METHOD AND APPARATUS FOR PERFORMING ELECTRORETINOGRAPHY, INCLUDING ENHANCED ELECTRODE

Abstract

Apparatus for use in performing electroretinography on a test subject, the apparatus comprising: at least one electrically conductive thread, the at least one electrically conductive thread comprising a first end and a second end, wherein the first end of the at least one electrically conductive thread is configured to mount to skin on one side of an eye of the test subject and the second end is configured to mount to skin on the opposite side of the eye of the test subject, such that the at least one electrically conductive thread is in contact with a surface film of an eye; and an electrically non-conductive coating applied to at least one region of the at least one electrically conductive thread, whereby to electrically isolate the at least one region of the at least one electrically conductive thread from the eye.

Claims

1. Apparatus for use in performing electroretinography on a test subject, the apparatus comprising: at least one electrically conductive thread, the at least one electrically conductive thread comprising a first end and a second end, wherein the first end of the at least one electrically conductive thread is configured to mount to skin on one side of an eye of the test subject and the second end is configured to mount to skin on the opposite side of the eye of the test subject, such that the at least one electrically conductive thread is in contact with a surface film of an eye; and an electrically non-conductive coating applied to at least one region of the at least one electrically conductive thread, whereby to electrically isolate the at least one region of the at least one electrically conductive thread from the eye.

2. Apparatus according to claim 1 wherein the first end of the at least one electrically conductive thread mounts to the skin on one side of the eye by way of a first sticky pad mounted to the first end of the at least one electrically conductive thread, and the second end of the at least one electrically conductive thread mounts to the skin on the opposite side of the eye by way of a second sticky pad mounted to the second end of the at least one electrically conductive thread, and further wherein the first sticky pad and the second sticky pad are electrically isolated from the skin.

3. Apparatus according to claim 2 wherein the second sticky pad comprises an electrical cable connector electrically connected to the second end of the at least one electrically conductive thread, and further wherein the electrical cable connector is configured to receive a lead connected to external electronics.

4. Apparatus according to claim 3 wherein the external electronics comprise at least one selected from the group consisting of an amplifier, a controller and a computer.

5. Apparatus according to claim 1 wherein the electrically non-conductive coating comprises a non-conductive material applied as a coating that is between 1 and 20 microns in thickness.

6. Apparatus according to claim 1 wherein the electrically non-conductive coating comprises silicone.

7. Apparatus according to claim 1 wherein the at least one electrically conductive thread comprises silver.

8. Apparatus according to claim 1 wherein the electrically non-conductive coating is applied to a first region of the at least one electrically conductive thread and a second region of the at least one electrically conductive thread, and further wherein the first region and the second region are separated from one another by a third region of the at least one electrically conductive thread, wherein the third region is not coated with the electrically non-conductive coating.

9. Apparatus according to claim 8 wherein the first region is proximate to the first end of the electrically conductive thread and has a length of 0.5 cm, and the second region is proximate to the second end of the electrically conductive thread and has a length of 2.5 cm, and further wherein the third region has a length of 3 cm.

10. Apparatus according to claim 2 wherein the first sticky pad and the second sticky pad comprise an adhesive for facilitating mounting to the skin.

11. Apparatus according to claim 1 wherein the first sticky pad and the second sticky pad comprise at least one material selected from the group consisting of soft foam, rubber, soft plastic or some combination thereof.

12. Apparatus according to claim 1 wherein the electrically non-conductive coating is configured to stiffen the at least one electrically conductive thread, whereby to facilitate positioning of the at least one electrically conductive thread relative to the eye.

13. A method for performing electroretinography on a test patient, the method comprising: providing apparatus comprising: least one electrically conductive thread, the at least one electrically conductive thread comprising a first end and a second end, wherein the first end of the at least one electrically conductive thread is configured to mount to skin on one side of an eye of the test subject and the second end is configured to mount to skin on the opposite side of the eye of the test subject, such that the at least one electrically conductive thread is in contact with a surface film of an eye; and an electrically non-conductive coating applied to at least one region of the at least one electrically conductive thread, whereby to electrically isolate the at least one region of the at least one electrically conductive thread from the eye; mounting the first end of the at least one electrically conductive thread to the skin on one side of an eye of the test subject, and mounting the second end of the at least one electrically conductive thread to the skin on the opposite side of the eye of the test subject, such that the at least one electrically conductive thread is electrically isolated from the skin, and such that at least one region of the electrically conductive thread is in electrical contact with the eye of the test subject.

14. Apparatus for use in performing electroretinography on a test subject, the apparatus comprising: at least one electrically conductive thread, the at least one electrically conductive thread comprising a first end and a second end, wherein the first end of the at least one electrically conductive thread is configured to mount to a first sticky pad and the second end of the at least one electrically conductive thread is configured to mount to a second sticky pad, wherein the first sticky pad is configured to mount to skin on one side of an eye of the test subject, and the second sticky pad is configured to mount to skin on the opposite side of the eye of the test subject; wherein the second sticky pad comprises a top surface and a bottom surface, and further wherein the second sticky pad comprises a conductive element mounted to the bottom surface, whereby to make electrical contact with the skin when the second sticky pad is mounted to the skin.

15. Apparatus according to claim 14 further comprising an electrical cable connector mounted to the second sticky pad, the electrical cable connector being in electrical connection with the at least one electrically conductive thread and the conductive element, and the electrical cable connector being configured to electrically connect to a lead connected to external electronics.

16. Apparatus according to claim 15 wherein the electrical cable connector comprises a first channel and a second channel, wherein the first channel is electrically isolated from the second channel, wherein the electrically conductive thread is electrically connected to the first channel, and wherein the conductive element is electrically connected to the second channel.

17. Apparatus according to claim 14 wherein the at least one electrically conductive thread further comprises an electrically non-conductive coating applied thereto, whereby to electrically isolate the at least one region of the at least one electrically conductive thread from the eye.

18. Apparatus according to claim 14 wherein the at least one electrically conductive thread is configured to contact the surface film of an eye, whereby to serve as an active electrode for performing electroretinography, and further wherein the conductive element is configured to contact the skin, whereby to serve as a reference electrode for performing electroretinography.

19. A method for use in performing electroretinography on a test subject, the method comprising: providing apparatus comprising: at least one electrically conductive thread, the at least one electrically conductive thread comprising a first end and a second end, wherein the first end of the at least one electrically conductive thread is configured to mount to a first sticky pad and the second end of the at least one electrically conductive thread is configured to mount to a second sticky pad; wherein the second sticky pad comprises a top surface and a bottom surface, and further wherein the second sticky pad comprises a conductive element mounted to the bottom surface, whereby to make electrical contact with the skin when the second sticky pad is mounted to the skin; mounting the first sticky pad to the skin of a test subject on one side of an eye of the test subject, and mounting the second sticky pad to the skin of the test subject on the opposite side of the eye of the test subject, such that the at least one electrically conductive thread is in electrical contact with the eye of the eye of the test subject; wherein the at least one electrically conductive thread is configured to serve as the active electrode for performing electroretinography; and wherein the conductive element is configured to serve as the reference electrode for performing electroretinography.

20. Apparatus for use in performing electroretinography on a test subject, the apparatus comprising: a sticky pad comprising a top surface and a bottom surface; wherein the bottom surface of the sticky pad comprises an adhesive for mounting the sticky pad to skin of the test subject; wherein the sticky pad is defined by a plane having a non-circular perimeter; wherein the non-circular perimeter comprises a wide portion and a narrow portion, wherein the wide portion is configured to be positioned adjacent to the temple of the test subject, and the narrow portion is configured to guide a conductive thread mounted to the sticky pad toward the eye of the test subject.

21. Apparatus according to claim 20 wherein the distance between the top surface of the sticky pad and the bottom surface of the sticky pad differs at different locations of the plane defined by the top surface of the sticky pad, such that the sticky pad comprises regions having varying widths.

22. Apparatus according to claim 20 wherein the sticky pad comprises at least one material selected from the group consisting of foam, plastic, rubber, fabric, or a combination thereof.

23. Apparatus according to claim 20 wherein at least one of a reference electrode and a ground electrode is mounted to the bottom surface of the sticky pad.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:

[0075] FIGS. 1 and 2 are schematic views showing an exemplary system for performing an ERG test on a test subject;

[0076] FIGS. 3 and 4 are schematic views of prior art DTL electrodes;

[0077] FIG. 5 is a schematic view showing typical positioning of a conductive thread of a prior art DTL electrode relative to the human eye;

[0078] FIG. 6 is a schematic view of a human eye, illustrating the anatomy of the eye and the relative electrical potential that can be measured at different regions of the eye;

[0079] FIGS. 7 and 8 are schematic views showing a novel DTL-style electrode formed in accordance with the present invention;

[0080] FIGS. 9, 9A, 10 and 10A are schematic views showing a novel bipolar electrode formed in accordance with the present invention;

[0081] FIGS. 11 and 12 are schematic views of a prior art DTL electrode illustrating round sticky pads used in connection with the same; and

[0082] FIG. 13 is a schematic view illustrating novel sticky pads formed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0083] The present invention comprises the provision and use of a new and improved DTL-style electrode comprising (i) a bipolar electrode, (ii) a conductive thread configured to measure the electrical response of only a select portion of the region of the eye contacted by the conductive thread, and/or (iii) sticky pads for mounting the novel electrode in place which permit a wider range of options for accurate placement of the electrode relative to the test subject's eye.

[0084] More particularly, the present invention can be characterized by reference to three novel aspects that can be used independently of one another, or in combination with one another, in order to improve the performance, inter-session repeatability, and cost effectiveness of performing ERG tests when compared against use of a traditional DTL electrode.

[0085] To summarize, the first novel aspect of the present invention comprises the provision and use of an electrode comprising a thin coating of non-conductive material that is applied to the outer surface of a portion of the length of the conductive thread of the electrode. The second novel aspect of the present invention comprises the provision and use of a novel electrode that incorporates a reference electrode into the electrode, thereby creating a bipolar electrode. The third novel aspect of the present invention comprises the provision and use of sticky pads having new shapes and/or materials that are a part of, or next to, the sticky pads so as to permit a wider range of mounting options.

[0086] The novel electrode of the present invention may hereinafter be referred to as a “DTL electrode” or “DTL-style electrode”, inasmuch as electrodes which mount to the eye in the manner of such prior art electrodes are commonly referred to as “DTL electrodes” by those of skill in the art. However, the novel electrode of the present invention is not a prior art DTL electrode, but merely mounts to the eye in a similar manner as existing DTL electrodes.

First Novel Aspect of the Invention:

Non-Conductive Coating on Electrode Thread

[0087] Looking now at FIGS. 7 and 8, there is shown a novel DTL-style electrode 100 formed in accordance with the present invention. Novel electrode 100 generally comprises a conductive thread 105, a first sticky pad 110 for mounting electrode 100 to the skin on one side of the eye of a test subject, and a second sticky pad 115 for mounting electrode 100 to the skin on the opposite side of the eye of the test subject. Conductive thread 105 may comprise a single conductive thread or, if desired, conductive thread 105 may comprise a bundle of conductive threads. A thin non-conductive coating 120 is applied to a portion of the outer surface of the conductive thread 105, whereby to electrically insulate that portion of the conductive thread from the anatomy, as will hereinafter be discussed in further detail. An electrical cable and connector 123 (FIG. 7), or an electrical connector pin 124 (FIG. 8) extends from second sticky pad 115 and is in electrical connection with conductive thread 105, whereby to permit electrode 100 to be connected to an amplifier and/or controller and/or computer in a manner that will be apparent to those of skill in the art in view of the present disclosure.

[0088] In one preferred form of the invention, non-conductive coating 120 is applied to conductive thread 105 at regions extending from the first and second sticky pads 110, 115 to a point near the center of the conductive thread, leaving an uncoated region 135 of conductive thread 105 uncoated where it will contact the cornea or the conjunctiva of the test subject, as will hereinafter be discussed. The use of non-conductive coating 120 on conductive thread 105 adjacent to sticky pads 110, 115 is primarily to improve the repeatability of placing the conductive (i.e., uncoated portion) of conductive thread 105 in the same position on the eye of the test subject each time electrode 100 is mounted to the test subject (i.e., to improve intersession repeatability) and also to isolate conductive thread 105 from electrical contact with the subject's skin and eye in locations that are not of primary interest in the ERG electrical potential measurement.

[0089] Conductive thread 105 of the novel electrode of the present invention may be provided in various forms. In one form of the present invention, non-conductive coating 120 comprises a material that can be thinly applied (e.g., a material that can be applied such that the resulting non-conductive coating 120 is only 1 to a few microns thick or thicker) to conductive thread 105 along a pre-defined length (i.e., in pre-defined regions) of the conductive thread.

[0090] If desired, electrode 100 may comprise two (or more) conductive threads 105, with each conductive thread 105 comprising one or more regions coated in non-conductive coating 120. By way of example but not limitation, in the case of a multi-thread electrode 100 (i.e., an electrode 100 comprising a plurality of conductive threads 105), non-conductive coating 120 may be applied to each conductive thread 105 individually, or non-conductive coating 120 may be applied to the entire bundle of conductive threads 105 at the same time.

[0091] Additionally, while FIG. 7 depicts a novel electrode 100 in which non-conductive coating 120 has been applied to two different ends (e.g., regions) of conductive thread 105, it should be appreciated that, if desired, non-conductive coating 120 may be applied to only one end of the conductive thread. Additionally, if desired, non-conductive coating may be applied to more than one region of conductive thread 105, and the coated regions of conductive thread 105 may be of various lengths, including different lengths on each side of the uncoated, conductive region of conductive thread 105.

[0092] By way of example but not limitation, and still looking at FIG. 7, in one preferred form of the present invention, electrode 100 comprises a conductive thread 105 that is 6 cm in length extending between first and second sticky pads 110, 115, with a first region 125 comprising non-conductive coating 120 extending a length of 0.5 cm from first sticky pad 110 towards second sticky pad 115, and with a second region 130 comprising non-conductive coating 120 extending a length of 2.5 cm from the second sticky pad 115 towards first sticky pad 110, whereby to leave an exposed conductive region 135 having a length of 3 cm). In a preferred form of the present invention, non-conductive coating 120 comprises silicone.

[0093] It should be appreciated that there are various different materials that may be used for first and second sticky pads 110, 115. More particularly, first and second sticky pads 110, 115 may comprise any material that permits an adhesive surface on one side (i.e., to enable the electrode to be mounted to the skin of the test subject), and that is also able to electrically isolate the conductive thread(s) 105 from the skin of the test subject. In a preferred form of the invention, first and second sticky pads 110, 115 comprise a material comprising soft foam, rubber, soft plastic or some combination of those materials, however, other materials may be used which will be apparent to those of skill in the art in view of the present disclosure.

[0094] The use of novel electrode 100 provides at least two significant benefits when compared to prior art DTL electrodes.

[0095] First, and looking now at the prior art DTL electrode depicted in FIG. 5, it will be appreciated that, with prior art DTL electrodes, the conductive thread of the prior art DTL electrode contacts many portions of the body in addition to the cornea or the conjunctiva (i.e., the two areas of the eye for which the electrical potential to be measured by the electrode is of the greatest interest for performing ERG tests). These “undesirable” areas for electrical contact include facial skin on both sides of the eye as well as the caruncula, and a large width of the sclera.

[0096] In contrast, because the conductive thread 105 of novel electrode 100 of the present invention is coated with non-conductive coating 120 in the regions of conductive thread 105 that would come into contact with the areas of the skin that are “undesirable” for electrical contact (i.e., facial skin on both sides of the eye, the caruncula and large portions of the outer edges of the sclera), the “undesirable” areas of the skin that non-conductive coating 120 contacts are electrically isolated. Electrically isolating the “undesirable” areas of the skin, maximizes electrical contact between the conductive portion of conductive thread 105 and the lower portion of the cornea or the upper portion of the conjunctiva, near the center of the eye.

[0097] Thus, the novel electrode 100 of the present invention increases the measured electrical potential signal because it is in electrical contact with higher voltage potential portions of the eye, compared to prior art DTL electrodes. Furthermore, non-conductive coating 120 eliminates variability of the measured potential emanating from the skin around the eye, given that the area of conductive thread 105 is no longer electrically in contact with the skin around the eye (i.e., due to the insulation provided by non-conductive coating 120).

[0098] The second significant benefit of novel electrode 100 is that the regions of conductive thread 105 coated in non-conductive coating 120 act to stiffen conductive thread 105. This enhances the ability of the clinician/technician to position the conductive portion of conductive thread 105 in the same position on the eye of the test subject with greater repeatability, from test to test, and helps ensure that conductive region 135 of conductive thread 105 is positioned so as to contact the most advantageous region of the test subject's eye (e.g., location B shown in FIG. 6).

[0099] Looking again at FIG. 6, without the provision of non-conductive coating 120 on conductive thread 105 provided by novel electrode 100, the conductive region of conductive thread 105 may end up disposed in positions ranging from location B through location E and, as shown in the table of FIG. 6, certain positions result in a variability of 30-50% in the amplitude measured, even if all other factors are the same.

[0100] In tests of novel electrode 100 utilizing non-conductive coating 120 comprising silicone to cover first region 125 of conductive thread 105 for a length of 0.5 cm extending from first sticky pad 110 towards second sticky pad 115, and non-conductive coating 120 comprising silicone to cover second region 130 of conductive thread 105 for a length 2.5 cm extending from second sticky pad 115 toward first sticky pad 110, significant improvements in intersession repeatability and ERG signal amplitude were achieved. Benchmark testing was conducted that entailed over 70 full-field ERG tests using commercially available prior art DTL electrodes and over 80 tests using the novel DTL-style electrode 100 of the present invention. In each test, the electrode was replaced on the test subject after performing an ERG, thereby requiring a new electrode to be placed on the test subject's eye each time, creating an intersession test scenario. In each of the full-field ERG tests the a-wave (cone response), b-wave (bipolar cell response) and PhNR (retinal ganglion cell response) were measured. In each case, a well-trained clinician placed the electrodes (either the prior art DTL electrode or novel electrode 100 of the present invention) as close as they could to the optimal position. The tests showed increased amplitudes recorded using the novel electrode 100 of the present invention when compared to the amplitudes recorded using prior art DTL electrodes: a-wave of +17%, b-wave of +18% and PhNR of +16%. Most importantly the intersession repeatability (defined as 1 standard deviation divided by the average amplitude, of each set of tests) of the novel electrode 100 of the present invention compared to prior art DTL electrodes for the a-wave, b-wave and PhNR improved from 17%, 18%, and 17% to be 9%, 7% and 7%, respectively. These are very significant intersession repeatability improvements that open new clinical applications for ERG testing in general.

Second Novel Aspect of the Invention: Bipolar Electrode

[0101] A second novel aspect of the present invention is the provision and use of a novel DTL-style electrode which incorporates a reference electrode into the electrode, thereby forming a bipolar electrode. As discussed above, for each ERG measurement, two electrode measurements are required, i.e., an “active” electrode measurement and a “reference” electrode measurement. The difference between the measurement recorded by the “active” electrode and the measurement recorded by the “reference” electrode is reported as the ERG amplitude by the ERG system. Prior art DTL electrodes have only used one electrode (i.e., such prior art DTL electrodes are monopolar), with the conductive thread of the DTL electrode constituting the single electrode in contact with the body.

[0102] The present invention improves upon prior art DTL electrodes by incorporating a second electrode to serve as the reference electrode, thus creating a bipolar DTL-style electrode.

[0103] More particularly, and looking now at FIGS. 9, 9A, 10 and 10A, there is shown a novel bipolar electrode 140 formed in accordance with the present invention. Bipolar electrode 140 generally comprises a conductive thread 145, a first sticky pad 150 for mounting bipolar electrode 140 to the skin on one side of the eye of a test subject, and a second sticky pad 155 for mounting bipolar electrode 140 to the skin on the opposite side of the eye of the test subject. Sticky pads 150, 155 comprise a non-conductive material and, if desired, may comprise several layers for “sandwiching” and isolating conductive elements of bipolar electrode 140 from one another as will be apparent to one of skill in the art in view of the present disclosure. Conductive thread 145 may comprise a single conductive thread or, if desired, conductive thread 105 may comprise a bundle of conductive threads. An electrical cable and connector 160 (FIGS. 9 and 9A), or an electrical connector pin 162 (FIGS. 10 and 10A), extends from second sticky pad 155 and is in electrical connection with conductive thread 145, whereby to permit bipolar electrode 140 to be connected to an amplifier and/or controller and/or computer in a manner that will be apparent to those of skilled in the art in view of the present disclosure. If desired, electrical cable and connector 160 may comprise two, electrically-isolated electrical channels for conducting electrical signals separately from conductive thread 145 and a second, separate electrical contact serving as a reference electrode, which will hereinafter be discussed in further detail.

[0104] Second sticky pad 155 comprises a bottom surface 165 having a conductive element 170 applied thereto (or mounted thereto), whereby to serve as a reference electrode in contact with the test subject's skin. Conductive element 170 (serving as the “reference” electrode) is electrically isolated from the conductive path of conductive thread 145 by a layer of the non-conductive material of which second sticky pad 155 is comprised.

[0105] Alternatively, if desired, conductive element 170 (serving as the “reference” electrode) may be mounted to bottom surface 165 of second sticky pad 155 so as to protrude in a radial direction from bottom surface 165 of second sticky pad 155. More particularly, in this form of the invention, conductive element 170 generally comprises a small tab (not shown) protruding from second sticky pad 155 which contacts the test subject's skin and is electrically isolated from the conductive path of conductive thread 145 (serving as the “active” electrode). In all cases, given that the second sticky pad 155 is intended to mount at a location at or near the temple of the test subject, the incorporation of conductive element 170 into second sticky pad 155 positions the “reference” electrode at one of the optimal locations for a reference electrode to be located when performing an ERG test.

[0106] A conductive connector wire 175 extends from conductive element 170 through second sticky pad 155 to electrical cable connector 160, whereby to transmit electrical signals from conductive element 170 to a channel of electrical cable connector 160. Conductive wire 175 is electrically isolated from conductive thread 145 in a manner that will apparent to one of ordinary skill in the art in view of the present disclosure.

[0107] Compared to using a monopolar prior art DTL electrode requiring a separate reference electrode, the advantages of the novel bipolar electrode 140 of the present invention include improved performance, ease of use and lower cost. Additionally, because novel bipolar electrode 140 incorporates the “reference” electrode into an element of bipolar electrode 140 (i.e., into second sticky pad 155 of bipolar electrode 140) it is much easier for the technician to position the reference electrode (i.e., conductive element 170) on the test subject in the same place over many tests, thus improving electrode performance and repeatability of the ERG test. And, by providing the “active” electrode (i.e., conductive thread 145) and the “reference” electrode (i.e., conductive element 170) in a single bipolar electrode (i.e., bipolar electrode 140), it takes the technician setting up a test subject for an ERG test less time to do so inasmuch as bipolar electrode 140 takes the same amount of time to apply to a test subject as a prior art monopolar DTL electrode, and no separate reference electrode element is required to be positioned on the test subject. Finally, due to its integrated design, novel bipolar electrode 140 is more cost effective to manufacture than the two separate electrodes previously required by prior art ERG systems (e.g., a monopolar DTL electrode and a separate reference electrode).

[0108] It should also be appreciated that in most ERG recordings a ground electrode is also utilized. If desired, the ground electrode can also be integrated into second sticky pad 155 of novel bipolar electrode 140 in a manner similar to the manner in which conductive element 170 is mounted to second sticky pad 155 to serve as the “reference” electrode (in which case, second sticky pad 155 would further comprise a second conductive connector wire for electrically connecting the ground electrode to electrical cable and connector 160 (or pin 162), and electrical cable and connector 160 would comprise an additional channel for carrying the electrical signal of the ground electrode). Thus, where second sticky pad 155 further comprises a ground electrode, the ground electrode would include a conductive element that would be electrically isolated from conductive element 170 (i.e., the “reference” electrode), while remaining in contact with the skin of the test subject.

[0109] Finally, it should be appreciated that, if desired, conductive thread 145 of bipolar electrode 140 may comprise the aforementioned non-conductive coating 120 over one or more regions of the conductive thread 145, whereby to provide the benefits associated with novel DTL-style electrode 100 discussed above.

Third Novel Aspect of the Invention: Novel Sticky Pad Shapes

[0110] A third novel aspect of the present invention is the provision and use of novel sticky pads comprising novel shapes and/or materials incorporated as a part of, or next to, the sticky pads.

[0111] More particularly, all prior art DTL electrodes currently in use utilize round sticky pads. See, for example, FIGS. 11 and 12, which show an exemplary prior art DTL electrode 180 comprising a first round sticky pad 185, a second round sticky pad 190, a conductive thread 195 extending therebetween, and an electrical cable connector 200 in electrical connection with conductive thread 195. As discussed above, it is preferably to provide sticky pads which electrically isolate the conductive thread (i.e., conductive thread 195 of an exemplary prior art DTL electrode) from skin around the eye, as well as to provide additional stiffness on, under (or both) to the conductive thread next to the eye.

[0112] The present invention recognizes that sticky pads comprising non-circular shapes offer the benefit of electrically isolating the conductive thread of the active electrode (i.e., conductive thread 105 and 145 of the novel electrodes of the present invention, or conductive thread 195 of a prior art DTL electrode) from skin directly next to the eye, while also providing additional stiffness of the thread just before it contacts the eye, whereby to help properly position the conductive thread across the eye.

[0113] More particularly, FIG. 13 shows novel sticky pads 205 comprising novel shapes formed in accordance with the present invention. It will be appreciated that novel sticky pads 205 may be used with novel DTL-style electrode 100, novel bipolar electrode 140, or prior art DTL electrode 180 in lieu of the first and second sticky pads of those electrodes. Sticky pads 205 can be used for the sticky pad on each side of the eye of the test subject, or for the sticky pad on only one side of the eye of the test subject. In each case, the widest portion of sticky pad 205 is used primarily to attach the sticky pad to the test subject's skin (e.g., near the temple of the test subject), and the narrower portion of sticky pad 205 is used to isolate the conductive thread (serving as the “active” electrode) from the skin of the test subject, and to guide the thread into the corner of the eye of the test subject. Various aspect ratios of these shapes are used to be accommodate the shape of a test subject's face in the region of the eye. Typically, the sticky pad to be mounted to the test subject nearest to the test subject's nose is smaller (and not as wide as) the sticky pad mounted to the temple side of the eye of the test subject. A wide array of sticky pads 205 comprising various shapes are shown in FIG. 13, where the view from above and from the side of sticky pads 205 show how the geometry of the sticky pads 205 may be configured such that (i) the shape of the sticky pad viewed from the top surface varies, and/or (ii) the depth of a particular region of the sticky pad viewed from the side varies. Any combination of the shapes/geometries depicted in FIG. 13 may be used to form novel sticky pads 205. Additionally, sticky pads 205 may comprise one or more materials selected from the group consisting of foam, plastic, rubber, fabric, and other materials (or combination of materials). A thin layer of adhesive (not shown) is preferably applied to a bottom surface of each sticky pad 205 so as to cover the full underside of the sticky pad, or just a portion of it. Reference and potential ground electrode pads may be incorporated as well, as will be apparent to one of ordinary skill in the art in view of the present disclosure.

Modifications

[0114] It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.