In-Air Fault Detection for Medical Ultrasonic Transducers
Ultrasound transducers are regularly used in medical clinics but their performance is known to deteriorate over time. Causes of this image quality degradation can include delamination between layers, physical breakage of components, short circuits and weakening crystals. Regular diagnostics on a weekly basis, for example, should be performed but current phantom and electrical test methods are time consuming and expensive. A potential alternative involves the analysis of reverberation patterns for a transducer operating in-air, but this approach requires detailed modeling.
Xi Engineering Consultants with Sheffield Teaching Hospitals NHS Foundation Trust have developed 2D and 3D COMSOL Multiphysics® models for a medical ultrasound transducer. These models take advantage of the MEMS Module to simulate a linear array of PZT crystals, backing, matching and lens layers. The propagation of both longitudinal and transverse waves through the transducer are captured at an excitation frequency of 4 MHz. The extension of this technique into 3D allows us to consider more realistic geometries and failure modes. By modeling common transducer defects we can predict the reverberation pattern produced by an in-air test, providing the basis for rapid and low-cost fault detection.
