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Bubble Detection Sensors for Non-conducting Liquids

Bubble Detection Sensors for Non-conducting Liquids. Craig E. Nelson - Consultant Engineer. Goals for Bubble Sensing Devices: Detect small bubbles in a small fluid channel without immersion of sensor parts in the channel Differentiate between a gas filled channel and a fluid filled channel

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Bubble Detection Sensors for Non-conducting Liquids

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  1. Bubble Detection Sensors for Non-conducting Liquids Craig E. Nelson - Consultant Engineer

  2. Goals for Bubble Sensing Devices: • Detect small bubbles in a small fluid channel without immersion of sensor parts in the channel • Differentiate between a gas filled channel and a fluid filled channel • Be sensitive to rather small gas fractions passing down the small fluid channel • Desirable Features: • Small and flat • Inexpensive • Reliable

  3. Zen – No Sensor Sensor: EIS Magnetostatic Methods: Magnetostatic Bubble Sensing – Impedance Method – 1 Coil Magnetostatic Bubble Sensing – Transformer Method – 2 Coils Magnetostatic Bubble Sensing – Gradiometer Method – 3 Coils Galvanic Contact Methods: Noble Metal Electrodic Methods Permittivity ( Capacitive ) Methods: Absolute Capacitance Differential Capacitance Mass flow Methods: Mechanical Resonance of Fluid Loaded Beams Ultrasonic Methods: Pitch – Catch Mechanical Impedance

  4. Nature of the Bubbles

  5. Nature of the Bubbles

  6. Nature of the Bubbles

  7. Nature of the Bubbles

  8. Nature of the Bubbles

  9. Electrical Impedance Bubble Sensing

  10. Electrodic Bubble Sensing Methods - MEMS

  11. Zen – No Sensor Sensor - EIS Measure the liquid electrical impedance using electrode already in place for other reasons.

  12. Capacitive Bubble Sensing Methods

  13. Mass Resonance Bubble Sensing - MEMS

  14. Optical Bubble Sensing Methods

  15. Optical Bubble Sensing Schemes Pitch – Bounce - Catch Pitch - Catch

  16. Optical Bubble Sensing – Pitch Catch Method

  17. Optical Bubble Sensing – TIR Method

  18. Optical Bubble Sensing – Pitch Catch Method Flow In Flow Out LED Photo detector This bubble detection method cannot discriminate between “all gas” and “all electrolyte”

  19. Optical Bubble Sensing – Pitch Catch Method

  20. Optical Bubble Sensing – Total Internal Reflectance ( TIR ) Method

  21. Optical Bubble Sensing – Pitch Bounce Catch Method

  22. Optical Bubble Sensing – TIR Method

  23. Effect of Target Distance and Orientation

  24. Optical Bubble Sensing – Pitch Bounce Catch Method Fiber optic path extension

  25. Critical angle In geometric optics, at a refractive boundary, the critical angle is the angle of incidence above which total internal reflection occurs. The angle of incidence is measured with respect to the normal at the refractive boundary. It is given by: where θc is the critical angle, n2 is the refractive index of the less dense medium, and n1 is the refractive index of the denser medium. This equation is a simple application of Snell’s law where the angle of refraction = 90°. Note: Total internal reflection only occurs when the incident ray is in the denser medium. If the incident ray is precisely at the critical angle, the refracted ray is tangent to the boundary at the point of incidence. For visible light traveling from glass into air (or vacuum), the critical angle is approximately 41°. For water into air (or vacuum), the critical angle is approximately 48.6°. For polycarbonate (n=1.59) into air (or vacuum), the critical angle is approximately 39°. Optical Sensing – Total Int. Reflection Method

  26. Optical Bubble Sensing – Other Geometries

  27. Optical Bubble Sensing – Other Geometries

  28. Optical Bubble Sensing – Other Geometries

  29. Optical Bubble Sensing – Other Geometries

  30. Electronics – Optical Sensing

  31. Optical Bubble Sensor Electronics - Basic

  32. Optical Bubble Sensor Electronics - Practical

  33. Optical Bubble Sensor Electronics - Practical

  34. Optical Bubble Sensor Electronics - Practical

  35. Optical Bubble Edge Detector

  36. Other Bubble Sensing Schemes

  37. Capacitive Bubble Sensing Methods

  38. Mass Resonance Bubble Sensing - MEMS

  39. Doppler Ultrasonic Bubble Sensing

  40. Ultrasonic Bubble Sensing – System Diagram

  41. Doppler Bubble Sensing – Signal Patterns

  42. Typical Ultrasonic Bubble Sensing Setup

  43. Bubble Sensing in Small Tubing - Cosense

  44. Ultrasonic Bubble Sensing - Resonance

  45. Commercial – Off – the – Shelf ( COTS ) Product Offerings

  46. Optical Sensing – Commercial Device - Hohner

  47. Ultrasonic Bubble Sensing - Introtek

  48. Ultrasonic Bubble Sensing - Zevex

  49. Optical Bubble Sensing – Erlich Industrial Dev.

  50. Optical Bubble Sensing – Optek

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