Microsensor with a well having a membrane disposed therein

• US 7,438,851 B2
• Filed: 04/30/2004
• Issued: 10/21/2008
• Est. Priority Date: 01/24/2001
• Status: Expired due to Term

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Brown, Richard B., Hower, Robert W.
• Primary Examiner(s): Noguerola; Alex
• Application Number:
  US10/837,067
• Publication Number:
  US 20040202583A1
• Time in Patent Office: 1,635 Days
• Field of Search: 257/253, 20440301-40315, 422 55- 60
• US Class Current: 422/552
• CPC Class Codes: B01L 3/5085 for multiple samples, e.g. microtitration plates
• CPC Class Codes: G01N 2035/1037 Using surface tension, e.g. pins or wires
• CPC Class Codes: Y10T 436/25 including sample preparation

Abstract

A micromachined device such as a solid-state liquid chemical sensor for receiving and retaining a plurality of separate liquid droplets at desired sites, a method of making the device and a method of using the device are provided. The technique works for both aqueous and solvent-based solutions. The device includes a substrate having an upper surface, and a first set of three-dimensional, thin film well rings patterned at the upper surface of the substrate. Each of the wells is capable of receiving and retaining a known quantity of liquid at one of the desired sites through surface tension. A method for patterning a membrane/solvent solution results in reproducibly-sized, uniformly-thick membranes. The patterning precision of this method allows one to place the membranes closer together, making the sensors smaller and less expensive, and the uniform film thickness imparts reproducibility to the sensors. The final film thickness can be controlled over a 3 to 50 micron range, and lateral dimensions can be as small as 20 microns using conventional materials. The simple patterning steps can be done on full wafers in a mass fabrication process. A second set of well rings may be photo-patterned at the same time as the first set of well rings to isolate functional groups on top of ion-selective membrane.

Claims

1. A microsensor, comprising:

a substrate;

a thin-film well having a thin-film structure disposed on the substrate; and

a membrane disposed in the well wherein the membrane includes a portion that extends over the thin-film structure and wherein a shape of an outside profile of the well allows surface tension to contain the membrane in the well.

2. The microsensor as claimed in claim 1, wherein the membrane extends beyond a volume defined by a height of the thin-film structure above the substrate and an area within the thin-film structure.

3. The microsensor as claimed in claim 2, wherein the membrane is retained through surface tension.

4. The microsensor as claimed in claim 3, wherein the thin-film structure includes a side wall having an outside corner with a small radius.

5. The microsensor as claimed in claim 4, wherein the substrate comprises a semiconductor substrate.

6. A microsensor, comprising:

a substrate;

a well having a thin-film structure disposed on the substrate;

a membrane disposed in the well wherein the membrane includes a portion that extends over the thin-film structure; and

a second well and a second membrane disposed in the second well such that the second membrane extends over the first-named membrane.

7. A microsensor, comprising:

a substrate;

a well having a thin-film structure disposed on the substrate wherein the thin-film structure is patterned to define a wall;

a membrane disposed in the well and having a peripheral portion limited by the thin-film structure; and

wherein the peripheral portion of the membrane extends beyond the wall to cover the thin-film structure and wherein a shape of an outside profile of the well allows surface tension to contain the membrane in the well.

8. The microsensor as claimed in claim 7, wherein the membrane extends beyond a volume defined by a height of the thin-film structure above the substrate and an area within the thin-film structure.

9. The microsensor as claimed in claim 8, wherein the membrane is retained through surface tension.

10. The microsensor as claimed in claim 9, wherein the thin-film structure includes a side wall having an outside corner with a small radius.

11. The microsensor as claimed in claim 10, wherein the thin-film structure comprises an epoxy.

12. The microsensor as claimed in claim 11, wherein the substrate comprises a semiconductor substrate.

13. A microsensor, comprising:

a substrate;

a well having a thin-film structure disposed on the substrate wherein the thin-film structure is patterned to define a wall;

a membrane disposed in the well and having a peripheral portion limited by the thin-film structure;

wherein the peripheral portion of the membrane extends beyond the wall to cover the thin-film structure; and

a second well and a second membrane disposed in the second well such that the second membrane extends over the first-named membrane.

14. A microsensor, comprising:

a substrate;

a well having a thin-film structure disposed on the substrate wherein the thin-film structure is patterned to define a vertical wall and a top; and

a membrane disposed in the well wherein a shape of an outside profile of the well allows surface tension to contain the membrane in the well and limit the membrane from flowing past the vertical wall wherein the membrane covers the top of the thin-film structure.