High sensitivity tunable radio frequency sensors

• US 9,464,994 B2
• Filed: 07/29/2014
• Issued: 10/11/2016
• Est. Priority Date: 07/30/2013
• Status: Active Grant

• Current Assignee: Clemson University
• Original Assignee: Clemson University
• Inventors: He, Yuxi, Sun, Jiwei, Wang, Pingshan, Cui, Yan, Moline, David
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): YENINAS, STEVEN LEE
• Application Number:
  US14/445,433
• Publication Number:
  US 20150035546A1
• Time in Patent Office: 805 Days
• Field of Search: 73/617.5, 738/61, 324/637, 324/638, 324/639, 324/641, 324/642, 324/646, 324/653, 324/659, 324/663, 324/667, 324/692, 324/693, 333/17.1, 333/174, 333/176, 333/235, 356/338, 356/451, 356/452, 356/453, 356/454, 356/455, 356/477, 356/478, 356/479, 356/480, 356/481, 435/7.24, 435/34, 435/287.1, 435/287.2, 435/288.7
• US Class Current: 1/1
• CPC Class Codes: G01B 9/02 Interferometers
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/1006 for cytology
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode

Abstract

Highly sensitive and tunable RF sensors that provide detection and analysis of single cells and particles are provided. The tunable RF sensors are configured as tunable interferometers, wherein cells or particles to be analyzed are passed through a channel, such as a microfluidic channel, across waveguides corresponding to reference and test branches of the interferometers. A network analyzer coupled to the interferometers can be configured to measure a plurality of scattering parameters, such as transmission scattering coefficients (S₂₁) of the reference and test branches, to evaluate characteristics of cells passing through the channel. A plurality of tunable interferometers may be employed, each interferometer operating in different frequency bands such that information obtain from the plurality of interferometers may be combined to provide further information.

Claims

1. An RF sensor for a material under test, comprising:

a plurality of interferometers, each interferometer comprising one or more fluidic channels each disposed across a reference branch and a test branch;

the reference branch comprising a first waveguide and the test branch comprising a second waveguide;

a first port associated with each of the plurality of interferometers, the first port configured to separate signals between a first transmission line and a second transmission line, the first transmission line operable to provide a reference RF signal to the first waveguide and the second transmission line operable to provide a test RF signal to the second waveguide;

a second port associated with each of the plurality of interferometers, the second port configured to recombine signals from the first transmission line and the second transmission line;

a signal analyzer coupled to the first port and the second port of each of the plurality of interferometers, the signal analyzer operable to measure one or more scattering parameters;

wherein each of the plurality of interferometers is associated with a different frequency band range.

2. The RF sensor of claim 1, wherein the signal analyzer is operable to provide RF energy associated with a different frequency band to each of the plurality of interferometers.

3. The RF sensor of claim 1, wherein the plurality of interferometers comprise a first interferometer associated with a frequency band of 20 MHz to 1 GHz, a second interferometer associated with a frequency band of 1 GHz to 18 GHz, and a third interferometer associated with a frequency band of 18 GHz to 40 GHz.

4. The RF sensor of claim 1, wherein the one or more scattering parameters comprise a voltage gain transmission coefficient |S₂₁|.

5. The RF sensor of claim 1, wherein the one or more fluidic channels comprise a microfluidic channel or a nano-fluidic channel.

6. The RF sensor of claim 1, wherein the one or more fluidic channels comprise gold.

7. The RF sensor of claim 1, wherein the first transmission line and second transmission line comprise one or more tuning elements coupled in series with the respective first and second waveguides.

8. The RF sensor of claim 7, wherein the one or more tuning elements comprise an attenuator circuit.

9. The RF sensor of claim 7, wherein the one or more tuning elements comprise a phase shift circuit.

10. The RF sensor of claim 1, wherein the test RF signal has a 180°

phase difference relative to the reference RF signal.

11. The RF sensor of claim 10, wherein each interferometer comprises two 90°

hybrid circuits.

12. The RF sensor of claim 1, wherein the signal analyzer is a variable network analyzer.

13. The RF sensor of claim 1, wherein the plurality of interferometers are selectively couplable to the signal analyzer by one or more switches.

14. The RF sensor of claim 1, wherein the material under test comprises a biological cell.

15. The RF sensor of claim 1, wherein the first waveguide and the second waveguide are coplanar waveguides.

16. The RF sensor of claim 1, wherein the first waveguide and the second waveguide are microstrip waveguides.

17. The RF sensor of claim 1, wherein the signal analyzer comprises one or more processors and a display, the one or more processors operable to provide a waveform associated with the one or more scattering parameters for display on a display device.