High-Q longitudinal block resonators with annexed platforms for mass sensing applications

• US 20070089519A1
• Filed: 06/09/2006
• Published: 04/26/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Ayazi, Farrokh, Hao, Zhili
• Granted Patent: US 7,819,011 B2
• Time in Patent Office: Days
• US Class Current: 73/649
• CPC Class Codes: G01H 11/08 using piezoelectric devices

Abstract

Disclosed are sensing apparatus, such as mass sensors, comprising longitudinal block resonators having annexed platforms that offer the improved mass sensitivity at micron scale, high-Q in air, simplicity of fabrication, and improved reliability. Exemplary mass sensors comprise a central block separated from a substrate. Two annexed platforms are coupled to the central block by way of two separating beams that are separated from the substrate. One or more anchors are coupled to the central block by way of support beams that are separated from the substrate by insulating material. One or more transducers are provided for actuating and sensing vibration of the central block and the annexed platforms. The transducers may employ capacitive and piezoelectric drive and sense schemes.

Claims

1. Apparatus comprising:

a central block separated from a substrate;

two annexed platforms coupled to the central block by way of two separating beams that are separated from the substrate;

one or more anchors coupled to the central block that are separated from the substrate by insulating material; and

one or more transducers for actuating and sensing vibration of the central block and the annexed platforms.

2. The apparatus recited in claim 1 wherein the sense electrode is coupled to one annexed platform and the drive electrode is coupled to the other annexed platform.

3. The apparatus recited in claim 1 wherein the transducer comprises capacitive drive and sense electrodes.

4. The apparatus recited in claim 1 wherein the transducer comprises piezoelectric drive and sense electrodes.

5. The apparatus recited in claim 1 wherein the transducer comprises piezoresistive drive and sense electrodes.

6. The apparatus recited in claim 1 further comprising:

an insulating material disposed between the substrate and the lateral anchors.

7. The apparatus recited in claim 1 further comprising a selective binding layer disposed on the annexed platforms.

8. The apparatus recited in claim 1 wherein the capacitive transducer comprises a sense electrode coupled to one annexed platform and a drive electrode coupled to the other annexed platform.

9. The apparatus recited in claim 1 wherein the piezoelectric transducer comprises a sense electrode coupled to one lateral anchor and a drive electrode is coupled to the other lateral anchor.

10. The apparatus recited in claim 1 wherein the one or more anchors are coupled along a lateral axis by way of two support beams to the central block.

11. Capacitive sensing apparatus comprising:

a central block separated from a substrate;

two annexed platforms coupled to the central block along a block axis by way of two separating beams and that are separated from the substrate;

one or more anchors coupled to the central block that are separated from the substrate by insulating material; and

one or more transducers for sensing vibration of the central block and the annexed platforms that comprise a capacitive sense electrode coupled to a first annexed platform and a capacitive drive electrode coupled to a second annexed platform.

12. The apparatus recited in claim 11 further comprising a selective binding layer disposed on the annexed platforms.

13. Piezoelectric sensing apparatus comprising:

a central block separated from a substrate;

two annexed platforms coupled to the central block along a block axis by way of two separating beams and that are separated from the substrate;

one or more anchors coupled to the central block that are separated from the substrate by insulating material;

a piezoelectric layer disposed on the central block, separating beams and anchors; and

one or more transducers for sensing vibration of the central block and the annexed platforms that comprises a piezoelectric sense electrode coupled to one anchor and a piezoelectric drive electrode is coupled to another anchor.

14. The apparatus recited in claim 13 further comprising a selective binding layer disposed on the annexed platforms.