Underwater sensing has extraordinary significance in ocean exploration (e.g., marine resources development, marine biology research, and marine environment reconnaissance), but the great difference between the marine environment and the land environment seriously prevents current traditional sensors from being applied in underwater sensing. Herein, we reported a fully hydrophobic ionogel with long-term underwater adhesion and stability as a highly efficient wearable underwater sensor that displays an excellent sensing performance, including high sensitivity, rapid responsiveness and superior durability. Of greater significance, the ionogel sensor showed tremendous potential in underwater sensing applications for communication, posture monitoring and marine biological research.

Natural locomotion such as walking, crawling, and swimming relies on spatially controlled deformation of soft tissues, which could allow efficient interaction with the external environment. As one of the ideal candidates for biomimetic materials, hydrogels can exhibit versatile bionic morphings. However, it remains an enormous challenge to transfer these in situ deformations to locomotion, particularly above complex terrains. Herein, inspired by the crawling mode of inchworms, an isotropic hydrogel with thermoresponsiveness could evolve to an anisotropic hydrogel actuator via interfacial diffusion polymerization, further evolving to multisection structure and exhibiting adaptive deformation with diverse degrees of freedom. Therefore, a dynamic mortise-and-tenon interlock could be generated through the interaction between the self-deformation of the hydrogel actuator and rough terrains, inducing continual multidimensional locomotion on various artificial rough substrates and natural sandy terrain. Interestingly, benefiting from the powerful mechanical energy transfer capability, the crawlable hydrogel actuators could also be utilized as hydrogel motors to activate static cargos to overstep complex terrains, which exhibit the potential application of a biomimetic mechanical discoloration device. Therefore, we believe that this design principle and control strategy may be of potential interest to the field of deformable materials, soft robots, and biomimetic devices.

• Mechanisms of membrane permeability enhanced by vaporized nanodroplets. • Cavitation induced by droplets compared with miicrobubbles at varied concentrations. • Membrane permeability enhanced by cavitation droplets and bubbles compared in vitro. • In vitro evaluation of the correlation between IC dose and membrane permeability. • BBB opening induced by vaporized nanodroplets and microbubbles compared in vivo.

To achieve the fast and accurate segmentation of ultrasound image, a novel edge detection method for speckle noised ultrasound images was proposed, which was based on the traditional Canny and a novel multiplicative gradient operator. The proposed technique combines a new multiplicative gradient operator of non-Newtonian type with the traditional Canny operator to generate the initial edge map, which is subsequently optimized by the following edge tracing step. To verify the proposed method, we compared it with several other edge detection methods that had good robustness to noise, with experiments on the simulated and in vivo medical ultrasound image. Experimental results showed that the proposed algorithm has higher speed for real-time processing, and the edge detection accuracy could be 75% or more. Thus, the proposed method is very suitable for fast and accurate edge detection of medical ultrasound images.

Brain imaging technology is widely used in the diagnosis of brain diseases. Computed tomography and magnetic resonance imaging are the most common imaging modalities used for clinical brain imaging, whereas ultrasound is rarely used because the skull substantially reduces the incident energy of ultrasonic waves to levels too low for imaging. However, remarkable developments of novel technologies in ultrasound brain imaging have been achieved recently, including Doppler-based imaging, contrast agent imaging, ultrasound elastography, and phase compensation imaging. Doppler-based imaging, including ultrafast Doppler imaging and functional ultrasound, is able to obtain reliable cerebral blood volume changes and has the best penetration depth and a better spatiotemporal resolution. Contrast agent brain imaging, including ultrasound localization microscopy, can obtain super spatial resolution vasculature maps over a large region within a few minutes of acquisition and reconstruction time. Ultrasound elastography reflects the stiffness of brain tissues. Phase correction imaging, such as time reversal mirror and spatiotemporal inverse filter, aims at focusing smoothly in the skull. These methods have been widely performed on animal models, newborn children, and adults in preclinical studies, with results demonstrating great potential in the diagnosis and treatment of brain diseases. This review discusses the ultrasound methods developed in recent years for brain imaging and highlights the promising future they hold.

Surface electromyography (sEMG) is currently the primary method for user control of prosthetic manipulation. Its inherent limitations of low signal-to-noise ratio, limited specificity and susceptibility to noise, however, hinder successful implementation. Ultrasound provides a possible alternative, but current systems with medical probes are expense, bulky and non-wearable. This work proposes an innovative prosthetic control strategy based on a piezoelectric micromachined ultrasound transducer (PMUT) hardware system. Two PMUT-based probes were developed, comprising a 23×26 PMUT array and encapsulated in Ecoflex material. These compact and wearable probes represent a significant improvement over traditional ultrasound probes as they weigh only 1.8 grams and eliminate the need for ultrasound gel. A preliminary test of the probes was performed in able-bodied subjects performing 12 different hand gestures. The two probes were placed perpendicular to the flexor digitorum superficialis and brachioradialis muscles, respectively, to transmit/receive pulse-echo signals reflecting muscle activities. Hand gesture was correctly predicted 96% of the time with only these two probes. The adoption of the PMUT-based strategy greatly reduced the required number of channels, amount of processing circuit and subsequent analysis. The probes show promise for making prosthesis control more practical and economical.