Precise delivery of therapeutic agents to targeted sites within the body is a significant challenge, especially in complex and confined physiological environments. Magnetically actuated microrobots offer a promising solution by enabling remote, controllable, and minimally invasive navigation; however, most existing microrobotic systems are fabricated from nondegradable materials and lack controlled drug release capability, which significantly limits their clinical translation. Here, we report 3D-printed biodegradable magnetic microrobots based on gelatin methacryloyl (GelMA) hydrogel capable of controlled therapeutic delivery. Using high-resolution direct laser writing, dual-layer GelMA microrobots with distinct crosslinking degrees were fabricated, enabling tunable degradation and controlled release of encapsulated drugs. The low-crosslinked outer shell functions as a protective barrier that prevents premature drug diffusion, while the highly crosslinked inner core enables sustained drug release during enzymatic degradation. The microrobots demonstrate excellent biocompatibility and controllable degradation in cellular environments. In addition, the integration of a biocompatible magnetic skeleton within the GelMA body enhances mechanical stability and enables precise magnetic actuation. This study presents a versatile strategy for developing biodegradable, magnetically actuated microrobots with controlled therapeutic release, offering strong potential for targeted drug delivery, tissue regeneration, and minimally invasive biomedical applications.

This paper proposes a very low frequency (VLF) magnetoelectric (ME) antenna featuring topologically optimized magnetic flux concentrating wing (MFCW). To evaluate its performance, three-dimensional finite element models are constructed to systematically compare the original antenna with rectangular and hemispherical MFCW configurations under a 1-V alternating voltage excitation. The results demonstrate that the optimized hemispherical configuration significantly outperforms the others. Specifically, it achieves a maximum internal magnetic flux density of 2.78 × 10−4 T. Furthermore, in the near field (at an axial observation distance of 0.1 m), it generates a magnetic flux density of 714.6 nT, representing a 39.39% enhancement over the 512.66 nT produced by the original antenna. This study provides a highly efficient and miniaturized transmitter design for deep-sea cross-medium communication systems.

Low-frequency MEMS vector hydrophones are limited by the inherently weak pressure-gradient response and inefficient underwater acoustic coupling. This letter presents a low-frequency pressure-gradient MEMS vector hydrophone based on AlN/Sc0.2Al0.8N composite piezoelectric films. The device employs a hexagonal diaphragm fabricated on an SOI platform with silicone-oil-filled cavities, enabling a pressure gradient to develop across the sensing units, which is subsequently converted into electrical signals through the piezoelectric effect. Furthermore, two orthogonally arranged pairs of sensing units enable two-dimensional vector acoustic sensing. Measurements show a stable dipole directivity from 50 Hz to 1 kHz and a receiving sensitivity of −163 dB (re: 1 V/ $\mu $ Pa) at 1 kHz. These results demonstrate the capability of the proposed hydrophone for high-precision low-frequency underwater vector acoustic sensing. [2026-0126]

Magnetic microrobots are promising platforms for targeted drug delivery, with sperm-inspired types attracting particular attention due to their flexible, wave-like motion. Despite significant progress in this field, the simple fabrication of sperm-like flexible robots remains a major challenge. This paper proposes a novel, universal strategy based on a magnetic head made of iron oxide and a flexible tail from filamentous algae for the fabrication of a bio-hybrid flexible sperm-like microrobot, which demonstrates potential for targeted drug delivery within microenvironments in the future. Based on its ingenious head-tail connection structure, the microrobot can effectively move under a precessing magnetic field and achieve reciprocating motion without turning back. Furthermore, vascular channel simulation experiments validate its excellent motion performance in microenvironments. This fabrication method is simple, versatile, and exhibits autofluorescence, providing a new pathway for the large-scale fabrication of high-performance medical microrobots.

Underwater physical signal collection is crucial for helping athletes evaluate health and optimize training methods. However, it is difficult for existing underwater devices to simultaneously collect stable and accurate subtle pulse signals and large motions in complex water environments. Herein, a flexible, waterproof, and stable underwater human physical signal collection system based on a flexible micropillar double-layer pressure sensor was proposed. The developed sensor is integrated with a micropillar sensing layer and packaging layer, which exhibit a dual-mode sensing range that includes subtle and high pressure with a rapid response. The sensing layer provides wide-range deformation for improving the sensing performance; the packaging layer reduces the influence of water flow on the sensor when sensing subtle pressure underwater, which provides support for the microstructure when it senses high pressure to enhance the sensing performance. The sensor can accurately recognize both subtle pulse vibrations and large-scale muscle expansion-contraction signals in water. Therefore, an underwater physical signal collection device (UPCD) was constructed with a micropillar sensor and an information storage circuit board. The status of an underwater athlete can be estimated through a machine learning method by analyzing the data collected from the UPCD, which can recognize the training and physical conditions and further assist in optimizing the training method.

Throughout the development of soft robots, shape memory alloy (SMA) actuators have received considerable attention due to their inherent advantages, such as high power-to-weight ratio, low driving voltage, and high response speed. This study presents a lattice-reinforced SMA actuator with improved response speed and increased deformation range. The SMA wires are used to drive the actuator to achieve bending, while the high elastic wire's elasticity is used to achieve recovery. The actuator is cast into a lattice structure with five connection nodes, named Lattice-N5. Lattice-N5's fast response properties are validated through finite element analysis and experiments. Compared with the actuator without lattice structure (nonlattice), lattice-N5's bending deformation increases by up to 390.59% and 204.4% under optimal (voltage of 20 V, duty ratio of 30%, and frequency of 4 Hz) and practical (voltage of 20 V, duty ratio of 20% and frequency of 1 Hz) conditions, respectively, while reaching a stable state more rapidly under a periodic actuation. Therefore, the lattice-reinforced actuator exhibits robust actuation capabilities and improved response frequencies and thus can be employed in a biomimetic jellyfish robot for underwater monitoring and detection by combining a flexible pressure sensor. Moreover, the jellyfish robot with Lattice-N5 actuators exhibits a speed improvement of 111% under the optimal condition (duty ratio of 20% and frequency of 4 Hz) and 55% under the practical condition (voltage of 20 V, duty ratio of 20% and frequency of 1 Hz) compared with the robot with the nonlattice. This study provides a simple and effective design scheme for improving the performance of SMA actuators and prompting the development of underwater soft robots.

Immunomodulatory microspheres represent an advanced class of biomaterials that function as comprehensive platforms integrating passive drug delivery and active immunoregulatory capabilities. This review synthesizes fundamental design principles-where engineered chemical (e.g., ion release, surface functionalization, redox modulation) and physical (e.g., size, morphology, stiffness) properties synergistically create "immune instruction systems" to reprogram pathological microenvironments. Their transformative applications span multisystem diseases. In orthopedics, microspheres recalibrate macrophage polarization (M1/M2) to resolve osteoarthritis inflammation and promote bone regeneration in osteoporosis. In gynecology, they overcome mucosal barriers to target ectopic lesions in endometriosis and enhance immunotherapy for Premature Ovarian Insufficiency. Moreover, in neurology, they penetrate the blood-brain barrier (BBB) to mitigate neuroinflammation in Alzheimer's disease and stroke. Despite its promise, clinical translation faces challenges, including tissue-specific delivery barriers (e.g., joint clearance, cervical mucus, and BBB penetration) and immune-related safety risks (e.g., cytokine release syndrome). Emerging solutions include stimulus-responsive designs, exosome-microsphere hybrids, and personalized formulations based on immune profiling. Future advancements require scalable manufacturing and long-term safety validation to realize the full potential of these platforms in precision immunotherapy.

Sea surface temperature plays a crucial role in the exchange of heat, gases, and materials between the ocean and atmosphere, profoundly influencing global climate, marine ecosystems, and atmospheric circulation. However, temperature variations at the air-sea interface are rapid and highly unstable, being affected by multiple dynamic factors, posing significant challenges for real-time monitoring. In this work, a rapid-response flexible temperature sensor was developed using polyimide film as the substrate. Based on the thermal expansion mechanism and finite element analysis, the optimal sensor structure and material composition were determined. The sensor was fabricated via screen-printing technology, employing a acrylic copolymer and polydimethylsiloxane (PDMS) as the composite matrix, with carbon black and nickel serving as conductive fillers. A PDMS encapsulation layer was applied to enhance waterproofing performance. Within the temperature range of 0-35 degrees C, the sensor exhibited a high temperature coefficient of resistance of 4.82%/degrees C, an excellent temperature resolution of 0.05 degrees C, an ultrafast response time of 40 ms, outstanding thermal stability over more than 500 heating-cooling cycles, and strong insensitivity to external stimuli such as bending, humidity, and pressure. When integrated into a marine buoy system for testing, the sensor accurately detected temperature fluctuations, demonstrating great potential for temperature monitoring at the air-sea interface.

Magnetically controlled continuum robots (MCRs) emerge as a novel type of flexible robotic system that overcomes the physical limitations of traditional rigid-link structures, exhibiting high compliance, minimal invasiveness, and high spatial freedom. Through non-invasive, precise manipulation using magnetic fields, MCRs can achieve navigation and positioning in complex and confined microenvironments such as blood vessels and cavities in the human body. Furthermore, MCRs have attracted increasing attention for minimally invasive intervention because they combine structural compliance with remote magnetic actuation. In this study, we first introduce the driving control of MCRs, including the driving principle and driving system. Next, we discuss different types of robots, such as guiding and steering robots, variable stiffness robots, multimodal motion robots, and bio-inspired continuum robots, as well as their fabrication materials and manufacturing processes. Subsequently, we analyze the achievements of these robots in the medical field, including cardiovascular treatment, cavity diagnosis and treatment, and bone and joint treatment. The review also discusses current challenges in control accuracy, biocompatibility, system integration, and clinical translation. Finally, we briefly summarize the research and discuss the current challenges and future development directions of MCRs.

This paper presents a wireless passive inductor-capacitor (LC) temperature sensor with controllable structural parameters and adjustable frequency. Combining an equivalent circuit model with electromagnetic simulation, the regulation laws of coil turns and dielectric layer thickness on the resonant frequency are quantitatively analyzed. Since the fundamental mechanism of LC frequency tuning is well-understood, the core contribution of this work lies in the specific characterization of the proposed sensor architecture, verifying the feasibility of achieving frequency-on-demand design through geometric optimization. In terms of manufacturing, Zinc (Zn) foil is used as the inductor material, and thermosensitive Polyethylene Glycol (PEG) is utilized as the dielectric layer. The sensor prototype is fabricated using laser micro-machining and lamination processes. Experimental results demonstrate that the sensor exhibits good linearity within the physiological temperature range, with an average sensitivity of 0.6 MHz/°C. Furthermore, it maintains effective wireless signal transmission at a coupling distance of up to 18 mm. This study provides theoretical basis and technical support for the frequency customization and structural design of wireless passive sensors.

Dual-mode sensors with ultrahigh sensitivity, wide detection range, linearity, and stable temperature response are highly desirable for monitoring in extreme environments. Here, we report a temperature-pressure dual-mode sensor that leverages a synergistic enhancement mechanism, combining the ion pump effect of hexagonal boron nitride (h-BN) with the strain-regulated conductive pathways of few-layer graphene (FLG) to boost sensitivity. The high rigidity of h-BN and the stress-dispersing role of FLG ensure mechanical stability under high load, withstanding 11200 and 6000 cycles at 1 and 6 MPa, respectively. As a result, the device achieves a record-high sensitivity of 4771.2 kPa-1 with a detection limit up to 10 MPa. Meanwhile, the platinum serpentine electrode temperature sensor fabricated via magnetron sputtering exhibits highly linear (R2 = 0.9993) and stable response characteristics within the temperature range of -20 to 140 °C after annealing treatment, with negligible pressure interference. This sensor is successfully applied to monitor lithium-ion battery expansion and deep-sea waves, capturing high-quality time-resistance-temperature sensing data. To further validate the sensor's data utility and achieve precise prediction of battery thermal behavior, we constructed a deep learning model based on the Informer architecture. This model enables high-precision short-time temperature prediction (MAE = 4.2 °C, range accuracy = 97.36%) using the sensor-acquired data, ultimately proving the scalability of this dual-mode sensing platform in high-performance multimodal sensing under extreme conditions.

Hydrophores play a vital role in collecting water samples in deep-sea exploration and marine engineering. Current actuating mechanisms for the release system of hydrophores often struggle with waterproof design, low energy efficiency, and slow response time. This paper presents a novel design method for hydrophores based on bidirectional shape memory alloy (SMA) actuators to provide a new solution for existing limitations. The SMA actuators used feature a sandwich structure consisting of two-layer SMA wires and middle-layer high-elasticity wires (HEWs), which can bend towards two directions to open or close the release hook, enabling efficient working of hydrophores. Simulation and experimental results demonstrate that the actuator exhibits exceptional reset rate and load capability. The designed hydrophore works well in laboratory tank tests, and field trials in the Yellow Sea validate its practicality in real underwater environments. This work not only offers an innovative solution for the design of deep-sea hydrophores for water sampling, but will also inspire the use of SMA actuators in deep-sea devices.

Miniaturized very low frequency (VLF) magnetoelectric (ME) antennas are essential for air–sea cross-media communication. However, in conventional magnetostric- tive (MS)–piezoelectric–MS (MPM) structures, asymmetric interfacial loading on the outer MS layers induces parasitic bending, which reduces axial modal purity and effective strain transfer, ultimately degrading radiation performance. To address this issue, this letter proposes a piezoelectric–MS–piezoelectric (PMP) ME mechanical antenna with a highly pure axial operating mode. Firstly, the symmetric PMP configuration is designed to provides more balanced interfacial loading on the central FeGa layer, thereby suppressing parasitic bending and enhancing longitudinal deformation. Moreover, the electro-mechanical-magnetic coupling radiation mechanism is analyzed to clarify the underlying radiation behavior. Subsequently, multiphysics simulations demonstrate improved stress response, modal purity, and magnetic-field radiation compared with the conventional MPM counterpart. Experimental results further show a 26.23% improvement in radiation performance at 1 m. Furthermore, stable ASK modulated cross-media communication demonstrates the potential of the proposed antenna for compact and low-power VLF air–sea communication.

Amino acid-based piezoelectric assemblies have been significantly developed. However, the piezoelectricity of natural non-proteinogenic amino acid assemblies remains rarely reported. Herein, we present a novel piezoelectric assembly of natural non-proteinogenic amino acid 5-hydroxytryptophan for energy harvesting. This work expands the family of biomolecule-based piezoelectric supramolecular materials.

Total hip replacement (THR) surgery has achieved significant success in alleviating pain from hip joint diseases and improving patients' quality of life. However, the challenge of precisely placing the acetabular implant during surgery can lead to complications, such as early loosening and wear of the implant. Traditionally, this critical step relies on the surgeon's experience and subjective judgment, lacking objective tools to monitor the pressure field within the acetabulum in real-time. This study presents the development of a highly sensitive micropyramid flexible sensor array, fabricated using microfine photolithography precision molding technology, for assisting pressure field monitoring in the acetabulum during THR. The compression of the pyramid microstructure results in large changes in contact area, allowing our single sensor to exhibit an ultrahigh sensitivity of 11 711.95 kPa(-1) within the 0-90-kPa pressure range, with a response/recovery time of 120/81 ms. Six independent sensors were integrated into a customized acetabular implant model, enabling the collection of pressure field data from the acetabulum. To simulate the surgical process, we modified the test platform, developed corresponding signal acquisition circuits, and a software system for real-time visualization of pressure distribution in the acetabulum, demonstrating the potential application of this system in assisting surgeons in precisely placing implants during THR surgery.

Magnetically driven algal microrobot swarms can access distant, small and complex spaces such as human body through magnetic tweezer system. In this study, magnetic diatom microrobots were fabricated using an adsorption magnetization technique, where ferroferric oxide (Fe3O4 magnetic nanoparticles were adsorbed onto diatom shells. An optimized magnetic tweezer system was employed to control their movement and execute a series of motion tasks. To enhance the control capability of the magnetic tweezer system, the size, material, and spatial arrangement of the neodymium iron boron (NdFeB) permanent magnets were optimized, with the optimal parameters determined through magnetic field simulations. Subsequently, square track, micro-maze, and counter-current experiments were conducted to evaluate the control performance of the optimized magnetic tweezer system on a magnetized diatom microrobot swarms (MDMS). Experimental results indicate that the optimized system can effectively control the movement of large-sized MDMS in complex environments while providing greater driving force.

In contrast to conventional high-strength, high-modulus fibers, spider silk uniquely combines high toughness, strength and diverse functionalities, enabling spiders to thrive in natural environments. However, replicating the sophisticated architecture and properties of spider silk through synthetic approaches, particularly via scalable fiber manufacturing processes, remains a formidable challenge. Herein, we report the tailored fabrication of spider silk-like structures in sodium polyacrylate and polyacrylamide (PANa-PAM) composite polymer hydrogel fibers via wet-spinning. The antisolvent-induced phase separation process modulates composite polymer microphase, yielding nascent PANa-PAM fibers abundant in hydrogen-bonded nanoclusters. Subsequent post-drawing for strain programming facilitates uniaxial polymer alignment and controlled crystallization. The optimized fiber comprises aligned microfibrils, polymer-rich rigid nanoclusters surrounded by polymer-loose regions, and β-sheet-like crystallites, closely mimicking the hierarchical architecture of natural spider silk. As a result, the composite fiber achieves a comprehensive set of spider silk-like properties and functionalities, including a toughness of 118.7 MJ m-3, a tensile strength of 172.3 MPa, 50% elastic strain recovery, 96% damping efficiency, 60% supercontraction, and moisture sensitivity. This bioinspired wet-spinning of composite polymer hydrogels offers a pathway to replicate biological fiber structures and attributes, enabling the production of high-performance and intelligent fibers for wearable technologies.

High-temperature thin-film thermocouples (TFTCs) have gained significant attention in the aerospace and energy industries due to their compact size and millisecond response time. Although previous studies have reduced the size of TFTCs to the millimeter scale, the heat flow field has continued to limit temperature measurement accuracy. To address this issue, this study used an electrohydrodynamic printing process to fabricate tungsten-rhenium TFTCs with a thickness at the micrometer scale. In the static test, the tungsten-rhenium TFTCs showed good performance with a measurement accuracy better than 1.2%, repeatability better than 0.99%, and a drift rate of 0.72%/h. In dynamic tests, the response time was 1.2 ms. Additionally, during flame gun heating tests, the response time and temperature measurement accuracy exceeded those of the standard thermocouple.

Anteromedial osteoarthritis (AMOA) is characterized by progressive and irreversible cartilage damage in anteromedial knee joint, and targeted therapies for it are lacking. To address this challenge, a magnetically controlled drug-loaded microrobot is developed based on Chlorella and incorporated quercetin, named M-CH@QUE, which is designed for precise drug delivery targeting AMOA. M-CH@QUE not only alleviated OA symptoms but also protected the cartilage and slowed the progression of AMOA. In vitro experiments demonstrated its excellent biocompatibility, drug-loading capacity, sustained-release properties, and precise control of flat surfaces and joint cartilage using a magnetic actuation system. In addition, the mechanisms are explored underlying the effects of quercetin. It is found that it promoted cell protection by enhancing insulin-like growth factor 1 receptor (IGF1R) phosphorylation and reducing intracellular oxidative stress. In vivo experiments revealed that M-CH@QUE accumulated in the medial knee joint of rats significantly slowed OA progression and effectively protected the cartilage. After 6 and 12 weeks of treatment, the M-CH@QUE significantly reduced both the Osteoarthritis Research Society International (OARIS) score and the Mankin score. In summary, the innovative M-CH@QUE design offers an effective strategy for alleviating AMOA symptoms and slowing the disease progression, thus presenting a highly promising option for treating AMOA.