Fluidic device with integrated capacitive micromachined ultrasonic transducers

• US 6,854,338 B2
• Filed: 07/12/2001
• Issued: 02/15/2005
• Est. Priority Date: 07/14/2000
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: Khuri-Yakub, Butrus T., Degertekin, F. Levent
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US09/905,087
• Publication Number:
  US 20020083771A1
• Time in Patent Office: 1,314 Days
• Field of Search: 738/612.7, 738/613.1, 738/612.6, 738/612.8, 738/612.9, 736/44, 736/42, 736/32, 735/99, 731/182, 347/54, 347/20, 347/68
• US Class Current: 73/861.27
• CPC Class Codes: B01F 31/85 with a vibrating element inside the receptacle
• CPC Class Codes: B01F 33/30 Micromixers
• CPC Class Codes: G01F 1/662 Constructional details
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01N 2291/011 Velocity or travel time
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/017 Doppler techniques
• CPC Class Codes: G01N 2291/018 Impedance
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/02872 Pressure
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• 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 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004

Abstract

The present invention provides fluidic devices and systems which have micromachined ultrasonic transducers integrated into microchannels. The ultrasonic transducers generate and receive ultrasonic waves. The transducers can be disposed and operated to measure fluid characteristics such as pressure, density, viscosity, flow rate and can also be used to mix and pump fluids.

Claims

1. A fluidic device comprising.

at least one microchannel, and

at least one capacitive micromachined ultrasonic transducer formed in one wall of said microchannel.

2. A fluidic device as in claim 1 in which the microchannel dimensions in the range 1 μ

m to 500 μ

m or more.

3. A fluidic device comprising:

a base of semiconductor material,

at least one capacitive micromachined ultrasonic transducer formed in said base of semiconductor material, and

a top having a microgroove sealed to said base with the microgroove over the ultrasonic transducer whereby to form a microchannel with an ultrasonic transducer in on wall of said channel.

4. A fluidic device as in claim 3 in which the microchannel has dimensions in the range of 1-500 μ

m.

5. A fluidic device as in claim 4 including at least two longitudinally spaced transducers and said top has its microgroove oriented both of said transducers.

6. A fluidic device as in claim 5 including a process for operating said ultrasonic transducers to measure the time-of-flight of ultrasound in the direction and the opposite direction of fluid flow and provide a measure of fluid velocity.

7. A fluidic device as in claim 5 including a processor for driving said ultrasonic transducers to generate Stoneley waves for pumping fluid in said channels.

8. A fluidic device as in claim 4 in which said microgroove includes a compliant membrane which is disposed opposite said ultrasonic transducer.

9. A fluidic device as in claim 8 in which a processor operates said transducer to generate ultrasonic pulses which are reflected by said membrane and processes the pulse and echo signal to measure the pressure of the fluid in said microchannel.

10. A fluidic device as in claim 9 including a plurality of ultrasonic transducers and membranes spaced along the channel to thereby measure the pressure drop along the channel.

11. A fluidic device as in claim 4 including a processor for said ultrasonic transducer to emit pulses which echo off the opposite wall and process the pulse and echo signals to provide a measure of the acoustic impedance of the fluid in said microchannel.

12. A flexible device as in claim 11 including a processor configured to process signals to and from said ultrasonic transducer and providing an output indicative of pressure.

13. A fluidic device as in claim 4 including a processor for operating said ultrasonic transducer to emit pulses and set ultrasonic resonance whereby to measure fluid properties or for counting particles in said fluid.

14. A fluidic device as in claim 4 in which the base is silicon or a dielectric material.

15. A fluidic device as in claim 4 in which the micromachined ultrasonic transducer is operated to mix fluids in the channel.

16. A fluidic device comprising.

at least one microchannel having opposed walls,

at least one capacitive micromachined ultrasonic transducer micromachined into one wall, and

a flexible membrane on the opposite wall opposite the ultrasonic transducer whereby ultrasonic waves from the ultrasonic transducer are reflected back to the transducer by the flexible membrane.

17. A fluidic device comprising.

a silicon base,

one or more capacitive micromachined ultrasonic transducers formed into said base, and

a top having a microgroove sealed to said base with the microgroove over said capacitive micromachined ultrasonic transducers.

18. A fluidic device as in claim 17 including at least two capacitive micromachined transducers spaced along said channel.

19. A fluidic device as in claim 17 including a processor for operating said transducers in a pulse echo mode.

20. A fluidic device as in claim 18 including a processor for operating said transducers to receive ultrasonic pulses from one another.

21. A fluidic device as in claim 19 in which said microgroove includes a compliant membrane opposite said ultrasonic transducer.

22. A fluidic device as in claim 18, including a processor for operating the micromachined ultrasonic transducer to mix fluids in the channel.

23. A fluidic device as in claim 17 in which the ultrasonic transducer is operated to pump fluids in said channel.

24. A fluidic device as in claim 17 in which said ultrasonic transducer is operated to measure fluid characteristics.