Methods and devices for generating high-amplitude and high-frequency focused ultrasound with light-absorbing materials
View Patent ↗A high-frequency light-generated focused ultrasound (LGFU) device is provided. The device has a source of light energy, such as a laser, and an optoacoustic lens comprising a concave composite layer with a plurality of light absorbing particles that absorbs laser energy, e.g., carbon nanotubes, and a polymeric material that rapidly expands upon exposure to heat, e.g., polydimethylsiloxane. The laser energy is directed to the optoacoustic lens and thus can generate high-frequency (e.g., ≧10 MHz) and high-amplitude pressure output (e.g., ≧10 MPa) focused ultrasound. The disclosure also provides methods of making such new arcuate optoacoustic lenses, as well as methods for generating and using the high-frequency and high-amplitude ultrasound, including for surgery, like lithotripsy and ablation.
1. A high-frequency light-generated focused ultrasound (LGFU) device, comprising:
a source of light energy; and
an arcuate optoacoustic lens comprising a composite layer that comprises a plurality of light absorbing particles and a dielectric material having a coefficient of volume thermal expansion greater than or equal to about 1×10 −5 ×K −1 ; wherein when the light energy is directed to the arcuate optoacoustic lens it is capable of generating focused ultrasound having a frequency of greater than or equal to about 10 MHz and an output pressure of greater than or equal to about 1 MPa.
2. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the arcuate optoacoustic lens is a concave lens.
3. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the arcuate optoacoustic lens has a geometrical design with an f-number (f#) of less than or equal to about 1.
4. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the composite layer has a depth of optical absorption less than or equal to about 30 μm.
5. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the light absorbing particles absorb greater than or equal to about 50% to less than or equal to about 100% of the light energy directed at the optoacoustic lens.
6. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the light absorbing particles comprise carbon nanotubes, graphene oxide, or combinations thereof.
7. The high-frequency light-generated focused ultrasound (LGFU) device of claim 6 , wherein the light absorbing particles are coated with an electromagnetic absorption material comprising gold.
8. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the dielectric material is a polymer comprising polydimethylsiloxane.
9. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the optoacoustic lens has a focal spot of about 75 μm in a lateral dimension and about 400 μm in an axial dimension, when the source of light energy is a laser having a pulse width less than or equal to about 10 ns, a repetition rate of greater than or equal to about 10 Hz, and greater than or equal to about 10 mJ of laser energy per pulse.
10. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the coefficient of volume thermal expansion greater than or equal to about 5×10 −4 K −1 .
11. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the light absorbing particles are axially shaped particles.
12. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein composite layer is substantially free of carbon black particles.
13. The high-frequency light-generated focused ultrasound (LGFU) device of claim 1 , wherein the output pressure of the focused ultrasound is greater than or equal to about 40 MPa.
14. A method of generating a high-frequency and high-amplitude focused ultrasound, the method comprising:
directing light energy at an arcuate optoacoustic lens that comprises a composite layer comprising a polymeric material and a plurality of light absorbing particles, wherein the composite layer has a depth of optical absorption less than or equal to about 30 μm, to generate a focused ultrasound having a frequency of greater than or equal to about 10 MHz and an output pressure of greater than or equal to about 1 MPa.
15. The method according to claim 14 , wherein the arcuate optoacoustic lens is a concave lens having a geometrical design with an f-number (f#) of less than or equal to about 1.