GB2309097A - Detecting the presence of fluid in multi-well plates - Google Patents

Abstract

A device for detecting the presence or absence of a fluid in a multi-well plate has a transparent perspex slab 3 with a black background 2 with a grid of circles sandwiched at the optimal focal length 4. When a multi-well plate with a clear base is placed on the slab 3 and viewed from above the meniscus of any colourless fluid in any of the wells acts as a concave lens and makes the circle appear smaller, thus showing whether a fluid is present in any particular well. The background may be a colour other than black and geometrical designs other than circles may be used.

Description

MENISCUS DETECTOR This invention relates to a piece of equipment to detect visually the absence or presence of a colourless liquid in an optically clear, flat bottomed tube, where the liquid does not fill the tube.

Optically clear flat bottomed 96 multi-well transparent plastic disposable plates are used in routine medical and research laboratories for diagnostic and quantitative estimations of a wide range of molecules. They are standard sized clusters of 96 mini "test tubes" used for large scale screening of liquid samples by established chemical or biochemical reactions resulting in the generation of a signal, which is usually the formation of a coloured product. This methodology is used world-wide and accounts for the use of millions of these plates daily.

Problems occur in the manual use of the plates because it is difficult to detect visually which wells are currently in use ie. contain liquid, as both the well and the liquid are transparent.

Some companies which sell expensive diagnostic assay kits that utilise these multi-well plates, add dyes to their reagents to visually assist in identifying the wells containing liquids.

However, scientists do not like to add unnecessary substances to their assays for fear of interference in spectrophotmetric measurement of the final coloured products.

According to the present invention, there is provided a standard sized transparent perspex slab containing at a fixed depth a grid of circles corresponding in size and layout to the pattern of wells in the standard sized plate of multi-wells. This is a simple optical aid, which any multiwell plate may be placed upon and when a colourless solution is added to a well the circle in the grid directly positioned below the well is dramatically reduced in size. This is due to the effect of a meniscus formed by the fluid added to the well. The meniscus effectively serves as a crude concave lens, reducing the circle image size as perceived by the eye.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 shows a 96 multi-well plate: a) top view, b) cross-section and c) cross-section with menisci formed by fluid in the wells.

Figure 2 shows the meniscus detector: a) top vieN! b) cross section and c) cross-section with the 96 multi-well plate containing fluid in position.

Figure 3 shows enlargement of a single well with meniscus formed by fluid and the light path from an image under the well to the eye.

Figure 4 shows the visual effect created by the meniscus detector when viewed through the base of a single well from above a) when it is empty and b) when it contains colourless liquid.

Figure 5 shows the v usual effect created by the meniscus detector when viewed through the base of a 96 multi-well plate for wells selectively filled with colourless fluid (small diameter circles) in contrast to those which are empty (large diameter circles).

Referring to the drawings, the meniscus detector Fig 2 comprises a transparent perspex slab 3 which allows a 96 multi-well plate Fig 1 to be located upon it Fig 2c in a precise position via guides 1 relative to visual alignment with a grid of circles on a black background 2, sandwiched at an optimal focal length 4 beneath it within the same perspex block Fig 2b and c.

The meniscus formed by colourless fluid added to a well acts as a crude concave lens Fig 3 which converges light from the circle image below it, making the image as observed by the eye appear smaller than the same image viewed through an empty well Figs 4 and 5. This being the principal for differentiation between a well that contains a colourless fluid and one that does not.

Although the grid of circles used in this equipment thus far gives a good resolution Fig 5, the circular images may be substituted for any geometrical design taking any colour in contrast to any colour of background. The images may also be of a transparent nature allowing illumination of the device from below, giving further visual assistance.

Claims (7)

1. A device which optically detects the presence or absence of a colourless nuid in a cylindrical compartment of transparent or non-transparent walls, but with an optically clear base.

2. A device as in Claim 1 where a geometric design positioned optimally below an optically clear flat-bottomed or round-bottomed compartment, visibly changes in size upon the addition of a colourless fluid.

3. A geometric design as in Claim 2 may take any shape forms or colour(s), spacing or dimension, or may be opaque for background illumination.

4. A geometric design as in Claim 2 or Claim 3 for optimal application to existing transparent or non-transparent cylindrical compartments with optically clear bases.

5. A claim is made for copyright of the geometric design both in spacing and dimension filed with the patent office as part of application number GB 9600701.8, for use with a standard 96 multiwell plate where the geometric symbols may be substituted for any other as in Claim 3.

6. A device as claimed in any preceding claim is made from plastics material, paper material, metal or wood or from a combination of these materials.

7. A device for the detection of a meniscus substantially as herein described and illustrated in the accompanying drawings.