Ultrasonic imaging of biofilms utilizing echoes from the biofilm/air interface

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 53; no. 1; pp. 185 - 192
• Main Authors: Holmes, A.K., Laybourn-Parry, J., Parry, J.D., Unwin, M.E., Challis, R.E.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-01-2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic impedance; Acoustics; Air; Algorithms; Bacteria - isolation & purification; Biofilms; Biological and medical sciences; Biosensors; Biotechnology; Catheters; Colony Count, Microbial - methods; Echoes; Exact sciences and technology; Ferroelectric films; Film thickness; Fourier transforms; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); General equipment and techniques; Image Interpretation, Computer-Assisted - methods; Imaging; Impedance; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Methods. Procedures. Technologies; Optical films; Physics; Substrates; Surface acoustic waves; Surface topography; Thickness measurement; Topography; Transducers; Ultrasonic imaging; Ultrasonic testing; Ultrasonics, quantum acoustics, and physical effects of sound; Ultrasonography - methods; Ultrasonography, Doppler, Pulsed - methods; Various methods and equipments; Water; Fourier transformation; Fast Fourier transformation; Air coupling; Ultrasound imaging; Layer thickness; Modeling; Surface metrology; Wavelength; Acoustic impedance; Thickness measurement; Biofilm; Acoustic image; Profilometry; Ultrasound; Surface conditions
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2006.1588404

Ultrasonic imaging of biofilms in water is difficult due to the very low contrast in acoustic impedance between the biofilm and water. In this paper, biofilms exposed to moist air are scanned through the substrate in order to obtain echoes from the biofilm/air interface. A 50 MHz scanning system was used to scan 1 mm /spl times/ 1 mm areas of biofilms in a 10 /spl mu/m grid pattern. Two fast Fourier transform (FFT) based methods for enhancement of the film thickness measurement resolution are compared. Using these techniques, the surface topography of biofilms with thickness less than the acoustic wavelength can be imaged.