Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1998-09-23
2001-09-11
Tung, T. (Department: 1743)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S403060, C204S418000, C204S419000
Reexamination Certificate
active
06287438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a sampling system and to a process for its production. Systems of this type can be used simply and universally in chemical and biochemical analysis.
2. Description of Prior Art
It is known that electrochemical sensors are used to determine concentrations of substances in liquids (cf. F. Oehme: Chemische Sensoren [Chemical sensors], Vieweg Verlag, Braunschweig, 1991).
Besides individual sensors, it is also possible, with the aid of semiconductor technology, to produce continuous-flow analysis systems with integrated sensor elements (DE 44 08 352).
Continuous-flow systems of this type have the particular advantage that not only the liquid medium to be measured, but also calibration liquids can be pumped alternately through the system, so that regular calibration of the sensors is possible.
It is also known that continuous-flow analysis systems of this type can be equipped with a simple sampling device—a microdialysis needle.
Furthermore, a particularly cost-efficient mass-production technique has been introduced for the production of individual sensors (DE 41 15 414).
A disadvantage with the prior art is that continuous-flow analysis systems using silicon technology can be produced with low costs per item only if the number of items needed exceeds 100,000 per year. The same is true as regards microdialysis needles, which at the present time are still produced using skilled labour techniques.
Furthermore, the connection technique for continuous-flow sensors and microdialysis needles has not been developed to an extent such that tube and channel connections for the liquid medium to be measured can be produced, without cross-sectional widening and dead volume, with tolerable outlay.
SUMMARY OF THE INVENTION
The object of this invention is therefore to provide a sampling system which is of simple design, universally usable on its own and in combination and produceable at low cost.
This object is achieved according to the invention with the features of Claim
1
for the sampling system, and with the features of Claim
31
for the production process.
The sampling system formed according to the invention for fluid analytes or analytes contained in fluids is made of a flat support, into which various holes are introduced through which the relevant fluid can enter a channel and then leave it again. The channel is covered at least partly by a cover on the opposite side from the support. Furthermore, use is made of a membrane which is permeable to the analyte and at least partly covers the channel on the open upper side of the latter. The regions left free by the cover can be used to take up the analyte or for direct measurement there.
This being the case, there is the possibility of arranging a separate channel support between the support proper and the membrane with the cover on top. The channel may, however, also be formed directly in the support.
If a channel support is used, it is favourable to provide it with additional holes which, when the sampling system formed according to the invention has been assembled, correspond to the abovementioned holes in the support.
The sampling system formed according to the invention is of very simple design and can be used universally for a variety of measurement tasks. There is thus the possibility, on the one hand, of taking the sample, separating the analyte to be determined from the carrier fluid, and taking it for subsequent analysis.
The sampling system may, however, also be used in direct combination with sensor elements, and for example concentrations of substances in a particular analyte can be taken directly from the sampling system.
In this case, the simple design, in particular, and consequently the very cost-effective production are advantageous.
Very simple and accurate measurements can thus be taken with the sampling system according to the invention, when use is made of correspondingly formed sensor elements, together with corresponding reference electrodes.
Furthermore, calibrations can be made in simple and favourable fashion.
An example of a sample system formed according to the invention may be designed such that a support
1
having at least two holes
4
,
5
is firmly connected to a channel support
6
having at least two holes
9
,
10
and at least one channel
11
, and the channel support
6
is firmly connected to at least one membrane
12
and the membrane
12
is firmly connected to a cover
13
, and the channel
11
can be supplied through the holes
4
,
5
as well as
9
,
10
with the analyte or a carrier liquid or carrier gas which contains it and flows through this channel and can pick up the analyte which is in contact with the membrane
12
, which is permeable to this analyte, in the uncovered region
14
of the membrane
12
, and the analyte, or alternatively the carrier liquid containing it, can flow through the channel past the openings
16
,
17
which are located in the cover
13
and into which it is possible to place electrochemical or optical sensor elements with which concentrations of substances or ion activities can be measured.
The support
1
and the channel support
6
are made of a material which is inert with respect to the analyte and the carrier fluid, for example of plastic (polyvinyl chloride (PVC), polyethylene (PE), polyoxymethylene (POM), polycarbonate (PC), ethylene/propylene copolymer (EPDM), polyvinylidene chloride (PVDC), polychlorotrifluoroethylene, polyvinyl butyral (PVB), cellulose acetate (CA), polypropylene (PP), polymethyl methacrylate (PMMA), polyamide (PA), tetrafluoroethylene/hexafluoropropylene copolymer (FEP), polytetrafluoroethylene (PTFE), phenol formaldehyde (PF), epoxide (EP), polyurethane (PUR), polyester (UP), silicone, melamine formaldehyde (MF), urea formaldehyde (UF), aniline formaldehyde, capton etc.).
The support
1
may, for example, also be manufactured from glass, ceramic or silicon. The same is true as regards the channel support
6
.
The holes
4
,
5
and
9
,
10
in the support
1
and in the channel support
6
as well as the channel
11
are produced in such a way that the support
1
and/or the channel support
6
are created by injection-moulding or compression techniques or the LIGA method with these structures, or these structures are subsequently produced by cutting, stamping, milling, boring, etching, laser cutting or electric discharge machining or the like.
The typical dimensions of the support
1
are for its length, from 1 to 10 cm, for its width from 0.5 to 5 cm, and for its thickness from 0.1 to 1 mm. The same or similar values apply to the channel support
6
. The holes
4
,
5
and
9
,
10
have diameters of between 0.1 and 10 mm. The width of the channel
11
is between 0.1 and 10 mm.
The solid connection between the support
1
and the channel support
6
may, depending on the material, be made according to the prior art by adhesive bonding, welding or laminating (in the case of plastics) or adhesive bonding (in the case of glass, ceramic, silicon) or anodic bonding (in the case of glass on silicon).
For the lamination of plastic sheets, special laminating sheets are also available on the market, which can be hot-laminated (for example CODOR sheet made of polyethylene and polyester from the company TEAM CODOR, Deutschland, Marl).
The membrane
12
is, depending on the application, formed as a dialysis membrane, gas-permeable membrane, lattice or fabric of plastic fibres, paper fibres or textile fibres. Its thickness is between 10 and 1000 &mgr;m. The following materials can be used for dialysis membranes: polycarbonate, cellulose acetate, cellulose hydrate, cuprophane, thomapor, regenerated cellulose, polyacrylonitrile, polysulphone, polyamide and polymethyl methacrylate etc.
The following materials can be used for a gas-permeable membrane: polyvinyl chloride (PVC), polyethylene (PE), polyoxymethylene (POM), polycarbonate (PC), ethylene/propylene copolymer (EPDM), polyvinylidene chloride (PVDC), polychlorotrifluoroethylene, polyvinyl butyral (PVB), c
Marshall & Melhorn LLC
Noguerola Alex
Tung T.
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