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BACKGROUND OF THE INVENTION
The present invention relates to an arrangement for measuring diffusing
particles. More particularly, it relates to an arrangement for measuring
diffusing particles, which has at least one monochromatic radiation source
and a light measuring device as well as at least one material-limited
indicator chamber which is permeable by particles to be measured and is
provided with an optical fluorescence indicator which is optically
changeable by the particles.
Arrangements of the above-mentioned general type are known in the art. The
known arrangements are used for example for measurements of blood
component oxygen and its partial pressure pO.sub.2 or carbon dioxide and
its partial pressure pCO.sub.2 invasibly or noninvasibly. For this purpose
the indicator chamber which is permeable by the particles to be measured,
known shortly as optode, is brought into operative communication with the
object to be measured and the change in the measuring light is measured by
the optode. One of such arrangements is disclosed, for example, in the
U.S. Pat. No. 3,769,961. In the arrangement in accordance with this patent
the electrodes which are arranged on a contact lens formed as an electrode
carrier measure blood components, such as for example oxygen or carbon
dioxide on an eyelid.
In this manner a noninvasive measurement of these blood components is
possible, since on the lid mucous membrane or the conjunctiva these blood
components have approximately arterial value, or differ from it only by a
constant factor.
The electrodes which in the known arrangement are used for measurements
have as all electrodes an aging and must be frequently subjected to
observations with considerable cost. Moreover, the wire lines for the
electrodes must be guided on the contact lens that leads to undesirably
affecting of the patients. Furthermore, the miniaturization of electrodes
is possible only to a limited extent. Also, other particle types such as
for example metabolism products from the metabolism of the eye or other
particles such as for example cations or anions lie at this measuring
location. They cannot, however, be measured since there are no suitable
sensors.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
arrangement for measuring diffusing particles which avoids the
disadvantages of the prior art.
In keeping with these objects and with others which will become apparent
hereinafter, one feature of the present invention resides, briefly stated,
in an arrangement for measuring diffusing particles, which has a carrier
body provided at its surface facing toward a lid with depressions, and
indicator chambers (optodes) are arranged in these depressions.
When the arrangement is designed in accordance with the present invention
it is possible to for example simultaneously measure several particle
types in a contactless manner, in that the optodes arranged on the carrier
body are irradiated directly after lifting of the eyelid or through the
eyelid with a testing light, and then the measuring light going out of the
optodes and its change is used for indicating purposes. Thereby here a
noninvasive method for measuring of the pH value takes place since
protones also with approximately arterial value are measured on the
eyelid. Because of the robust state of the optodes, the arrangement is non
problematic in handling and its compatibility for the patients is very
good as the known compatibility of the contact lenses. Since moreover,
optical indicators are provided for a whole range of diffusing particles,
the measuring region is considerably increased as compared with the
measurements by electrodes. For example, with the aid of optodes also the
glucose concentration on the lid can be measured.
An especially fine and at the same time intensive irradiation of the
optodes is obtained when, in accordance with another feature of the
present invention, light conductors are provided inside the carrier body
and lead from one or several coupling surfaces arranged at the edge of the
carrier body to the optodes.
If in special measuring conditions the utilization of wire conduits is not
desirable, then, in accordance with a further feature of the present
invention, a monochromatic radiation source, for example a light diode and
the associated radiation receiver can be arranged in the carrier body. The
irradiation of the optodes and the measurement of the radiation changes
take place directly by the optodes. Several such arrangements can also be
used.
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 drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a view showing an arrangement for measuring diffusing particles
in accordance with a first embodiment of the present invention;
FIG. 1A is a perspective view showing an optode of the inventive
arrangement;
FIG. 2 shows an arrangement for measuring diffusing particles in accordance
with a second embodiment of the present invention;
FIG. 2A is a view showing a modification of an element of the arrangement
of FIG. 2;
FIG. 3 is a view showing an arrangement for measuring diffusing particles
in accordance with a further embodiment of the present invention; and
FIGS. 3A and 3B are views showing modifications of the third embodiment of
the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
An arrangement for measuring diffusing particles shown in FIG. 1 has a
carrier body which is identified with reference numeral 10. The carrier
body has a surface 11 which is arranged to lie on an eyelid and provided
with depressions 1010, 1011 . . . The depressions have a rear side which
can be formed reflective. Optodes 110, 111 . . . are arranged in the
depressions 1010, 1011 . . . Such optodes are composed, for example, of
synthetic plastic foil with indicators arranged in it, as shown in FIG. 1.
During irradiation with light they produce a predetermined fluorescent
light with a wavelength depending upon the indicator. The fluorescent
light or "measuring light" 30 has a different color than a testing light
31. The measuring light 30 as well as the testing light 31 in FIG. 1 are
transported by a light conductor 20 which can have several fibers. A known
optical means can easily separate it from the measuring light and detect.
The device required for this is known in the art and therefore not shown
here.
The indicator which produces this fluorescent light is, in turn, influenced
by a type of the particles to be measured, for example oxygen which goes
from the inner surface of an eyelid 40 and is in a diffusing equilibrium
with the capillary oxygen in the mucous membrane of the eyelid, and
changes its fluorescent light emission in correspondence with the
concentration of the oxygen.
The measurements of pO.sub.2 and pCO.sub.2 takes place through the eyelid
with the aid of the optodes 110, 111 . . . , and therefore there are no
distortions by the atmosphere. This is possible since the fluorescent
light of the indicator can be well filtered from the reflected radiation.
Furthermore, the optodes can be produced without difficulties from
bio-compatible materials, so that neither toxic nor contaminating
processes are released by the measurement. By optical disengagement of the
optodes with the aid of a reflecting or absorbing layers the possible
irradiation in the retina during the measurements can be excluded.
The thus measured intensity of the fluorescent light is multiplied by a
corrective factor which is determined by calibration. The deviation of the
partial pressure from the arterial pressures can be eliminated by a
further correction.
For special measurement tasks an optode 112 can be arranged in an open lid
gap. Furthermore, several optodes can be provided in the arrangement,
particularly for simultaneous measurements of several types of particles
or physical parameters, such as for example, the oxygen concentration, the
CO.sub.2 partial pressure, the pH value, the glucose concentration, the
temperature and the like.
The arrangement for measuring diffusing particles shown in FIG. 2 is used
when the pO.sub.2 value, the pH value, or the pCO.sub.2 value is measured
with an open lid and therefore the irradiation does not have to take place
through the eyelid.
For this purpose, the depression 1010 is arranged at an edge of the carrier
body 10 so far that the lid 40 permenantly covers this optode. The light
conductor which transports the testing light 31 and the measuring light 30
irradiates a coupling surface 105 which is an end surface of a light
conduit 106 conducting the irradiation to the optode 110. The light
travels for example over a mirror 107 of an optode holder 108. The
measuring light going from the optode travels back over the same path.
An arrangement 1100 shown in FIG. 2A is a one-piece formation of the
individual parts, namely the coupling surface 105, the light conductor
106, the mirror 107, and the optode holder 108. It can be produced as an
integral element and inserted into the carrier body 10 provided with the
respective passages.
FIG. 3 shows an arrangement for measuring diffusing particles in which
conductors a, b, c are provided on the carrier body. It is thereby
possible to arrange color detecting light diodes 120 and photoreceivers
121 in the carrier body, so that they are supplied by the conductors a, b
and their signals are taken via the conductors b, c. Depending upon the
available space, arrangements of FIG. 3A or FIG. 3B are utilized.
In this case, arrangement 1200 or 1210 are composed of units which include
a light diode 120, a mirror 122, a photoreceiver 121, and an optode holder
123, and arranged in the carrier body 10.
It will be understood that each of the elements described above, or two or
more together, may also find a useful application in other types of
constructions differing from the types described above.
While the invention has been illustrated and described as embodied in an
arrangement for measuring diffusing particles, it is not intended to be
limited to the details shown, since various modifications and structural
changes may be made without departing in any way from the spirit of the
present invention.
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
characteristics of the generic or specific aspects of this invention.
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