Multi-dimensional transducer array and beamforming for ultrasound imaging
The electrodes for a CMUT are split to provide separate transmit and receive bias and alternating current electrodes. The transmit electrodes of different elements are interconnected, such as rows sharing bias and columns sharing transmit alternating signals. The bias is used to select an aperture in elevation, and only a sufficient number of transmit beamformer channels to use the selected aperture are needed. On receive, the full multi-dimensional array may be used with integrated beamformer electronics.
1. An ultrasound transducer for medical imaging, the ultrasound transducer comprising:
a multi-dimensional array of elements, each of the elements comprising at least one capacitive membrane ultrasound transducer cell having a membrane over a cavity and having at least first and second electrically isolated electrodes on a same side of the cavity, third and fourth electrically isolated electrodes on another same side of the cavity opposite the first and second electrically isolated electrodes;
a first electrical interconnection connecting the first electrodes along a first direction of the multi-dimensional array such that different elements spaced along the first direction are electrically connected together; and
a second electrical interconnection connecting the second electrodes along a second direction, different than the first direction, of the multi-dimensional array such that different elements spaced along the second direction are electrically connected together.
2. The ultrasound transducer of claim 1 further comprising integrated beamforming electronics within a substrate, the capacitive membrane ultrasound transducer cells being on or in the substrate, the fourth electrodes connected with the integrated beamforming electronics such that the fourth electrodes for each element are electrically isolated from other elements.
3. The ultrasound transducer of claim 2 wherein the first electrical interconnection connects with a transmit bias source and wherein the second electrical interconnection connects with a receive bias source.
4. The ultrasound transducer of claim 2 wherein the third electrodes connect with a transmit beamformer, the elements in columns connecting to common channels of the transmit beamformer.
5. The ultrasound transducer of claim 1 further comprising a third electrical interconnection connecting the third elements along the first direction of the multi-dimensional array such that different elements spaced along the first direction are electrically connected together.
6. The ultrasound transducer of claim 1 wherein the first electrical interconnection comprises a signal trace bridging over the second electrode at each cell, an insulation material separating the signal trace and the second electrode.
7. The ultrasound transducer of claim 1 wherein the first electrode is along an outer edge of the membrane and the second electrode is at a center of the membrane.
8. The ultrasound transducer of claim 1 wherein the first electrical interconnection connects with a transmit bias source and wherein the second electrical interconnection connects with a receive bias source.