Optical imaging and phototherapy in deep tissues face notable challenges due to light scattering. We use encoded acoustic holograms to generate three-dimensional acoustic fields within the target medium, enabling instantaneous and robust modulation of the volumetric refractive index, thereby noninvasively controlling the trajectory of light. Through this approach, we achieved a remarkable 24.3% increase in tissue heating rate in vitro photothermal effect tests on porcine skin. In vivo photoacoustic imaging of mouse brain vasculature exhibits an improved signal-to-noise ratio through the intact scalp and skull. These findings demonstrate that our strategy can effectively suppress light scattering in complex biological tissues by inducing low-angle scattering, achieving an effective depth reaching the millimeter scale. The versatility of this strategy extends its potential applications to neuroscience, lithography, and additive manufacturing.

Wearable ultrasound has been widely developed for long-term, continuous imaging without the need for bulky system manipulation and repeated manual locating. To potentially lead to more accurate and reliable imaging monitoring, this work presents the design, fabrication, and evaluation of a novel high-frequency wearable ultrasound array belt (WUAB) for small animal echocardiography. The fabrication process involved precise dicing technology for a λ-pitch design. The 20 MHz WUAB consists of two matching layers, piezoelectric composite with 128 channels, customized flexible circuit substrate, acoustic backing layer, and customized belt structure with designed end tip and insertion point for wearability. The resulting WUAB demonstrates sensitivity of -5.69 ± 2.5 dB and fractional bandwidth of 57 ± 5 %. In vivo experiments on rat model showed expected echocardiography and B-mode images of rat heart. These results represent significant promise for future longitudinal studies in small animals and real-time physiological monitoring.

Medical ultrasound technology provides zero-radiation, non-invasive, high-penetration and high-resolution evaluation of body organs for diagnosing various diseases. However, challenges remain for emerging ultrasonic bioelectronics in terms of novel material exploration, structural flexibility, wearable integration. Here, we present a 64-channel lead-free ultrasound line imaging array transducer developed from biofriendly potassium sodium niobate-based ceramics, which enables wearable multimodal imaging through the incorporation of multilevel material structure engineering and flexible device design. On the materials engineering aspect, the lead-free ceramics exhibits superior piezoelectricity (d₃₃ ~ 630 pC N⁻¹, k₃₃ ~ 0.66) by restoring long range ferroelectric ordering and suppressing excessive polar nanoregions. In terms of device architecture, the miniaturized array integrates 64 lead-free 1-3 piezo-elements on a flexible printed circuit board and a bioadhesive hydrogel layer for acoustic coupling and robust adhesion to the skin, enabling portable, high-precision operation with a center frequency of 8.36 MHz and a −6 dB bandwidth of over 40%. In wearable applications for the human body, this array demonstrates real-time high-resolution vascular imaging, blood flow dynamics, and elastography of muscle dynamics, advancing the next generation of wearable ultrasound technologies.

Large aperture 2D arrays benefit from improved lateral resolution at depth, due to the dependence of beamwidth on the inverse of the aperture width, and improved contrast resolution due to electronic focusing. We have been developing modular large aperture multi-row 1,024 (64 azimuth × 16 elevation) element, 2D arrays based on custom-designed and locally integrated Application Specific Integrated Circuit (ASIC) multiplexing devices. The implemented handheld large array prototype probe for human imaging consists of multiple rows with multiplexed synthetic aperture in elevation and planewave transmits in azimuth. The pitch of the acoustic array is 650 μm in azimuth by 1,000 μm in elevation, with a 2.4 MHz (FBW=88%) center frequency and total active aperture of 42 mm × 16 mm. We interfaced the large aperture array and multiplexing ASICs, along with local preamplifier devices for improved sensitivity, and a local FPGA for digital ASIC control, to a configurable ultrasound imaging platform and demonstrate 2D orthogonal and full 3D-beamformed imaging. The implemented imaging prototype includes local buffering for improved sensitivity of the high impedance 2D array elements, and realizes penetration down to 140 mm, experimental lateral/axial resolution at 67 mm of 1.1 mm/0.4 mm, and maximum experimental CNR of 2.1 for 8 mm cylindrical cysts, and 1.7 for 10 mm spherical cysts. We demonstrate in-vivo imaging of liver in human volunteers utilizing a hermetically-sealed and safety-validated handheld prototype of the large 2D array. Preliminary results are promising for clinical imaging in future studies.

Liposomes possess the potential to enhance drug solubility, prolong the duration of circulation, and augment drug accumulation at the tumor site through passive and active targeting strategies. However, there is a lack of studies examining the in vivo tumor penetration capabilities of liposomes of varying sizes, which hampers the development of drug delivery systems utilizing liposomal nanocarriers. Here, we present an indocyanine green (ICG)-loaded liposomes-assisted photoacoustic computed tomography (PACT) for directly evaluating the tumor penetration ability of liposomal nanocarriers in vivo. Through the utilization of microfluidic mixing combined with extrusion techniques, we successfully prepare liposomes encapsulating ICG in both large (192.6 ± 8.0 nm) and small (61.9 ± 0.6 nm) sizes. Subsequently, we designed a dual-wavelength PACT system to directly monitor the in vivo tumor penetration of large- and small-size ICG-encapsulated liposomes. In vivo PACT experiments indicate that ICG-loaded liposomes of smaller size exhibit enhanced penetration capability within tumor tissues. Our work presents a valuable approach to directly assess the penetration ability of liposomal nanocarriers in vivo, thereby facilitating the advancement of drug delivery systems with enhanced tumor penetration and therapeutic efficacy.

Ultrasound A-scan is an important tool for quantitative assessment of ocular lesions. However, its usability is limited by the difficulty of accurately localizing the ultrasound probe to a lesion of interest. In this study, a transparent LiNbO₃ single crystal ultrasound transducer was fabricated, and integrated with a widefield fundus camera to guide the ultrasound local position. The electrical impedance, phase spectrum, pulse-echo performance, and optical transmission spectrum of the ultrasound transducer were validated. The novel fundus camera-guided ultrasound probe was tested for in vivo measurement of rat eyes. Anterior and posterior segments of the rat eye could be unambiguously differentiated with the fundus photography-guided ultrasound measurement. A model eye was also used to verify the imaging performance of the prototype device in the human eye. The prototype shows the potential of being used in the clinic to accurately measure the thickness and echogenicity of ocular lesions in vivo.