Ultrasound Transducer Simulation Page
BioSono Inc. was founded in the summer of 2007 in Silicon Valley, California. BioSono provides a cyberspace (www.biosono.com) where researchers, engineers, and students can find useful reference and educational materials, conduct acoustic simulation, post questions on design and development, and get answers. The online KLM based transducer acoustic stack simulation, which is currently free, can help you choose piezoelectric, matching and backing material, and a tuning electrical network. The output from the model includes electrical transmit impedance, acoustic receive impedance, and both the impulse and pulse-echo response. The ultrasound beam profile simulation is a free web/email based service. This simulation can provide the calculated transmitted ultrasound pressure field under certain excitation for a given transducer aperture in a number of different geometrical configurations, including circular elements (flat and concave piston), rectangular elements, linear arrays, convex arrays, and 2D arrays. The simulation is based on Field II, which is a free program that utilizes the spatial impulse response method, and has been validated by many researchers for accuracy. The calculation is too time-consuming, and it may take up to one day for the server to send the user results by email. The ultrasound wave propagation simulation is also a free web/email based service. For a given 2D space, and a given target (round or square), an .avi or .gif movie file will be generated with an either a spherical, or plane incident wave passing through it. It may take up to one day for the server to send user results by email. In addition to the web based acoustic simulation, we also provide customized, more complicated simulations, transducer, and electrical designs.
ultrasound beam simulation longitudinal view
ultrasound beam simulation cross view

Ultrasound Animation

Ultrasound wave propagation

Ultrasound wave through matching layer

Doppler Ultrasound


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Ultrasound transducer design procedure:
Center Frequency:
The center frequency of an ultrasound transducer is determined by the application. A higher frequency generates an ultrasound beam with energy that is more confined, and attenuates faster. For imaging, it means better resolution and reduced imaging depth. Back to Top
The bandwidth of ultrasound transducer is an important factor for imaging. When imaging is based on the ultrasound pulse-echo method, the bandwidth of the ultrasound transducer determines the pulse length, and thus, the axial resolution. The best axial resolution can be achieved is half of the pulse length. Normally, a transducer with a 50% bandwidth is an acceptable lower limit for B-mode imaging. Higher bandwidths correspond to heavier damping, causing a lower sensitivity. Back to Top
Geometry Size
Geometry size is determined by the target lateral resolution. For a round or square transducer shape, the lateral resolution can be calculated using our "Ultrasound Calculator". For a given depth, a focused transducer will provide a narrower beam with an increase in aperture size. If the application requires steering the beam or dynamically changing the focal depth, an array type of ultrasound transducer is necessary. Our "Beam Profile Simulation" can accurately predict the ultrasound beam from common ultrasound transducer shapes. Back to Top
Active Material Selection
If the ultrasound transducer equivalent diameter is bigger than 3~5 times of the active material thickness, the material will work in thickness mode. In thickness mode, the primary parameter to consider is a high kt. Otherwise, the parameter of interest should be k33. The second parameter to consider is the dielectric constant. Since most electronic cables and pulsers have an impedance of 50?, it is important to design a transducer that can match that same impedance to prevent loss. For a small area transducer, an active material with a higher dielectric constant is preferred. Our "Ultrasound Calculator", can quickly calculate the impedance. Back to Top
Matching and Backing
Most piezoelectric material has a high Q-factor, which is the inverse of percentage bandwidth. Backing materials can provide damping to achieve a desired bandwidth. Matching layers can also be added to improve the energy coupling between the impedance of PZT (33MRyl) and target impedance (1.5MRyl for soft tissue). Our "Transducer KLM Model Simulation" can predict the electrical impedance and transmitted or received pulse of the transducer. Back to Top
Tuning or Electrical Matching Network
The ultrasound transducer structure has a capacitive component at the center frequency. Simple tuning is to remove this capacitive element using a series, or shunt inductor. Our "Ultrasound Calculator" provides a quick value if the impedance of the transducer at center frequency is known. To match the cable and achieve best pulse shape, our "Transducer KLM Model Simulation" is best. Back to Top
Our Ultrasound Transducer Simulation or Modeling includes four parts: KLM model based transducer simulation or modeling, wave propagation, beam profile, and imaging simulation. There are three types of popular ultrasound transducer electrical equivalent models: The Mason model, The Redwood model, and The KLM model. The KLM model based simulation simulates the mechanical-electrical resonance property of the ultrasound transducer. The wave propagation simulation is based on the solution to the wave equation, and boundary conditions that model how a wave propagates and reflects when it encounters an object. Beam profile simulations predict the resolution of a transducer given a certain excitation. Imaging simulation gives simulated images from a phantom for theoretical conditions.

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