Nanochannel filter

• US 5,234,594 A
• Filed: 06/12/1992
• Issued: 08/10/1993
• Est. Priority Date: 06/12/1992
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture, the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Tonucci, Ronald J., Justus, Brian L.
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US07/897,628
• Time in Patent Office: 424 Days
• Field of Search: 210/500.26, 210/496, 210/510.1, 264/49
• US Class Current: 210/500.26
• CPC Class Codes: B01D 39/2003 Glass or glassy material
• CPC Class Codes: B01D 63/061 Manufacturing thereof
• CPC Class Codes: B01D 63/066 with a porous block having membrane coated passages
• CPC Class Codes: B01D 67/0058 by selective elimination of components, e.g. by leaching
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/04 Tubular membranes
• CPC Class Codes: B01D 71/04 Glass
• CPC Class Codes: G01N 2030/528 Monolithic sorbent material
• CPC Class Codes: G01N 30/466 with separation columns in parallel
• CPC Class Codes: G01N 30/60 Construction of the column
• CPC Class Codes: G01N 30/6043 in parallel
• CPC Class Codes: G01N 30/6069 with compartments or bed substructure

Abstract

The present invention provides a wafer-like glass filter having channels therethrough having an average diameter of less than 1 micron, and further provides methods of making the filter.

Claims

1. A method for forming a filter comprising the steps of:

inserting acid etchable glass rods into respective inert hollow glass tubes;

heating said rods and tubes to fuse each respective rod to a respective tube;

drawing each of said fused rods and tubes to reduce the diameter of the rods and tubes to thereby form a filament;

stacking a plurality of said filaments together to form a stack of filaments;

heating the stack of filaments to fuse the filaments together to form an elongated bar having a plurality of channels filled with etchable glass;

drawing said bar until each of the channels has a diameter of less than 1 micron;

cutting the elongated bar to form a wafer-like filter;

annealing the filter at an elevated temperature; and

acid etching the etchable glass in the wafer-like filter to form channels therethrough having an average diameter of less than about 1 micron.

2. A method according to claim 1, wherein the tubes are hexagonal in cross-section and the matrix has a hexagonal close-packed configuration.

3. A method according to claim 1, wherein the etchable glass has a rate of etching 10⁵ to 10⁷ as great as the rate of etching of the inert glass.

4. A glass filter made according to the method of claim 1.

8. A glass filter made according to the method of claim 1.

5. A method for forming a filter comprising the steps of:

stacking acid etchable glass filaments with acid inert glass filaments to form a stack of filaments having an oriented array of acid etchable glass filaments;

heating the stack of filaments to fuse the filaments together to form an elongated bar having a plurality of channels filled with etchable glass;

drawing said bar until each of the channels has a diameter of less than 1 micron;

cutting the elongated bar to form a wafer-like filter;

annealing the filter at an elevated temperature; and

acid etching the etchable glass in the wafer-like filter to form channels therethrough having an average diameter of less than about 1 micron.

6. A method according to claim 5, wherein said filaments are hexagonal in cross-section and the filter has a hexagonal close-packed configuration.

7. A method according to claim 5, wherein the etchable glass has a rate of etching 10⁵ to 10⁷ as great as the rate of etching of the inert glass.

9. A method according to claim 5, wherein said filaments are selected from round, aquare, and semicircular cross-sectional shapes and said filter has a configuration selected from hexagonal and aquare close packed configurations.

10. A method according to claim 5, wherein the etchable glass has a rate of etching 10⁵ to 10⁷ as great as the rate of etching of the inert glass.

11. A glass filter made according to the method of claim 5.