Medical electrode

The present invention provides a medical electrode, which comprises an annular adhesive pad (203) to be attached to a living being, a conductive pad (205) disposed in the central hole (207) of the annular adhesive pad, a first conductive snap element (209), a conductive element (211) and a sealing film (213). The conductive element (211) is configured to establish electrical communication between the conductive pad (205) and the first conductive snap element (209) and the sealing film (213) is attached to the annular adhesive pad (203) and to fix at least a portion of the conductive element (211) between the annular adhesive pad (203) and the sealing film (213). The flexibility and/or length of the conductive element is chosen to be large enough so as to allow the first conductive snap element (209) to move without causing the conductive pad (205) to move, resulting in reliable electrical contact between the conductive pad and the skin of the living being.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2015/065165, filed on Jul. 2, 2015, which claims the benefit of European Patent Application No. 14183400.2, filed on Sep. 3, 2014 and PCT/CN2014/081579, filed on Jul. 3, 2014. These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to an electrode, in particular a medical electrode for establishing electrical contact with a living being to acquire physiological signals from said living being.

BACKGROUND OF THE INVENTION

In modern medicine, many medical apparatus are developed to acquire physiological signals from a living being by means of a medical electrode attached to the living being. For example, an ECG (electrocardiograph) device is widely used to acquire medical (i.e. biopotential) signals containing information indicative of electrical activity associated with the heart and pulmonary functions. An electrode is used to establish electrical connection between the ECG device and the skin of a living being, for example, a person or an animal and acquire physiological signals, which are one of the important bases for diagnosis of cardiovascular diseases or for monitoring cardiovascular and other physiological functions.

Stress Testing ECG is a diagnostic test performed on a person living with suspected or known cardiovascular disease, most commonly coronary artery disease (CAD). The stress testing procedure often requires the target person to exercise either on a treadmill or bike. Holter ECG is a diagnostic test performed on persons whose heart disease can only be detected through prolonged ECG monitoring or recording that normally takes 24 hours or even long. During Holter recording or monitoring, unavoidably, there would be frequent body movement of the person as a part of everyday life. To ensure quality of acquired ECG signals, both Stress ECG and Holter ECG require quality electrode to establish reliable electrical contact with the skin of the person.

FIG. 1is an exploded perspective view of a conventional electrode used for an ECG device andFIG. 2is a sectional view of the electrode ofFIG. 1when it is attached to the skin of a living being, for example, a person or an animal.

As shown inFIG. 1andFIG. 2, an existing medical electrode131generally comprises an annular adhesive pad133having double-sided adhesive tape147and a central hole137, a conductive pad135such as a foam pad filled with a conductive gel and disposed in the central hole137of the annular adhesive pad133. The electrode131further comprises a first conductive snap element139, a second conductive snap141and a sealing film143which is disposed between the first and second snap elements. The first conductive snap element139is to be attached to a first side135aof the conductive pad135, and be snapped into the second conductive snap141. The outer portion of the sealing film143is attached to one side133aof the annular adhesive pad133.

The electrode may comprise a release liner145, which is attached to a second side133bof the annular adhesive pad133and can be removed before applying the electrode to a person. In use, the second conductive snap element141of the medical electrode131is snapped into a connector element C of a lead wire L, which transfers acquired signals to the ECG device.

Obviously exercising on a treadmill or bike, or body movements as part of everyday life may cause the lead wire L to move. When the lead wire L is fixed to the medical electrode, the mechanical force caused by the movement via the lead wire L will transferred from the first and second conductive snap elements and causes conductive pad135to move relative to the skin S of the living being, which in turn changes the electrical contact impedance between the conductive pad135and the skin S. This causes ECG signals distortion and introduces negative impact on ECG signal monitoring and diagnosis of relative disease.

To solve this problem, a known method is to use software algorithm to filter or correct the distortion or the interference after a noisy ECG waveform is acquired, but the software filtering may unexpectedly remove many ECG details due to lack of precise information of the movement causing such distortion. Thus, there is a need to provide an improved medical electrode for ECG devices, in particular, for Stress ECG and Holter ECG monitoring or diagnosis.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a medical electrode comprises an annular adhesive pad having a central hole and configured to be attached to a living being; a conductive pad disposed in the central hole of the annular pad and configured to be in direct contact with the living being; a first conductive snap element; a conductive element configured to establish electrical communication between the conductive pad and the first conductive snap element; and a sealing film configured to seal the conductive pad and to fix at least a portion of the conductive element between the annular adhesive pad and the sealing film, wherein the flexibility and/or length conductive element is chosen to be large enough so as to allow the first conductive snap element to move without causing the conductive pad to move. In this way, when the lead wire moves, the mechanical force transferred from the lead wire to the first conductive snap element will not cause relative movement between the conductive pad and the living being. As a result, the electrical contact impedance between the conductive pad and the living being will not change with body movement, thereby preventing the acquired physiological signals from being distorted.

More advantageously, the medical electrode further comprises a second conductive snap element into which the first conductive snap element is snapped; and a support sheet disposed between the first conductive snap element and the second conductive snap element. The support sheet comprises a central portion, an outer portion and an inner portion between the central portion and the outer portion. The central portion of the support sheet is sandwiched between the first and second conductive snap element, the outer portion of the support sheet is attached or adhered to the first side of the annular adhesive pad, and the inner portion of the support sheet is free from the annular adhesive pad and is designed in a way that allows at least a part of the inner portion of the support sheet to move relative to the outer portion of the support sheet.

Also more advantageously, the support sheet has one or more slits formed in the inner portion of the support sheet that enables the inner portion of the support sheet to deform when it is stressed with mechanical force transferred from lead wire via the second conduction snap element. This allows the inner portion of the support sheet to move relative to the outer portion of the support sheet with more freedom and without causing the outer portion of the support sheet and thus the annular adhesive pad to move and effectively increases reliability of the electrical contact between the conductive pad and the skin of the person when the body movement causes the lead wire to move.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

As shown inFIGS. 3 and 4, a medical electrode201according to the present invention comprises an annular adhesive pad203, a conductive pad205, a first conductive snap element209, a conductive element211and a sealing film213.

The annular adhesive pad203has a central hole207and is to be attached to a living being such as a person or an animal. The conductive pad205is disposed in the central hole207of the annular adhesive pad203and to be in direct contact with the skin S of the person. Advantageously, the conductive pad205is a foam pad filled with conductive gel.

The first conductive snap element209is disposed adjacent to the sealing film213. The conductive element211is configured to establish electrical connection between the conductive pad205and the first conductive snap element209and it can be a conductive foil or a strip with one end connected to the first conductive snap element209and the other end connected to the conductive pad205.

The sealing film213is configured to be attached to a first side203aof the annular adhesive pad203to prevent the conductive pad205, in particular the conductive gel, from escaping from the central hole207of the annular adhesive pad203. Meanwhile, the sealing film213also fixes at least a portion of the conductive element211between the annular adhesive pad203and the sealing film213.

The medical electrode201may further comprises a release liner215configured to be attached to a second side203bof the annular adhesive pad203, for example, by means of a double-sided adhesive tape217. The second side203bof the annular adhesive pad203is opposite to the first side203aof the annular adhesive pad203and is to be attached or adhered to the person when the medical electrode201is applied. In the state of use, the release liner215is removed, the annular adhesive pad203having double-sided adhesive tape217is adhered to the skin S of the person.

When the medical electrode201is used with an ECG device, the first conductive snap element209of the medical electrode is snapped into a connector element C of a lead wire L, which transfer acquired signals to the ECG device (not shown in the figures). The body movement of the person will cause lead wire L and thus the first conductive snap element to move. To protect the conductive pad from the mechanical force imposed on the first conductive snap element, the flexibility or the length of the conductive element211is designed to be large enough so as to absorb or accommodate the mechanical force and thus allow the first conductive snap element209to move without causing the conductive pad205to move. As a result, the electrical contact impedance between the conductive pad205and the skin S of the person will not change with movement of the lead wire L, and therefore, ensure stable and accurate ECG signals acquisition.

Advantageously, the medical electrode201according to the present invention further comprises a second conductive snap element219and a support sheet221. The support sheet221is disposed between the first conductive snap element209and the second conductive snap element219. Specifically, the support sheet221comprises a central portion221a, an outer portion221band an inner portion221cbetween the central portion221aand the outer portion221b. The central portion221aof the support sheet221is sandwiched between the first conductive snap element209and the second conductive snap element219, when the second conductive snap element209is snapped into the first conductive snap element219. The outer portion221bof the support sheet221is attached or adhered to the first side203aof the annular adhesive pad203for example by means of a double-sided adhesive tape223while the inner portion221cof the support sheet221is free from the first side203aof the first pad203. The inner portion221cof the support sheet221is designed in a way that allow at least a part of the inner portion221cof the support sheet221has freedom to move relative to the outer portion221bof the support sheet221without causing the annular adhesive pad203to move.

As the sealing film and a part of the conductive element are sandwiched between the annular adhesive pad and the support sheet, it is possible to prevent the sealing film from becoming detached from the annular adhesive pad due to movement of the part of conductive element caused by the first snap element.

In one embodiment, the support sheet221is made from an elastic material, and the inner portion221cand the outer portion221bof the support sheet221can be made of different elastic material with different flexibility. Preferably the inner portion221cof the support sheet221is more flexible than the outer portion221bof the support sheet221to allow the inner portion221chas freedom to move without causing the outer portion of the support sheet221to move.

Alternatively, the support sheet221may be made from a polymer material with more rigidity than a support sheet221made from elastic material. In such a case, to ensure that the inner portion221cof the support sheet221has freedom to move relative to the outer portion221bof the support sheet221, a plurality of slits is formed in the inner portion221cof the support sheet221.

FIGS. 5, 6 and 7show an exemplary support sheet221. As shown in theFIGS. 5 and 6, a first pair of arc-shaped slits225a,225bis formed diametrically opposite each other in the inner portion221cof the support sheet221. Advantageously, a second pair of arc-shaped slits225c,225dwith radius larger than that of the first pair of arc-shaped slits225a,225bmay be formed diametrically opposite each other in the inner portion221cof the support sheet221. Preferably, the second pair of arc-shaped slits225c,225dare offset from the first pair of slits225a,225bby a certain angle, for example 85°-90°.

It should be understood that the number of slits is not limited to two pairs and more than two pairs of slits are also feasible. Further, the slits may be in any suitable shape, for example a linear or curved shape. For example, only one spiral slit may be formed in the inner portion221cof the support sheet221. Of course, more than one spiral slit is feasible. Since the inner portion221cof the support sheet221has one or more slits, the inner portion221cof the support sheet221is more flexible than the outer portion221bof the support sheet221. Thus, when the first and second conductive snap element is stressed due to movement of lead wire L, the inner portion221cof the support sheet221may deform and thus move relative to the outer portion221bof the support sheet221.FIG. 7shows such a possible deformation or movement of the inner portion221cof the support sheet221.

In use, the second conductive snap element219of the medical electrode is snapped into a connector element C of a lead wire L leading to the ECG device (not shown in the figures), the release liner215is removed and the medical electrode201is subsequently applied and attached to the skin S of the person by the double-sided adhesive tape217, as shown inFIG. 5. When the lead wire moves due to the person's exercises on a treadmill or bike or by body movements, a mechanical force is generated that causes the first conductive snap element209and the second conductive snap element219to move. The flexibility or deformability of the inner portion221cof the support sheet221allows the inner portion221cof the support sheet221to move together with the first conductive snap element209and the second conductive snap element219. As a result, the mechanical force generated by movement of the lead wire due to the person's exercises on a treadmill or bike or by body movements will not be transferred to the outer portion of the support sheet221and thus the annular adhesive pad203. As the flexibility and/or length of the conductive element211is chosen to be large enough so as to allow a part of conductive element211to follow the inner portion221cof the support sheet221Thus, a reliable electrical connection from the conductive pad205to the second conductive snap element219via the conductive element211and the first conductive snap element209is guaranteed. That is to say, irrespective of whether the lead wire moves perpendicularly to or along the skin S of the person, a mechanical force caused by the movement of the lead wire will not be transferred to the conductive pad205. Thus, there is no relative movement between the second pad205and the skin S of the living being. As a result, the electrical contact impedance between the annular adhesive pad205and the skin S of the person will not change with the movement of lead wire. The stability and accuracy of ECG signals acquisition are improved.

Although the preferred embodiments of the present invention are interpreted as electrodes for an ECG device, it should be understood that the electrode according to the present invention may be used also with other medical devices, for example an EEG (electroencephalogram) device.

Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims.