Synchronous one-pole surface acoustic wave resonator

• US 8,960,004 B2
• Filed: 03/29/2011
• Issued: 02/24/2015
• Est. Priority Date: 09/29/2010
• Status: Active Grant

• Current Assignee: George Washington University
• Original Assignee: George Washington University
• Inventors: Zaghloul, Mona E., Ou, Hsu-Cheng
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): WEST, PAUL M
• Application Number:
  US13/075,088
• Publication Number:
  US 20120073390A1
• Time in Patent Office: 1,428 Days
• Field of Search: 735/79, 735/80, 331/154
• US Class Current: 73/579
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: H03H 9/6476 the tracks being electrically parallel

Abstract

A surface acoustic wave resonator including an input interdigital transducer (IDT), an output IDT, and a pair of gratings with each being spaced from each other by a predetermined distance and attached to a substrate. In at least one embodiment, the distance is equal to one-half of the wavelength of the acoustic wave produced by the input IDT. In a further embodiment, the surface acoustic wave further includes a polymer layer and a biomedical coating covering at least a part of the polymer layer. The surface acoustic wave resonator has uses in the mass sensor and communications fields.

Claims

1. A surface acoustic wave resonator comprising:

a substrate that is a 128°

YX LiNbO₃ crystal;

an input interdigital transducer mounted to said substrate, said input interdigital transducer having a plurality of electrode pairs;

an output interdigital transducer spaced a distance L from said input interdigital transducer and mounted to said substrate, said output interdigital transducer having a plurality of electrode pairs;

a first grating spaced the distance L from said input interdigital transducer and mounted to said substrate;

a second grating spaced the distance L from said output interdigital transducer and mounted to said substrate; and

wherein said distance L equals

2. The surface acoustic wave resonator according to claim 1, wherein

said input interdigital transducer and said output interdigital transducer have an identical number of electrode pairs;

and

said first and second gratings each include at least 15 shorted reflectors.

3. The surface acoustic wave resonator according to claim 2 having an insertion loss between 0 dB and −

5 dB.

4. The surface acoustic wave resonator according to claim 1, further comprising:

a second input interdigital transducer mounted to said substrate, said second input interdigital transducer having a plurality of electrode pairs;

a second output interdigital transducer spaced a distance L from said second input interdigital transducer and mounted to said substrate, said second output interdigital transducer having a plurality of electrode pairs;

a third grating spaced the distance L from said second input interdigital transducer and mounted to said substrate;

a fourth grating spaced the distance L from said second output interdigital transducer and mounted to said substrate; and

wherein said input interdigital transducer, said output interdigital transducer, said first grating and said second grating are aligned along a first path of the acoustic waves generated by said input interdigital transducer,

said second input interdigital transducer, said second output interdigital transducer, said third grating and said fourth grating are aligned along a second path of the acoustic waves generated by said second input interdigital transducer, and

said first path and said second path are parallel to each other.

5. The surface acoustic wave resonator according to claim 4, wherein

said first input interdigital transducer, said first output interdigital transducer, said second input interdigital transducer, and said second output interdigital transducer each have an identical number of electrode pairs;

and

said first, second, third, and fourth gratings each include at least 15 shorted reflectors.

6. The surface acoustic wave resonator according to claim 5 having an insertion loss between 0 dB and −

4 dB.

7. The surface acoustic wave resonator according to claim 4, further comprising:

a polymer layer covering said first input interdigital transducer, said first output interdigital transducer, said second input interdigital transducer, said second output interdigital transducer, said first grating, said second grating, said third grating, and said fourth grating; and

a biochemical coating over at least a part of said polymer layer.

8. The surface acoustic wave resonator according to claim 7, wherein

said polymer layer includes polyvinyl chloride, and

said biochemical coating includes gold with a plurality of analytes attached to said gold.

9. A mass sensor comprising:

a support member,

a surface acoustic wave resonator comprising

a substrate that is a 128°

YX LiNbO₃ crystal,

an input interdigital transducer mounted to said substrate to receive an input electrical signal and transmit a pair of corresponding acoustic waves within said substrate, said input interdigital transducer having a plurality of electrode pairs,

an output interdigital transducer spaced a distance L from said input interdigital transducer and mounted to said substrate to receive the acoustic waves generated by said input interdigital transducer and transmit an output electrical signal, said output interdigital transducer having a plurality of electrode pairs,

a first grating spaced the distance L from said input interdigital transducer and mounted to said substrate,

a second grating spaced the distance L from said output interdigital transducer and mounted to said substrate,

a polymer layer having a bottom surface attached to said input interdigital transducer, said output interdigital transducer, said first grating, and said second grating, and

a biochemical coating over at least a portion of a top surface of said polymer layer;

a first connector in electrical communication with said input interdigital transducer; and

a second connector in electrical communication with said output interdigital transducer; and

wherein said distance L equals

10. The surface acoustic wave resonator according to claim 9, wherein

said polymer layer includes polyvinyl chloride, and

said biochemical coating includes an analyte capture binding surface.

11. The mass sensor according to claim 9, further comprising an enclosure having

a housing connected to said first connector and said second connector, and

a cover connected to said housing, and together said housing and said cover define a cavity in which said surface acoustic wave resonator resides;

and

wherein said first connector and said second connector each include

a jack external to said housing,

a mounting member attached to said support member and extending towards a center of said enclosure from said jack;

said support member includes tracings electrically connecting each jack to the respective interdigital transducer; and

said surface acoustic wave resonator further includes a well disposed above at least said input interdigital transducer and said output interdigital transducer.

12. The mass sensor according to claim 11, wherein said well is disposed above at least one of said first grating and said second grating.

13. The mass sensor according to claim 9, further comprising a controller electrically connected to said first connector and said second connector, said controller is capable of transmitting the input electrical signal to said first connector and receiving the output electrical signal from said second connector with any difference in frequencies between the input electrical signal and the output electrical signals representing a presence of a mass.

14. The mass sensor according to claim 9, further comprising:

a chamber defining a space with a plurality of walls in which said support member and said surface acoustic wave resonator reside;

a heating member in thermal communication with said surface acoustic wave resonator;

a fan in communication with the space defined by said chamber;

a temperature sensor in said chamber; and

a controller electrically connected to said heating member and said fan.

15. The mass sensor according to claim 9, wherein said input interdigital transducer includes electrode pairs spaced such that the acoustic wave produced is between 100 MHz and 1 GHz.

16. The mass sensor according to claim 9, wherein said surface acoustic wave resonator further includes

a second input interdigital transducer mounted to said substrate to receive an input electrical signal and transmit a second pair of corresponding acoustic waves within said substrate, said second input interdigital transducer having a plurality of electrode pairs;

a second output interdigital transducer spaced a distance L from said second input interdigital transducer and mounted to said substrate, said second output interdigital transducer having a plurality of electrode pairs;

a third grating spaced the distance L from said second input interdigital transducer and mounted to said substrate;

a fourth grating spaced the distance L from said second output interdigital transducer and mounted to said substrate; and

wherein said input interdigital transducer, said output interdigital transducer, said first grating and said second grating are aligned along a first path of the acoustic waves generated by said input interdigital transducer,

said second input interdigital transducer, said second output interdigital transducer, said third grating and said fourth grating are aligned along a second path of the acoustic waves generated by said second input interdigital transducer,

said first path and said second path are parallel to each other, and

said polymer layer further covers said second input interdigital transducer, said second output interdigital transducer, said third grating and said fourth grating.

17. A mass sensor comprising:

a support member;

a support structure on which sits said support member;

a first acoustic wave resonator and a second acoustic wave resonator, each of which includes

a piezoelectric substrate that is a 128°

YX LiNbO₃ crystal,

an input interdigital transducer mounted to said substrate to receive an input electrical signal and transmit a pair of corresponding acoustic waves within said substrate, said input interdigital transducer having a plurality of electrode pairs,

an output interdigital transducer spaced a distance L from said input interdigital transducer and mounted to said substrate to receive the acoustic waves and transmit a reference output electrical signal, said output interdigital transducer having a plurality of electrode pairs,

a first grating spaced the distance L from said input interdigital transducer and mounted to said substrate, and

a second grating spaced the distance L from said output interdigital transducer and mounted to said substrate;

a first connector;

a second connector;

a third connector;

a fourth connector; and

a controller electrically connected to said first connector, said second connector, said third connector, and said fourth connector, said controller is capable of transmitting an input electrical signal to said first connector and said third connector and receiving output electrical signals from said second connector and said fourth connector with the difference in frequency in the output electrical signals representing a presence of a mass; and

wherein at least one of said first surface acoustic wave resonator and said second surface acoustic wave resonator further includes a well disposed over at least two of said input interdigital transducer, said output interdigital transducer, said first grating, and said second grating; and

said support member is connected to said first connector, said second connector, said third connector, and said fourth connector, said support member includes lines electrically connecting the following

said input interdigital transducer of said first surface acoustic wave resonator to said first connector,

said output interdigital transducer of said first surface acoustic wave resonator to said second connector,

said input interdigital transducer of said second surface acoustic wave resonator to said third connector, and

said output interdigital transducer of said second surface acoustic wave resonator to said fourth connector; and

wherein said distance L equals λ

/2.

18. The mass sensor according to claim 17, wherein

said input interdigital transducer, said output interdigital transducer, said second input interdigital transducer, and said second output interdigital transducer of said surface acoustic wave resonator and said second acoustic wave resonator each have an identical number of electrode pairs;

and

said first, second, third, and fourth gratings each include at least 15 shorted reflectors.