Photoactuators with programmable and multimode deformations have attracted significant attention due to their potential applications in various soft devices. However, most existing photoactuators are triggered by free-space illumination, which becomes problematic when direct optical access is restricted. Although using optical waveguides can overcome this limitation, achieving complex and programmable deformations in waveguide photoactuators remains challenging owing to difficulties in controlling the energy conversion within actuators. Here, a gradient-loading strategy of photothermal material is reported to achieve programmable and multimode deformations in optical fiber taper (OFT)-based waveguide photoactuator (OWPA), by analyzing light propagation behaviors, calculating fractions of various factors contributing to energy attenuation, and controlling the uniform photothermal conversion. The microscale OFT reduces the actuator thickness, thus improving the deformation amplitude and providing sufficient programmable space for designing complex deformations. Multimode deformations including S-shaped, W-shaped, and helical deformations are achieved, utilizing various patterning schemes. As a proof-of-concept, a single OWPA efficiently captures conical and cylindrical objects is demonstrated. It is posited that the proposed approach, which is based on the quantitative analysis of light propagation and employs a gradient-loading strategy, could serve as a guiding principle for the development of other waveguide photoactuators with designable deformations.

Wearable thermoelectric generators (TEGs) offer a promising route toward self-powered, body-integrated electronics. However, conventional sandwich-structured TEGs (s-TEGs) suffer from inherent limitations due to degraded thermal and electrical performance under device-level mechanical flexibilization, making it challenging to simultaneously achieve high voltage, high power output, and stretchability, particularly in outdoor environments with heat-exchange complexities. Here, we present a hierarchical-morphology TEG (h-TEG) that integrates high-aspect-ratio thermoelectric (TE) couples, high-packing-density TE chiplets, and a stretchable architecture embedded in low-thermal conductivity, ultrasoft elastomers. A flexible nanofibrous radiative cooling (RC) metasurface, spectrally engineered for facilitating thermal emission and solar irradiation rejection, is further incorporated to enhance device performance. By decoupling TE and mechanical functionalities, the h-TEG delivers consistently high performance in voltage density (6.67 mV cm-2 K-1), power density (9.59 mu W cm-2 K-1), and stretchability (up to 120%), effectively overcoming the trade-offs typical of s-TEGs. This hierarchical integration ensures stability across diverse thermal environments, while the h-TEG with RC achieves 3-and 8-fold higher power and voltage, respectively, compared with conventional s-TEGs with RC, even under strong solar irradiation (similar to 900 W m-2) and high ambient temperature (33 degrees C). The hierarchical strategy paves the way toward next-generation TEGs with synergistically high output performance and mechanical adaptability.

The clinical diagnosis of functional gastrointestinal disorders primarily relies on symptom assessment and physical examination, methods that are inherently limited due to undetermined specific biomarkers and susceptibility to subjective judgment. Electrophysiological techniques offer a clinically practical approach by precisely recording the electrical activities of the intestines, providing deeper biophysical insights. However, in vivo electrophysiological investigation of the intestines remains challenging, such as the stability of the electrode-tissue interface, high-frequency signal transmission, motion artifact, and signal interpretation. This study developed an endoscopic-based high spatiotemporal electrophysiological recording device, by integrating balloon catheters and flexible three-dimensional electrode arrays with a mapping function. We integrated the 3D electrode array on a scalable balloon catheter and deployed this device in rabbits, achieving a stable collection of multiphasic electrophysiological signals from the intestinal mucosa. In vivo electrophysiological recordings identified observable spike bursts associated with intestinal motility, as well as coordinated periodic pulses potentially related to intestinal pacemaker activities, revealing their activation modulation patterns. Further, longer-duration non-periodic spike bursts were also observed to link to spontaneous non-periodic peristaltic contractions. This technique realized through minimally invasive procedures, achieves a high spatiotemporal resolution in electrophysiological recording, providing a powerful tool for the diagnosis and research of functional bowel diseases.

Developing stimulus-responsive materials (SRMs) with reversible, large, and reprogrammable multi-responsiveness is crucial for soft actuators and intelligent devices, which remains challenging. In this study, regenerated silk fibroin with hierarchical structure is utilized to specially design a reprogrammable multi-stimuli-responsive protein film and versatile soft actuators. The freestanding fibroin films exhibit notable thermal contraction (-1383 ppm K-1) and humidity-responsiveness that can be repeatedly regulated by easy post-treatment with Ca2+ as desired. The actuating and regulating mechanisms involve reversible conformational change that is magnified into macroscopic deformations by hierarchical structure, and the roles of material structure and ambient conditions in determining actuating performances are analyzed based on thermodynamics. Driven by humidity gradient, the fibroin film demonstrates spontaneous flipping locomotion, self-oscillation with tunable frequencies, bio-butterfly wing flapping, and transformation from 2D to 3D structure. Moreover, reprogrammable deformations at specific regions are achieved in multi-stimuli-driven PET/fibroin film actuators owing to the straightforward Ca2+-content-based tunability of the responsiveness. The fibroin-based actuators can be used as artificial muscles to drive the high-frequency wing-flapping of a bio-dragonfly and soft gripper to grasp, lift, and transfer objects. The simple yet effective strategy presented herein provides valuable inspiration for designing advanced SRMs and soft actuators with reprogrammable multi-responsiveness. A free-standing, large-size fibroin film is prepared to enable versatile soft actuators. The fibroin film shows notable thermal contraction and humidity responsiveness that can be repeatedly regulated by Ca2+ treatment. The obtained soft actuators exhibit multimode and programmable deformations driven by fluctuations in ambient conditions, including self-oscillation, bio-butterfly wing flapping, reprogrammable bending, and high-frequency artificial muscle for bio-dragonfly. image

High-fidelity and comfortable recording of electrophysiological (EP) signals with on-the-fly setup is essential for health care and human-machine interfaces (HMIs). Microneedle electrodes allow direct access to the epidermis and eliminate time-consuming skin preparation. However, existing microneedle electrodes lack elasticity and reliability required for robust skin interfacing, thereby making long-term, high-quality EP sensing challenging during body movement. Here, we introduce a stretchable microneedle adhesive patch (SNAP) providing excellent skin penetrability and a robust electromechanical skin interface for prolonged and reliable EP monitoring under varying skin conditions. Results demonstrate that the SNAP can substantially reduce skin contact impedance under skin contamination and enhance wearing comfort during motion, outperforming gel and flexible microneedle electrodes. Our wireless SNAP demonstration for exoskeleton robot control shows its potential for highly reliable HMIs, even under time-dynamic skin conditions. We envision that the SNAP will open new opportunities for wearable EP sensing and its real-world applications in HMIs.

Developing thermally contractive polymeric materials with controlled conformational changes that enable more efficient actuation mechanisms has long been an ambitious goal. However, the utilization of naturally derived assemblies with biodegradable and reversible capabilities has, thus far, been hindered by the challenges associated with organizing the hierarchical nanostructures. Herein, hierarchically structured building blocks in regenerated fibroin were utilized to construct a thermal-responsive protein film through a friction-induced assemble strategy. By preserving the protofibrils within the regenerated silk film, we enable the efficient storage and transfer of elastic energy to external loads. The freestanding fibroin film, with pre-extended molecular chains, thus produced exhibited an exceedingly high negative thermal expansion (-1220 ppm K-1) and work capacity (similar to 203 J kg(-1)). The comprehensive analysis involving synchrotron infrared spectroscopy, in-situ Raman spectroscopy, and molecular dynamics simulations has confirmed that the actuating mechanism entails a reversible conformational change initiated by H-bonds, which is then amplified into macroscopic deformations by the hierarchical structure. This newly discovered, low-energy-driven mechanism paves the way for the creation of flexible protein assemblies with high-performance actuation capabilities.

Multimodal neural interfaces open new opportunities in brain research by enabling more sophisticated and systematic neural circuit dissection. Integrating complementary features across distinct functional domains, these multifunctional neural probes have greatly advanced the interrogation of complex neural circuitry. However, introducing multiple functionalities into a compact form factor for freely behaving animals presents substantial design hurdles that complicate the device or require more than one device. Moreover, fixed functionality poses challenges in meeting the dynamic needs of chronic neuroscience inquiry, such as replacing consumable parts like batteries or drugs. To address these limitations, the modular implantable neural device (MIND) is introduced with a one-touch magnetic assembly mechanism. Leveraging the seamless exchange of neural interface modules such as optical stimulation, drug delivery, and electrical stimulation, MIND ensures functional adaptability, reusability, and scalability. The versatile design of MIND will facilitate brain research by enabling simplified access to multiple functional modalities as needed.

Continuous and cuff-less blood pressure (BP) monitoring based on pulse transit time has been extensively explored in wearable electronics. However, both the accuracy and wearing comfort are impeded by the limited sensitivity, skin conformability and breathability of conventional pulse sensors. Here, silk nanofibrous iontronic pressure sensors made entirely of biocompatible materials were demonstrated for accurate, skin-friendly and long-term BP measurement. The sensor achieved a high sensitivity (138.5 kPa -1 ) by incorporating ionic deep eutectic solvents (DES) and engineering micro-structured electrodes, which enables the accurate measurement of pulse waveforms. High flexibility and gas-permeability (2056 g m -2 h -1 ) of the sensor render a conformal contact with the skin and prevent the signal deterioration by sweat, thus improving the signal accuracy and stability during long-term on-skin BP monitoring. Together with the electrocardiogram, both systolic and diastolic BPs could be estimated with mean ± standard deviation of 0.6 ± 3.57 mmHg and 0.7 ± 3.72 mmHg, respectively, meeting the standard of Association for the Advancement of Medical Instrumentation.

Real time monitoring of respiratory status during sleep is essential to provide immediate feedback for people with sleep apnea syndrome (SAS). Conventional strategies to monitor sleeping status rely on polysomnography or inflexible chip sensors. However, the devices used in these methods have poor wearability and comfort and are inconvenient to operate. Here, we report a multifunctional, integrated and low-power wireless flexible sensing platform based on biocompatible bacterial cellulose (BC) and graphene hybrids, which can be used not only for monitoring physiological signals and respiration, but also for Morse-code-based wireless communication. Combining the excellent conductivity of graphene and the high mechanical properties of BC, 3D porous Graphene/BC bioaerogel exhibits outstanding pressure sensing properties with a wide operating range (20 pa to 30 kPa), high sensitivity and cycling stability. Moreover, graphene oxide (GO)/BC exhibits excellent humidity sensing performance and realizes real-time monitoring of respiratory waveform and frequency. Finally, wear wireless flexible pressure and humidity sensors for extended periods of time during sleep can provide simultaneously diagnostic data for SAS. This original work shows that the wireless sensor system reported here has potential applicability in the field of medical science and military applications.

The conventional heating, ventilation, and air conditioning (HVAC) systems are based on a set-point control approach that only considers the temperature of the environment without reflecting the thermophysiological status of the occupant. This approach not only fails to fully satisfy individual thermal preferences, but it also makes an HVAC operation energy-inefficient. One possible solution is to control the indoor thermal condition based on an accurate prediction of the occupant's thermal comfort to prevent any unnecessary energy consumption. Here, we present an artificial intelligence (AI) wearable sensor-based human-in-the-loop HVAC control system that is operated on a real-time basis reflecting the thermophysiological condition of the occupant to automatically improve their thermal comfort while reducing the energy consumption of the building. The wristband-type, AI-based, three-point wearable temperature sensor offers excellent thermal comfort prediction accuracy (93.9%), enabling a human-centric HVAC control operation. A proof-of-concept demonstration of closed human-in-the-loop HVAC control using the AI-enabled wearable sensor system confirms both the accuracy of the thermal comfort prediction and the energy-efficiency of this approach, demonstrating its potential as a new solution that improves the occupant's thermal comfort and provides building energy savings.

Liquid metal (LM) exhibits a distinct combination of high electrical conductivity comparable to that of metals and exceptional deformability derived from its liquid state, thus it is considered a promising material for high-performance soft electronics. However, rapid patterning LM to achieve a sensory system with high sensitivity remains a challenge, mainly attributed to the poor rheological property and wettability. Here, we report a rheological modification strategy of LM and strain redistribution mechanics to simultaneously simplify the scalable manufacturing process and significantly enhance the sensitivity of LM sensors. By incorporating SiO2 particles into LM, the modulus, yield stress, and viscosity of the LM-SiO2 composite are drastically enhanced, enabling 3D printability on soft materials for stretchable electronics. The sensors based on printed LM-SiO2 composite show excellent mechanical flexibility, robustness, strain, and pressure sensing performances. Such sensors are integrated onto different locations of the human body for wearable applications. Furthermore, by integrating onto a tactile glove, the synergistic effect of strain and pressure sensing can decode the clenching posture and hitting strength in boxing training. When assisted by a deep-learning algorithm, this tactile glove can achieve recognition of the technical execution of boxing punches, such as jab, swing, uppercut, and combination punches, with 90.5% accuracy. This integrated multifunctional sensory system can find wide applications in smart sport-training, intelligent soft robotics, and human-machine interfaces.

Traditional rigid ocean pressure sensors typically require protection from bulky pressure chambers and complex seals to survive the large hydrostatic pressure and harsh ocean environment. Here, we introduce soft, flexible pressure sensors that can eliminate such a need and measure a wide range of hydrostatic pressures (0.1 MPa to 15 MPa) in environments that mimic the ocean, achieving small size, high flexibility, and potentially low power consumption. The sensors are fabricated from lithographically patterned gold thin films (100 nm thick) encapsulated with a soft Parylene C film and tested in a customized pressure vessel under well-controlled pressure and temperature conditions. Using a rectangular pressure sensor as an example, the resistance of the sensor is found to decrease linearly with the increase of the hydrostatic pressure from 0.1 MPa to 15 MPa. Finite element analysis (FEA) reveals the strain distributions in the pressure sensor under hydrostatic pressures of up to 15 MPa. The effect of geometry on sensor performance is also studied, and radially symmetric pressure sensors (like circular and spike-shaped) are shown to have more uniform strain distributions under large hydrostatic pressures and, therefore, have a potentially enhanced pressure measurement range. Pressure sensors of all geometries show high consistency and negligible hysteresis over 15 cyclic tests. In addition, the sensors exhibit excellent flexibility and operate reliably under a hydrostatic pressure of 10 MPa for up to 70 days. The developed soft pressure sensors are promising for integration with many platforms including animal tags, diver equipment, and soft underwater robotics.

Multimodal tactile sensors are a crucial part of intelligent human‐machine interaction and collaboration. Simultaneous detection of proximity, pressure, and temperature on a single sensor can greatly promote the safety, interactivity, and compactness of interaction systems. However, severe signal interference and complex decoupling algorithms hinder the actual applications. Here, this work reports a flexible optoelectronic multimodal sensor capable of detecting and decoupling proximity/pressure/temperature by integrating a light waveguide and an interdigital electrode (IDE) into a compact fibrous sensor. Negligible signal interference is realized by combining heterogeneous sensing mechanisms of optics and electronics, which encodes proximity into capacitance, pressure into light intensity and temperature into resistance. The sensor exhibits a large sensing distance of 225 mm with fast responses for proximity detection, a pressure sensitivity of 0.42 N −1 , and a temperature sensitivity of 7% °C −1 . As a proof of concept, a doll equipped with the sensor can accurately discriminate and detect various stimuli, thus achieving safe and immersive interactions with the user. This work opens up promising paths for self‐decoupled multimodal sensors and related human/machine/environment interaction applications.

Compliant elastomer tubing with a fabric "jacket" has been essential in various applications as soft robotic actuators, such as in biomedical exomuscles and massage therapy implements. Here, our study shows that a similar design concept can be an effective strategy in realizing passive regulation in the tube's distension, as well as in preventing aneurysm-like asymmetric rupture of the tube. A custom hydraulic pressure testing rig was built to perform experiments. The jacketed tubes initially deform rapidly as pressure increases, but a self-regulation behavior suppresses the tube's continued distension by strain-stiffening of the "jacket". In addition, highly asymmetric distension, common to elastomeric tubes due to imperfection in fabrication, is prevented dramatically by the "jacket". A three-dimensional finite element model predicts the distension of all tested tubes quantitatively across the entire experimental pressure ranges and beyond. Incorporating custom-designed kirigami relief patterns in the "jackets" expands the potential of the elastomeric tubes.

Wearable human–machine interface (HMI) is an advanced technology that has a wide range of applications from robotics to augmented/virtual reality (AR/VR). In this study, an optically driven wearable human-interactive smart textile is proposed by integrating a polydimethylsiloxane (PDMS) patch embedded with optical micro/nanofibers (MNF) array with a piece of textiles. Enabled by the highly sensitive pressure dependent bending loss of MNF, the smart textile shows high sensitivity (65.5 kPa−1) and fast response (25 ms) for touch sensing. Benefiting from the warp and weft structure of the textile, the optical smart textile can feel slight finger slip along the MNF. Furthermore, machine learning is utilized to classify the touch manners, achieving a recognition accuracy as high as 98.1%. As a proof-of-concept, a remote-control robotic hand and a smart interactive doll are demonstrated based on the optical smart textile. This optical smart textile represents an ideal HMI for AR/VR and robotics applications.

Photoactuators have attracted significant interest for soft robot and gripper applications, yet most of them rely on free-space illumination, which requires a line-of-site low-loss optical path. While waveguide photoactuators can overcome this limitation, their actuating performances are fundamentally restricted by the nature of standard optical fibres. Herein, we demonstrated miniature photoactuators by embedding optical fibre taper in a polydimethylsiloxane/Au nanorod-graphene oxide photothermal film. The special geometric features of the taper endow the designed photoactuator with microscale active layer thickness, high energy density and optical coupling efficiency. Hence, our photoactuator show large bending angles (>270°), fast response (1.8 s for 180° bending), and low energy consumption (<0.55 mW/°), significantly exceeding the performance of state-of-the-art waveguide photoactuators. As a proof-of-concept study, one-arm and two-arm photoactuator-based soft grippers are demonstrated for capturing/moving small objects, which is challenging for free-space light-driven photoactuators.

The ability to sense heat and touch is essential for healthcare, robotics, and human–machine interfaces. By taking advantage of the engineerable waveguiding properties, we design and fabricate a flexible optical microfiber sensor for simultaneous temperature and pressure measurement based on theoretical calculation. The sensor exhibits a high temperature sensitivity of 1.2 nm/°C by measuring the shift of a high-order mode cutoff wavelength in the short-wavelength range. In the case of pressure sensing, the sensor shows a sensitivity of 4.5% per kilopascal with a fast temporal frequency response of 1000 Hz owing to the strong evanescent wave guided outside the microfiber. The cross talk is negligible because the temperature and pressure signals are measured at different wavelengths based on different mechanisms. The properties of fast temporal response, high temperature, and pressure sensitivity enable the sensor for real-time skin temperature and wrist pulse measurements, which is critical to the accurate analysis of pulse waveforms. We believe the sensor will have great potential in wearable optical devices ranging from healthcare to humanoid robots.

Abstract Reconfigurability of a device that allows tuning of its shape and stiffness is utilized for personal electronics to provide an optimal mechanical interface for an intended purpose. Recent approaches in developing such transformative electronic systems (TES) involved the use of gallium liquid metal, which can change its liquid–solid phase by temperature to facilitate stiffness control of the device. However, the current design cannot withstand excessive heat during outdoor applications, leading to undesired softening of the device when the rigid mode of operation is favored. Here, a gallium‐based TES integrated with a flexible and stretchable radiative cooler is presented, which offers zero‐power thermal management for reliable rigid mode operation in the hot outdoors. The radiative cooler can both effectively reflect the heat transfer from the sun and emit thermal energy. It, therefore, allows a TES‐in‐the‐air to maintain its temperature below the melting point of gallium (29.8 ℃) under hot weather with strong sun exposure, thus preventing unwanted softening of the device. Comprehensive studies on optical, thermal, and mechanical characteristics of radiative‐cooler‐integrated TES, along with a proof‐of‐concept demonstration in the hot outdoors verify the reliability of this design approach, suggesting the possibility of expanding the use of TES in various environments.