WO2001051219A2

WO2001051219A2 - Method and apparatus for applying a marker

Info

Publication number: WO2001051219A2
Application number: PCT/GB2001/000064
Authority: WO
Inventors: Michael John Fox
Original assignee: Willett International Limited
Priority date: 2000-01-14
Filing date: 2001-01-10
Publication date: 2001-07-19
Also published as: AU5789401A; WO2001051219A3; GB0000788D0

Abstract

The present invention provides a method for applying a marker material to a surface of a carrier so as to form deposits of the marker materials at predetermined locations upon the surface of the carrier to which a sample of a product to be assessed can be applied so as to interact with the marker material in the deposit to provide a characteristic spectrum upon radiation of the predetermined location with IR, UV or other radiation. The marker material is applied through the nozzle of a continuous ink jet printer. The droplets of fluid striking the surface have a sufficiently low kinetic energy, that they do not cause an unacceptable level of disturbance of the layer and/or of scattering of the applied marker material upon the surface of the carrier. The carrier is a planar glass slide having an absorbent layer comprising fumed silica in a gelatin binder.

Description

TITLE: METHOD AND APPARATUS

The present invention relates to a method and apparatus, notably to a method for applying a fluid to a test slide and apparatus for carrying out the method.

BACKGROUND TO THE INVENTION:

It has been proposed to verify the authenticity of a sample of a product, for example a fluid, by incorporating one or more marker materials therein or applying to an exposed surface thereof in the case of a solid product, which fluoresce when exposed to IR, UV or other radiation, see for example British Patent No 2,298,713 and US Patents Noose 5,292,855, 5,336,714, 5,614,008 and 5,665,151. Such processes operate to detect the presence or absence of the characteristic fluorescence when a sample of the product being assessed is exposed to specified radiation. However, such methods require the incorporation of the marker material into or onto the product or its packaging and this may be undesirable, for example when the product is a fragrance, beverage or foodstuff.

It has been proposed in for example US Patent No 5,753,511 to apply a marker chemical or other reagent to the surface of a slide or other carrier. The marker undergoes an interaction, which may be chemical, physical or some other change, with one or more of the components in the fluid to be assessed to give a material which gives a specific radiation or reflectance spectrum when the carrier is exposed to IR, UV or other radiation. The term marker is used herein to denote a material which is intended to undergo an interaction with a material to be assessed so as to give a resultant material which gives a characteristic spectrum when that material is exposed to IR, UV or other radiation. By applying a plurality of different marker materials to the carrier, a plurality of interactions can take place to provide a plurality of spectra whose combination provides a unique fingerprint to characterise the fluid being tested. In this way it is possible to determine whether an ink or other fluid is the authentic product of a given manufacturer. By suitable selection of the marker materials and/or by the use of a sufficiently large number of marker materials, the determination can be made sufficiently selective to be able to detect differences between batches of supposedly identical products from the same manufacturer or between products from different sites . By applying the marker material to the carrier and applying a sample of the fluid to be assessed to the carrier, problems of contamination of the fluid by the marker material are avoided.

By testing a sample of a product initially when it is produced, the manufacturer can provide a reference spectrum for that product. By applying a sample of the fluid under assessment to a carrier carrying the same marker materials, the characteristic spectrum of that sample can be determined. Comparison of that spectrum with the reference spectrum obtained initially, will enable the manufacturer or his customer readily to determine whether the sample corresponds to the authentic material .

Such a method of authentification is described in the specification of US Patent No 5,753,115 and the subject matter of that specification is incorporated herein by reference and is denoted hereinafter as the test method.

In order to carry out the test method, a suitable marker material is applied to a suitable carrier. The preferred carrier is a glass slide, since glass is usually substantially inert to any of the fluids to be assessed and will not generate extraneous spectra which could mask or distort the spectra from the marker material/sample interaction which it is desired to observe. It is also preferred to apply the marker material to a layer of an inert absorbent material applied to the surface of the carrier so that the amount of marker material carried by the carrier and its position on the carrier can be held to within specified tolerances. Preferably, the absorbent material is particulate silica, for example fumed silica, which is secured as a layer of predetermined thickness to the underlying glass slide by means of a film of gelatin or other inert binder/adhesive.

The marker material is applied to such a silica-coated slide to achieve the desired rate of application of the marker to a given area of the plan area of the slide. If desired, the surface of the slide can be sub-divided into a plurality of discrete areas, for example by a grid of upstanding walls or ridges on the surface of the slide. Each of the discrete areas carries a single selected marker material or mixture of marker materials. By applying different marker materials to different areas, a single slide carrying a plurality of marker materials could be produced so that a plurality of spectra could be generated by applying the fluid to be assessed to the surface of that slide. This would enhance the ability of the assessment to discriminate accurately between closely related samples. However, currently proposed methods for the application of the marker material to the surface of the slide are cumbersome and slow so that commercial scale production of the slides presents a problem. Furthermore, changes of the reservoirs containing the marker materials are required to permit application of different marker materials to a single slide, which is time consuming and may lead to mis-alignment of the application of the marker material to the carrier. A continuous ink jet printer is a non-contact technique by which closely controlled droplets of a fluid can be accurately applied to a substrate. Prima facie, such a technique would seem suitable for applying the marker material to the slide or other carrier or to the absorbent layer on such a carrier. However, we have found that the use of a conventional continuous jet ink jet printer produces test slides which perform erratically. This would preclude the use of such printers to apply the marker materials to the slides or other carriers, especially where the carrier carries an absorbent layer.

We have found that the erratic performance is due to uneven application of the marker materials over the plan area of the slide and scattering of the re-radiated or reflected radiation. Where the marker fluid is applied directly to the surface of the carrier, this surface will usually be a non-absorbent surface and spattering and uneven film formation on the surface may occur. This will result in uneven application of the marker material and possible contamination of adjacent areas of the surface of the carrier to which different marker materials have been applied. Where the marker material is carried in an absorbent layer applied to the carrier, we have found that the layer is disturbed by the application of the droplets of the marker material .

We have further found that these problems are due to the fragility of the absorbent layer and the excessive kinetic energy in the droplets when they strike the surface of the carrier or the absorbent layer. We have found that these problems can be reduced by selecting the ink jet printer and/or modifying its design and/or operation so that the kinetic energy of the droplets has a sufficiently low value to avoid significant disturbance of the absorbent layer or spattering of the marker material . Such a modification is contrary to the established criteria for 10 ) M t I-¹ in o in o ϋl o Ul rr tr ft⁾ a ft⁾ tr o rr

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the resultant reduction of the rate of fluid application to the slide or other carrier is not usually detrimental and can be accepted.

It may also be desirable to vary the frequency of the piezoelectric transducer used to break up the jet of fluid into individual droplets and to use a higher frequency so as to reduce the size of droplet formed. This will often require the replacement of the piezoelectric transducer conventionally used, since this usually has an optimum frequency of operation and this cannot be significantly altered. Another factor in the operation of the printer which can be modified to reduce the kinetic energy of the droplets formed is to reduce the pressure at which the fluid is fed to the nozzle of the printer. This will reduce the volume of fluid flowing per unit time through the nozzle orifice and hence the size of droplet formed as the transducer breaks up the jet of fluid into individual droplets. The pressure required to form droplets successfully at the nozzle outlet is however dependent upon the viscosity, and hence the temperature and composition, of the fluid being ejected through the nozzle.

By suitable adjustment of each of these variables it is possible to produce droplets which have sufficiently low a kinetic energy to reduce the disruption of the absorbent layer or spattering of the marker material to an acceptable level whilst still retaining the advantages of high speed of fluid application and accuracy of placement of the droplets upon the surface of the carrier or the absorbent layer. The optimum nozzle orifice bore diameter, ink pressure, viscosity and other factors of the operation of the ink jet printer can be established by simple trial and error tests. Typically, it will be desired to reduce the kinetic energy of the droplets striking the surface of the absorbent layer or carrier to between 5 and 35, typically from 10 to 25, notably about 20, picojoules.

The invention can be applied to the application of a wide range of fluids containing a wide range of marker materials to a wide range of absorbent layers or carriers, depending upon the fluids to be sampled and the nature of the carrier and absorbent layer. The optimum form of marker fluid can readily be determined from knowledge of the chemistry of the various components of the sample, the marker material and test slide using conventional chemical and physical techniques and ingredients . Suitable marker materials and their uses are described in for example US Patent No 5,753,115 and other marker materials include those described in US Patents Noose 5,292,855, 5,336,714, 5,614,008 and 5,665,151.

Suitable fluid carrier media for the marker chemicals include water, lower alkanols, esters and ketones and mixtures thereof, notably those which are readily volatile and in which the alkyl moieties contain from 1 to 3 carbon atoms. The marker materials can be dissolved, emulsified or suspended in the carrier medium. If desired, the fluid compositions containing the marker materials can contain other ingredients to assist the jet-ability thereof and such other ingredients can be those conventionally used in ink jet formulations. For example, the composition can contain a film forming binder to aid formation of a deposit containing the marker material which is secured to the particles in the absorbent layer or to the surface of a non-absorbent carrier, and thus reduce potential migration of the marker material within the absorbent layer or upon the surface of the slide or other carrier.

The carrier and the absorbent layer can be selected from a wide range, for example from amongst those described in US Patent No 5,753,115. The carrier can be a planar glass

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Hi Ω ft⁾ ii 0 rt tr Φ 01 rt ii tf CO Φ ti φ μ- 3 Φ Φ rr ft⁾ 0 tr ti Φ Hi rt ti μ- Φ φ ft⁾ Ω ft⁾ ti Φ φ ft⁾ 01 Φ Hi rt μ- μ- 0 TJ ti 0 Hi tr Φ ø ø μ- φ ti Φ rt μ- ø i ti a tr •< 3 ti ii 01 0 ti ft⁾ ø O φ 01 ø 0 μ- rt 0 rt Φ Hi tr 01 Ω ti tr φ

Φ 3 ti Ω O Ω ti ti 0 0 01 ft⁾ μ- H tr Hi Φ rt tr μ- ^ tr μ- φ 01 φ ft⁾ a Hi Hi 0 ft⁾ Ω O O Ω Φ Hi Φ ii ø μ- O 3 Φ 3 Φ Ω ti

01 rt ø μ- μ- ft⁾ ti ø tr rt 0 Φ Hi ft⁾ t a Ω ft⁾ O φ Hi ø ft⁾ Ω < O ø rt ø Ω φ o rt 0 ti ft 01 a Φ O a O μ- r rt a ft⁾ μ- μ- ti Ω ti rt μ- Ω tr ti 10 tr 01 O ø μ-

3 3 rt μ- rt a Hi a tr tr ft⁾ Ω μ- 0 a 0 Φ 0 W CO φ O rt Φ φ » Hi Φ O Φ

0⁾ S. ≤ a tr tr rt ti ft Φ Φ tr Φ a a Hi Ω φ ≤ ø μ- IQ ≤ rt • ø • ti ft⁾ μ- 0 IQ Φ 01 φ ti φ rt μ- ti rt Φ 0 ti μ- Φ ti 0 3 μ- tr tr Hi 0 rr μ- O ft⁾ tr < μ- Φ O 10 tr rt 01 C- ø ft 0 ft⁾ 01 μ- Φ 0 ti rt

Φ TJ tr Φ Hi ø 01 Oi Φ μ- a ft 01 Hi ⁽_J. Φ φ tr 01 3 O ti rr rr ti μ] O X ti Hi 0 Ω ø μ- ft Ϊ μ- φ Φ φ ft⁾ rt ft⁾ ϋ TJ T φ φ 3 tr 3 0

0 ft⁾ 0 ft⁾ ti φ ti Ω ø 01 tr r rt 01 ft 01 φ rt tr ø ti Φ ti ft⁾ Φ φ O Hi

3 ti 0 01 3 Hi r *< ft⁾ ft⁾ !_J. Ω μ- tr φ Hi 01 Φ Φ ft 01 0 ii ii X ti 0 φ ft⁾ ft⁾ ft ii 01 Φ rr ft⁾ 0 ti Φ ti 10 Φ TJ 01 t-¹ μ- 01 ti TJ < ft⁾ X ft⁾ TJ Φ ti <! rr μ- φ ft tr Ω tr ti rt Φ tr »i 01 μ- £ ø μ- 01 rt Φ μ- 3 μ- ^ Φ 3 Φ

Φ μ- Hi 0 g^< Φ Φ Hi Φ μ- ft rt 0 μ- φ ti μ- ft⁾ TJ tr Ω ft ft⁾ rt φ ti M TJ ft⁾ ft⁾ ti ii rr Hi ti ft⁾ O Φ ti TJ Φ 01 if a r Φ o. rt ft⁾ -> φ Φ rt Φ rt tr ti i-¹ 01 ti rt - μ- •^• φ 01 TJ 0 O ti O ti TJ 01 rt 01 ft tr ^ Ω ti 01 Φ 3 Φ rt Φ tr ft⁾ ti 3 • . ti Hi 3 TJ TJ μ- ft⁾ φ 0 Φ Ω Φ Φ rt rt ti ft⁾ ti rt tr ft⁾ μ- ft⁾ Φ μ-

0 φ 0 ft⁾ μ- Φ O a ti φ ti ti 0 O ti 0 ti μ- ft⁾ μ- tr ft⁾ rt su Ω 01 rt

Hi a ti Hi a rt ft⁾ ti ti φ rt Φ ft tr ti 0 3 rt ft⁾ 3 Oi ft⁾ Φ Φ Ω

0 rt Φ 0 Ω rt tr ft⁾ rt Φ ft⁾ Φ rt Ω T O 3 tr Φ s- μ- ti Ω 3 O ft⁾ μ- ii Oi ii O φ TJ rt r 01 H o a 0 Ω ft⁾ o TJ ft⁾ Φ Hi 0 tr _— , ft⁾ ø μ- O ft⁾ Hi ti 01 μ- 3 3 tr Φ tr O Hi rt d rt 01 ^ ti Hi φ μ- 01 ti iQ ft⁾ ^ ti

3 01 0⁾ TJ TJ φ Ω 0 ft Φ O a ft⁾ ti μ- μ- Hi O rt Φ o 3 μ- £ μ- Ω ti ti ft⁾ 0⁾ ft⁾ ti Hi TJ Φ O rt ft⁾ Ω 3 rt O Φ ft⁾ . — 0 ft⁾ Φ μ-

X Φ Ω ft H, ft⁾ rt ft⁾ TJ 01 0 μ- Ω ft⁾ tr TJ 01 01 ti ti H rt rt Φ Φ 01 rt ti Hi ft tr < M • O Φ ii rr Φ Φ *— * h-¹ tr ø rt ti Φ 0 μ- μ- O tr Φ Φ • ; 0 ø tr i 0 Φ Φ ft⁾ μ- ti Φ a Hi φ rt H. Φ ti a 0 ^■3 Φ Hi 01 ti 01 ø

Φ rt ii ^• Hi 01

of marker materials simultaneously without the need to change reservoirs of marker material as with the application methods of the present proposals.

If desired, a series of arrays of print heads can be used to apply a plurality of marker materials to a single slide or other carrier. Alternatively, the slide can be transported through a series of printer stations where arrays of print heads apply marker materials to different areas of the slide successively. Such a transport mechanism could be a rotary table or an x/y movement and can be operated under microprocessor control to provide an automated operation for the application of marker materials to a slide.

The invention has been described above in terms of the application of a single marker material to a single selected area of the surface of the absorbent layer on a carrier. However, it will be appreciated that in some cases it may be possible to apply two or more marker materials to the same selected area. Furthermore, the surface to which the marker material is applied need not be absorbent, but may be structured in some other manner to define and retain the marker material within the confines of a selected area of the carrier surface. Thus, for example, the surface of the carrier may be subdivided physically by walls or the like into separate cells or areas, as is the case with an analytical cell, and the marker material applied in a binder which forms a film of the marker material upon the floor or base of the cells or areas. Such a form of construction may be desirable where the scanning of the test slide to which a sample of the fluid to be assessed is to be viewed in a conventional automated sample analysis machine.

The invention also provides an apparatus for applying a fluid containing a marker material for use in the test method, which apparatus comprises a mechanism for moving a carrier, upon which the marker material is to be applied, relative to an application mechanism by which a predetermined amount of the marker material is to be applied to a selected area of the carrier or a surface layer carried by the carrier, characterised in that the application mechanism comprises a continuous ink jet printer which has been selected and/or whose design and/or operation has been modified so that the kinetic energy of the droplets from the printer striking the carrier or surface are reduced to a level at which any spattering of the droplets or disturbance of the surface layer are reduced to an acceptable level .

Preferably, the kinetic energy of the droplets is less than 40 picojoules, e.g. 8 to 40 picojoules.

It will be appreciated that the ink jet printer for present use may have been manufactured ab initio specifically for use in the method of the invention. In such a case the printer design and its operation will have been selected to ensure the desired low level of kinetic energy for the droplets. The term selected as used herein is therefore to be construed to include printers which have been designed and manufactured ab initio to meet the requirements of the present invention, as well as conventional printers which have been selected as suitable for present use because, co-incidentally, they produce droplets having sufficiently low a kinetic energy for present use.

The term acceptable is used herein in relation to the spattering of the marker material and disturbance of the surface layer carried by the carrier to denote that any such spattering or disturbance which may occur does not produce spectral information from inspection of the sample which cannot be used in the test method. The level of distortion which may be acceptable in any given case is readily determined by simple trial and error tests.

Claims

CLAIMS :

1. A method a method for applying a marker material as hereinbefore defined to a surface of a carrier so as to form deposits of a predetermined amount of one or more marker materials at one or more predetermined locations upon the surface of the carrier to which a sample of a product to be assessed can be applied so as to interact with the marker material in the deposit to provide a characteristic spectrum upon radiation of the predetermined location with IR, UV or other radiation, characterised in that a selected amount of the marker material is applied as a fluid to a selected area of the surface of the carrier or of a layer carried by the carrier using a continuous ink jet printer apparatus which has been selected and/or whose operation and/or design has been modified so that the droplets of fluid striking the surface or the surface layer do not cause an unacceptable level of disturbance of the layer and/or of scattering of the applied marker material upon the surface of the carrier.

2. A method as claimed in claim 1, characterised in that the kinetic energy of the droplets is less than 40 picojoules.

3. A method as claimed in claim 2, characterised in that the kinetic energy of the droplets is from 8 to 35 picojoules.

4. A method as claimed in any one of the preceding claims, characterised in that the carrier is a planar glass strip or slide.

5. A method as claimed in any one of the preceding claims, characterised in that the carrier has an absorbent layer applied to a face thereof and the marker material is applied to that layer. ι UJ to to " μ> in o in o in o in ft⁾ ft⁾ TJ ti Ω s: TJ TJ μ- 01 3 01 3 μ> μ- 0 H

TJ ft⁾ TJ ii Φ ft⁾ tr ti ti ø ft) o O 0 ft⁾ μ> ø O

TJ ^>< TJ Φ ^• _*-> ti μ- Φ O rt 3 Ω ti rt • •

Φ ft ft⁾ ti Ω ft <! Φ TJ ft⁾ Φ ft⁾ Φ ft⁾ μ- i μ- Φ rt μ- tr Φ μ- ti rt 01 ti 1—1.

Ω φ rt μ- φ rt ft ft⁾ Φ μ- 3 μ- ≥ φ 3 > ft⁾ Ω ft Φ <! ti ft⁾ Φ φ Ω O ft⁾ rt ft⁾ TJ rt ft⁾ rt ft⁾ ti Φ TJ ti rt 0 0 ti O -> TJ ti 3 μ- ti rt 3 TJ 3 0⁾ 01 X ft⁾ TJ Φ o ϋ O μ- rt 0 ft⁾ μ- S φ 0⁾ ii i φ rt ø μ- ø O TJ ti 0 Ω μ- 0⁾ 0 ti 0 01 ft⁾ μ- ti tr φ ft⁾ Φ O ft⁾ Φ tr rt TJ ti rt ø 0

3 ft ft ft⁾ a rt Oi 0⁾ tr TJ o 3 3 tr ø rt 3 i φ 01 0 ø ti ti 0 ft⁾ Φ 01 Φ ft⁾

Ω tr Φ ft⁾ ≤ 01 oi rt O rt ft ii ii rt ft⁾ tr ^ 3 ft⁾ tr o Ω tr 9 ft Φ Φ Φ Hi Φ 01

0⁾ Φ O TJ μ- Ω Ω ft Φ 0 tr ti TJ μ- O 01 ti ø rt Ω 0 TJ Ω 0 ft⁾ φ Ω Φ μ- 0 ii ø μ- Ω μ- tr rt 0 tr rt ti 3 rt fl⁾ 01 & tr ft⁾

01 Φ Φ rt μ- TJ μ- μ- ft⁾ 01 μ- φ ft⁾ 01 ft⁾

3 Oi Ω rt ti 0 01 ti rt 0 01 rt Hi TJ rt μ-

Ω O ft⁾ tr μ- 0 rr Ϊ 0 ti 01 0 TJ ft⁾ rt 3

Ω ft⁾ ft⁾ rt Φ 01 μ- Φ ft⁾ ti ø 0 Φ

O ϋ ti μ- Φ ≤ Ω ϋ tr ft⁾ rt O Φ ^ rt ft

M ti Φ rt O 3 01 μ- φ Ω μ- μ- rt

TJ μ- ft⁾ tr ø ft⁾ rt 01 3 Φ O ft ø ft⁾ tr μ- ti Φ Φ ti ft⁾ tr TJ ft⁾ ft⁾ 0 0⁾ Φ IQ \-> Φ ø μ- ti O 3 X Φ r 01 0 Φ

01 - 3 φ φ 3 H Ω Φ 01 TJ μ- ft⁾ ^ 01 Ω

Φ ft⁾ Ω H φ rt ti φ 0 ti

K tr Ω * ø 0

01 Ω rt H μ- 01 rt ti Φ Φ Hi ft⁾ ti ft⁾ tr tr X ft⁾ 3 tr ø ft⁾ 01 tr ft ft 01 Hi μ- ft⁾ ft⁾ φ Φ ø ft⁾ ft⁾ 3 Φ Φ 3 Φ 0 ft⁾ 3 ii ti μ- rt ø < ft O rt rt μ- tr Ω

Ω ft⁾ Ω 01 Φ μ- 0 μ- Ω ti Φ 0 ft Φ Φ μ>

0 Ω ft⁾ 3 3 ti 01 0 TJ ø Ω ft⁾ Φ ti ti

0 rt ti ft⁾ μ- 3 ti o 0⁾ ti 3 ft⁾ Ω Φ O ft Φ ti rt σ 0⁾ 0 rt ø ti TJ μ- 0 μ- O μ- ii μ- Φ ^• O tr μ- ti ø 01 ø ti ø μ- Φ ti O rt ti φ tr Φ Φ φ ø rt & ft⁾

0 01 ti μ- μ- ti tr ft⁾ Φ ti ft ft ti ft⁾ φ ft⁾

0 Φ ft> tr 01 φ ft ft Φ μ- Ω TJ ø ft O μ- 3 ti μ- Φ ft⁾ rt rt ft⁾ ft⁾ ø 0 ft⁾ TJ

01 ii Ω rr O ft⁾ TJ TJ O Φ 3 Ω μ- i Ii μ- μ- tr O <! ti rt o TJ ti O Φ ø Φ ti * : μ- ø ft⁾ 01 μ- ft⁾ μ- 01 ≤ 3 0 iQ μ- μ-

0 ft⁾ tr 0 Oi 0 μ- μ- tr μ- 0 0 o. Φ ø rt 01 rt Φ to μ- 0 rt φ μ- ø rt Hi 0⁾ Φ ti CO tr 0 0 ft⁾ ft Ω Φ 01 oi ti oi rt rt 0 rt tr ft O ft⁾ 3 Ω ø φ r tr TJ tr μ- Hi O 01 ft⁾ ti 01 ti rt ft⁾ Φ TJ Φ 0 0 ft⁾ Ω ti μ- μ- 0 rt Ω -^y 0 rt 0 ft⁾ t ø TJ tr Φ μ- tr ft⁾ 0 H Φ Φ IQ r-¹ φ Φ Φ 01 φ ti ft φ ft μ- ft⁾ rt rt 0 Φ ø 01 O ti ti

printer which has been selected and/or whose design and/or operation has been modified so that the kinetic energy of the droplets from the printer striking the carrier or surface are reduced to a level at which any spattering of the droplets or disturbance of the surface layer are reduced to an acceptable level .

12. Apparatus as claimed in claim 11, characterised in that the kinetic energy of the droplets is less than 40 picojoules.