Soft robotic systems operating in liquid environments require propulsion mechanisms that combine structural compliance, stable thrust generation, and low hydrodynamic disturbance. However, conventional mechanical propulsion methods often rely on moving components that generate acoustic noise, pulsatile flow, and turbulence, limiting their use in delicate fluidic environments. Here, we present a centimeter-scale fully soft swimming robot powered by an integrated electroosmotic microchannel propulsion module. Each compact module, with a volume of 0.04 cm3, incorporates 120 parallel microchannels and liquid metal electrodes within a flexible elastomeric body, directly converting electrokinetic transport into continuous fluid thrust without mechanical moving parts. The module maintains consistent thrust output under substantial bending deformation, demonstrating mechanical resilience and operational reliability within a soft robotic body. As a functional demonstration, the robot achieves a swimming speed of 2.85 body lengths per second and a turning speed of 62° s-1 using a single module, while consuming only 60 mW of power. It also exhibits a high thrust capacity, pushing objects up to 13 times its own weight. A dual-module configuration enables programmable locomotion, including in-place rotation and rapid directional switching. The robot further demonstrates safe interaction with live aquatic organisms, highlighting its potential for low-disturbance operation in sensitive liquid environments. These results establish embedded electroosmotic microchannel propulsion as a materials-enabled strategy for soft actuation, microfluidic propulsion, and bioinspired robotic systems.

Given the urgent demand for flexibility in intelligent devices, liquid metals and flexible polymers have emerged as effective materials for the fabrication of flexible coils. However, the majority of current flexible coils show a single number of layers with sparse intra-layer structure, which impairs their sensing and actuation performance. Here, a multilayer high-density liquid metal coil (MHD-LMC) is introduced, which can be largely expanded by increasing the number of layers. Moreover, as the number of layer increases, MHD-LMC demonstrates excellent performance in both contact/non-contact sensing and actuation. As a pressure sensor, MHD-LMC is integrated into robot arm to distinguish pressing and sliding pattern. MHD-LMC can also detect a weak magnetic field as low as 50 μT, which enables it to detect the direction of electromagnetic field sources, such as a Helmholtz coil. Finally, MHD-LMC is utilized to fabricate a flexible electromagnetic pump, achieving a maximum flow rate of 11.35 mL min−1 and remaining its pumping performance under the pressed and bent conditions. In addition, the pump is capable of sensing its bending angle and subjected pressure. It provides the basis for expanding the application range of liquid metal-based complex flexible electronics, which holds significant potential for adoption in flexible robotics.

Flexible sensing technology is pivotal for emerging applications across various fields but is highly vulnerable to electrostatic discharge (ESD), compromising signal integrity and risking permanent failure in both sensors and signal processing circuits. Leveraging the high electrical conductivity and excellent fluidity of liquid metals, this work proposes a liquid metal wire grid shielding layer with a precisely designable thickness for ESD protection. Through systematic optimization with simulation and experimentation, this work identified the optimal width, height, and spacing of the wire grid as 3000 mu m, 500 mu m, and 500 mu m, respectively. Experimental results show that the shield significantly reduces sensor signal interference under 10 kV ESD while retaining performance under stretching (up to 10%) and bending (8 mm radius). This work provides a practical and effective integration strategy to enhance the reliability of flexible physical sensors in dynamic, high-ESD environments.

Magnetically responsive scaffolds are extensively utilized in tissue engineering for their ability to simulate dynamic three-dimensional (3D) cell microenvironment in a rapid, reversible, and contactless manner. However, existing magnetic scaffolds struggle to provide tunable dynamic compression comparable to natural tissues due to the weak magnetism of magnetic nanoparticles and the mechanical brittleness of hydrogels. Here, we propose a biomimetic 3D magnetic scaffold offering tunable and stable magnetically induced compression for dynamic 3D cell culture. By employing hard magnetic particles NdFeB@SiO2 and a mechanically stable elastomer, Ecoflex, the scaffold achieves 15

Precise droplet manipulation is critical in material synthesis, biochemical detection, and tissue engineering. However, the droplet velocity and volume manipulated by magnetic techniques are restricted owing to the low magnetic force exerted on magnetic particles and beads. Furthermore, magnetic particles are prone to contaminate droplets owing to residues and corrosion. To address these issues, this paper proposes a hydrophilic hard-magnetic soft robot (HMSR) with strong magnetic controllability and chemical stability for precise droplet manipulation. A porous HMSR was synthesized by incorporating NdFeB particles and sacrificial sugar particles into an Ecoflex elastomer. Oxygen plasma treatment was applied to make the HMSR become hydrophilic and thus enhance the driving force exerted on droplets. Three forms of droplet manipulation were demonstrated: droplet transport, droplet splitting, and robot–magnet detachment. Theoretical analysis and experimental results revealed that the critical HMSR speed requisite for droplet transport and splitting was inversely proportional to the droplet volume. Notably, a 50 μl droplet was transported in a 20 mT magnetic field at a maximum velocity of 200 mm/s. The maximum droplet volume that the HMSR could transport reached 900 μl. Benefiting from its chemical stability, HMSR successfully manipulated chemical reactions of acidic and alkaline droplets. Additionally, the HMSR achieved targeted removal of microparticles through droplet adhesion to them. This HMSR with precise droplet manipulation capability holds broad prospects for applications in biochemical detection, material synthesis, and surgical robotics.

In this work, a flexible battery structure is fabricated using soft lithography and three-dimensional (3D) printing technology. Ga _52.5 Sn _39.5 Zn _8 anode material, Bi _67 In _33 cathode material, and alkaline hydrogel electrolyte are introduced to form the flexible battery. A variety of circuit structures are fabricated to realize the series-parallel integration of different numbers of single cells and achieve the fabrication of batteries with different voltages and powers, with a maximum open-circuit voltage (OCV) of 4.6 V and a maximum output power of 1.193 mW. A reconfigurable soft battery group is proposed, and the regulation of the battery voltage has been realized through the microfluidic perfusion process without the need for an external variable-voltage circuit. We have also fabricated an EGaIn-NaOH microfluidic switch to achieve the control of the light emitting diode (LED). In addition, a wristband with a flexible battery is demonstrated to realize power supply to a liquid crystal display (LCD) with a clock or a temperature sensor.

This work proposes a liquid-metal-based calorimetric micro-flow sensor within a polydimethylsiloxane (PDMS) chip. It can measure the flow rate of fluid in microscale channels, with a range as low as several microliters per minute. This in-chip sensor is proposed to solve the issue of detecting the flow rate in microfluidic systems. To make the sensor compatible with PDMS microfluidic chips, low-melting-point gallium-based alloy and bismuth-based (bi-based) alloy are used to make the micro heater and bi-metal thermocouples, for these alloys can be easily injected into a PDMS chip to form electrodes. To minimize heat resistance (or temperature difference) between fluid and the detecting ends of thermocouples, these ends are directly exposed to liquid in the flow channel with the help of a special reversible bonding technology. Thermocouples are connected in series to improve the sensor's response. A novel method to bond and electrically connect the sensor to a print circuit board is also elaborated. Since the calorimetric flow sensor is sensitive to heating power, fluid temperature and environment cooling, a dimensionless parameter less independent of these factors is deduced from heat transfer theory, and this idea is used in result processing to offset the bad effect. Experiments with pure water show that this sensor can be used to detect flow rates, with a resolution up to 4 mu l min-1 mV-1 and a range of 12 mu l min-1 in this case, and that at different heating powers, the thermal potential results vary significantly whereas the dimensionless results nearly keep the same. Present work indicates that this sensor has the potential to be integrated into a PDMS microfluidic system and to provide accurate and stable results if a dimensionless method is used in data processing.

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90 degrees, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 degrees C.

In this paper, we propose a novel liquid metal microheater utilizing a textured structure. This microheater effectively solves the problem of the liquid metal in the PDMS flow channel fracturing at a certain temperature and significantly increases the maximum operating temperature that can be achieved by the current liquid metal microheater. Experimental results demonstrate that this new structured microheater can achieve a maximum operating temperature exceeding 300 °C. To explain the performance improvement and the reasons behind liquid metal fracture, corresponding experiments were conducted, and explanations were provided based on the experimental results. Subsequently, we verified the mechanical flexibility of the microheater and found that it exhibits excellent tensile and bending resistance. Finally, utilizing its good mechanical flexibility, the microheater was successfully attached to the side wall of a cup, resulting in the boiling of water.

Complex and precise 3D microfabrication technology is the basis for the development of fields including chip-based bioassay, microelectronic communication, and micromachine manufacturing. Among them, assembled 3D structures provide new ideas to the development of 3D integration of 2D components due to their convenience and high efficiency. In this work, a micro-casting/assembly technique that can create 3D micro devices is provided with bismuth-based liquid metal (LM). The liquid metal is first injected into a micro-mold. The micro-mold is made by polydimethylsiloxane (PDMS) and porous polycarbonate track-etched (PCTE) membranes. The mold is then treated with ethanol and deionized water to release the inner injected 2D micro metal components. The effect of each parameter on the generated metal structures is experimentally validated and a LM line with a minimum width of 10 mu m is also obtained. For making more functional components, the 2D structures are assembled into 3D. To demonstrate the potential of the technique, reconfigurable micro-antennas and 3D flow sensors are fabricated and tested at the end of this work, demonstrating potential applications for the micro casting/assembly technology. Deposition and transfer of liquid metal microstructures through microfluidic channels and porous PC membranes have been accomplished, and signal-sensitive antenna structures have been created as a result. Furthermore, the liquid metal is transformed from two to three dimensions using mortise and tenon joints, and the structure is created to be both artistic and useful.image

A low-voltage drivable integrated parallel EOP cluster drive system is proposed, and its integrated pump-valve drive system is expected to solve the shortcoming of electroosmotic pumps in terms of long-time storage and driving.

Glaucoma is the world's second-leading irreversible eye disease causing blindness. Although the pathogenesis of glaucoma is not particularly well understood, high intraocular pressure (IOP) is widely recognized as a significant risk factor. In clinical practice, various devices have been used to measure IOP, but most of them cannot provide continuous measurements for a long time. To meet the needs of glaucoma patients who experience frequent fluctuations in the IOP and require constant monitoring, we fabricated an implantable piezoresistive IOP sensor based on microfluidic technology. The sensor has a sensitivity of 0.00257 Ω/mbar and demonstrates excellent linearity, stability, and repeatability. According to the calibration data, the average measurement error is ±0.5 mbar. We implanted it into the vitreous of a rabbit and successfully detected its IOP fluctuations. The sensor is simple in design, easy to fabricate, and can be used for long-term continuous IOP measurements. It presents a new approach for microfluidic-based IOP sensors and offers a novel method for the daily care of patients with glaucoma.

This paper proposes a method for pressure driven rapid reconfigurable liquid metal patterning. A sandwich structure of "pattern-film-cavity" is designed to complete this function. Both sides of the highly elastic polymer film are bonded with two PDMS slabs. One PDMS slab has microchannels patterned on the surface. The other PDMS slab has a large cavity on its surface for liquid metal storage. These two PDMS slabs are bonded together, face to face, with the polymer film in the middle. In order to control the distribution of the liquid metal in the microfluidic chip, the elastic film will deform under the high pressure of the working medium in the microchannels and then extrude the liquid metal into different patterns in the cavity. This paper studies the factors of liquid metal patterning in detail, including external control conditions, such as the type and pressure of the working medium and the critical dimensions of the chip structure. Moreover, both a single-pattern and a double-pattern chip are fabricated in this paper, which can form or reconfigure the liquid metal pattern within 800 ms. Based on the above methods, reconfigurable antennas of two frequencies are designed and fabricated. Meanwhile, their performance is simulated and tested by simulation and vector network tests. The operating frequencies of the two antennas are respectively significantly switching between 4.66 GHz and 9.97 GHz.

In this paper, a convenient process for the fabrication of flexible liquid metal mesh films (LMMF) is proposed first. Then, the light transmittance and square resistance characteristics of LMMF are studied theoretically and experimentally. The light transmittance of the LMMF can reach 85% when the line width and spacing are 50  μ m and 1000  μ m, respectively. Furthermore, as an example of LMMF, a coplanar waveguide loop antenna is designed and fabricated that contains an LMMF with a line width of 50  μ m and a line spacing of 500  μ m. The measured square resistance and transmittance for the LMMF are 0.0456 Ω /sq and 72%, respectively. The measured peak gain of the antenna is 3.38 dBi while the average efficiency is 61%. The antenna’s working frequency covers most of the S-band, C-band, and X-band, as well as multiple channels of fifth generation (5G) communication. Therefore, the antenna can be used in fields such as radar and mobile communication. Uniquely, the fabricated antenna performs well in terms of light transmission, conductivity, and flexibility. In particular, it remains stable in stretching and bending deformation. As a highly light-transmissive stretchable flexible antenna, the antenna is equipped with various functions such as concealability, conformability, and reconfigurability. This LMMF-based antenna has good prospects for applications in the fields of flexible electronics and transparent electronics.

Drug delivery systems based on porous soft biomaterials have been widely reported because of stimuli-responsive drug release and their inherent reservoirs for drug storage. Especially, magnetic-responsive porous soft biomaterials achieve rapid and real-time control of drug release due to the magnetic field-triggered large deformation. However, the drug release profiles of these materials are difficult to predict and repeat, which restrict them from releasing drugs in the required dosage. Here, we report a soft capsule based on a flexible hard-magnetic elastomer foam (HEF) for magnetically controlled on-demand drug delivery. The HEF capsule contains an inner HEF and an outer elastomer shell. The HEF exhibits low elastic modulus (10 kPa) and highly interconnected pores (81% interconnected pores). Benefitting from the novel precompressed magnetization, the compressive deformation of HEF reaches 66%. Thus, an adjustable drug release rate ranging from 0.02 to 1.7 mL/min in the HEF capsule is achieved. The deformation-triggered drug release profiles of the HEF capsule under the magnetic field are accurately predicted, allowing 85% accuracy in drug dosage regulation and more than 90% maximum cumulative drug release. Especially, the HEF capsule is proven capable of acting as a soft robot to perform magnetically driven drug delivery in a human stomach model. HEF can potentially serve as a soft robot for biomedical applications in the human body.

Neural electrodes are core devices for research in neuroscience, neurological diseases, and neural-machine interfacing. They build a bridge between the cerebral nervous system and electronic devices. Most of the neural electrodes in use are based on rigid materials that differ significantly from biological neural tissue in flexibility and tensile properties. In this study, a liquid-metal (LM) -based 20-channel neural electrode array with a platinum metal (Pt) encapsulation material was developed by microfabrication technology. The in vitro experiments demonstrated that the electrode has stable electrical properties and excellent mechanical properties such as flexibility and bending, which allows the electrode to form conformal contact with the skull. The in vivo experiments also recorded electroencephalographic signals using the LM-based electrode from a rat under low-flow or deep anesthesia, including the auditory-evoked potentials triggered by sound stimulation. The auditory-activated cortical area was analyzed using source localization technique. These results indicate that this 20-channel LM-based neural electrode array satisfies the demands of brain signal acquisition and provides high-quality-electroencephalogram (EEG) signals that support source localization analysis.

Multiparameter sensors that can individually monitor mechanical and thermal signals from multiple stimuli have attracted immense attention. Due to interferences caused by signal crosstalk, it is a challenge for multiparameter sensors to simultaneously differentiate mechanic and thermal stimuli within a broad working range. Herein, a liquid‐metal‐based stretchable dual‐parameter sensor that can simultaneously detect deformation (0–4.5 mm) and temperature (0–60 °C) is fabricated. The sensor adopts a multilayer structure in which a capacitive deformation‐sensing unit is stacked on top of a resistive temperature‐sensing unit. The deformation unit possesses excellent linear responses ( R 2 = 0.999) and ultralow detection limit (0.04 mm, ≈0.02%). Attributed to these merits, the deformation unit can be used to monitor physiological actions (e.g., finger bending, swallowing, and speaking). The temperature unit exhibits strong stability under multiple stimuli. With the cooperation of the two units, the dual‐parameter sensor can accurately differentiate deformation and temperature stimuli with an average error of 0.04 mm and 0.82 °C. Because of these remarkable performances, the sensor can achieve real‐time acquisition of the deformation and temperature change during finger movements. The dual‐parameter sensing abilities of the sensor indicate its promising potential in human motion monitoring and wearable devices.

This work proposes an “N2-1” sacrificial strategy to help to improve the accuracy of the bonding technique from the existing level. The target micropattern is copied N2 times, and (N2-1) of them are sacrificed to obtain the most accurate alignment. Meanwhile, a method for manufacturing auxiliary solid alignment lines on transparent materials is proposed to visualize auxiliary marks and facilitate the alignment. Though the principle and procedure of alignment are straightforward, the alignment accuracy substantially improved compared to the original method. With this technique, we have successfully fabricated a high-precision 3D electroosmotic micropump just using a conventional desktop aligner. Because of the high precision during the alignment, the flow velocity is up to 435.62 μm/s at a driven voltage of 40 V, which far exceeds the previous similar reports. Thus, we believe that it has great potential for high precision microfluidic device fabrications.

This research work reports a novel method to achieve fast liquid metal (LM) injection in blind-end microchannels which is especially suitable for multi-layer microfluidic chips. This method is based on a texture-like surface bonding technology. The texture-like surface is fabricated on a polydimethylsiloxane (PDMS) slab with standard soft-lithography technology and bonded with another PDMS slab with microelectrode patterns on it. When injected with LM, the texture-like structure can prevent the LM from entering but allows the air inside to be released during the injection to achieve perfect blind-end complex LM electrodes. The experimental results show that it can achieve fast and perfect LM injection in the blind-end pattern and can also prevent the large area of the flat chamber from collapsing during bonding. We also parametrically studied the texture structure's size for bonding strength between the texture structure and the blank PDMS surface. In addition, we integrate three layers of blind-end complex liquid metal patterns into one multi-layer chip using this technology and later use this structure to realize series connection of two LM-based electroosmotic micropumps (EOP). Compared with the conventional LM-based EOP, the structure of the EOP chip was greatly simplified and resulted in a higher level of integration.

This study presents a U-shaped dual-frequency-reconfigurable liquid-metal monopole antenna. Eutectic Gallium–Indium (EGaIn) was used as a conductive fluid and filled in the two branches of the U-shaped glass tube. A precision syringe pump was connected to one of the branches of the U-shaped tube by a silicone tube to drive EGaIn, forming a height difference between the two liquid levels. When the height of liquid metal in the two branches met the initial condition of L1 = L2 = 10 mm, and L1 increased from 10 mm to 18 mm, the two branches obtained two working bandwidths of 2.27–4.98 GHz and 2.71–8.58 GHz, respectively. The maximum peak gain was 4.00 dBi. The initial amount of EGaIn also affected the available operating bandwidth. When the liquid metal was perfused according to the initial condition: L1 = L2 = 12 mm, and L1 was adjusted within the range of 12–20 mm, the two branches had the corresponding working bandwidths of 2.18–4.32 GHz and 2.57–9.09 GHz, and the measured maximum peak gain was 3.72 dBi. The simulation and measurement data corresponded well. A series of dual-frequency-reconfigurable antennas can be obtained by changing the initial amount of EGaIn. This series of antennas may have broad application prospects in fields such as base stations and navigation.