DD271953A1 - DEVICE FOR AUTOMATIC PHOTOMETRIC ANALYSIS OF SMALLEST SAMPLES - Google Patents

Abstract

The invention relates to a device for the automatic photometric analysis of very small sample quantities, with which transmission (extinction) and fluorescence measurements can be carried out. In a Traeger waveguide tracks are implemented, with their surface at least in sections in optical contact with at least one sample. For each waveguide path, means implemented in the carrier for coupling electromagnetic radiation into the waveguide paths are provided. For integration into peripheral technology, the carrier is mounted on a means of transport which makes contact with means for sample preparation and aftertreatment. The solution, in various embodiments, allows simultaneous and automatic analysis of multiple discrete samples at the same or different wavelengths as well as continuously supplied samples at different wavelengths. Fig. 1

Description

Field of application of the invention

The invention serves for the automatic determination of the transmission (extinction) and fluorescence of predominantly liquid samples, especially for very small sample volumes below about 10μΙ. The areas of application are in medicine, vetorin medicine, agriculture, biology and biotechnology and chemistry.

Characteristic of the known technical solutions

Known photometer assemblies usually consist of a light source, a sample chamber with sample holder, a photoelectric receiver and an electronic part for Gedienung, Stoerung and data analysis. Frequently, a spectrally selecting system is also integrated. Imaging systems are used to guide the electromagnetic radiation between the light source and the receiver

 To streamline the analysis, the photometer unit is connected to peripheral devices. These are:

- Facilities for sample preparation

- Facilities for feeding the sample into the measuring vessel (metering technique)

- Means for supplying one or more consecutive vessels in the beam path

- Means for tempering and

- Equipment for removing the sample and cleaning the measuring vessels

The interaction of the photometer unit with the peripheral devices as well as the measurement formation and evaluation can be controlled by microprocessors, which allows the automatic measurement of multiple samples.

The disadvantage of the above-mentioned technical solutions is that for the simultaneous detection of several identical or different types of samples or for the automation of the analysis implementation significant equipment expense is necessary. The miniaturization of the photofinisher unit for its use "on site" are limited.

Furthermore, it is known to exploit the interaction of evanescent waves with the sample in photometric arrangements.

In IP 181291 it is proposed to guide the radiation with an optical fiber through the liquid sample located in a special cuvette.

EP 206433 proposes to guide the electromagnetic radiation by means of total reflection in a prism. The prism dives into the 7U examining sample, the evanescent extensions of the guided wave interact with the sample.

The interaction of evanescent portions of guided waves with samples to be examined is well suited if sample components adsorbed on the waveguide are to be detected (EP 170376).

Also, the interactions of evanescent portions guided waves with the sample exploiting known technical solutions do not offer the possibility of extensive miniaturization of the photometer, a use for process control, the simultaneous detection of multiple P: above and extensive automation.

Object of the invention

The aim of the invention is to achieve a high sample throughput with low equipment complexity and to increase the universality of applicability.

Explanation of the essence of the invention

The object is to develop a compact photometer unit for measuring even the smallest sample volumes, which allows to simultaneously and automatically analyze both multiple discrete samples at the same or different wavelengths as well as continuously supplied samples at different wavelengths in various embodiments and with low device complexity in peripheral technology integi! art can be.

According to the invention, the object is achieved by a photometric device for the automatic analysis of minute sample quantities, in which spectrally selected radiation is directed to a receiver in a photometer unit after irradiation with a sample, and the photometer unit is coupled to means for sample preparation and after treatment in that at least one waveguide path is implemented in a carrier at least as part of the radiation-guiding means, the surface of which is in optical contact with at least one sample with its surface at least in sections. For each waveguide path, means implemented in the carrier for coupling electromagnetic radiation into the waveguide path are provided. The carrier is mounted on a transport means, which establishes a contact of the carrier with the means for sample preparation and aftertreatment.

Since the waveguide tracks have a higher refractive index relative to the carrier material, the electromagnetic radiation 7u of the sample to be examined and, after interaction with the latter, is guided to the receiver or another optical component.

In order to avoid losses in the guidance of the radiation, the carrier and the waveguide tracks consist of a material which is transparent to the radiation to be conducted.

To accommodate the samples to be examined, either sample containers placed on the sample carrier or a channel guided through the carrier are provided.

When sample vials are placed on the carrier, the implemented waveguides are parallel to the surface of the carrier and close to the surface. The bottom or wall of each sample vessel is formed by the waveguide carrier with at least one implemented waveguide path.

The evanescent extensions of the waves guided in the waveguide tracks are adsorbed on Gi and their interaction with the sample. By measuring the intensity of the guided wave with a receiver at the end of the waveguide path, before and after placing the sample in a sample vessel, the absorbance of the sample and the quantities derived therefrom (e.g.

Concentration) determinable.

Since an effective interaction of the evanescent extensions of a guided wave with the sample takes place only in a layer with a thickness on the order of the wavelength of the guided mode, even very small sample quantities are sufficient for one measurement.

To disperse these small amounts of sample evenly over the waveguide path after pipetting, means for distributing the sample in the cuvette are advantageous, which in the simplest case consist of pressing a cover onto the sample analogously to the cover glass known from microscopy. The speed of analysis can be increased by arranging several probes on each waveguide path. For this purpose, the samples are pipetted one after the other into the sample vessels, whereby the following measuring cycle is maintained:

1. Measuring the radiation intensity at the end of the waveguide path

2. Pipette into the first sample vessel and measure at the end of the waveguide path

3. Pipette into the second sample vessel and measure at the end of the waveguide path, etc.

It is advantageous to coat the boundary of the sample vessels which is formed by the waveguide path or which carries the waveguide path. Thus, by means of solvent-repellent and sample-adsorbing substances whose layer thickness is small compared to the wavelength of the guided mode and non-absorbent for the latter, the detection sensitivity is increased.

In addition to transmission and extinction measurements, it is also possible with the device described to measure the fluorescence of the sample excited by the evanescent waves. For this purpose, a further boundary wall of the sample vessels is designed as a radiation receiver or such adjacent to a transparent boundary wall of the sample vessel.

Due to the described interaction with the evanescent foothills of the guided wave surface regions of the sample are measured in the immediate vicinity of the waveguide.

If volume ranges are to be included in the measurement, the wall of the sample vessel, which is perpendicular to the longitudinal extent of the waveguide path, is formed as a decoupling prism for electromagnetic radiation from the waveguide path. The refractive index of this decoupling prism is equal to or greater than that of the waveguide path.

In order to measure the extinction, the wall of the sample vessel facing the decoupling prism is formed or the wall of the sample vessel opposite the decoupling prism is transparent, and a radiation detector is arranged downstream of it.

To measure the fluorescence, the wall formed as a radiation detector or its downstream receiver is perpendicular to the decoupling prism.

Instead of Auskoppelprismas also a decoupling grid can be used, which is located on the implemented waveguide path and forms a wall of the sample cuvette.

If the sample is not pipetted into attached Uuvetten, but pumped through a channel in the carrier, the wave guide tracks are implemented in the carrier so that they at least partially form a wall of the channel.

The photometric measurement is carried out by the interaction of the evanescent extensions of the sensed waves with the sample.

Fluorescence measurements can be carried out by forming the wall of the channel opposite the waveguide path as a radiation receiver, or the wall is designed to be transparent and has a radiation receiver arranged downstream of it.

Simultaneous measurements of both several samples and the same samples at different wavelengths are made possible by the device according to the invention with a plurality of waveguide tracks implemented in the carrier in which polychromatic or monochromatic radiation is guided.

When conducting polychromatic radiation, the end of the waveguide at which the radiation emerges via an imaging holographic grating on a receiver assembly such. As a diode array or a CCD line or matrix mapped. This makes it possible to measure the spectral dependence of the sample simultaneously by the interaction of the evanescent waves with the sample.

For coupling monochromatic radiation into the waveguide tracks, either a coupling-in grating, a coupling prism (which has a monochromatic laser light source integrated into the carrier at the beginning of each waveguide path) are provided.

For the coupling of monochromatic radiation by means of gratings or prisms, the effect is exploited that a waveguide at a certain wavelength leads to the radiation which is coupled into the waveguide at a certain angle, the so-called "zigzag angle" It is thus possible to couple monochromatic radiation into the waveguide tracks from a polychromatic parallel beam bundle by specifying the angle of incidence on the grating or the prism. The polychromatic beam is therefore directed onto the coupling prism or grating via a mirror which can be independently varied for each waveguide path.

If convergent polychromatic radiation falls on the coupling grating or prism, then polychromatic radiation is coupled into the waveguide path.

The laser light sources at the beginning of a waveguide path are advantageously designed as distributed feedback lasers, which are pumped either optically or electrically.

It is also advantageous if in the support in addition electrical pathways are implemented, which serve for sample temperature control and their bestimmor control.

An automatic cycle for the measuring process is realized by successively and cyclically bringing the carrier into contact with the means of sample dosing and the distribution of the samples as a means of sample preparation and the aftertreatment means consisting in the cleaning of the measuring surfaces, so that an interaction can take place.

embodiment

The invention will be explained below with reference to the schematic drawing. Show it:

Fig. 1: the representation of a carrier according to the invention

2 shows another carrier according to the invention

3 shows a first sample vessel

4 shows a second sample vessel

Fig. 5: a carrier suitable for flow measurements.

Fig. 6: the arrangement of carriers according to the invention on a rotating drum as a means of transport

According to FIG. 1, a coupling-in grating 2 and two waveguide tracks 3, 4 are implemented in a carrier 1. As cuvettes 6.7, b and 9 trained sample containers are placed on the support 1 so that their bottoms are formed by the carrier 1 with the running on the surface of shaft glide 3,4 and whose side walls are made of material whose refractive index is smaller than which is the waveguide. Polychromatic beams 10,11, emanating from unillustrated sources of radiation, are directed to the coupling grid 2 via independently adjustable mirrors 12,13. Detectors 14,15 are downstream of the waveguide tracks 3,4 at a small distance of about 0.1 mm. As a result of the radiation beams 10, 11 directed onto the coupling grating 2 via the mirrors 12, 13, radiation modes having a different wavelength λ are excited as a function of the angle of incidence in the waveguide paths 4, which results from the equation

λ = d sin α + (sin φ) for the Efeugung on the grid (1st order) determined at oblique incidence of radiation. There are

d = lattice constant

α = angle of incidence

φ = "zigzag" angle of the guided radiation in the waveguide

A blazed grating increases the coupling efficiency.

Of course, the coupling-in grating 2 must also be replaced by an equivalently acting prism. The photometric measurement of predominantly liquid samples, which are located in the sample receiving vessels, takes place by the absorption of the evanescent extensions of the guided in the waveguide tracks 3.4 modes through the samples, with a layer thickness of a few pm is sufficient.

To increase the measuring sensitivity, it is possible to apply to the surface of the support 1, a solvent repellent 'ind sample adsorbing substance as a layer of 1 nm to 10 nm thickness. In the case of water-soluble samples, for example, phenylsilane is suitable.

In the solution shown in FIG. 2, radiation sources 16, 17 are also integrated into the carrier 1 in addition to the waveguide tracks 3, 4. These are designed as distributed feedback lasers (DFB lasers), which are optically pumped by the radiation beams 10, 11. Depending on the period of the modulation of the refractive index of the DFB laser, the wavelength coupled into the waveguide is fixed.

For the solutions described, sample vessels 18 (FIG. 3) can also be used, whose one cell wall is designed as a decoupling prism 19 r, a refractive index greater than or equal to the refractive index of the waveguide tracks 3 or 4. The decoupling prism 19 opposite cuvette wall then represents a radiation receiver 20.

The photometric measurement with these cuvettes is not carried out by the absorption of evanescent waves, but by the absorption of the decoupled prism 19 from the waveguides 3.4 radiation coupled, which is registered after passage through the sample in the sample vessel 18 with the detector 20.

In fluorescence measurements, a wall directed perpendicular to the decoupling prism 19 is designed as a radiation receiver.

For both types of measurement described, of course, there is also the possibility, the radiation receiver of the respective sample vessel wall, which must then be transparent to the radiation, nachordnen.

The sample vessel 21 shown in FIG. 4, the opening of which faces upwards, is optically connected to the waveguide path 3 (or 4) via a decoupling grid 22, which is applied directly to the waveguide path 3 (or 4). On the decoupling grid 22 opposite sample vessel wall, a photodiode 23 is applied as a receiver.

Analogously to the example shown in FIG. 3, the sample vessel wall, which is arranged downstream of the photodiode 23, can also be formed as a photodiode itself.

In the carrier 1 according to the invention shown in FIG. 5, radiation sources 16, 17 are likewise integrated as in the example according to FIG. Through the carrier 1, a channel 24 is passed, can be pumped through the sample liquid for a continuous analysis. A portion of a wall of the channel 24 is formed by sections of the waveguide tracks 3,4.

Also in this illustrated example, a wall of the channel can be formed as a radiation receiver or the wall is such a nachordenbar to perform fluorescence measurements can.

If polychromatic radiation is to be conducted in the waveguide tracks 3, 4 for sample examination, the ends of the waveguide tracks 3,4 in all examples form the entrance gaps of a polychromatograph in which the incoming radiation is directed by an imaging holographic grating onto a receiver arrangement.

Since there are sufficiently well-known examples for such a polychromator arrangement, the drawing should be omitted.

Furthermore, in all carrier variants, electrical conduction paths can be provided for temperature control purposes.

In Fig. 6, three carriers are 1,1 ', 1 "mounted on a rotating about an axis 25 support frame 26 so that cyclically three different positions can be traversed, in which dosing, measuring, cleaning and drying takes place.

Claims (15)

Claims 1. A device for the automatic photometric analysis of the smallest sample quantities, in which in a photometer unit spectrally selected radiation after interaction with a sample by radiative means is directed to a receiver, and the photometer unit is coupled to means for sample preparation and aftertreatment, characterized in that a support is implemented, at least as part of the radiation-guiding means, at least one waveguide path having its surface at least in sections in optical contact with at least one sample, and means implemented for each wave path in the support for coupling electromagnetic radiation into the waveguide path, and in that the carrier is fastened on a transport means which establishes contact of the carrier with the means for sample preparation and after-treatment. 2. Device according to claim 1, characterized in that the waveguide tracks extend parallel to the surface of the carrier and complete with this and at least one sample vessel is placed on each waveguide path, so that a spatial boundary formed by the carrier and the optical contact is made. 3. Device according to claim 1, characterized in that the waveguide tracks at least partially form a wall of a provided in the carrier as a sample vessel channel through which the sample to be examined is pumped. 4. Device according to claim 2 or 3, characterized in that the carrier is traversed for heating with electrical conductor paths. 5. A device according to claim 2, characterized in that for producing the optical contact additionally a grid between the waveguide path ur.d sample cuvette is provided. 6. Device according to claim 2 to 4, characterized in that at least one grating or prism is provided as a means for polychromatic coupling convergent polychromatic radiation in the waveguide tracks. 7. Device according to claim 2 to 4, characterized in that is provided as a means for coupling spectrally selected "radiation in the waveguide tracks at least one grid implemented in the carrier, is directed to the parallel polychromatic radiation at a variable angle of incidence. 8. Device according to claim 2 to 4, characterized in that as a means for coupling spectrally selected radiation in the waveguide tracks at least one prism is provided, is directed to the parallel polychromatic radiation at a variable angle of incidence. 9. Device according to claim 2 to 4, characterized in that as a means for coupling spectrally selected radiation in the waveguide tracks for each waveguide path in the carrier an optically or electrically pumped laser light source is integrated. 10. Device according to claim 9, characterized in that the laser light sources are tunable in their wavelength distribution. 11. The device according to claim 2 to 10, characterized in that the standing in optical contact with a waveguide path boundary of a sample vessel with a layer of 1 nm to 10 nm thickness is occupied, which is lösungsmittelbaweisend and probenadsorbierend. 12. A device according to claim 2, characterized in that the means for coupling the electromagnetic radiation facing sample vessel wall is designed as Auskoppelprisma. 13. Device according to claim 2,3,5 or 12, characterized in that a further sample vessel wall is designed as a radiation receiver. 14. Device according to claim 2,3,5 or 12, characterized in that a further sample vessel wall, which is formed radiation-transparent, a radiation receiver is arranged downstream. 15. A device according to claim 6, characterized in that the radiation exit end of at least one waveguide path serves as the entrance slit of a polychromator, and the exiting radiation is directed via an imaging holographic grating on a receiver assembly. For this 2 pages drawings