Liquid purification or separation – Filter – Supported – shaped or superimposed formed mediums
Reexamination Certificate
2001-07-10
2004-11-02
Fortuna, Ana (Department: 1723)
Liquid purification or separation
Filter
Supported, shaped or superimposed formed mediums
C210S500270, C204S403060, C204S409000, C204S410000, C204S415000, C422S050000
Reexamination Certificate
active
06811037
ABSTRACT:
DESCRIPTION
The invention relates to a sensor- and/or separating element comprising a membrane arrangement which can be used in particular for the separation of substances and for the detection of molecules in sensor elements as part of separating devices for chemical substances or as part of electrochemical measuring cells and can be used preferentially for chemical analysis in biotechnology and industrial process control.
The invention further relates to a process for the production of the aforesaid sensor- and/or separating element and the use thereof.
As part of an electrochemical measuring cell for the separation of gas molecules and detection in a three-electrode system, DE 3 841 621 C2 has disclosed polymer membranes arranged on support bodies with channels of 50-300 &mgr;m length disposed at a distance from the edge of 5 &mgr;m, said polymer membranes conventionally being polymer membranes used for semi-permeable oxygen diffusion. They are characterised by the fact that the support body consists of metals or plastics with a conductive surface coating. This design is also characterised by an electrolyte which is arranged in the channel structures and together with the metallized or conductive surface forms the three-phase boundary vis-a-vis electrolytic gas.
Similar arrangements comprising a metallic support body as electrode are described in U.S. Pat. No. 3,767,552.
Another device comprising support bodies of the previously mentioned type which form capillaries or capillary-like openings is described in DE 4 018 597 and U.S. Pat. No. 5,202,011. These known arrangements are characterised by solid support structures with relatively long channels between a polymer covering layer and further elements of electrochemical measuring cells. As such solid, voluminous support bodies have a poor molecule-separating capacity, no applications have previously been described for these.
Additionally, DE 41 15 414 C2 has disclosed a sensor- and/or separating element for the semi-permeable diffusion of molecules comprising a mechanically stable substrate having a a through-opening and the semi-permeable membrane arranged in the through-opening. This publication has also disclosed a process for the production of a separating- and/or sensor element wherein a through-opening is formed in a substrate by a processing means, a semi-permeable membrane is introduced into the through-opening and a plurality of electric terminals connected to the membrane are formed.
As here the semi-permeable membrane is formed in the through-openings in that a liquid is introduced therein, from which liquid an ion-selective membrane then forms, relatively thick membranes are obtained which substantially fill the depth of the through-openings very limited. The diffusion capacity is consequently very limited. To improve the diffusion capacity it is necessary to reduce the thickness of the substrate and the cross-sectional area of the through-openings. The possible extent of such a reduction is however dependent upon the particular materials used and therefore such a reduction is possible only to a very limited extent since the stability and durability of the semi-permeable layer and the overall structure are impaired by such a reduction.
Finally, WO 91/11710 A1 has disclosed a sensor- and/or separating element for the semi-permeable diffusion of molecules comprising a mechanically stable substrate having a through-opening and a perforated, semi-permeable membrane connected to the substrate. This document also discloses a process for the production of a sensor- and/or separating element wherein a through-opening is formed in the substrate by a processing means, a semi-permeable membrane is applied to the substrate in such manner that the through-opening is spanned and a plurality of electric terminals are formed.
As in this known sensor- and/or separating element the semi-permeable membrane spans the through-openings, the membrane must be relatively thick if it is to span the relatively large-area through-openings in a stable manner or the cross-sectional area of the through-openings must be relatively small if the membrane is to be made relatively thin. In either case a mutual dependency exists between the nature of the membrane material, the cross-sectional area of the through-openings and the minimum thickness of the membranes with which adequate stability and durability of the membrane across the through-openings are provided. In practice, as in the case of the above described sensor- and/or separating element according to DE 41 15 414 C2, these conditions lead to a relatively low diffusion throughput with relatively limited stability and fairly limited durability of the semipermeable layer.
The object of the present invention is in particular to provide a sensor- and/or separating element of the type mentioned in the introduction which, while providing excellent mechanical stability and durability of the semi-permeable layer, permits a substantially increased diffusion of the molecules to be detected and/or separated.
This object is achieved in accordance with the invention by a sensor and/or separating element for the semi-permeable diffusion of molecules comprising the following:
a) a mechanically stable substrate having at least one through-opening,
b) a perforated membrane which is fluid tightly connected to the substrate and which extends at least across the through-openings; and
c) at least one semi-permeable layer which is applied in firmly adhering manner to one or both sides of the membrane at least in the perforated region thereof in that the semi-permeable layer or semi-permeable layers is/are secured mechanically in the adjacent perforations and/or by chemical-structural and/or physical adhesion and/or adhesive intermediate layers and/or covalent surface bonding to the adjacent surfaces of the membrane, optionally of the substrate or a metallic film optionally additionally applied to one or both sides of the membrane.
In this way the invention provides a sensor- and/or separating element which permits the throughputs of molecules to be varied and adjusted as desired by means of a practically arbitrary selection of the size and spacing of the perforations of the membrane to which the semi-permeable layer is applied.
Such a sensor- and/or separating element facilitates the provision of a membrane which serves as support membrane for the semi-permeable layer or layers and which is an ultra-thin membrane whose thickness preferably ranges between 50 &mgr;m and 10 nm, particularly preferably between 20 &mgr;m and 100 nm.
Preferably, depending upon its embodiment, the sensor- and/or separating element according to the invention is designed in such manner that
A) the semi-permeable layer preferably is a polymer layer, more perferably it consists of one or more organic polymers which is/are preferably adherent or adhesive-like and/or
B) the substrate and the membrane are made of similar or different materials from the group consisting of mechanically stable, inorganic and organic materials; and/or
C) the substrate and the membrane are made of similar or different organic polymers; and/or
D) the organic polymers are from the group consisting of polycarbonate, polystyrene, polytetrafluoroethylene and polyamide; and/or
E) the material of the membrane differs from the material of the substrate in respect of its processibility by a predetermined chemical and/or physical processing means, such that the substrate can be removed by the processing means whereas the membrane substantially cannot be attacked by the processing means; and/or
F) the membrane preferably consists of silicon, one or more silicon compounds and/or a material containing silicon and/or another semiconductor material, and particularly preferably the membrane consists of silicon dioxide, silicon nitride, silicon oxynitride, glass and/or quartz, while the substrate consists of a material which can be chemically converted into the membrane material or can be coated with the membrane material in firmly adhering manner; and/or
G) the perforations ha
Burns Doane Swecker & Mathis L.L.P.
Fortuna Ana
Fraunhofer-Fesellschaft zur Forderung Derangewandten Forschung E
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