carpel tunnel syndrome to be performed during activity or therapy.

[0076] FIGs. 9A to 9D illustrate various other embodiments of the sensor 200 of the present disclosure. Comparing the sensors 200 shown in FIGs. 9A, 9B and 9C, the sensors 200 may have similar electrode configurations, i.e. similar stimulating zone 210 and sensing zone 220, but with different flexible substrates 202. Therefore, based on the same electrode configuration, the sensors 200 may be configured for different applications or scenarios with the change of the flexible substrate 202, enabling a patient- specific or customizable sensor 200 for assessment. For example, the sensor 200 in FIG. 9A and 9C may include brace slots suitable for attaching the sensor 200 to a patient’s hands for assessing carpel tunnel syndrome. In contrast, the sensor 200 if FIG. 9B may include foldable fingers and adhesive pads / layers which are suitable for attaching to the patient’s hands for assessing another form of peripheral neuropathy in the hand.

[0077] In various embodiments, referring to the sensors 200 in FIGs. 9D, 9E and 9F, the stimulating zone 210 may be identical to the sensing zone 220. This allows the same electrodes / electrode pairs to be used for both stimulating zone 210 and sensing zone 220, easing the manufacturing / assembling process. In some examples, the number of stimulating electrode pairs 21 1 / 213 may be identical to the number of sensing electrode pairs 221 / 223 / 225. This allows the sensor 200 to have an equal number of stimulating electrode channels and sensing electrode channels simplifying data acquisition / transmission.

[0078] Further, referring to FIGs. 9E and 9F, in various embodiments, the stimulating zone 210 may include sub-zones 210a / 210b. Each of the sub-zones 210a / 210b may correspond to respective attachment pads 219a / 219b. Therefore, each of the attachment pads may be customized or made according to application requirements. For example, the attachment pad 219a of sub-zone 210a may be a compressible elastic pad while attachment pad 219b of sub-zone 210b may be an electrically conductive adhesive pad. In situations where the type of attachment pad suitable for the application is uncertain, the sub-zones 210a / 210b allow the assessment to be performed using different attachment pads, and hence increasing the measurement robustness / accuracy. Similarly, the sensing zone 220 may also include sub-zones 220a / 220b, with each of the sub-zones 220a / 220b corresponding to respective attachment pads 229a / 229b.

[0079] In some embodiments as shown in FIGs. 9G and 9H, in applications where a relatively larger electrode area is desirable, the stimulating zone 210 may include a single pair of stimulating electrode 211, and the sensing zone 220 may also include a single pair of sensing electrode 221.

[0080] In various embodiments as shown in FIGs. 10A to 1 IB, the sensor 200 may include a connecting pad 209 or a connecting strip coupled to the exterior surface 202b of the flexible substrate 202. The flexible connecting pad 209 may provide a respective electrical connection from the connector to the stimulating zone 210, the sensing zone 220, and the ground electrode 230. In various embodiments, the connecting pad 209 may be flexible. For example, the connecting pad 209 may have elastic properties similar to the substrate 202. In some examples, the connecting pad 209 may include a flexible ribbon. In some examples, the connecting pad 209 may be integrated with the flexible substrate 202 providing integrated connections from the connector to the stimulating zone 210, the sensing zone 220 and the ground electrode 230.

[0081] FIG. 12 illustrates a method 700 of determining neuropathy according to various embodiments. The method 700 includes: in 710, receiving at least one sensing signal from a sensor; in 720, determining a degree of neuropathy based on the at least one sensing signal. In some embodiments, determining the degree of neuropathy further includes: in 730: determining the degree of neuropathy based on selected ones of the at least one sensing signal. In some embodiments, the method 700 further includes: in 740, sending a stimulating signal to at least one stimulating electrode.

[0082] In some embodiments, the method 700 further includes selecting at least one sensing electrode pair from the plurality of sensing electrode pairs based on the at least one sensing signal. In some embodiments, the method 700 further includes determining the degree of neuropathy based on respective sensing signals from the at least one sensing electrode pair.

[0083] In some embodiments, the method 700 further includes sending a stimulating signal to at least one of the plurality of stimulating electrode pairs. In some embodiments, the method700 further includes sending the stimulating signal sequentially to each of the plurality of stimulating electrode pairs. In some embodiments, the method 700 further includes determining the degree of neuropathy based on a respective time duration between a peak of the stimulating signal and respective peak of the at least one sensing signal. In some embodiments, the method 700 further includes removing noise from the at least one sensing signal.Experiments

[0084] FIG. 13A to 13C shows an experimental setup for the proposed sensor system and sensor. Feasibility tests were performed by attaching the proposed sensor to the superficial peroneal nerves with comparisons to conventional nerve conduction study systems for a reliable measurement. The proposed sensor comprises a flexible sensor array embedded onto an adhesive patch. The array has multiple conductive points, forming a grid of test points. When attached to the skin, the anay adheres closely to the dorsum of the foot to provide good contact against the skin overlying the superficial peroneal nerve. The multi-point or multifocal sensor array ensures that at least some of the test points will be in contact with the correct location overlying the superficial peroneal nerve. The enables proper stimulation and recording of the CV and SNAP. In the tests, the correct conductive points on the grid were identified via a software system that will scan systematically through the grid. As an example, the processor or computing algorithm makes use of peak-to-peak values, thresholding, and time -based averaging for assessing the sensing signals or waveforms. Upon the identification or selection of the preferred contact points, the processor applies a step-up or impulse voltages to the stimulating zone, and identifies the nerve conduction velocity and the Peak-to-peak signal amplitudes from the sensing signals from the sensing zone. Experimental data shows a nerve response in DPN subject to be in the 6-7 milliseconds (ms) range in comparison to a nerve response in the 3-4 milliseconds (ms) range for a normal subject. The test duration is within 5 minutes.

[0085] In the feasibility tests, three different distal nerves of the foot, namely i) Medial plantar nerve; ii) Medial plantar proper digital nerve; and iii) Superficial peroneal nerve were investigated. In the feasibility studies, the medial plantar nerve and medial plantar proper digital nerve proved to be unsuitable for NCS readings due to the thick skin on the sole of the feet which is overlayed with larger muscles. This resulted in weak signals and unwantedinterference from motor conduction. In contrast, the superficial peroneal nerve was identified as a suitable target nerve for identifying periphery neuropathy with high reproducibility and validity of sensing signals. This is due to the superficial peroneal nerve being close to the skin and not covered by big muscle groups. Further, the topography of the adjacent skin area is relatively flat, allowing good and reliable contact by sensors. Therefore, the superficial peroneal nerve was identified as a target nerve for detection of early-stage diabetic periphery neuropathy.

[0086] FIG. 14 shows the results from the proposed sensor system, in which the sensor was attached adjacent to the superficial peroneal nerve. The sensing signals, such as the peak-to- peak signals and time artefacts, from the tests are constant and reproducible over multiple tests. A survey on healthy volunteers shows that most test subjects do not feel discomfort during the test. Further, an assessment / test with a single stimulating signal of 10mA in voltage amplitude and 0.1s in voltage duration is able to provide the volunteers with a sensation feeling. Further, at least 1 of the 3 sensing electrode pahs were able to give a data set suitable for data computation and periphery neuropathy assessment.

[0087] The following observations were noted during the test earlier with diabetic test subjects wherein two sensors: a first sensor with a longer measurement gap and a second sensor with a shorter measurement gap, were used. Using the first sensor, the subject felt a higher sensation of the stimulating signal / pulse at 10mA compared to the stimulating signal at 20mA. With the shorter sensor, the subject felt a higher sensation at 20mA down to the toes compared to the midfoot for lower simulation. Overall, the first sensor induces less sensation in the patient in comparison to the second sensor. This places a limit or a cap on the maximum measurement gap in the sensor, in which a measurement gap longer than the limit results in a drop in sensor performance.

[0088] Further, two different conventional nerve conduction study systems were used to validate the suitability of identifying the superficial peroneal nerve as the target nerve for periphery neuropathy assessment. The systems are 1) Natus VikingQuest from Natus Neurology Inc and 2) Powerlab 15T from AD Instruments. The Natus VikingQuest is an FDA approved system for nerve conduction studies, and was used as a reference NCS in the study. The Neuro Amp EX is a biosignal acquisition system which allows flexibility in processing the data collected and serves as the core hardware for the NCS experiments. FIG. 15 shows the sensing signals obtained by the Powerlab 1 T system using the proposed sensor. The resultsarc comparable to results (FIG. 16) from the FDA approved Natus VikingQuest (C) and the results from the proposed system (FIG. 14), exhibiting consistency in results across the NCS platforms (the proposed system, the VikingQuest system, the PowerLab system).

[0089] In further experiments, the proposed sensor was connected to a conventional Cadwell nerve conduction system and compared to conventional electrodes also connected to the Cadwell nerve conduction system. Table 1 below shows the experimental results from both the proposed sensor and the conventional electrodes. It may be observed that the proposed sensor exhibits comparable results with conventional electrodes, while providing the benefits of a faster, more precise, and easier attachment of the sensor.Table 1 . Comparison between proposed sensor and conventional electrodes

[0090] The foregoing shows the benefits of the proposed sensor system and sensor in determining the presence or the onset of DPN in its early stages. The proposed sensor system and sensor may be similarly used in other applications, e.g., the sensor system / sensor may be used for early detection of peripheral neuropathy for other non-diabetic conditions. For example, the sensor system / sensor may be used for the detection of nervous-related or neuropathy conditions, such as but not limited to the carpel tunnel syndrome. In some embodiments, the sensor system may be implemented to facilitate regular, semi-automated screening for peripheral neuropathy or diabetic peripheral neuropathy as part of the diabetic foot screening in the primary healthcare setting.

[0091] The proposed sensor may be based on the principles of nerve conduction studies (NCS) which arc often regarded as an objective measure of nerve function. The proposed sensor may be utilized for both motor nerve conduction studies as well as sensory nerveconduction studies. Sensory nerve action potential amplitude (SNAP) and conduction velocity (CV) are sensitive indicators of nerve degeneration in patients. In diabetic patients, impairment of the peroneal nerve is often the most prominent, and the amplitude of sensory nerve action potential is one of the sensitive measures of peripheral neuropathy. The proposed sensor and sensor system provide high sensitivity and repeatability, with reproducible results from the quantifying of SNAP and CV on a robust screening platform, providing an assessment and detection of the onset of early DPN as well as for monitoring of DPN progression.

[0092] In some embodiments, the sensor may be integrated with cxisting / convcntional nerve conduction studies systems, allowing smooth integration with medical care facilities as well as the existing medical care protocols. Further, integration with existing nerve conduction studies systems similarly allows mapping of the sensory function of nerves, such as the superficial peroneal nerve (SPN), through neural stimulation and signal pulses.

[0093] In some embodiments, the sensor may be a flexible sensor for conforming to curvatures of a target surface, such as a body part of a patient, and yet provide a consistent and objective measurement regardless of the size and / or curvature of the body part. This means that repeatable and comparable measures may be taken for the same patient over time even if the body part (c.g,. the lower limb) has some swelling or muscle loss. This also means that same sensor may be used with multiple subjects to obtain meaningful data for clinical studies, etc. Further, the flexible sensor may include locating or positioning portions for assisting in the attachment of the sensor to the target surface. The sensor may also provide a predetermined measurement distance between a stimulation area and a sensing area, thus allowing a fast and efficient sensor attachment process that ensures repeatable and objective measurements, in addition to a sensing signal with high sensitivity and low noise. This enables a smooth and relatively easy administration or application of the sensor, e.g., the proposed sensor enables sensing of the pertinent nerves without the need for specialists to precisely identify the correct location for placement of a monofilament. The proposed sensor can be used with minimal discomfort for early detection of peripheral neuropathy. Further, the ease of implementation allows the sensor or sensor system to be incorporated into an efficient peripheral neuropathy screening program at primary healthcare facilities such as polyclinics. The repeatability of the proposed sensor and sensor system allow the nerve conduction parameters (such as nerve conduction velocity and amplitude) in patients with peripheral neuropathy to be quantified and monitored regularly.

[0094] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding, and are not intended to be exhaustive. Modifications may be made by one of ordinary skill in the art without departing from the scope disclosed.

Claims

Claims1. A sensor for determining neuropathy, the sensor comprising: a flexible substrate defining a measurement axis; a plurality of stimulating electrode pairs coupled to the substrate, the plurality of stimulating electrode pairs defining a stimulating zone; and a plurality of sensing electrode pairs coupled to the substrate, the plurality of sensing electrode pairs defining a sensing zone, the sensing zone and the stimulating zone being spaced apart by a predetermined measurement gap along the measurement axis, wherein the plurality of stimulating electrode pairs are distributed in the stimulating zone along the measurement axis, wherein the plurality of sensing electrode pairs are distributed in the sensing zone along the measurement axis.

2. The sensor according to claim 1, wherein a first stimulating electrode pair and a first sensing electrode pair are spaced apart by a first electrode spacing along the measurement axis, and a second stimulating electrode pair and a second sensing electrode pair are spaced apart by a second electrode spacing along the measurement axis, wherein each of the first electrode spacing and the second electrode spacing are equal to or larger than the measurement gap.

3. The sensor according to claim 2, wherein the first electrode spacing and the second electrode spacing have a common length.

4. The sensor according to claim 2, wherein the first stimulating electrode pair and the second sensing electrode pair are spaced apart by a third electrode spacing along the measurement axis, wherein the third electrode spacing is larger than the first electrode spacing.

5. The sensor according to claim 1, wherein the plurality of sensing electrode pairs are distributed in the sensing zone along a lateral axis transverse to the measurement axis.

6. The sensor according to claim 5, wherein the plurality of stimulating electrode pahs are distributed in the stimulating zone along the lateral axis.

7. The sensor according to claim 1, wherein the plurality of sensing electrode pairs and the plurality of stimulating electrode pairs are in a staggered arrangement.

8. The sensor according to claim 1 , further comprising a ground electrode coupled to the substrate, the ground electrode being disposed between the plurality of stimulating electrode pairs and the plurality of sensing electrode pairs along the measurement axis.

9. The sensor according to claim 1, further comprising a first attachment pad, the first attachment pad coupling the plurality of stimulating electrode pairs to a contact surface of the substrate.

10. The sensor according to claim 9, wherein responsive to attaching the first attachment pad to a target surface, the plurality of stimulating electrode pairs are held in contact with the target surface.

11. The sensor according to claim 9, further comprising a second attachment pad, the second attachment pad coupling the plurality of sensing electrode pairs to the contact surface of the substrate.

12. The sensor according to claim 11, wherein responsive to attaching the second attachment pad to a target surface, the plurality of sensing electrode pairs are held in contact with the target surface.

13. The sensor according to claim 11, wherein at least one of the first attachment pad and the second attachment pad is an adhesive pad, the adhesive pad comprising a predetermined amount of electrically conductive adhesive.

14. The sensor according to claim 11, wherein at least one of the first attachment pad and the second attachment pad comprises an elastic pad, the elastic pad being compressibleto apply a contact force on the respective electrode pairs upon attachment of the sensor to a target surface.

15. The sensor according to claim 1, wherein the substrate comprises at least one locating portion disposed laterally of the sensing zone.

16. The sensor according to claim 15, wherein each of the at least one locating portion comprises a laterally-extending flange defining an aperture.

17. The sensor according to claim 15, wherein the substrate comprises a pair of locating portions disposed in mirror symmetry relative to the measurement axis.

18. The sensor according to claim 15, wherein the at least one locating portion is sized to at least partially receive a reference body part, and wherein the reference body part is defined by a lateral malleolus of a subject.

19. The sensor according to claim 1 , further comprising an adhesive layer coupled to a contact surface of the substrate.

20. The sensor according to claim 1, wherein the substrate includes multiple foldable fingers, and wherein at least one of the multiple foldable fingers is foldable independently of any other of the multiple foldable fingers.

21. The sensor according to claim 1 , further comprising a brace, wherein the substrate defines at least one slot in engagement with the brace.

22. The sensor according to claim 1, further comprising an electrical connector in electrical connection with the respective plurality of stimulating electrode pairs and plurality of sensing electrode pairs.

23. A sensor system, comprising: the sensor according to any one of the previous claims; and a processor in signal communication with the sensor, the processor being configured to:receive at least one sensing signal from at least one of the plurality of sensing electrode pairs, and determine a degree of neuropathy based on the at least one sensing signal.

24. The sensor system according to claim 23, wherein the processor is further configured to determine the degree of neuropathy based on selected ones of the at least one sensing signal.

25. The sensor system according to claim 23, wherein the processor is further configured to select at least one sensing electrode pair from the plurality of sensing electrode pairs based on the at least one sensing signal.

26. The sensor system according to claim 25, wherein the processor is further configured to determine the degree of neuropathy based on respective sensing signals from the at least one selected sensing electrode pair.

27. The sensor system according to claim 23, wherein the processor is further configured to provide a stimulating signal to selected ones of the plurality of stimulating electrode pairs.

28. The sensor system according to claim 27, wherein the processor is further configured to provide the stimulating signal sequentially to each of the plurality of stimulating electrode pairs.

29. The sensor system according to claim 27, wherein the stimulating signal comprises an impulse signal.

30. The sensor system according to claim 27, wherein the processor is further configured to determine the degree of neuropathy based on a respective time duration between a peak, of the stimulating signal and a respective peak of the at least one sensing signal.

31. The sensor system according to claim 23, wherein the processor is further configured to denoise the at least one sensing signal.

32. A method of determining neuropathy, the method comprising: receiving at least one sensing signal from a sensor; and determining a degree of neuropathy based on the at least one sensing signal, wherein the sensor comprises: a flexible substrate; a plurality of stimulating electrode pairs coupled to the substrate, the plurality of stimulating electrode pairs defining a stimulating zone; and a plurality of sensing electrode pairs coupled to the substrate, the plurality of sensing electrode pairs defining a sensing zone, the sensing zone forming a measurement gap with the stimulating zone along a measurement axis, wherein the plurality of stimulating electrode pairs are distributed in the stimulating zone along the measurement axis, wherein the plurality of sensing electrode pairs arc distributed in the sensing zone along the measurement axis.

33. The method according to claim 32, wherein determining the degree of neuropathy further comprises: determining the degree of neuropathy based on selected ones of the at least one sensing signal.

34. The method according to claim 32, further comprising selecting at least one sensing electrode pair from the plurality of sensing electrode pairs based on the at least one sensing signal.

35. The method according to claim 34, further comprising determining the degree of neuropathy based on respective sensing signals from the at least one sensing electrode pair.

36. The method according to claim 32, further comprising providing a stimulating signal to at least one of the plurality of stimulating electrode pairs.

37. The method according to claim 36, further comprising providing the stimulating signal sequentially to each of the plurality of stimulating electrode pairs.

38. The method according to claim 36, wherein the stimulating signal comprises an impulse signal.

39. The method according to claim 36, further comprising determining the degree of neuropathy based on a respective time duration between a peak of the stimulating signal and respective peak of the at least one sensing signal.

40. The method according to claim 32, further comprising denoising the at least one sensing signal.

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