DE102008042554A1 - Portable monitoring device for monitoring respiration of patient suffering from e.g. sleep apnea, has elastically deformable electrodes arranged adjacent to insulation layer made of dielectric elastomer material - Google Patents

Abstract

The device (1) has an extension sensor (6) with elastically deformable electrodes (8, 9) and an evaluation unit (12) that is connected with the sensor in a signal-transmitting manner. The elastically deformable electrodes are arranged adjacent to an insulation layer (7) made of dielectric elastomer material such as acrylate and/or silicone. The elastomer material exhibits an elasticity modulus between 0.1 and 20 Mega Pascal. The sensor is designed as a condenser with which that electrodes are electrically insulated from each other by the insulation layer.

Description

State of the art

The The invention relates to a monitoring device for monitoring at least one physiological parameter according to Preamble of claim 1.

The Respiration monitoring is gaining in age expectant society increasingly important for a variety of patients. Especially for patients who are suffering from a chronic obstructive pulmonary disease or respiratory or sleep apnea, is a long-term monitoring of breathing of great Importance. Because the patients are monitored in daily routine It is necessary to use a sensor on the one hand provides accurate measurement data and on the other hand has a high wearing comfort and also inexpensive can be used in large quantities.

From the publication "Knitted Bioclothes for Health Monitoring", N. Taccini, G. Loriga, A. Dittmar, R. Paradiso, Proceedings of the 26th Annual International Conference of IEEE EMBS, San Francisco, CA, USA, September 1-5, 2004 It is known to use strain sensors based on the piezoresistive principle. In these, a special ferroelectric polymer (FE polymer) is used, which changes its resistance when stretched due to the piezoelectric effect and the superimposed geometry change. A disadvantage of the known monitoring device is that FE polymers have a high modulus of elasticity of about 400 MPa. In order to achieve the largest possible sensor effect, the FE polymers would have to withstand strains of 10% to 50%, but this is hardly feasible.

From the US 2002/0032386 A1 For example, a respiration monitoring apparatus is known in which respiration is measured by measuring the electrical resistance of a looped electrical conductor disposed on a stretchable textile tape. The inherently rigid electrode follows an expansion of the insulating layer due to its wavy arrangement.

Disclosure of the invention

Technical task

Of the Invention is based on the object, an alternative monitoring device for at least one physiological parameter, in particular to monitor breathing, to suggest, on the one hand high strains are measurable and on the other hand a high wearing comfort be offered. Preferably, the monitoring device, in particular the at least one strain sensor of the monitoring device, be inexpensive to produce and provide accurate measurement data.

Technical solution

These Task is with a monitoring device with the Characteristics of claim 1 solved. Advantageous developments The invention are specified in the subclaims. In the Within the scope of the invention, all combinations are omitted at least two of in the description, the claims and / or features disclosed in the figures.

Of the Invention is based on the idea, an elastically deformable Electrode, preferably immediately, on an insulating layer to be arranged, which comprises dielectric elastomeric material. Prefers is the, the elastically deformable electrode bearing insulation layer completely formed of dielectric elastomeric material. Dielectric elastomers are characterized by being very soft are, so a low modulus of elasticity of preferably have about 0.1 MPa to 20 MPa. In addition, allow They realize large elastic strains, depending on Material of up to 250%. Preferably, the elastically deformable, supported by the insulating layer electrode the same or a similar modulus of elasticity to stresses between the layers to avoid. This is for example conceivable, the electrode of a layer of dielectric elastomeric material form, which with electrically conductive particles, for example Graphite dust, is offset. Preferably, it is in the elastically deformable Electrode formed around an elastically deformable material Electrode, wherein also an embodiment feasible is at which the electrode only due to the arrangement on the elastic deformable insulation layer is elastically deformable.

In Development of the invention is provided with advantage that the dielectric elastomeric material has a modulus of elasticity between about 0.1 MPa and about 20 MPa. This default will For example, met by acrylates or silicones. by virtue of The low modulus of elasticity allows a high wearing comfort will be realized.

Particularly accurate measurement data can be obtained if the strain sensor is designed as a capacitor in which at least two elastically deformable electrodes are separated from one another by a layer of dielectric elastomer material, ie are electrically insulated from one another. The ability to obtain particularly accurate measurement results is due to the fact that when at both ends facing away from each other the thickness of the dielectric (dielectric elastomer material / insulating layer) changes and, on the other hand, the electrode surface is deformed so that its dimension perpendicular to the pulling direction (slightly) smaller, but the dimension in the pulling direction (clearly) gets bigger. In other words, the area of the strain sensor increases under tensile loading, resulting in a significant, measurable increase in the electrical capacitance of the device. Overall, a cost-producible capacitive strain sensor is obtained with the large strains are precisely detectable and measurable. Because of the low modulus of elasticity, the wearing comfort is good compared to Fe polymer-based strain sensors. In addition, the flat strain sensor can be very easily introduced into stretchable textile fabric and can be integrated with an evaluation integrated into a chest band, which does not (significantly) hinder the patient in his daily movements.

In Further development of the invention is as at least one capacitor trained strain sensor associated with an evaluation, the like is formed that they change the dimension of the Detecting strain sensors on the basis of a capacitance measurement can and / or which is a measure of strain, in particular the Measure the amount of strain on the basis of a capacitance measurement can. It is particularly preferred if the evaluation unit is such is designed to give the measurement result with regard to the physiological parameters to be monitored, in particular with regard to respiration, can evaluate or evaluate.

additionally or alternatively it is possible for the evaluation unit to be such form that this a change in length of the Detecting strain sensor based on a resistance and / or conductivity measurement is formed and / or that the evaluation unit based on a Resistance and / or conductivity measurement a measure of the strain is determined. It is very particularly preferred if the evaluation unit the measurement result with regard to the physiological to be monitored Parameters, in particular respiration, evaluated. In case that the detection or determination of the elongation over a Resistance and / or conductivity measurement is done is it is not necessary, but preferred, the strain sensor as a capacitor train.

to Measurement of resistance or conductivity can, as mentioned, a previously described capacitor structure of Strain sensor can be realized, in which case the Effect that is made use of as a result of stretching the electrical leakage through the insulation layer dielectric elastomer, that is, the currents between two Electrodes, which in turn is replaced by a resistance and / or conductivity measurement measured directly and optionally can be evaluated.

at In a simpler embodiment, the strain sensor includes for measuring the resistance or the electrical conductivity only a single layer of the lektrischem elastomer, the coated with an electrically conductive layer (electrode), For example, printed with graphite dust. It is special preferably, the electrode thus obtained on both facing away from each other Ends to contact electrically or with the evaluation to connect.

As mentioned in the beginning, it is preferred that the at least one, preferably flat, in particular rectangular contoured, Electrode an electrically conductive powder material, in particular graphite, includes. This is more preferably in an elastically deformable Material introduced and / or on such a material, in particular by Printing, applied. Preferably, the elastic, the electrically conductive powder material having material to dielectric elastomeric material. A particularly efficient option for applying the electrically conductive powder material is to print this, preferably suspended.

In particular, when the strain sensor is formed as a capacitor, it is preferred if the strain sensor is formed as a multi-layer structure having a plurality of layers of a dielectric elastomer, wherein preferably between each two spaced apart dielectric elastomer layers (insulation layers) an electrode layer is disposed. To produce the multilayer structure, it is possible to arrange a plurality of planar electrodes between laminated, dielectric elastomer layers. Depending on whether or not the strain sensor is to be designed as a capacitor, it is possible to isolate the electrode layers from one another via the dielectric elastomer or, in particular for a resistance measurement, to connect them electrically conductively, for example by the electrode layers being parallel or in Series are switched. A parallel connection allows a simpler evaluation of a resistance measurement. A series connection of at least two elastomer layers is advantageous with regard to the realization of larger measuring sections, while at the same time realizing minimum dimensions and thus achieving an improved resolution. A series connection is distinguished, for example, by a corresponding connection can be realized cher cher electrode layers, or alternatively by simply folding a coated on both sides, in particular printed, dielectric elastomer strip.

All particularly preferred is an embodiment of the monitoring device, in the at least one, as previously described trained, strain sensor is fixed to a stretchable, in particular textile fabric, for example, to form a chest strap in this way, or immediately to be integrated into a tight-fitting garment.

in the With regard to the possibility of forming the electrodes There are different possibilities. Preferred is these are elastic materials with a high relative permittivity, or to materials, such as dielectric elastomers, by Addition of additives, such as ferroelectric Materials in powder form a high relative permittivity to reach. It is also possible to use a to realize special embodiment of a shoulder strap, its design preferably oriented to the anatomical point of view.

Especially preferred is an embodiment variant in which dielectric Elastomer is formed as a self-adhesive film, whereby it is possible the strain sensor obtained in this way simply onto a textile, for example, a garment or a chest belt, to stick.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings. These show in:

1 a first embodiment of a monitoring device in which a strain sensor is designed as an elongate capacitor and

2 an alternative embodiment of a monitoring device with a multilayer strain sensor.

embodiments the invention

In The figures are the same elements and elements with the same Functions marked with the same reference numerals.

In 1 is a mobile surveillance device 1 shown to monitor human respiration. The monitoring device 1 includes a chest strap 2 , the two connectable outer sections 3 . 4 , each of a solid, substantially non-stretchable textile tape and a middle section 5 made of a textile stretch material. On the middle section 5 of the chest strap 2 is a strain sensor 6 arranged with the middle section 5 (elastically stretchable textile tape) is sewn.

The strain sensor 6 is, as will be explained below, formed as a capacitive elastomer sensor, and includes a central, flat, rectangular contoured insulation layer 7 made of dielectric elastomer material, here silicone. The dimension of the insulation layer 7 in the direction of the longitudinal extent of the chest strap 2 is much larger than their width extension and quite considerably larger than the thickness extension into the plane of the drawing.

The insulation layer 7 is sandwiched between two elastically deformable electrodes (electrode layers) 8th . 9 which are made in the embodiment shown by printing with electrically conductive material. It is noteworthy that the stacking direction of the illustrated multilayer structure comprising the electrode layers 8th . 9 and the insulation layer 7 substantially perpendicular to the surface of the human body is feasible, with one not in the vertical direction, but in the direction of the width extension of the strain sensor 6 , So a parallel to the human body oriented stacking direction can be realized.

The two electrodes 8th . 9 are electrically contacted by a respective connecting line 10 . 11 which becomes an evaluation unit 12 leads, which is equipped with a data memory and / or a data transmission unit. With the help of the evaluation unit 12 is the capacity and therefore a change in capacitance of the electrodes 8th . 9 with interposed insulating layer 7 formed capacitor measurable. The measured capacitance is a measure of the size of the strain or the length of the strain sensor 6 ,

In an alternative, not shown embodiment, for example, one of the electrodes 8th . 9 electrically conductive at both ends with the evaluation unit 12 be contacted, which is preferably formed in this case, that they the electrical resistance of the electrode 8th which depends on the actual length and cross-section of the strain sensor 6 ,

In 2 an alternative embodiment is shown. Recognizable again is the chest strap 2 , with its end, fixed sections 3 . 4 , which can be fixed to each other, for example via a smoothing device, not shown. To recognize is further that the evaluation unit 12 at the right in the plane of the drawing, fixed section 4 is fixed.

In contrast to the embodiment according to 1 , includes the strain sensor 6 in the embodiment according to 2 a total of three insulation layers 7a . 7b . 7c , in each case between the insulation layers 7a and 7b such as 7b and 7c a flat electrode 8th . 9 is arranged. In the embodiment according to 2 is an advantage that the strain sensor 6 is designed as a self-adhesive film and with the middle section 5 (Textile section) of the chest strap 2 is glued. The electrodes 8th . 9 are formed by printing electrically conductive particles on dielectric elastomer (insulation layer). It can be seen that the electrodes 8th . 9 analogous to the embodiment according to FIG 1 via electrical connection lines 10 . 11 with the evaluation unit 12 are connected, which is designed to carry out capacitive measurements. The measurement results are known as such or have already been assessed (eg pathologically / not pathologically borderline) stored in a data memory (not shown) and / or transmitted to a corresponding receiving station via a data transmission unit (also not shown), preferably via radio.

In the event that the evaluation unit 12 is designed for measuring an electrical resistance, so the effect can be exploited that the electrical leakage through the middle insulation layer 7b change when the strain sensor 6 is stretched. This can be measured and evaluated directly via a resistance change, and / or a conductivity measurement.

In an alternative, not shown, embodiment, the strain sensor consists 6 of a dielectric elastomer layer which is coated with an electrically conductive layer, such as graphite dust, wherein the electrode thus obtained preferably electrically contacted at two spaced-apart ends or with the evaluation unit 12 connected is.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2002/0032386 A1 [0004]

Cited non-patent literature

• - "Knitted Bioclothes for Health Monitoring", N. Taccini, G. Loriga, A. Dittmar, R. Paradiso, Proceedings of the 26th Annual International Conference of the IEEE EMBS, San Francisco, CA, USA, September 1-5, 2004 [0003]

Claims (10)

Monitoring device for monitoring at least one physiological parameter, in particular respiration, comprising at least one strain sensor ( 6 ) with at least one electrode ( 8th . 9 ) and one with the strain sensor ( 6 ) signal-conducting connected evaluation unit ( 12 ), characterized in that the elastically deformable electrode ( 8th . 9 ) adjacent to at least one insulating layer ( 7 . 7a . 7b . 7c ) comprising dielectric elastomer material. Monitoring device according to claim 1, characterized in that the dielectric elastomer material, preferably an acrylate and / or a silicone, a modulus of elasticity, between about 0.1 MPa and about 20 MPa. Monitoring device according to one of claims 1 or 2, characterized in that the strain sensor ( 6 ) is formed as at least one capacitor, in which at least two elastically deformable electrodes ( 8th . 9 ) insulation layer comprising the dielectric elastomer material ( 7 . 7a . 7b . 7c ) are electrically isolated from each other. Monitoring device according to claim 3, characterized in that the evaluation unit ( 12 ) a change in the dimensions of the strain sensor ( 6 ) is formed detecting based on a capacitance measurement. Monitoring device according to one of the preceding claims, characterized in that the evaluation unit ( 12 ) a change in the dimension of the strain sensor ( 6 ) is formed detecting based on a resistance and / or conductivity measurement. Monitoring device according to one of the preceding claims, characterized in that the at least one electrode ( 8th . 9 ) comprises electrically conductive powder material, in particular graphite. Monitoring device according to one of the preceding claims, characterized in that the at least one electrode ( 8th . 9 ) is applied by printing. Monitoring device according to one of the preceding claims, characterized in that the strain sensor ( 6 ) is formed as a multilayer structure, the plurality of insulating layers ( 7 . 7a . 7b . 7c ) of dielectric elastomer, preferably each with one between two insulating layers ( 7 . 7a . 7b . 7c ) arranged electrode ( 8th . 9 ). Monitoring device according to one of the preceding claims, characterized in that at least two, preferably via an insulating layer ( 7 . 7a . 7b . 7c ) of dielectric elastomer spaced apart, preferably parallel, expandable electrodes ( 8th . 9 ) are connected in parallel or in series. Monitoring device according to one of the preceding claims, characterized in that the strain sensor ( 6 ) is fixed to a stretchable, in particular textile, fabric, preferably on a garment.