Optical indicator device for the remote measurement of physical changes in a test subject

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BACKGROUND OF THE INVENTION

This invention relates to an optical indicator device.

Optical indicator devices have already been used biologically for the measurement of concentrations of specific particles. In these devices the indicator was provided with a membrane which was permeable in a selective manner by specific particles through diffusion and means were provided at the opposite side of the membrane to cause the optical indication of the concentration of particles which had penetrated the membrane. Through the separation of the specific particles entering the inner indicator space from the known amount of other particles, a fairly exact measurement could be accomplished.

This type of measurement and indicating device is free of undesirable reaction on the test subject and furthermore is not likely to result in wrong measurements. The device, besides, is quite sturdy and can be used without special preparation. This type of indicator has, however, heretofore been used only for measuring concentrations. Indicators for measuring other physical parameters have not been available. However, in biological practice which has to do with living tissue the measurement of pressure or temperature is extremely important if a reaction on the test subject through undesirable degrees of concentration is to be excluded.

For instance, the control of the temperature parallel with the measurement of the glucose concentration is of great significance since there occur temperature variations up to 10% which, for instance in case of diabetics. are not tolerable.

It is therefore an object of the present invention to provide for indicators which are optically responsible to physical parameters. An incidental object is that such indicators must be available without undue expense and must be usable without complex preparations.

ESSENCE OF THE INVENTION

This object in its essence is solved by using indicators in which the indication is effected by a substance forming a mesophase. Such materials are generally known as liquid crystals. They have been used as optoelectrical indicators. However, their use for biological purposes in living test subjects is believed novel.

If the indicator for instance is in the form of a microcapsule these materials can be embedded in living tissue so as to provide for a remote control of the temperature of a specific tissue layer. In general technology methods are known to measure the color- or fluorescence variations occurring through transparent surfaces which may have been contaminated with interfering materials. For the measurement of the temperature a liquid crystal forming a cholesteric phase is particularly suited.

It is preferred to use indicator spaces for measuring the glucose concentration simultaneously with an indicator as above described and containing a cholesteric compound for determining the temperature. This makes it possible to control both the glucose concentration and the temperature which will often avoid critical conditions in diabetics in intensive care patients.

The usefulness of the indicators of the invention can be made available for other purposes by employing liquid crystals in a nematic phase. These indicators will permit also to measure mechanical pressure, mechanical impulses and electrical or magnetic fields.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The drawing in diagrammatical form indicates a device according to the present invention.

DETAILS OF THE PREFERRED EMBODIMENT

With reference to the drawing it will be seen that a test subject MO is provided with an indicator capsule 1 which may be embedded in its tissue. This capsule comprises an oxygen permeable membrane and the space within the membrane is filled with a pyrene buteric acid compound.

In addition there is provided a measuring capsule 2 which has an optically permeable, fluid-tight membrane and in which is disposed in its inner space a compound consisting of dipalmitoyl phosphatidylcholine+1-aniline-8-naphthalene sulfonate. An additional indicator capsule 3 contains pyrene buteric acid and glucoseoxydase.

L.sub.1 indicates monochromators for generating light to cause fluoresence of the pyrene buteric acid. L.sub.2 indicates a source of light for causing fluoresence of the 1-aniline-8-naphthalene sulfonate.

The light detectors are indicated by the reference letter D.sub.1 for the detector for the fluorescent light of the pyrene buteric acid and as D.sub.2 for the detector for the fluorescent light of the naphthalene sulfonate.

Any glucose present in the test subject can be measured as follows.

In the indicator capsule 1 having a glucose-permeable membrane the amount of oxygen present in the subject is measured. In the oxygen capsule 3 having a glucose-permeable membrane a measurement is effected of the proportion of oxygen which remains after the glucose which entered the indicator capsule 3 has reacted with oxygen due to the presence of the glucoseoxydase in that capsule. There can thus be determined the oxygen difference, i.e. oxygen residue between the measurement in capsule 1 and the measurement in capsule 3. This difference is proportional to the glucose concentration which can thus be determined with corresponding detectors.

Simultaneously the temperature in the reaction space of the indicator capsule 2 is continuously controlled since any change of the temperature will result in a variation of the intensity of the fluoresent light emanating from the indicator capsule 2.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characterisetics of the generic or specific aspects of this invention.

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