3D photoacoustic computed tomography(3D-PACT)has made great advances in volumetric imaging of biological tissues,with high spatial-temporal resolutions and large penetration depth.The development of 3D-PACT requires h...3D photoacoustic computed tomography(3D-PACT)has made great advances in volumetric imaging of biological tissues,with high spatial-temporal resolutions and large penetration depth.The development of 3D-PACT requires high-performance acoustic sensors with a small size,large detection bandwidth,and high sensitivity.In this work,we present a new high-frequency 3D-PACT system that uses a microring resonator(MRR)as the acoustic sensor.The MRR sensor has a size of 80μm in diameter and was fabricated using the nanoimprint lithography technology.Using the MRR sensor,we have developed a transmission-mode 3D-PACT system that has achieved a detection bandwidth of~23 MHz,an imaging depth of~8 mm,a lateral resolution of 114μm,and an axial resolution of 57μm.We have demonstrated the 3D PACT’s performance on in vitro phantoms,ex vivo mouse brain,and in vivo mouse ear and tadpole.The MRR-based 3D-PACT system can be a promising tool for structural,functional,and molecular imaging of biological tissues at depths.展开更多
Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-...Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-wavelength dielectric metasurfaces are highly desirable because they can facilitate fabrication and integration with both electronics and mechanically tunable platforms.Unfortunately,because their constitutive phase-shifter elements exhibit strong electromagnetic coupling between neighbors,the design requires a global optimization methodology that considers the non-local interactions.Here,we propose a global evolutionary optimization approach to inverse design non-local metasurfaces.The optimal designs are experimentally validated,demonstrating the highest efficiencies for the thinnest transmissive metalenses reported to-date for visible light.In a departure from conventional design methods based on the search of a library of pre-determined and independent meta-atoms,we take full advantage of the strong interactions among nanoresonators to improve the focusing efficiency of metalenses and demonstrate that efficiency improvements can be obtained by lowering the metasurface filling factors.展开更多
基金sponsored by American Heart Association Collaborative Sciences Award (18CSA34080277)the United States National Institutes of Health (NIH)grants R21EB027981,R21 EB027304,RF1 NS115581 (BRAIN Initiative),R01 NS111039,and R01 EB028143+2 种基金Chan Zuckerberg Initiative Grant (2020-226178),all to J.YaoNIH grant P41GM135018 was awarded to H.Zhang and C.Sunsupported by the U.S.Department of Energy,Office of Science,under Contract No.DEAC02-06CH11357.
文摘3D photoacoustic computed tomography(3D-PACT)has made great advances in volumetric imaging of biological tissues,with high spatial-temporal resolutions and large penetration depth.The development of 3D-PACT requires high-performance acoustic sensors with a small size,large detection bandwidth,and high sensitivity.In this work,we present a new high-frequency 3D-PACT system that uses a microring resonator(MRR)as the acoustic sensor.The MRR sensor has a size of 80μm in diameter and was fabricated using the nanoimprint lithography technology.Using the MRR sensor,we have developed a transmission-mode 3D-PACT system that has achieved a detection bandwidth of~23 MHz,an imaging depth of~8 mm,a lateral resolution of 114μm,and an axial resolution of 57μm.We have demonstrated the 3D PACT’s performance on in vitro phantoms,ex vivo mouse brain,and in vivo mouse ear and tadpole.The MRR-based 3D-PACT system can be a promising tool for structural,functional,and molecular imaging of biological tissues at depths.
基金This work was performed at the Center for Nanoscale Materials,a U.S.Department of Energy Office of Science User Facility,and supported by the U.S.Department of Energy,Office of Science,under Contract No.DE-AC02-06CH11357This research used resources of the National Energy Research Scientific Computing Center,a U.S.Department of Energy Office of Science User Facility,supported by the U.S.Department of Energy,Office of Science,under Contract No.DE-AC02-05CH11231.
文摘Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-wavelength dielectric metasurfaces are highly desirable because they can facilitate fabrication and integration with both electronics and mechanically tunable platforms.Unfortunately,because their constitutive phase-shifter elements exhibit strong electromagnetic coupling between neighbors,the design requires a global optimization methodology that considers the non-local interactions.Here,we propose a global evolutionary optimization approach to inverse design non-local metasurfaces.The optimal designs are experimentally validated,demonstrating the highest efficiencies for the thinnest transmissive metalenses reported to-date for visible light.In a departure from conventional design methods based on the search of a library of pre-determined and independent meta-atoms,we take full advantage of the strong interactions among nanoresonators to improve the focusing efficiency of metalenses and demonstrate that efficiency improvements can be obtained by lowering the metasurface filling factors.
