The quarter-wavelength (λ/4) acoustic matching layer is a vital component in medical ultrasonic transducers, which can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. At high frequencies (>50MHz), the λ/4 matching layers become extremely thin and the characterization of its properties becomes very challenging. We report a novel method to measure the phase velocity and attenuation of ultra-thin layers using the λ/4 matching principle. The method has been successfully used to measure a 14.6μm Epo-Tek 301 epoxy film on glass substrate and a 9.5μm sol-gel silicon oxide colloidal/polymer composite film on Si substrate.
All Science Journal Classification (ASJC) codes
- Acoustics and Ultrasonics