Michiel PostemaProfessor of Experimental Acoustics

KIOGE, Almaty 2012

INSTITUTT FOR FYSIKK OG TEKNOLOGI

Using ultrasound to separate oil, gas, and water

• bubble radius ~ mm

• no-slip interfaces: stable

• film drainage: very slow

Foam and froth decay

In this talk:

• I am going to explain what a foam is;

• I am showing how to get rid of foam;

• I am going to to show how to force coated bubbles in a liquid to form a foam.

Postema M, et al. Ultrasound-induced microbubble coalescence. UMB 2004 30(10):1337–1344.

What is a foam?

Postema M, et al. Ultrasound-induced encapsulated microbubble phenomena. UMB 2004 30(6):827–840.

Expanding bubble coalescence

30 × 30 (µm)²

21 × 21 (µm)²

30 × 30 (µm)²

30 × 30 (µm)²

Postema M, et al. Ultrasound-induced microbubble coalescence. UMB 2004 30(10):1337–1344.

Bubble coalescence within 1 microsecond

High-speed microscopy

Historic cameras

• cameras– 8 – 128 frames– Max. speed (Mfps)

1. 0.001 (Redlake)2. 15 (Brandaris)3. 100 (Imacon 468)

– 10 – 330 ns exposure

• ultrasound– 1 – 10 cycles– 0.5 & 1.7 MHz– P- = 0.04 – 0.85 MPa

Jetting

24 µm bubbleJet 0,33 µs later

60 fl jet volume

Postema M et al. IEEE T UFFC 2002(3):c1; Postema M et al. Med Phys 2005 32(12):3707–3711.

Transducer Manufacture

Multiple Piezo elementsdiced from the same wafer

Transducer Manufacture

Elements lapped down to thickness using slurry of Al2O3 in water

Ag paint for electrode

UV tape as form keeper

Very light S-38 microballoon filled epoxy backing

Pr e

s su r

e

Time

-60 kPa

+60 kPa

2 µs

Microbubbles in an ultrasound field

Postema M et al. Ultrasound-induced encapsulated microbubble phenomena. UMB 2004 30(6):827–840.

• 88 × 58 (µm)² area

• Tx=0.5 MHz, MI=0.09

• Equilibrium radius 6 µm

Microbubble resonance frequencies

Postema M, Hiltawsky KM, Schmitz G. Ultraschallkontrastmittel – Grundlegende Überlegungen. In: Molecular Imaging – Innovationen und Visionen in der medizinischen Bildgebung; Niederlag W, Lemke HU, Semmler W, Bremer C, Eds. Dresden: Health Academy 2006 (1):131–146.

• 88 × 58 (µm)² area/frame• Tx=0.5 MHz, MI=0.67• Equilibrium diameter = 4 µm

Fragmentation

Postema M et al. Presented at Erasmus MC, 2002.

Acoustic tablet smashing

Postema M, Smith AJ. Tablet Processing Unit. UK patent application GB0820586.6 2008; international publication number WO/2010/055337.

• 46 × 30 (µm)² area, solid shell

• Tx = 1.7 MHz, PNP 1.5 MPa

Postema M, et al. Med Phys 2005 32(12):3707-3711.

Sonic cracking

Radiation forces

Kotopoulis S, Postema M. Microfoam formation in a capillary. Ultrasonics 2010 50(2):260–268.

Radiation forces

Kotopoulis S, Postema M. Microfoam formation in a capillary. Ultrasonics 2010 50(2):260–268.

Conclusions

• We have been able to drive microbubbles through saturated fluids, forcing the bubbles to cluster and form microfoams at equal distances.

• These microfoams were then driven out of the fluid.

• Ultrasound-assisted separation is a cheap technique that may have applications on a much bigger scale.

Summary of phenomena

Postema M, Gilja OH, van Wamel A. CEUS and sonoporation. In: Postema M. Fundamentals of Medical Ultrasonics. London: Spon Press 2011 205–217.

Diffusion

Postema M et al. Nitric oxide delivery by ultrasonic cracking: some limitations. Ultrasonics 2006 44:e109–e113.

• 40 × 40 (µm)² areas• Tx=0.5 MHz

• ≈ 1.1/8 kg s–2

= r+t+v+s

Postema M, de Jong N, Schmitz G. The physics of nanoshelled microbubbles. Biomed Tech 2005 50(S1):748-749.

Elastic bubbles

Phase difference petween P(t) and R(t)

Postema M, Schmitz G. Ultrasonic bubbles in medicine: influence of the shell. Ultrason Sonochem 2007 14(4):438–444.