Intravascular ultrasound imaging apparatus, interface architecture, and method of manufacturing
Solid-state ultrasound imaging devices, systems, and methods are provided. Some embodiments of the present disclosure are particularly directed to compact and efficient ultrasound transducer scanner formed from a substantially cylindrical semiconductor substrate. In some embodiments, an intravascular ultrasound (IVUS) device includes: an ultrasound scanner assembly disposed at a distal portion of the flexible elongate member, the ultrasound scanner assembly including a semiconductor substrate having a plurality of transistors formed thereupon. The semiconductor substrate is curved to have a substantially cylindrical form when the ultrasound scanner assembly is in a rolled form, and the plurality of transistors are arranged in a cylindrical arrangement when the ultrasound scanner assembly is in the rolled form. In one such embodiment, the device further includes a plurality of ultrasound transducers formed upon the semiconductor substrate and arranged in a cylindrical arrangement when the ultrasound scanner assembly is in the rolled form.
1. An ultrasound imaging device, comprising:
a flexible elongate member configured to be positioned within a vessel of a patient; and
an ultrasound scanner assembly disposed at a distal portion of the flexible elongate member and including a silicon substrate, the silicon substrate comprising a plurality of transistors and a plurality of ultrasound transducers formed thereupon, the silicon substrate comprising a first end and an opposite, second end,
wherein the silicon substrate is curved to have a substantially cylindrical form when the ultrasound scanner assembly is in a rolled form such that the first end and second end are adjacent to one another, wherein the silicon substrate is continuous around a circumference of the substantially cylindrical form between the first and second ends,
wherein the plurality of transistors are arranged in a cylindrical arrangement when the ultrasound scanner assembly is in the rolled form, and
wherein a thickness of the silicon substrate renders the silicon substrate flexible to be curved into the substantially cylindrical form.
2. The device of claim 1 , wherein the plurality of transistors includes transducer control circuitry and the plurality of ultrasound transducers are formed upon the silicon substrate and electrically coupled to the transducer control circuitry, wherein the plurality of ultrasound transducers are arranged in a cylindrical arrangement when the ultrasound scanner assembly is in the rolled form.
3. The device of claim 2 , wherein each transducer of the plurality of ultrasound transducers includes a plurality of transducer elements electrically connected in parallel.
4. The device of claim 2 , wherein each transducer of the plurality of ultrasound transducers includes at least two groups of transducer elements, wherein the at least two groups of transducer elements are independently addressable by the transducer control circuitry.
5. The device of claim 2 further comprising an insulating layer formed over the plurality of transistors and the plurality of ultrasound transducers such that the insulating layer is outside the plurality of transistors and the plurality of ultrasound transducers when the ultrasound scanner assembly is in the rolled form.
6. The device of claim 2 , wherein the plurality of ultrasound transducers includes a CMUT transducer comprising:
a dielectric material formed over the silicon substrate;
a vacuum gap formed within the dielectric material;
a diaphragm formed over the vacuum gap; and
an electrode formed over the diaphragm.
7. The device of claim 6 , wherein the diaphragm, the vacuum gap, and the silicon substrate have a combined thickness of less than or substantially equal to 10 μm.
8. The device of claim 6 , wherein the vacuum gap has a thickness substantially equal to 0.1 μm.
9. The device of claim 6 , wherein the diaphragm has a thickness substantially equal to 1 μm.
10. The device of claim 6 , wherein the plurality of ultrasound transducers includes a piezoelectric micromachined ultrasound transducer (PMUT) comprising:
a chamber formed within the silicon substrate; and
a piezoelectric film formed over the chamber.
11. The device of claim 10 , wherein the piezoelectric film and the silicon substrate have a combined thickness of between approximately 5 μm and approximately 10 μm.
12. The device of claim 1 , wherein the plurality of transducer elements includes CMUT transducer elements.
13. The device of claim 1 , wherein the plurality of transducer elements includes thin-film piezoelectric transducer elements.
14. The device of claim 1 , wherein the silicon substrate further includes germanium.
15. The device of claim 14 , wherein the thickness of the silicon substrate is less than or substantially equal to 10 μm as measured when the ultrasound scanner assembly is in a flat form.
16. The device of claim 1 , wherein the ultrasound scanner assembly further includes a ferrule disposed within the substantially cylindrical form of the silicon substrate when the ultrasound scanner assembly is in the rolled form.
17. The device of claim 16 further comprising an epoxy disposed between the ferrule and the silicon substrate.
18. The device of claim 16 , wherein the ferrule includes an inner lumen adapted to pass a guide wire.
19. The device of claim 1 , wherein the plurality of transistors each includes a gate structure and a gate width direction extending along a longitudinal axis of the substantially cylindrical form.