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Accurate Sizing of Monodisperse Microbubble Suspensions by Optical Attenuation Spectroscopy
Martin R P van den Broek1, Hidde G Sikkema1, Niladri S Satpathi1
1BIOS/Lab on a Chip Group, Max Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute for Nanotechnology, Faculty of Electrical Engineering, Mathematics & Computer Science, University of Twente, Enschede, The Netherlands.
Ultrasound in Medicine & Biology
|November 1, 2025
Summary
Optical attenuation spectroscopy (OAS) accurately sizes microbubbles, offering a new standard for ultrasound contrast agents. This label-free method provides rapid and precise measurements, outperforming traditional techniques.
Area of Science:
- Biophysics
- Acoustics
- Materials Science
Background:
- Accurate microbubble sizing is essential for comparing ultrasound contrast agent models with experimental data.
- A definitive gold standard method for microbubble sizing is currently lacking.
Purpose of the Study:
- To introduce and validate optical attenuation spectroscopy (OAS) as a precise method for sizing monodisperse microbubble suspensions.
- To compare the accuracy of OAS with established sizing techniques.
Main Methods:
- Optical attenuation spectroscopy (OAS) was employed using a spectrophotometer to obtain optical attenuation spectra.
- A Mie scattering model was fitted to the spectra to determine modal bubble radius and polydispersity.
- OAS sizing results were compared against Coulter Counter, brightfield microscopy, and fluorescence microscopy.
Main Results:
- OAS measurements demonstrated excellent agreement (±1.5%) with fluorescence microscopy.
- Coulter Counter overestimated microbubble radius by 4-11% compared to OAS.
- Brightfield microscopy consistently overestimated radius by 0.45 μm relative to fluorescence microscopy.
Conclusions:
- Optical attenuation spectroscopy (OAS) is a versatile, convenient, and label-free method for sizing microbubble suspensions.
- OAS offers rapid data acquisition within seconds.
- OAS presents a viable alternative to current microbubble sizing methods.
