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US 6,199,257 B1Granted
Method of making a flow cell for light absorption measurement of small volume samples
AssigneeThermo Separation Products Inc.
InventorsMiner Nelson Munk, Douglas Alan Perry, Brian Robert Said
Life of this patent
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Abstract
A process for making a flow cell having an internal flow passage of a material having a refractive index less than that of water or having the internal walls of the flow passage coated or otherwise covered with such a material is provided. The flow cell so produced substantially totally internally reflects light along the cell bore.
Claims13
A process for making a flow cell for light absorption measurement comprising the steps of:
- forming a predetermined thickness of a material having an index of refraction lower than that of water around a process tool having a predetermined diameter and a controlled surface smoothness such that the surface smoothness, inner diameter, and wall thickness of said material are consistently controlled;
- removing said process tool intact from said material leaving a flow passage through said material, said flow passage including first and second ends;
- and
- positioning first and second light transmission devices through which light is directed adjacent said first and second ends of said flow passage such that said material internally reflects at least about 80% of the light directed into said flow passage.
1 more element
A process for making a flow cell for light absorption measurement comprising the steps of:
- providing a housing for said flow cell, said housing having an inner cavity and an inner wall which accepts said flow cell, said housing further having a first end and a second end and wherein said housing comprises a hollow tube including a polytetrafluoroethylene outer layer and a copolymer of tetrafluoroethylene and hexafluoropropylene inner layer;
- coating a predetermined thickness of a material having an index of refraction lower than that of water around the exterior surface of a mandrel having a predetermined diameter and a controlled surface smoothness such that the surface smoothness, inner diameter, and wall thickness of said material are consistently controlled;
- internally coating said inner wall of said housing with said material by placing said externally coated mandrel into said inner cavity of said housing, causing said material to adhere to said housing inner wall;
- removing said mandrel intact from said cavity thereby leaving said material adhered to said inner wall of said housing and forming said flow cell with a flow passage having an inlet and an outlet through which a liquid phase sample to be analyzed is directed;
- and
- positioning first and second light transmission devices through which light is directed adjacent said first and second ends of said flow passage such that said material internally reflects at least about 80% of the light directed into said flow passage.
3 more elements
A process for making a flow cell for light absorption measurement comprising the steps of:
- providing a housing for said flow cell, said housing having an inner cavity and an inner wall which accepts said flow cell, said housing further having a first end and a second end and wherein said housing comprises a hollow tube including a polytetrafluoroethylene outer layer and a copolymer of tetrafluoroethylene and hexafluoropropylene inner layer;
- coating a predetermined thickness of a material having an index of refraction lower than that of water around the exterior surface of a mandrel having a predetermined diameter and a controlled surface smoothness such that the surface smoothness, inner diameter, and wall thickness of said material are consistently controlled;
- internally coating said inner wall of said housing with said material by placing said externally coated mandrel into said inner cavity of said housing, causing said material to adhere to said housing inner wall;
- removing said mandrel intact from said cavity thereby leaving said material adhered to said inner wall of said housing and forming said flow cell with a flow passage having an inlet and an outlet through which a liquid phase sample to be analyzed is directed;
- and
- positioning first and second light transmission devices through which light is directed adjacent said first and second ends of said flow passage such that said material internally reflects at least about 80% of the light directed into said flow passage, and wherein said step of causing said material to adhere to said housing wall comprises applying heat to said housing to shrink said outer layer of polytetrafluoroethylene and melt said inner layer of said copolymer of tetrafluoroethylene and hexafluoropropylene.
3 more elements
Dependencies are inferred from the claim text.