WO2001035823A1

WO2001035823A1 - Sensor for measuring bioelectric signals

Info

Publication number: WO2001035823A1
Application number: PCT/FI2000/000998
Authority: WO
Inventors: Arto Remes; Pekka Tolvanen
Original assignee: Mega Elektroniikka Oy
Priority date: 1999-11-17
Filing date: 2000-11-15
Publication date: 2001-05-25
Also published as: AU1527501A; FI19992463A

Abstract

The invention relates to a sensor, in particular, a sensor used for measuring and/or stimulating electric bio-signals, which sensor is comprised of a measuring component (1) made of plastic material, to which one or more electricity-conducting electrodes (2, 3) have been mounted. The electrodes (2, 3) of a sensor formed according to the invention are made of electricity-conducting plastic material and are joined into one whole structure with the measuring component.

Description

Sensor for measuring bioelectric signals

The invention relates to a sensor, in particular, a sensor used for measuring and/or stimulating electric bio-signals, which sensor is comprised of a measuring component made of plastic material, to which one or more electricity-conducting electrodes have been mounted.

Different sensors, or corresponding devices, are used for measuring electric signals, i.e. electric bio-signals, from the muscles. There are different sensors, previously known, by which muscles can be exercised through stimulation by the sensors. Some sensors can be used both for measuring electric signals of the muscles, as well as for stimulating them.

Conventional measuring or stimulating sensors comprise, in general, a sensor component, to which is mounted the necessary electronics and connecting methods, in addition to a measuring component, which is placed on, mounted or lead to the muscle group, or corresponding part, to be measured, for measuring and stimulating. The measuring components of sensors currently in use are generally made of plastic material adapted for the purpose, and the electrodes connected to them arc made of metal. These metal electrodes are connected to the measuring component by a casting process comprised of many phases, or by other means adapted for the purpose.

There are many disadvantages associated with the production and operation of these kinds of sensor measuring components. During the production process, excess material (such as metal shavings or burrs) or form defects (such as notches) can be left on the metal electrodes and/or the plastic surface, or in their seams. Sensors often must also be treated manually during production, whereupon parts being manufactured get contaminated, which in turn necessitates a separate cleaning phase, which increases production costs. The casting process per se imposes limitations on the design of the sensor. The method of production sets limitations on the number, positioning and form of electrode contacts, as well as on their surface area.

When sensors are being used, they often come into a corrosive environment, whereupon metal components which are vulnerable to oxidation and rusting cause problems. A certain disadvantage is that the measuring component may contain different materials which cause internal friction. Corroded or oxidized metal components cause excess impedance and thus cause the deterioration of the sensor's measuring properties. Additionally, the metal components contain metal parts with different impurities which are irritating to the skin or mucous membrane. The object of the invention is to provide a sensor, whereby the disadvantages associated with current sensors will be eliminated. In particular, the object of the invention is to provide a sensor, which is simple to produce, easy to clean, reliable in its operation, safe and easy to use, and which is simple in structure. Additionally, the object of the invention is to provide a sensor, which has electrodes which can easily and simply be moved into different places.

The object of the invention is accomplished with a sensor, the characteristics of which are presented in the claims.

Electrodes in a sensor formed according to the invention are made from electricity- conducting plastic material and are connected to the measuring component as a single structure. This sort of structure is easy to produce by casting, for example, using a two- toned casting technique, or it is possible to produce by other means. When casting the measuring component using a two-toned casting technique, it can be produced with one die-casting, yielding an advantageous unit price. Production can be automatized, whereby die-casting and packaging of the product after casting transpires automatically. Thus, there are no manual phases during production which will contaminate the product. Using this method of production, a consistent level of quality can be obtained in large series.

A sensor formed in accordance with the invention is reliable and dependable in its operation, because it does not contain any metal components, which are vulnerable to oxidation and rusting, which could cause the deterioration of the quality of the signal. Additionally, this sensor lasts longer and has a longer operating life than corresponding products containing metal. A further advantage is that the structure does not contain different materials, which cause internal friction.

Other advantages of the invention are, for example, that there are no seams or other notches in the structure, which are difficult to clean. Additionally, the thermal expansion coefficients of different components are approximately the same, whereupon the measuring component of the sensor does not become damaged due to differing thermal expansion coefficients within the components during the casting process or when cleaning at high temperatures. Another advantage is that there are no metal parts in the measuring component which irritate the skin or mucous membrane, nor are there any processing remains, which could cause ulcers. The sensor is pleasant to use, because the sensor's measuring component does not contain any metal parts, which, in different temperatures, could cause an unpleasant feeling on the skin or in the mucous membrane during measuring or stimulation. In a certain advantageous application of the invention, the measuring component is mainly a tubular structure. This kind of structure can be used for different applications, known per se, for example, as an EMG and stimulation sensor in treating incontinentia faecalis or urinae or for other corresponding applications, such as, for example, as a measuring sensor in uro-dynamic and gynecological applications.

In another application of the invention, the measuring component is mainly a filamentous structure. This kind of sensor can be used effectively, for example, for invasive measuring in the throat, esophagus or urethra. The advantages of a filamentous sensor are that it is bendablc and flexible to suit the varied nature of human anatomy, and that the plastic is biologically compatible with body tissue.

In a third application of the invention, the measuring component is mainly flat in structure. This kind of sensor can be effectively used, for example, to replace disposable electrodes, which are currently in use, being placed on the surface of the skin for measuring/ stimulation. Because this kind of sensor is easy to clean, it can be used repeatedly. Several different electrodes can be integrated into the flat plastic sensor, whereby the standardized distances between electrodes arc obtained, as well as the sensor setting to be repeated on the muscles to be measured/stimulated.

A certain advantage of the invention is that the measuring component is easy to modify, such that the number of electrode contacts, shape and surface area are open to choice. Additionally, the shape of the measuring area in relation to the muscles to be measured is open to choice.

In a certain advantageous application of the invention, electrodes are mounted lengthwise along the measuring component and a distance apart from one another. Thus, electrodes are placed, for example, at equal distances from one another, and they can measure the properties of different muscles on different sides.

In another further application of the invention, at least one electrode is mounted horizontally across the measuring component, at a distance from the other electrodes. This electrode can be, for example, a ground rod, and the structure of the measuring component will be such that it enables this kind of form.

In the following further application of the invention, one or more electrodes extend from one end of the sensor to the other in a twisting pattern on the surface of the measuring component. These kinds of electrodes formed according to the structure of the invention are easy to produce.

In a certain further application of the invention, one or more electrodes are electrodes on the surface of the measuring component, and one or more electrodes are mounted encircling them. With this kind of structure, interference is effectively eliminated when the device is in use.

In a certain further advantageous application of the invention, the electrodes are made from two or more kinds of plastic material, which conduct electricity in different ways. For example, the ground rod can be made of a different plastic material. When using two or more different plastic materials, the electrical adaptation of the sensor can be optimized to fit the electronics, which carry out the measuring/produce the stimulation flow. Another advantage is that, depending on the intended purpose, for example, rigid and flexible plastic material can be used in the same structure.

In the following application of the invention, at least some of the electrodes protrude above the surface of the measuring component. With this kind of structure, measuring electrodes extend effectively on the surfaces of the muscles and measuring signals are easily distinguishable.

In the following application of the invention, an electricity-conducting gel is applied to the surface of the measuring component. This kind of gel enhances the electro conductivity, improves the measured results and helps the sensor to stay in place at the point that is being measured/stimulated.

The invention will now be described in more detail with reference to the accompanying drawings, in which

Figure 1 illustrates a certain application of a sensor formed according to the invention, as viewed at an angle from below,

Figure 2 illustrates the measuring component of a sensor formed according to Figure 1 and an enlarged diagram of its structure,

Figure 3 illustrates a certain second application of the measuring component of a sensor formed according to the invention, as viewed al an angle from below, Figure 4 illustrates a certain other application of the measuring component of a sensor formed according to the invention, as viewed at an angle from the side, and

Figures 5 and 6 illustrate certain other applications of the measuring component of a sensor formed according to the invention, as viewed at an angle from above. All measuring components 1 according to Figures 1 -6 comprise electrodes 2, 3 for measuring and/or stimulation. The measuring component 1 is produced from plastic material and the electrodes 2, 3 are made from electricity-conducting plastic material and are joined with the rest of the measuring component into one whole structure. These electrodes and their materials are shown in dark colors in the figures.

In an application according to Figures 1 and 2, the sensor comprises a measuring component 1 and a sensor component 10. The measuring component 1 in this application is a hollowed out component, which is comprised of a tubular structure. The electrodes 2 are mounted on the sides of this tubular structure, such that they extend down the length of the measuring component and are a distance away from one another. Electrodes mounted according to Figure 2 extend at least partially through the measuring component and have been made with contact surfaces 5. The sensor component, as it is illustrated in Figure 1 , is also comprised of a tubular structure, which is inserted into the hollow tubular structure of the measuring component. This sensor structure has contact surfaces 6, which correspond to the contact surfaces of the measuring component. When these contact surfaces come into contact with one another, data from the electrodes is transferred to the measuring and observation equipment, which is in the sensor component, or may be some distance away from the sensor component.

The measuring component illustrated in Figure 3 comprises one electrode 3 which is mounted horizontally across the measuring component, and it is a distance away from the other electrodes 2. In this application, the electrode 3 is a ground rod and the other electrodes 2 are measuring electrodes. In this application, the measuring electrodes 2 arc formed such that they are narrow in the middle and wider at the ends. The shape of the electrodes can vary in different ways in different applications of the invention.

The measuring component 1 illustrated in the application in Figure 4 is filamentous. The electrode 2 is on the end of the filamentous structure, and a short distance below it is the ground rod 3.

The measuring component 1 illustrated in the application in Figure 5 is a component flat in structure. The measuring electrode 2 and the ground rod are electrodes on the surface of the measuring component. The middle of the measuring component 1 has several, in this application four, measuring electrodes 2, and a ground rod 3 encircling them.

The measuring component 1 illustrated in the application in Figure 6 is also a flat- structured component. Electrodes 2, 3 are electrodes on the surface of the measuring component, and they are arranged such that they extend across the width of the flat structure, and they are mounted a distance away from one another. Measuring components according to Figures 5 and 6 are suitable, for example, for measuring the skin's surface and its different properties.

The invention is not limited to the illustrated advantageous applications. It can vary within the frames of the inventive idea set forth in the claims.

Claims

1. A sensor, in particular, a sensor used for measuring and/or stimulating electric bio- signals, which sensor is comprised of a measuring component (1) made of plastic material, to which one or more electricity-conducting electrodes (2, 3) have been mounted, characterized in that the electrodes (2, 3) are made from electricity-conducting plastic material, and are joined into one whole structure with the measuring component.

2. A sensor formed in accordance with Claim 1 , characterized in that the measuring component ( 1 ) is primarily tubular in structure.

3. A sensor formed in accordance with Claim 1 , characterized in that the measuring component ( 1 ) is filamentous in structure.

4. A sensor formed in accordance with Claim 1 , characterized in that the measuring component ( 1 ) is flat in structure.

5. A sensor formed in accordance with any of Claims 1 -4, characterized in that the electrodes (2, 3) are mounted along the length of the measuring component ( 1) and at a distance from one another.

6. A sensor formed in accordance with any of Claims 1-5, characterized in that at least one electrode (3) is mounted horizontally across the measuring component, at a distance from the other electrodes (2).

7. A sensor formed in accordance with any of Claims 1-3, characterized in that one or more electrodes are electrodes on the surface of the measuring component, which extend from one end of the sensor to the other in a twisting pattern.

8. A sensor formed in accordance with any of Claims 1 or 4-6, characterized ^' in that one or more electrodes (2a) are electrodes on the surface of the measuring component, and in that one or more electrodes (3a) are mounted encircling them.

9. A sensor formed in accordance with any of Claims 1-8, characterized in that the electrodes are made from two or more plastic materials which conduct electricity in different ways.

10. A sensor formed in accordance with any of Claims 1-9, characterized in that at least some of the electrodes protrude above the surface of the measuring component ( 1).

1 1. A sensor formed according to any of Claims 1 -10, characterized in that electricity- conducting gel has been applied to the surface of the electrode.