P2L-4 Ultrasonic Detection and Quantitative Analysis of Microscopic Bubbles and Particles in Solution: Enhanced by Attenuation Compensation

In many technical and medical applications microscopic bubbles and particles play an important role. For a non-invasive and quantitative estimation of the particle characteristics acoustic properties along the path of sound propagation are of major concern. When applying clamp-on probes that can be used with a variety of tubes the compensation of the acoustic attenuation is crucial for reliable parameter estimation. In addition, the acoustic properties of the tube material vary as a function of environmental conditions. An ultrasonic probe that enabled an automated and real-time compensation for attenuation properties was under investigation. The set up employs ultrasound in pulsed wave Doppler mode to provide a higher sensitivity for moving objects. Experiments on different tubes (wall-thickness and material) were performed. Glass beads with Gaussian distributed diameters between 300 mum and 400 mum were used as bubble-phantoms. The means and standard deviations of the particle sizes were estimated from the compensated and uncompensated signals. Size estimates were in the range between 100 and 700 mum with a standard deviation of up to 100% when using uncompensated signals. Standard deviations of the estimates applying the compensation algorithm were 50% with mean values of approximately 380 mum. The described method for attenuation compensation was implemented in the bubble counter system BCC200 (GAMPT mbH, Zappendorf, Germany). It enables a precise monitoring of the occurrence of microscopic bubbles and solid particles for the application in open heart surgery and will increase the patient safety. With its performance the BCC200 can also be employed for the development of arterial filters and oxygenators in biomedical applications and for quality control in industrial applications