WO1986000713A1

WO1986000713A1 - Apparatus for optical measurement of liquids

Info

Publication number: WO1986000713A1
Application number: PCT/SE1985/000273
Authority: WO
Inventors: Ragnar Winberg
Original assignee: Ragnar Winberg
Priority date: 1984-07-10
Filing date: 1985-07-08
Publication date: 1986-01-30
Also published as: SE8403648L; EP0220184A1; SE8403648D0

Abstract

An apparatus in which optical measurement of liquid, especially blood, may be carried out quickly and easily, at low cost and with great accuracy. The apparatus comprises two thin, flexible carrier tapes (9, 10) between which liquid is present on the occasion of measurement. At least one of said tapes is transparent, and at least one of said tapes is coated with a reaction medium. The two tapes are adapted to be moved forward such a distance after each measurement that new liquid may be applied to areas to which liquid has not been applied before. The two tapes can be moved together and enter a narrow gap of predetermined width, in which measurement is carried out.

Description

APPARATUS FOR OPTICAL MEASUREMENT OF LIQUIDS

The present invention relates to an apparatus for optical measurement of liquids, especially blood, i.e. for determining the effect of the liquid on light trans¬ mitted through a layer of the liquid. It is the object of the invention to provide such an apparatus capable of carrying out the measurement quickly and easily, at low cost and with great accuracy.

To this end, the apparatus has been given the cha¬ racteristic features stated in the independent claim. Preferred embodiments of the apparatus are disclosed in the dependent claims-

Two embodiments of an apparatus according to the invention will be described in detail below, reference being had to the accompanying drawings which also show the tapes included in the apparatus.

Fig. 1 is in principle a lateral view, partly in section, of an apparatus according to the invention;

Fig. 2 shows a part of the apparatus according- to Fig. 1 as seen in section A-A; Fig. 3 shows in principle the construction of a first variant of a tape;

Fig. 4 shows the tape according to Fig. 3 as seen in section B-B;

Fig. 5 shows in principle the construction of a second variant of a tape;

Fig. 6 shows the tape according to Fig. 5 as seen in section C-C;

Fig. 7 shows in principle the construction of a third variant of a tape; Fig. 8 shows the tape according to Fig. 7 as seen in section D-D;

Fig. 9 shows a second embodiment of an apparatus part formed as a cassette; and

Fig. 10 shows the cassette in Fig. 9 as seen in section E-E.

Figs. 1 and 2 illustrate a supporting member 1 of glass containing a light emitting diode 2. A similar supporting member 3 contains a photocell 4. Reels 5 and 6 are rotatably mounted, and disc brakes 7 and 8 are arranged to brake the rotation of the reels. Tapes 9 and 10 are wound on the reels Feed reels 11 between which the tapes 9 and 10 are inserted are provided for feeding the tapes 9 and 10. For easy handling, the used tape sections can be cut off by cutting devices 12. From the reels 5 and 6_Λ the tapes 9 and 10 are passed over the glass members 1 and 3 in close engagement there¬ with.

Between the tapes, a narrow gap 13 is formed which is narrowest (thinnest) between the light emitting- diode and the photocell and widens upwards and downwards. Because of their tension_r the tapes lie close against the glass members 1 and 3 at the gap, and the interspace between the tapes can here be kept at exactly the same dimension during all measurements. In the section between the light emitting- diode and the photocell, the glass members 1 and 3 are plane and parallel or very slightly curved. In the area of measurement, the gap formed between the tapes may have a thickness of, for example, 0.1 mm. The tapes 9 and 10 are identical and consist of transparent polyester and have a thickness of, for example, 30 μm. The polyester has been coated with a thin and uniform layer of a reaction medium. In this respect, the tapes are reminiscent of tape recorder tapes which also consist of coated polyester. Since the thickness of the polyester tapes as well as the thickness of the coating can be kept precise, also the gap thickness remains precise. The reaction medium may be a solid material or a semi-solid material, especially a gel. Below the gap 13, there is a support 14 which in this case is an endless strip, having a thickness of, for example, 0.5 mm and a width of 10 mm and adapted to be advanced about two rolls 15. A scraper 16 can scrape the strip clean. The strip 14 may be arranged such that it can be lowered a millimetre or two below the gap 13 while the tapes 9 and 10 are advanced. The details in the Figure do not have the correct proportions. For better clearness, the gap, for example, has been drawn excessively wide. The arrangement may be such that the tape edges run against one another in the gap without affecting the gap thickness in the area of mea- surement. This is not shown in the Figures.

Figs. 3 and 4 illustrate a carrier tape 17 of transpa¬ rent polyester which may have a thickness of 28 μ and a width of 12 mm. On the carrier tape,, three ribbons 18, 19 and 20 are provided containing different, reaction media. Such a tape may be used together with a tape carrying no reaction medium. It may be used also with an identical tape which is wound up such that, upon use, ribbons having the same reaction medium will face one another in the gap 13. When using the above-mentioned tapes, three light emitting diodes and three corresponding photocells, arranged side by side in the- glass members 1 and 3, are required. The reaction medium on one ribbon may be exchanged for an indicating dye.

Figs. 5 and 6 show a slightly thicker, but still thin and flexible carrier tape 21. Perforations 25 for feeding the tape have been punched along both edges of the tape. Between said perforations, there are stroke marks 26 for optical reading and control of the apparatus. Two different reaction media have been applied in the form of thin square layers 23 and 24. Here, the apparatus is intended to perform one type of analysis in every second feeding position and a different type of analysis in the other feeding positions. The tape may be combined with a tape carrying no reaction medium or with an identical tape, care being taken that the same types of reaction medium will be facing one another in the gap 13.

Figs. 7 and 8 illustrate a tape in which recesses have been formed. These recesses have the form of a rectangular surface 27 with a narrow duct 28 extending therefrom to serve as an air outlet. The recesses may have a depth of, for example, 95 μm. Two recesses.are here shown side by side,. They are provided with different reaction media. Such a tape may be combined with an identical tape or a completely smooth, transparent tape. Upon use,^" a couple of recesses may have a position such that their lower areas lie between two light emitting diodes and the associated photocells which have been arranged side by side.

On use of the apparatus, a drop of liquid is supplied to the upper part of the gap 13 and, by a combination of gravitational and capillary forces, will quickly enter the gap and completely fill out the area between the tapes 9 and 10 between the glass members 1 and 3. The capillary force prevents the liquid from dripping down from the gap. The liquid may be stopped also by the support 14. If the liquid is blood for e.g. a haemo— globin examination, a so-called HB test, a drop of blood may be transferred to the upper part, of the gap directly from a punctured finger tip or via a lancet or pipette.

The apparatus may be arranged such that, when a sufficient amount of dyed liquid has entered the area of measurement, the apparatus gives a signal and, after a period of time for which the apparatus has been set, measurement and recording of said liquid are carried out while the tapes are advanced, for example 15 mm, by the reels 11. The tapes are then cut off by means of the devices 12. The tape may also be advanced for example 5 mm beyond the area taken up by the liquid between the tapes. After the tapes have been advanced, the apparatus is ready for the next test.

The mixing of liquid and reaction medium may be expedited by subjecting e.g. the glass members 1 and 3 to vibration.

Apparently, the most advantageous arrangement is one in which the two carrier tapes are transparent, and the light emitting diode and the photocell are posi¬ tioned as shown in Fig. 1. It is, however, possible to provide one tape with a specular layer of vacuum- metallised aluminum, in which case the light emitting diode and the photocell are arranged on the same side.

Measurement or analysis of the liquid may also be carried out in a manner other than by using a photo¬ cell. Although the._apparatus has been designed for the analysis of liquids, especially blood, and primarily for HB measurement, it may also be used for albuminoid and diabetic tests etc.

Since the apparatus may be supplied with undiluted blood, its operation is quick and uncomplicated. Further¬ more, since some steps, such as dilution etc., are ex¬ cluded, the analysis is reliable and depends only on the accuracy in the operation of the photometer and tapes. The use of thin tapes allows two reels to accom- modate material for thousands of measurements, and there¬ fore the cost of each measurement is low.

In Figs. 9 and 10, a part of the apparatus is formed as a cassette 29 for the tapes 9 and 10. In this cassette 29, the tapes 9 and 10 are arranged to run from the wind-off reels 5 and 6 via scraper and/or brake means 30 and 31 consisting of, for example, foamed plastic, and past tape tensioning means in the form of resilient arms 32 and 33, to special wind-up reels 34 and 35. Said resilient arms 32 and 33 are adapted to keep the tapes 9 and 10 tensioned so as to lie closely against the supporting members 1 and 3 which are not included in the cassette 29 but are shown by dashed lines in Fig. 9. By means of gear wheels 36 and 37 on the reels 34 and 35 and by gears 38 and 39 engaging with said gears and with one another, the tapes 9 and 10 can be simultaneously transported from the reels 5 and 6 to the reels 34 and 35. For moving the tapes, one of the reels 34 and 35 or one of the gears 36-39 may be attached to a turning knob 40 or the like for manual advance of the tapes 9 and 10.

As shown in Fig. 10, the cassette 29 is provided with a lid 41. To facilitate introduction of the tapes 9 and 10 into the gap 13 between the supporting members

1 and 3, the tapes 9 and 10 may be loosely adhered, for example glued, to one another along an initial section between the reels 5, 6 and the reels 34, 35. The adhesion must be so light that the tapes may be separated after mounting of the cassette 29 in the apparatus.

Finally, it will be appreciated that the invention is not limited to the embodiments described above but also comprises variants. Thus, the supporting members ^" 1 and 3 may consist of a transparent material other than glass and may also, completely or partly, consist of an opaque material, for example if the light source

2 and the light detector 4 extend all the way to the gap between the supporting members.- Use may also be made of fiber optics, in which case the light source 2 and the light detector 4 are separated from the sup¬ porting members 1 and 3.

Claims

1. An apparatus for optical measurement of liquids, c h a r a c t e r i s e d by two thin, flexible carrier tapes (9, 10) extending through a narrow gap (13) in a predetermined spaced apart relationship, at least one of said carrier tapes carrying, on its side in the gap facing the other tape, a reaction medium, and at least one carrier tape being transparent on the occasion of measurement when liquid is present between said tapes in the gap in which optical measurement is made by means of light transmitted across said gap,, the said two tapes furthermore being movable forward through the gap such a distance that for each measurement new liquid is ap¬ plicable to tape areas to which liquid has not been applied before.

2. An apparatus as claimed in claim 1, c h a r a c ¬ t e r i s e d in that the two tapes (9, 10) are iden¬ tical and provided with a reaction medium in a uniform layer over the whole of one surface.

3. An apparatus as claimed in claim 1, c h a r a c - t e r i s e d in that at least one of said tapes (9,

10) contains more than one type of reaction medium.

4. An apparatus as claimed in 1, c h a r a c t e r ¬ i s e d in that at least one of said tapes (9, 10) has recesses (27) which on the occasion of measurement are filled with said liquid.

5. An apparatus as claimed in claim 1, c h a r a c ¬ t e r i s e d in that said gap (13) is formed by two tape supporting members {1, 3) making the gap narrowest in the area of measurement in which the tapes lie closely against said supporting members.

6. An apparatus as claimed in claim 1, c h a r a c ¬ t e r i s e d by means (32, 33) for tensioning said tapes (9, 10) at least within said gap.

7. An apparatus as claimed in claim 1, c h a r a c - t e r i s e d by a cassette (29) for accommodating said tapes (9, 10) .

8. An apparatus as claimed in claim 7, c h a r a c ¬ t e r i s e d in that each tape (9, 10) extends from a wind-off reel (5, 6) to a wind-up reel (34, 35).

9. An apparatus as claimed in claim 7, c h a a c ¬ t e r i s e d in that said tapes (9, 10) are loosely adhered to one another along a section to facilitate introduction of said tapes into said gap.

10. An apparatus as claimed in claim 7, c h a r a c t e r i s e d by means (36-40) for simultaneous turning of said wind-up reels (34, 35).