Cellulose, as a component of green plants, becomes attractive for fabricating biocompatible flexible functional devices but is plagued by hydrophilic properties, which make it easily break down in water by poor mechanical stability. Here we report a class of SiO₂-nanoparticle-decorated bacteria-cellulose meta-skin with superior stability in water, excellent machining property, ultrathin thickness, and active bacteria-repairing capacity. We further develop functional ultrasonic metasurfaces based on meta-skin paper-cutting that can generate intricate patterns of ~10 μm precision. Benefited from the perfect ultrasound insulation of surface Cassie-Baxter states, we utilize meta-skin paper-cutting to design and fabricate ultrathin (~20 μm) and super-light (<20 mg) chip-scale devices, such as nonlocal holographic meta-lens and the 3D imaging meta-lens, realizing complicated acoustic holograms and high-resolution 3D ultrasound imaging in far fields. The decorated bacteria-cellulose ultrasonic metasurface opens the way for exploiting flexible and biologically degradable metamaterial devices with functionality customization and key applications in advanced biomedical engineering technologies.

Portal hypertension is a serious symptom of chronic liver diseases, which can lead to many critical complications, such as the formation of varices related to upper digestive bleeding, ascites, infection, hepatic encephalopathy, renal failure, and even death. As a result, portal pressure monitoring has important prognostic and clinical implications. The hepatic venous pressure gradient measurement, a gold-standard method applied to monitor portal pressure, is invasive and only available in experienced centers. Over the past decade, noninvasive methods aimed at monitoring the portal pressure have been increasingly investigated, including serum markers, radiological features, ultrasound elastography, doppler and contrast-enhanced ultrasonography. In this study, we focused on both invasive and noninvasive methods for portal pressure monitoring and explored their roles in clinical setting. The advantages and limitations of various techniques for future research are also discussed.

Contactless manipulation of particles and cells using sound radiation forces that can be tuned and adjusted in real time has become important in various applications. These applications include display technology, biomedical sensors, imaging devices, and diagnostic tools. Phononic crystals have many properties that could be beneficial for tunable manipulation in a microfluidic channel. We use phononic crystals to tune sound fields in a microfluidic channel for controllable manipulation of microparticles and cells. An arbitrary stop-and-go motion of particles and cells along a predefined path in the channel is experimentally demonstrated. Analytical and computational modeling reveals how the resonances of phononic crystals tune the sound fields and radiation forces for the desired manipulations. These concepts and realizations of dynamic manipulation of particles in the microfluidic channel advance the development of the microfluidic channel for dynamic acoustic manipulation technologies, particularly benefiting tunable cell analysis.

Microbubbles are considered a promising tool for noninvasive estimation of local blood pressure. It is reported that the subharmonic scattering amplitude of microbubbles decreases by 9 to 12 dB when immersed in the media under an ambient pressure variation from 0 to 180 mmHg. However, the pressure sensitivity still needs to be improved to satisfy clinical diagnostic requirements. Here, we investigated the effects of acoustic parameters on the pressure sensitivity of microbubbles through measuring the acoustic attenuation and scattering properties of commercially available SonoVue microbubbles. Our results showed that the first harmonic, subharmonic, and ultraharmonic amplitudes of microbubbles were reduced by 6.6 dB, 10.9 dB, and 9.3 dB at 0.225 mechanical index (MI), 4.6 dB, 19.8 dB, and 12.3 dB at 0.25 MI, and 18.5 dB, 17.6 dB, and 12.6 dB at 0.3 MI, respectively, when the ambient pressure increased from 0 to 180 mmHg. Our finding revealed that a moderate MI (0.25–0.4) exciting microbubbles could significantly improve their sensitivities to detect ambient pressure.

Neuromuscular abnormality is the leading cause of disability in adults. Understanding the complex interplay between muscle structure and function is crucial for effective treatment and rehabilitation. However, the substantial deformation of muscles during movement (up to 40%) poses challenges for accurate assessment. To address this, we developed a wearable structural-functional sensing patch (WSFP) that enables synchronous analysis of muscle structure and function. The WSFP incorporates a soft, stretchable electrode array for high-performance electrophysiological monitoring with low contact impedance and high stability. Its innovative design absorbs skin deformation stress, ensuring stable adhesion of a flexible ultrasound transducer array, offering higher-fidelity imaging. With dynamic tissue imaging, it allows real-time visualization of muscle structure. The WSFP achieves superior accuracy in dynamic action recognition and disease assessment compared to single-modal methods, maintaining stable operation during motion for up to 72 hours. This study advances neuromuscular system analysis and improves diagnostic precision.