Moiré superlattice-driven bionic hydrogel robot with programmable multifunctionality

Domain: chemistry
Published: 2026-02-18
Editorial outcome: major_revision

Abstract
The flexibility and intelligent responsiveness of hydrogel robots offer great potential for exploration in narrow and complex environments. However, the integration of sensors with hydrogel robotic bodies remains challenging. Inspired by marine organisms, this paper presents an anemone-like light-driven hydrogel robot (ALHR) for directional infrared radiation detection. We fabricated via ultrasonic-assisted stacking a black phosphorus/tungsten disulfide (BP/WS2) moiré superlattice, showing high dual-mode photothermal-photovoltaic conversion performance. Based on this, a composite poly(N-isopropylacrylamide) (PNIPAM) hydrogel was used to build the base plate and tentacle structures of the ALHR. Specific illumination was found to trigger the photothermal effect of the BP/WS2 moiré superlattice, allowing for directional movement. When the tentacles retract and contact the bottom electrode, photocurrent signals are conducted for infrared detection. The ALHR can work in specialized spatial environments, providing a promising method for early overheating fault identification in equipment. This study proposes a universal design framework for multifunctional hydrogel robots by integrating responsive units with driving units to leverage the synergistic effects of multiple materials.

Introduction
Flexible hydrogel robots with biomimetic structures show great application potential in complex scenarios that humans can’t access, like deep-sea exploration, confined spaces, and high-radiation environments. This is due to their excellent biocompatibility, deformability, and environmental adaptability1–4. By integrating functional units such as sensors and actuators into hydrogel matrices to imitate the morphology and behavior of natural organisms, researchers can effectively combine the unique physicochemical properties of hydrogels with the excellent capabilities of biological systems5–8. This method gives robots intelligent features like autonomous mobility and real-time perception, creating opportunities for the development of flexible bionic robots9–11. However, two main bottlenecks still exist in this field. Firstly, the high water content and softness of hydrogels often reduce the performance and stability of integrated sensors, making traditional microelectronic fabrication techniques inappropriate. Secondly, current research mainly focuses on achieving single functions (such as actuation or drug delivery) and has difficulty in balancing robotic mobility and sensing capabilities. Achieving the integration of actuation-sensing remains a challenging task12,13. Therefore, how to enhance the response speed, structural stability, and sensing compatibility of hydrogel robots simultaneously through innovative material and structural design has become a crucial scientific problem that needs urgent solutions in this field.

To tackle these challenges, exploring materials that combine both actuation and sensing functions is a key breakthrough. Among different actuation strategies, light-driven actuation is regarded as an ideal option for building smart hydrogel robots. This is because it is non-contact, highly precise, has a rapid response, and excellent biocompatibility14–20. Among them, poly(N-isopropylacrylamide) (PNIPAM), due to its excellent thermosensitive properties, has become a typical material system for preparing photodriven hydrogels when combined with photothermal converters21–23. Traditional methods rely on complex integrated designs to couple sensing and driving functions, but this makes the system even more unstable11,24. Therefore, developing an innovative structural composite material with both photothermal actuation and optoelectronic sensing capabilities is the fundamental solution to the sensor-hydrogel compatibility problem.

According to the latest research findings, the emerging moiré superlattice materials have demonstrated excellent performance that can meet various requirements. This periodic structure, formed by stacking two two-dimensional (2D) materials with different lattice constants or orientations25,26, provides a unique moiré potential field. This field can effectively adjust interlayer exciton dynamics, phonon vibration modes, and band structures, offering a platform for synergistically optimizing photothermal and photovoltaic performance27–36. Despite the great potential of moiré superlattices, current research mainly focuses on systems such as graphene. There is still limited systematic exploration of heterojunctions and their dual-function characteristics involving BP, a material with an inherently high photothermal coefficient, and other 2D materials.

This work introduces a universal framework to realize multifunctional integrated hydrogel robots. At the materials level, we designed and synthesized black phosphorus/tungsten disulfide (BP/WS2) moiré superlattices using an ultrasonic-assisted stacking method. The moiré potential field in this material enhances phonon-photon coupling to improve photothermal conversion efficiency while simultaneously promoting the separation and transport of photogenerated carriers, resulting in dual photothermal-photovoltaic response characteristics. At the design level, inspired by sea anemone feeding behavior, we integrated the BP/WS2 moiré superlattice with a PNIPAM flexible matrix to construct an anemone-like light-driven hydrogel robot (ALHR). The base plate generates photothermal effects under illumination to drive directional motion, while the tentacles sense infrared radiation and produce photocurrent signals, effectively integrating coordinated motion and sensing. Furthermore, the photothermal driving capability of ALHR enables it to adapt well to various complex environments and confined spaces. Its photoelectric conversion ability allows for the detection of overheated areas of the equipment, demonstrating its potential as an overheating monitoring robot. Finally, we propose a universal strategy centered on function-oriented moiré superlattice-hydrogels, where modular integration and synergistic coupling of responsive units with flexible substrates enable on-demand design of intelligent soft robots with diverse sensing and actuation capabilities. This research not only provides materials and methods for high-performance integrated actuator-sensor robots but also establishes a universal technical pathway and design paradigm for future multifunctional soft robots based on advanced 2D materials.

Results
Structural design and synthesis
Inspired by the structural and functional elegance of sea anemones37, we have developed an ALHR, as depicted in Fig. 1a. The ALHR features a large, soft base plate that mimics the anemone’s ability to anchor itself, serving as a brake during movement. The base plate is primarily composed of a BP/WS2-PNIPAM composite hydrogel, synthesized via a one-pot cross-linking method using N-isopropylacrylamide (NIPAM) as the polymer monomer and a homogeneously dispersed BP/WS2 moiré superlattice as the photothermal agent. The tentacle-like structures are made of standard PNIPAM hydrogel, coated with a BP/WS2 film on the surface, enabling light sensing and morphologic changes akin to those of anemone tentacles. The BP/WS2 moiré superlattice is pivotal to the ALHR’s functionality, exhibiting photothermal and photovoltaic properties due to its unique structure38. The BP/WS2 moiré superlattice, prepared through an ultrasound-assisted stacking method, leverages the slight lattice mismatch between BP and WS2. This mismatch creates long-periodic moiré patterns, enhancing near-infrared light absorption and enabling superior photovoltaic and photothermal conversion capabilities. As illustrated in Fig. 1a (right inset), the BP/WS2-PNIPAM composite hydrogel undergoes thermal-induced contraction under the driving light source (like 660 nm light), leading to bending and deformation. Upon light cessation, the hydrogel reabsorbs water and returns to its original state, driving the robot’s movement through friction. The direction of movement is precisely controllable. The tentacle’s BP/WS2 functional layer detects infrared radiation from overheated areas, triggering both photothermal and photoelectric effects. The photothermal effect causes localized warming and contraction, while the photoelectric effect converts light energy into exciton energy, generating a photocurrent (Fig. 1a, left inset). Here, we chose 660 nm light as the driving light source since this wavelength is different from the required detection signal band. Additionally, 660 nm light irradiation causes a weak photothermal response in the BP/WS2 moiré superlattice, leading to a slight temperature rise. This mildly drives the phase transition of the hydrogel in the substrate layer and avoids excessive water loss that might damage its internally stable cross-linked structure. Its weak response property also reduces the interference to the monitoring system caused by the tentacle contraction induced by the driving light source. This dual-response mechanism ensures accurate, real-time overheating detection. As shown in Fig. 1b, the ALHR operates through two primary functional modules: movement driven by the base plate and detection facilitated by the tentacles. When illuminated by a light source (such as 660 nm light), the base plate’s BP/WS2 photothermal agent converts light into heat, causing water loss and deformation in the hydrogel. This reversible bending-straightening cycle, regulated by light, propels the ALHR in a specific direction. Upon approaching an overheating source, the tentacle’s BP/WS2 layer detects near-infrared radiation (such as 808 nm wavelength), inducing a photothermal response that contracts the PNIPAM hydrogel. This contraction brings the functional layer into contact with a bottom electrode, conducting a photocurrent that signals the overheating location. When the ALHR moves away, the photothermal effect diminishes, the tentacle returns to its original form, and the electrical signal ceases. This reversible contact-disengagement cycle enables precise overheating detection, leveraging the synergistic effects of photothermal and photoelectric responses.

Characterization of moiré superlattices
The synthesis and characterization of BP/WS2 moiré superlattices constitute the cornerstone of the ALHR’s overheating detection functionality. Bulk BP powder was first prepared via high-energy ball milling using red phosphorus as the precursor. Few-layer BP nanosheets were subsequently obtained through ultrasound-assisted liquid-phase exfoliation. X-ray diffraction (XRD) patterns (Fig. 2a) provided conclusive evidence that the van der Waals forces existing between the BP layers were disrupted. This disruption was attributed to the substantial energy released upon the rupture of ultrasonic cavitation bubbles39. As a result, the successful synthesis of BP was achieved. Concurrently, scanning electron microscopy (SEM) images (Supplementary Fig. 1) revealed that the as-prepared BP nanosheets possessed clearly defined edges and distinctive lamellar structures. The size distributions of these nanosheets fell within the range of 10-20 μm, endowing them with excellent specific surface area characteristics. WS2 nanosheets were synthesized using chemical vapor deposition (CVD), wherein sulfur vapor reacted with WO3 vapor deposited on silicon wafers in a dual-temperature zone tube furnace. As shown in Supplementary Fig. 2, the WS2 nanosheets exhibit the characteristic lamellar structure of 2D materials, with sizes ranging from 100 to 200 nm, smaller than those of the BP nanosheets. The XRD patterns of WS2 display characteristic peaks corresponding to the (002), (004), (104), and (110) crystallographic planes, which align well with the standard 2H-phase WS2 reference, confirming its high crystallinity and specific crystalline structure. To construct the BP/WS2 moiré superlattice, an inkjet printing technique was employed to uniformly deposit an ultra-low concentration of BP nanosheet dispersion onto the surface of WS2, followed by thorough drying to ensure intimate contact. The XRD patterns of the resulting composite reveal characteristic peaks of WS2 at 2θ = 16.5°, 37.7°, and 68.6°, alongside peaks at 38° and 57.8° attributed to BP. Additionally, the broad, bun-like peaks of BP between 10° and 30° are preserved in the composite. Notably, the dominance of WS2 peaks in the composite is primarily due to the relatively low loading ratio of BP, while the weakened intensity of the (020) peak of BP may result from changes in the number of layers along the stacking direction and slight lattice distortions induced by the formation of the moiré superlattice. Raman spectral analysis (Fig. 2b) provides further insights into the vibrational modes of the BP/WS2 composite. The in-plane vibrational modes of BP are observed at 360 cm-1 and 470 cm-1, while the out-of-plane vibrational modes exhibit significant shifts compared to intrinsic BP (Supplementary Fig. 3). These shifts are primarily attributed to the modification of atomic vibrational environments induced by interlayer coupling and the moiré potential field, which arise from the formation of the moiré superlattice. This results in changes in phonon frequencies, manifesting as a redshift of the Raman characteristic peaks. Similarly, the in-plane vibrational mode of WS2 is observed at 350 cm-1, with its out-of-plane vibrational mode also slightly shifted relative to intrinsic WS2 (Supplementary Fig. 4). This indicates that the phonon vibrational modes of WS2 are similarly modulated by the moiré potential, leading to a weakening of the vibrational frequencies. At the microscopic level, the BP/WS2 moiré superlattice is characterized by large BP sheets encapsulating smaller WS2 sheets (Fig. 2c). Transmission electron microscopy (TEM) images clearly reveal the layered morphology and distribution states of the 2D materials. As shown in Fig. 2d, the lattice spacings of BP (0.46 nm) and WS2 (0.25 nm) are simultaneously observable along the b-axis direction. Due to the significant difference in lattice constants between the two materials, their atomic arrangements do not completely overlap when stacked together. Instead, as illustrated in Fig. 2e, periodic dislocation and overlap regions form, where the atomic interactions in the dislocation regions differ from those in the overlap regions. This results in a larger-scale periodic modulation across the entire stacked structure, known as the moiré pattern. Furthermore, the orthorhombic crystal structure of BP and the hexagonal crystal structure of WS2 possess different symmetries. When these materials are stacked to form a moiré superlattice, their distinct symmetries complement and influence each other, generating a symmetry feature. The TEM and scanning transmission electron microscopy (STEM) images in Fig. 2f further corroborate the formation of a periodic pattern with a larger scale, confirming the presence of a moiré superlattice between BP and WS2 due to the interference of their atomic layers. The changes in the interfacial electronic states also reflect the modulation of the moiré superlattice. As shown in Fig. 2g, compared to the intrinsic materials, X-ray photoelectron spectroscopy (XPS) shows that the BP/WS2 moiré superlattice displays characteristic peaks at 32.7 eV and 34.8 eV, corresponding to the W 4f7/2 and W 4f5/2 orbitals, respectively, with an overall redshift. Additionally, the excitation of 5p3/2 orbital electrons is observed. This phenomenon suggests that the moiré potential modulates the electron cloud density of W atoms. The formation of flat bands and increased electron localization induces a quantum confinement effect, causing electrons to preferentially occupy confined orbitals. Consequently, the excess energy of the X-ray electrons used in the test excites the 5p3/2 orbital electrons. A similar effect is observed for the S atoms (Fig. 2h), while the increased binding energy of the P 2p orbital electrons (Fig. 2i) confirms their role as electron donors in the composite. The interlayer coupling alters the overall electron cloud distribution, enhancing electron localization near the W atoms. According to the binding energy calculation formula, the composite material (Fig. 2j) exhibit significantly higher electron binding energy compared to intrinsic BP (Supplementary Fig. 5) and WS2 (Supplementary Fig. 6), indicating stronger electron binding. This modulation profoundly influences the light absorption properties of the system. For WS2, the Fermi level shift shows that the moiré potential effectively adjusts the potential energy distribution of W atoms near the interface, causing the localization of their electron clouds. When electrons are localized around W atoms, their shielding effect on the inner-shell electrons of W 4f is strengthened. According to Coulomb’s law, this strengthened shielding weakens the nucleus’s effective attraction to the 4f electrons, thus reducing their binding energy. In composite materials, BP serves as an electron donor. It transfers electrons to WS2, which in turn reduces the surface electron density of WS2. This enhances the ability of atomic nuclei to confine electrons, leading to an increase in the work function compared to the intrinsic material. As illustrated in Fig. 2k, the composite material integrates the absorption peaks of both BP and WS2, with a notably enhanced absorption in the infrared band. This confirms the effective modulation of the material’s optical properties. Furthermore, based on the light absorption characteristics (Fig. 2l), the band gap of the composite is calculated to be approximately 1.93 eV, consistent with the expected results.

Optical properties and response mechanisms
BP/WS2 moiré superlattices exhibit different physical phenomena that are markedly distinct from those of their intrinsic counterparts, owing to their unique interlayer coupling and energy band modulation properties. Through systematic experiments, we demonstrate that the BP/WS2 moiré superlattice achieves highly efficient light-to-heat energy conversion under optical excitation. As illustrated in Fig. 3a, the system temperature exhibits a significant increase with irradiation time. Notably, this photothermal conversion behavior is observed across multiple wavelength bands (Fig. 3b), with the 808 nm band being particularly prominent: the system temperature rapidly rises from an initial 22 °C to 51.9 °C within 600 s of irradiation, achieving a temperature increase of 29.9 °C. This result aligns closely with the material’s light absorption spectrum characteristics shown in Fig. 2k. Furthermore, the BP/WS2 moiré superlattice demonstrates excellent reproducibility in photothermal conversion (Fig. 3c). In periodic light-switching experiments, the system responds rapidly to optical stimuli and recovers stably to the initial temperature after irradiation ceases, highlighting the remarkable stability of its photothermal effect. Quantitative analysis of the photothermal conversion efficiency (PCE) based on established formulas40 reveals that the BP/WS2 moiré superlattice outperforms single-component WS2 in the UV and NIR bands, particularly at 808 nm, where its PCE reaches an impressive 72.1% (Fig. 3d). Further investigations reveal that the BP/WS2 moiré superlattice efficiently converts photon energy: a portion is dissipated as heat through phonon vibrations, while the remainder is transported by photogenerated carriers to generate photocurrent. Under a bias range of −2 to 2 V, the current under illumination significantly exceeds that in the dark state (Fig. 3e), confirming the material’s photo-responsive properties. Even more remarkable are the zero-bias experimental results (Fig. 3f): the photocurrent response exhibits strong wavelength dependence, with particularly high photoelectric conversion efficiencies at 405, 610, 808, and 940 nm, consistent with the light absorption spectrum. Notably, the 808 nm band generates a maximum photocurrent of 514.2 nA at zero bias, with photocurrent intensity positively correlated with light intensity (Fig. 3g). We also performed continuous spectral photoresponse testing on the BP/WS2 thin film (Supplementary Fig. 7). The results demonstrate that the device exhibit significant photoresponse capabilities across multiple bands in the ultraviolet, visible, and near-infrared regions, with particularly performance in the near-infrared band. At the same low power density, multiple representative spectral bands (405, 532, 650, 808 and 940 nm) were selected for independent irradiation experiments. As shown in Supplementary Fig. 8, the results demonstrate that even at such low light intensities, the device maintains observable and relatively stable photoresponse signals in the near-infrared band. In contrast, response signals in the other tested bands are significantly weaker, falling below the effective detection threshold. To fully characterize the photovoltaic properties, we calculated the responsivity (R) and specific detectivity (D*)41, defined as:

R = (Ip - Id) / (PS) (1)

D* = RS0.5 / (2eId)0.5 (2)

Where Ip and Id denote the currents under illumination and in the dark, respectively, P is the optical power density, and S is the effective light-receiving area. The BP/WS2 moiré superlattice exhibits optoelectronic performance, as shown in Fig. 3h, with a maximum responsivity of 4.14 A/W and a specific detectivity as high as 12 × 1011 Jones. Additionally, the material demonstrates rapid response times, with rise and fall times of 70 ms and 48 ms, respectively (Fig. 3i), indicating its ability to swiftly adapt to optical signal changes. As elucidated by experimental data (Supplementary Figs. 9–14) and a direct comparison (Fig. 3j), the BP/WS2 moiré superlattice surpasses the performance of pristine BP and WS2 in both photothermal conversion and photovoltaic applications, particularly under 808 nm illumination. Compared to other similar materials, it demonstrates an overall leading edge across multiple performance parameters (Fig. 3k, Supplementary Table 1), underscoring its potential for advanced optoelectronic and energy conversion applications.

The photothermal and photoelectric response mechanisms of BP/WS2 were investigated using first-principles calculations. The results show that the work function of the composite material is approximately 4.791 eV, lying between those of BP and WS2, suggesting intermediate electron confinement capability (Supplementary Figs. 15–19). When illuminated, the composite efficiently absorbs photon energy and generates carriers on its surface. Some of this energy is released through non-equilibrium carrier recombination, while another portion is captured by defect energy levels within the bandgap and subsequently re-emitted to the conduction band. During this relaxation process, phonon scattering occurs, converting photon energy into thermal energy. In the BP/WS2 moiré superlattice, periodic moiré potential wells confine interlayer excitons, greatly extending their lifetime. As these excitons relax, they preferentially transfer energy to the lattice through nonradiative recombination, emitting phonons. This mechanism synergistically combines BP’s inherent photothermal properties with the confinement effect of the moiré potential, markedly enhancing photothermal conversion efficiency. Band structure analysis of the three components (Supplementary Fig. 20-26) indicates that the moiré superlattice significantly modulates the composite’s band structure, generating numerous flat bands with corresponding peaks in the density of states. Within these bands, electron density is relatively high, forming localized states. Driven by interlayer coupling from the moiré potential field, these localized states are periodically distributed across the system, regulating charge distribution in the barrier region. This confinement enhances electron aggregation and restricts carrier diffusion, requiring greater energy for transitions across energy barriers. The resulting confined electron-hole pairs are known as moiré excitons, which remain stable even at room temperature. For the BP/WS2 moiré superlattice, the enhanced localized states raise the energy required for non-equilibrium carriers to cross these barriers. Interestingly, the photothermal effect partially facilitates this process. The competition and synergy between these effects improve carrier separation and transport. Additionally, the modulation of the band structure by the moiré superlattice leads to more selective light absorption in the system.

Functionality of ALHR devices and expansion
Leveraging the photothermal and photoelectric response properties of BP/WS2 moiré superlattice materials, we designed an ALHR by integrating this material into a hydrogel system. The BP/WS2 moiré superlattice serves dual roles as both a photothermal driving agent and a thermal sensing material. As illustrated in Fig. 4a, the ALHR mimics the structure of an anemone, comprising two main components: a mobile basal disk and responsive tentacles. The tentacle-like structures were fabricated using a one-step method in a specific mold. PNIPAM hydrogels were prepared using NIPAM as the polymer monomer and N,N’-Methylenebisacrylamide (BIS) as the cross-linking agent. The BP/WS2 film was subsequently coated onto the top of these hydrogels. The temperature-sensitive PNIPAM hydrogels exhibit shrinking and deformation under the photothermal effect of BP/WS2, with the tentacle shape guiding the downward contraction. The basal disk of the ALHR was similarly prepared using a specific mold. The material composition is analogous to that of the tentacles, with the addition of BP/WS2 moiré superlattice material uniformly dispersed within the hydrogel network. This ensures that when any part of the basal disk is exposed to specific light, the BP/WS2 material rapidly heats the exposed area due to its superior photothermal conversion capability. The resulting temperature increase causes localized shrinkage and buckling of the hydrogel due to water loss. Upon cessation enabling the ALHR to perform walking movements akin to those of an anemone. The compatibility of materials between the tentacles and basal disk facilitates straightforward assembly, culminating in the final preparation of the robot as depicted in Fig. 4b and Supplementary Fig. 27.

To validate the ALHR’s capability for motion and overheating detection, we conducted a series of tests. First, we examined the response of the basal disk material to light. As shown in Fig. 4c, under 660 nm light, the basal disk exhibited a consistent and uniform temperature increase of approximately 14.4 °C. This behavior demonstrated reversibility and stability in periodic switching tests (Fig. 4d) and was directly correlated with light intensity (Fig. 4e). Stronger light intensities generated more heat, enabling the system temperature to exceed the lower critical solution temperature of the PNIPAM hydrogel, initiating the phase transition.

We irradiated one side of the basal disk with 660-nm red light, which induced shrinkage deformation on the illuminated side of the basal disk. Under the influence of high-temperature conditions, this side gradually warped without experiencing complete water loss. This warping led to the contraction of the base plate, causing its tail end to move forward. After a certain period, when the light source was removed, the temperature decreased, and the basal disk relaxed. Relying on friction, the base plate accomplished light-driven peristaltic motion. Due to the differences in their own morphological structures and irradiation methods, the basal disk and tentacles exhibit completely distinct deformation behaviors, as shown in the Supplementary Fig. 28. To assess performance degradation under different conditions, we first placed tentacle samples in an unencapsulated, open environment at room temperature. As shown in Fig. 4g, the results showed that after 7 days, their response speed remained above 85% of the initial value. We found that the total weight loss rate was about 12% over 7 days, which closely matched the performance degradation rate. This confirms that water evaporation is the main factor affecting long-term performance. Figure 4h shows the drive performance stability of the base plate under continuous on-off light cycles (660 nm laser, 19 mW/cm2, 120 seconds per cycle). The base plate changes as illustrated in the diagram. The results indicate that after 200 cycles (about 6.7 hours in total), the decay rate of the base plate’s bending angle was below 5%, and the response speed remained basically unchanged. This demonstrates that our robot has excellent cyclic operational stability and fatigue resistance. We mainly attribute this remarkable stability to the dense three-dimensional network structure of the PNIPAM hydrogel, which can effectively hold a large number of water molecules. Moreover, our BP/WS2 moiré superlattice has high photothermal conversion efficiency, lowering the energy threshold for actuation. This enables a rapid response at lower overall temperatures, thus minimizing excessive heating of the hydrogel and the associated intense thermal evaporation effects.

Under illumination at a wavelength of 660 nm, the base plate undergoes a periodic bending-straightening cycle (Fig. 5a and Supplementary Movies 1 and 3). Specifically, rapid photothermal heating induces upward bending at the disk center and forward retraction of its rear end; upon light removal, cooling restores the structure to its original configuration. Driven by friction, the front edge advances forward, yielding the morphology observed in the physical image on the left. This process exhibits excellent repeatability, enabling the light-driven disk to achieve an average crawling speed of approximately 2 mm/s under modulated illumination. Our ALHR demonstrates distinct advantages over previously reported designs, as shown in Supplementary Table 242–46. Experimental testing has confirmed that our ALHR showcases remarkable motion performance. It can adapt to a wide range of media and different pipeline conditions, enabling efficient optical actuation and flexible locomotion (refer to Supplementary Table 3). In contrast, under 808 nm near-infrared light irradiation (which mimics thermal radiation), the tentacle mainly undergoes a contraction-expansion cycle: light triggers downward contraction, which is followed by slow recovery after illumination ceases, as shown in the inset. Owing to its geometric constraint, this motion occurs primarily along the vertical axis as illustrated (Fig. 5b and Supplementary Movie 2). The described behaviors were experimentally verified. During actuation, the light intensity of the driving source significantly influences the locomotion speed of the disk (Fig. 5c), showing a positive correlation with the former. Furthermore, the speed also increases with the on-off switching frequency of the light (Fig. 5d). Experimental measurements indicate that the maximum locomotion speed is attained at a frequency of 0.6 Hz. Beyond deformation, the tentacle’s detection functionality was also verified. We fixed two contact electrodes at a specific height on the tentacle’s base. As shown in the illustration, only when the tentacle contracted under the photothermal drive of BP/WS2 did the BP/WS2 at the top contact the electrodes, enabling rapid conduction of photogenerated carriers to transmit electrical signals externally (Fig. 5e, Supplementary Movie 4 and Fig. 29). No current was detected in the loop without contact, while the current magnitude varied with light intensity during contact. We also evaluated the spatial resolution of the temperature detection system. After securing a black body heat source, the entire ALHR was mounted on a precision-movable platform and translated along a straight line toward and away from the heat source. During this motion, the ALHR transitioned from the ‘non-overheated’ to the ‘overheated’ state at position x1, where the tentacle contacted the bottom electrode, and reverted to the ‘non-overheated’ state at position x2 when the tentacle detached from the bottom electrode. This procedure was repeated 50 times. The spatial resolution was defined as:

Δx = x2 - x1 (3)

Among them, x1 and x2 represent the average values of multiple sets of test data for x1 and x2, respectively. The results show that the spatial resolution of ALHR is 2.037 m. In scenarios where overheating detection is needed in complex pipelines and similar environments, our ALHR can move flexibly under the action of light. When it senses near-infrared radiation from an overheating point, it rapidly generates an electrical signal, thus reporting the overheating risk to the external environment. To verify its performance, we simulated the cooling oil lines inside a transformer using a 50-mm-diameter smooth-surfaced plastic water supply pipe with an elbow. As shown in Fig. 5g, the whole experiment was carried out in a dark, room-temperature, atmospheric environment. Thermocouple probes with controlled temperatures were placed every 10 centimeters to simulate overheating sources, and the temperature of each thermocouple was labeled on the curve. Experimental results have shown that the ALHR can respond promptly to temperatures ranging from 380 to 453 K during its movement. Thanks to its excellent flexibility and deformability, the ALHR can adapt well to the complex environment and confined spaces within the transformer ducts. It can nimbly bypass obstacles and smoothly navigate through curved and narrow pipelines to reach areas inaccessible to traditional inspection equipment, which verifies its application potential as a type of overheating monitoring robot.

Although this study validates the application potential of BP/WS2 moiré superlattices in constructing light-driven infrared-detecting anemone hydrogel robots, its significance extends beyond this specific material’s performance. It lies in presenting a universal design framework and integration strategy. This framework can be broadly applied to multifunctional soft robots based on diverse advanced two-dimensional materials, particularly moiré superlattice systems. As depicted in Fig. 5h, the designed soft robot features two core functional units: a driving module and a sensing module. On the one hand, the drive module must achieve controllable photothermal conversion with precise regulation of response intensity, speed, and spatial distribution. Integrated into a thermosensitive hydrogel matrix, this module induces material contraction/deformation through the photothermal effect. Material selection should prioritize moiré systems with high photothermal conversion efficiency (e.g., strongly coupled TMD heterojunctions and specific-angle graphene), or other 2D heterostructures suitable for flexible hydrogel environments (e.g., BP/Graphene, TMDs; see Supplementary Table 436,47–53). Preparation depends on achieving uniform nanomaterial dispersion within the hydrogel network, ensuring interface compatibility and long-term stability, achievable via optimized dispersion methods. On the other hand, the core requirements for the sensing module are efficient photoelectric detection within the target wavelength band, demanding high photoelectric conversion efficiency, a rapid response speed, excellent wavelength selectivity, and signal stability. Integrated onto a flexible structure, this module must achieve a drive-contact-conduction sequential response. Material selection prioritizes moiré systems with high photoelectric conversion efficiency and narrow or tunable response wavelengths (e.g., well-matched TMD heterojunctions, bandgap-tunable BP heterojunctions; see Supplementary Table 4). Fabrication primarily employs interfacial integration methods, with key challenges including strong adhesion between thin films and flexible substrates, efficient interfacial charge transport, and structural integrity.

Functional integration and response coordination between the drive and sensing modules are central to the system design. Drawing inspiration from nature’s intricate structure-function synergies, efficient biomimetic structural design effectively addresses this challenge. Furthermore, the tailored selection of sensing materials based on specific application requirements (e.g., environmental monitoring, drug delivery, environmental adaptation, and micro-sensing units) enables diverse signal detection and transmission capabilities.

In summary, this study achieves standardized integration of hydrogel robots through functional module decomposition and core requirement definition, guided by design principles of function-material matching, structure-function coupling, and response synergy. It provides a material-agnostic, universal methodology for systematically integrating the optoelectronic/photothermal properties of advanced two-dimensional materials with the flexibility, actuation, and biocompatibility of hydrogels. The successful application of BP/WS2 moiré superlattices in ALHR serves as a robust demonstration of this framework’s efficacy and versatility.

Methods
Preparation Materials
Red phosphorus (RP, ≥ 99.99%), tungsten trioxide (WO3, ≥ 99.8%), ammonium fluoride (NH4F, ≥ 99.8%), N-isopropylacrylamide (NIPAM, ≥ 98%), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO, 97%), and N,N’-Methylenebisacrylamide (BIS, 98%) were all purchased from Aladdin Chemical Co., Ltd. Precipitated sulfur (S, CP) and acetone (C3H6O, AR) were obtained from Sinopharm Chemical Reagent Co., Ltd. Polymethylmethacrylate (PMMA, average Mw 100,000-120,000) and hydrofluoric acid (48 wt.% in H2O, ≥ 99.99%) were purchased from Shanghai Macklin Biochemical Technology Co., Ltd. Potassium hydroxide (KOH, AR) was procured from Guangdong Guanghua Sci-Tech Co., Ltd. Absolute ethanol (C2H5OH, AR) was bought from Tianjin Fuyu Fine Chemical Co., Ltd. All materials were used directly without purification, except for N-isopropylacrylamide.

Preparation of WS2
The Si/SiO2 substrate was immersed in acetone and cleaned in an ultrasonic cleaner for 15 min. Subsequently, it was rinsed with acetone, absolute ethanol, and deionized water for 5 min each to remove the organic matter and impurities remaining on the substrate surface. Then, it was fully dried in a vacuum drying oven. 600 mg of S powder was weighed and placed in a quartz boat as the sulfur source, and 40 mg of WO3 powder was taken and placed in another quartz boat as the tungsten source. The cleaned substrate was inverted above the WO3 powder. The two quartz boats were placed into a specially-made long quartz tube and then put into a dual-temperature-zone tube furnace. Argon was introduced as a protective gas. The temperature of the S powder was set at 200 °C, and that of WO3 was 850 °C. The system was heated for 30 min to ensure complete reaction. After the furnace temperature had completely dropped to room temperature, the substrate was taken out and rinsed three times with absolute ethanol and deionized water, respectively, to remove the surface residues. Thus, WS2 on the Si/SiO2 substrate was obtained.

Transfer of WS2 nanosheets
A sufficient amount of PMMA solution was spin-coated on the surface of WS2 on the Si/SiO2 substrate and heated at 80 °C for 2 min to ensure full adhesion between them. A supersaturated KOH solution was prepared, and the substrate with spin-coated PMMA was placed in the solution to separate WS2 from the substrate. The floating WS2/PMMA hybrid structure on the surface was rinsed multiple times with deionized water to remove the residual KOH solution. A BOE solution (20 g of ammonium fluoride, 30 mL of deionized water, and 7 mL of hydrofluoric acid) was prepared, and the Si/SiO2 substrate was soaked in it for 5 min to etch the window. The etched substrate was carefully used to pick up the WS2/PMMA hybrid structure and heated on a hot plate for 15 min to enhance its adhesion. The target substrate was immersed in acetone for 1 h to fully dissolve the PMMA. After being taken out, the surface was thoroughly cleaned with isopropanol and then dried with nitrogen. In this way, the WS2 nanosheet structure on the specific substrate was obtained.

Preparation of BP nanosheets
A certain amount of red phosphorus powder was mixed with grinding balls and placed in a planetary ball mill for 48 h of full mixing and ball-milling to obtain high-purity bulk black phosphorus powder. A certain amount of black phosphorus powder was fully stirred with absolute ethanol for 4 h to obtain a black phosphorus dispersion in absolute ethanol. The dispersion was placed in a double-layer beaker and subjected to ultrasonic treatment in a cold-water bath for 10 h to break the inter-layer van der Waals forces by the action of ultrasound. After centrifuging the dispersion at 2152 × g for 30 min, the supernatant was taken as the BP nanosheet dispersion.

Preparation of BP/WS2 composites
The BP nanosheet dispersion was uniformly sprayed on the surface of WS2 nanosheets using an inkjet printer and vacuum-dried in a vacuum drying oven for 4 h to improve the adhesion between them. After taking it out, Au electrodes were thermally evaporated inside and outside the window of the substrate, and thus the BP/WS2 composite on the Si/SiO2 substrate was obtained. The WS2 nanosheets on the substrate surface were scraped off, fully dispersed in absolute ethanol, and then ultrasonically blended with the BP nanosheet dispersion for 30 min to obtain the BP/WS2 composite dispersion. Through a series of preliminary experiments for optimization, the mass ratio of BP nanosheets to WS2 nanosheets was determined to be 1:8.

Preparation of Anemone-like Light-driven/light-detecting Hydrogel Robots
4.8 g of purified NIPAM powder, 0.12 g of TPO, and 0.13 g of BIS were taken and added with 2 mL of absolute ethanol and 7 mL of deionized water, and the mixture was stirred for 30 min to ensure full dissolution. The solution was placed in a vacuum oven and evacuated for 10 min to eliminate the internal bubbles. Then it was poured into a tentacle-shaped mold and refrigerated at 5 °C for 12 h to form a cross-linked colloid. For the base part of the anemone-like hydrogel robot, 2 mL of the BP/WS2 composite dispersion was used instead of absolute ethanol. Other operations were similar to those for the tentacle part. After defoaming, it was poured into the base mold and also refrigerated to form a colloid. After 12 h, it was taken out and cured under a 395-nm ultraviolet lamp for 10 min. Then the hydrogel was taken out and thoroughly rinsed with deionized water to remove the residual monomers on the surface. After assembling the tentacles and the base, it was soaked in deionized water for 3 h to fully swell. Finally, the BP/WS2 film was spin-coated on the tip of the tentacles and ALHR was obtained by low-temperature drying at 25 °C for 48 h. The substrate has a length of 20 mm, a width of 4 mm, and a thickness of approximately 3 mm. Each tentacle is 14 mm long and has a diameter of 2 mm. Six tentacles in total are arranged in a 3 × 2 configuration. The base plate contains 7.5-8% (by mass) of the BP/WS2 molar superlattice material and 50-65% (by mass) of water. The tentacles contain 2-3% (by mass) of the bimodal photoresponsive film and 50-65% (by mass) of water.

Equipment
Equipment: The surface morphology was characterized by a field emission scanning electron microscope (FEI, Verios G4) and a transmission electron microscope (FEI, Talos F200X). The phase composition of the material was analyzed using an X-ray diffractometer (D8 DISCOVER A25). For different types of spectroscopy and property analysis, the following equipment was used. Raman spectra were obtained with a micro-confocal Raman spectrometer (WItec, Alpha300R). An ultraviolet-visible spectrophotometer (Shimadzu, UV-3600) was employed for absorption spectroscopy, and a multi-functional parameter analyzer (Keithley, 4200A-SCS) was used for electrical property analysis. Specific wavelength illumination experiments were carried out using power-tunable 365 nm, 405 nm, 515 nm, 550 nm, 610 nm, 660 nm, 808 nm, and 940 nm lasers. The laser beams irradiated the sample perpendicularly. Under the monochromatic light of different wavelengths provided by a monochromator (Model Omni-λ3009, ZOLTAN HanGuang Co.), the optical response of the device was recorded by a source meter (Model 6517B, Keithley). The response times were measured with an oscilloscope equipped with an electronic shutter (Model MSO4054, Tektronix). Photothermal measurements were conducted using a light source with a fixed power density, which was calibrated to be 45.0 ± 0.5 mW/cm2 using an optical power meter (Model 1936-R, Newport). Unless otherwise stated, this power density was applied for all experiments. The surface temperature was measured by an infrared thermal imager (Hikvision, P10) at a data acquisition rate of 10 Hz.

Data availability
Relevant data supporting the key findings of this study are available within the article and the Supplementary Information file. All raw data generated during the current study are available from the corresponding authors upon request.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "In this manuscript, BP/WS2 moiré superlattice materials with dual photothermal and photovoltaic responses were prepared and integrate it into PNIPAM hydrogel to design an anemone-like light-driven/light-detecting hydrogel robot. The research is meaningful, the writing is well-organized and I would like to recommend its publication after some necessary revisions. My detailed comments are as follows:\n(1) There are many types of moiré superlattice materials. What are the advantages of BP/WS2? Why is the photothermal and photovoltaic performance better than that of others?\n(2) In the article, the driving light source sometimes is 660 nm and sometimes is 808 nm. Fig. 3b shows that the photothermal effect is more pronounced at 808 nm than 660 nm. Why not all use 808 nm?\n(3) On page 17 “This result aligns closely with the material’s light absorption spectrum characteristics (Fig. 3c)”. Fig. 3c is not the absorption spectrum. Please provide the absorption spectrum of BP/WS2 moiré superlattice in the SI.\n(4) In Fig. 3a-3c, the system temperature is irradiation intensity dependent. Please provide the intensity value.\n(5) The experimental part of the article lacks many details, such as the ratio of BP/WS2 for the moiré superlattice preparation, the content of moiré superlattice in the hydrogel, which would facilitate others to replicate the experiment.\n(6) Due to the inevitable evaporation of water, especially under the stimulation of photothermal effects, the stability of the hydrogel robot is of utmost importance. Please provide the corresponding data.", "reviewer_2": "The manuscript fabricated BP/WS2 moiré superlattice via an ultrasound-assisted stacking method and investigated its photothermal and photovoltaic properties. An anemone-like light-driven/light-detecting hydrogel robot was prepared by compounding PNIPAM hydrogel. Under specific light conditions, based on the photothermal response, the robot can move under light drive and recognize infrared radiation.\n1. Generally, the manuscript emphasize on the properties of moiré superlattice. The part related to robot is relatively weak. The motion and sensing functions needs more investigations.\n2. In Fig. 5c–f, the temperature rise and bending cycles are demonstrated, but the quantitative motion performance of the robot is not analyzed. Please provide the bending angle vs. illumination time and movement velocity vs. power density curves to evaluate reproducibility and fatigue behavior.\n3. The XPS spectra show slight blueshifts in W 4f and P 2p peaks, which are ascribed to “quantum confinement and flat band formation”. However, this is speculative, and more evidence/discussion should be presented. Additionally, please rule out surface charging or oxidation effects, especially considering BP’s high reactivity in air.\n4. The article compares the photodetection performance of WS₂ and BP/WS₂. Why is there no comparison with standalone BP?\n5. This manuscript currently limits the characterization of the robot's photoresponse to the 365-808 nm range. A key question for its practical relevance is whether its functionality can be extended to the infrared spectrum?\n6. Furthermore, does the robot possess broad-range photodetection capabilities, particularly under low-intensity light conditions?\n7. The schematic in Fig. 5j shows an ALHR moving through pipes. The actual experimental environment e.g., medium, illumination, and thermal source should be presented.", "reviewer_3": "The manuscript presents the design of a multifunctional biomimetic hydrogel robot that integrates a BP/WS₂ moiré superlattice to achieve both photothermal actuation and photoelectric sensing for real-time overheating detection. This concept leverages the unique interlayer interactions between BP and WS₂ to enhance both photothermal and photovoltaic performance, and integrates this dual-function material into a PNIPAM hydrogel to create an anemone-inspired light-driven robot capable of directional locomotion and infrared radiation detection. The work is technically solid and represents a meaningful contribution to the integration of sensing and actuation in soft robotic systems. However, the scientific novelty lies more in the integration strategy and application demonstration than in a fundamental breakthrough in materials science or robotic mechanisms. Moiré superlattices themselves are not new, and their optoelectronic properties have been extensively reported. Thus, the conceptual advance of this work is largely application-driven rather than rooted in the discovery of new physics.\nThe abstract and introduction provide clear motivation for the need to integrate sensing and actuation functions in hydrogel robots and highlight the potential advantages of using moiré superlattices. However, the problem statement remains too general and does not sharply define the specific performance limitations of existing soft robots that the proposed system overcomes. To meet the high conceptual and scientific threshold of Nature Communications, the authors should more clearly articulate the scientific and technological gap and emphasize why BP/WS₂ moiré superlattice provides a distinct solution compared to existing photothermal or photoresponsive materials. This will strengthen the impact narrative of the manuscript.\nThe experimental work is thorough, including extensive material characterization (XRD, Raman, TEM, UPS, XPS, UV-Vis) that supports the formation of the moiré superlattice. The performance metrics reported such as the 72.1% photothermal conversion efficiency, 4.14 A/W responsivity, and 12 × 10¹¹ Jones detectivity, are impressive and support the claim of enhanced optoelectronic response. The robot demonstration is conceptually appealing, showing how the base and tentacle components can respond to light and infrared stimuli, respectively. However, the manuscript lacks quantitative benchmarking against state-of-the-art systems in terms of robot performance. Parameters such as actuation speed, bending displacement, response time, spatial resolution, and robustness under prolonged operation should be evaluated and compared to competing photothermal actuators. Moreover, the environmental stability and practical functionality of the robot should be further tested, especially under fluidic or more realistic pipeline conditions.\nA significant weakness of the presentation is the absence of video demonstrations. Since the core of the work involves a soft robot that moves and senses based on photothermal and photoelectric cues, including high-quality supplementary videos would greatly strengthen the manuscript’s impact, making the concept more intuitive and convincing. Visual content would also help reviewers and readers better evaluate the claimed responsiveness and motion behavior, which is difficult to fully convey through static figures alone.\nThe discussion effectively explains the underlying mechanism of enhanced photothermal and photoelectric response through DFT calculations and analysis of energy band modulation. However, it is focused mainly on material properties and less on the broader design framework that this strategy enables for other multifunctional hydrogel robots. To elevate the conceptual weight of the work, the authors should extend the discussion to generalize this integration strategy beyond BP/WS₂ to other moiré or 2D systems, positioning it as a versatile platform for multifunctional soft robotics.\nThe manuscript is generally well written, but some sentences are overly long and descriptive, particularly in the abstract, introduction, and conclusion. The writing should be tightened for clarity, and the novelty should be emphasized more directly. In addition, the title should be revised to better reflect the main focus of the study. Currently, the title emphasizes the moiré superlattice but does not sufficiently highlight the hydrogel robot or its application in real-time thermal surveillance, which is the true strength of this work. A more application-reflective title may help align expectations and better communicate the contribution of the study.\nOverall, this is a strong applied research paper with high-quality material characterization and a creative integration concept. However, in its current form, it may not fully meet the high conceptual threshold of Nature Communications. To improve its chances, the authors should: (i) sharpen the novelty and gap statement, (ii) provide quantitative robot performance benchmarking, (iii) add video demonstrations, (iv) revise the title for clarity and accuracy, and (v) generalize the discussion to strengthen conceptual significance. If these revisions are made, the work could be more competitive. At present, the most appropriate recommendation is major revision."}, "author_response": "Response to Reviewers\n\nReviewer #1 (Remarks to the Author):\nIn this manuscript, BP/WS moiré superlattice materials with dual photothermal and\n2\nphotovoltaic responses were prepared and integrate it into PNIPAM hydrogel to design an\nanemone-like light-driven/light-detecting hydrogel robot. The research is meaningful, the\nwriting is well-organized and I would like to recommend its publication after some necessary\nrevisions. My detailed comments are as follows:\n1. There are many types of moiré superlattice materials. What are the advantages of BP/WS ?\nResponse: Thank you very much for your valuable comments.\nWe selected the BP/WS moiré superlattice as our research subject based on an in-depth\n2\nexamination of the current landscape of moiré physics research and a profound understanding\nof the future demands for high-performance photonic devices. The innovation and superiority\nof this system are manifested in the following three aspects:\nFirst, in material design, we have addressed a research gap by achieving a significant\nadvancement in spectral response range. Current research on moiré superlattices primarily\nfocuses on graphene and transition metal dichalcogenide systems, while moiré physics based\non black phosphorus remains largely unexplored [1]. Our work specifically aims at deepening\nthe innovative research on this new material structure. Currently, both TMD/TMD\nhomojunctions and graphene/TMD heterojunctions face limitations in spectral coverage. The\nformer exhibits bandgaps concentrated between 1.0-2.5 eV, failing to extend into the infrared\nregion. The latter, while benefiting from graphene’s broad-spectrum absorption, sacrifices\nspectral selectivity due to its zero-bandgap structure, with performance ultimately limited by\nthe TMD component [2,3]. BP’s most distinctive feature is its layer-dependent direct bandgap,\ncontinuously tunable from ~2.0 eV in monolayers to ~0.3 eV in bulk. This property endows BP\nwith unique potential to span the spectral range from mid-infrared to visible light [4]. Our work\npioneers the use of black phosphorus with this layer-dependent, continuously tunable direct\nbandgap (0.3-2.0 eV). To construct functionally complementary heterojunctions, we selected\nmonolayer WS as the counterlayer. As a typical TMD material, WS exhibits a large direct\n2 2\nbandgap (~2.1 eV) and a robust exciton absorption peak [5], providing efficient high-energy-end\ncomplementarity to BP’s bandgap range. Thus, when the two form a moiré superlattice, the\noptical absorption range of the system can be precisely controlled across the mid-infrared to\nvisible spectrum through active control of parameters such as layer number, stacking angle, or\napplied electric field.\nBeyond the optical advantages of the materials themselves, the intrinsic physical mechanisms\nof the BP/WS moiré superlattice further enhance its potential in photothermal and photovoltaic\n2\napplications. Black phosphorus (BP) is well-known as a highly efficient photothermal material\nbecause of its high light absorption rate and numerous non-radiative recombination pathways\n[6]. A key finding in our work is that the periodic potential wells in the moiré superlattice can\neffectively confine interlayer excitons, greatly extending their lifetime. This offers a time\nwindow for exciton energy to be efficiently converted into lattice vibrations through non-\nradiative relaxation pathways. Thus, the moiré potential field is not just a regulator of electronic\nstates; it becomes an ultrafast pathway for the efficient and directional conversion of light\nenergy into heat. In the BP/WS moiré superlattice, the moiré periodic potential field creates\n2\nmoiré wells that effectively confine interlayer excitons, significantly prolonging their lifetime.\nDuring the relaxation process, these long-lived excitons tend to transfer energy to the lattice\nthrough non-radiative recombination, emitting it as phonons. This combines the inherent\nphotothermal advantage of BP with the confinement effect of the moiré potential, achieving a\nsynergistic enhancement and notably improving the photothermal conversion efficiency.\nFinally, regarding the device potential, we have demonstrated significant control over light-\nmatter interactions. The periodic structure of the BP/WS moiré superlattice creates unique\n2\nmoiré flat bands and potential wells near the Fermi level, which greatly strengthens the light-\nmatter interactions. This strong coupling effect directly facilitates the generation and separation\nof non-equilibrium carriers, offering an ideal physical environment for the subsequent\nrelaxation processes of photogenerated energy, such as those of excitons or non-equilibrium\ncarriers. This indicates that the BP/WS moiré system has inherent structural advantages for\n2\nboth photovoltaic applications that need efficient carrier separation and photothermal\napplications that require efficient energy relaxation.\nIn summary, the BP/WS moiré superlattice we propose is not just a simple material stack.\nsynergize deeply, and physical mechanisms closely match performance goals. The tunable wide\nbandgap of BP, combined with the strong visible-light absorption of WS , jointly creates a\n2\nbroad-spectrum light-harvesting platform. Meanwhile, the periodic potential field modulation\nof the moiré superlattice offers a core physical pathway for efficient energy conversion by\noptimizing exciton and carrier dynamics. We believe these dual advantages give our system\ngreat potential, far exceeding existing frameworks in the development of next - generation high-\nperformance, broad-spectrum photonic devices.\nIn response to your query, we have further emphasized the relevant sections to ensure that you\nand other readers can more readily understand the advantages of our BP/WS moiré superlattice\n2\nmaterial. The specific revisions are as follows:\n“In the BP/WS moiré superlattice, periodic moiré potential wells confine interlayer excitons,\n2\ngreatly extending their lifetime. As these excitons relax, they preferentially transfer energy to\nthe lattice through nonradiative recombination, emitting phonons. This mechanism\nsynergistically combines BP’s inherent photothermal properties with the confinement effect of\nthe moiré potential, markedly enhancing photothermal conversion efficiency.……For the\nBP/WS moiré superlattice, the enhanced localized states raise the energy required for non-\n2\nequilibrium carriers to cross these barriers. Interestingly, the photothermal effect partially\nfacilitates this process. The competition and synergy between these effects improve carrier\nseparation and transport. Additionally, the modulation of the band structure by the moiré\nsuperlattice leads to more selective light absorption in the system.”\nRelevant reference\n[1] Liu Y. et al. Moiré superlattices and related moiré excitons in twisted van der Waals\nheterostructures. Chem. Soc. Rev. 50, 11, 6401-6422 (2021).\n[2] Andersen, T. I. et al. Excitons in a reconstructed moiré potential in twisted WSe /WSe\n2 2\nhomobilayers. Nat. Mater. 20, 480-487 (2021).\n[3] Yuan, L., Zheng, B., Kunstmann, J. et al. Twist-angle-dependent interlayer exciton diffusion\nin WS₂-WSe₂ heterobilayers. Nat. Mater. 19, 617-623 (2020).\n[4] Chen, S. et al. Infrared optoelectronics in twisted black phosphorus. Nat Commun 15, 8834\n(2024).\n[5] Cong, C. et al. Optical properties of 2D semiconductor WS . Adv. Opt. Mater. 6, 1700767\n2\n(2018).\n[6] Ma, H., Xue, M. Recent advances in the photothermal applications of two-dimensional\nnanomaterials: photothermal therapy and beyond. J. Mater. Chem. A 9, 17569–17591 (2021).\n2. In the article, the driving light source sometimes is 660 nm and sometimes is 808 nm. Fig.\n3b shows that the photothermal effect is more pronounced at 808 nm than 660 nm. Why not all\nuse 808 nm?\nResponse: We sincerely appreciate your thorough review of the manuscript and the\nconstructive feedback you've provided. The key point you raised about the selection of the\ndriving light-source wavelength is truly significant, revealing a shortcoming in our original\nexplanation of the relevant design rationale. We deeply apologize for this oversight. In response\nto your concerns, we offer the following detailed clarification.\nOur hydrogel robot is designed to fulfill two core functions: “mobility actuation” and\n“environmental sensing.” The physical basis for these functions is the unique photothermal\nresponse (for actuation) and photoelectric response (for sensing) of the BP/WS moiré\n2\nsuperlattice material. The crucial aspect is that these two response modes overlap within the\nmaterial's spectral response range. Therefore, during the design, we must carefully choose the\nwavelength of the driving light source to precisely separate the two functions and avoid\ninterference with the monitoring signal during the driving process. This selection should ensure\nthat it can effectively trigger the driving mechanism and be spectrally different from the\nmonitoring target, which is the radiation emitted by the overheated source being detected.\nThe radiation from overheated sources usually concentrates in the infrared spectrum. We chose\n660 nm red light as the driving light source mainly to achieve significant spectral separation\nfrom typical overheated source radiation (here, we use an 808 nm wavelength light source as\nan example). This spectral separation ensures that while the robot is actively moving, the\ndetection module at the tip of its tentacle can accurately identify the infrared radiation emitted\nby external overheating sources. It prevents the driving light source from interfering with the\ndetector or causing misinterpretation. This is a critical prerequisite for reliable and autonomous\nenvironmental monitoring.\nOur systematic characterization of the BP/WS moiré superlattice material shows that its\n2\nabsorption coefficient at 660 nm is lower than its absorption peaks in the near-infrared range.\nThis directly causes the material’s photothermal conversion efficiency and photoresponse to be\nat a controllable suboptimal level at this wavelength. We cleverly turned this weakness into a\ndesign advantage. The moderate photothermal effect produced by 660 nm light can induce a\ncontrollable thermal-responsive contraction in the hydrogel, which drives the robot’s\nmovement. However, its intensity is much lower than the peak photothermal effect at 808 nm.\nThis effectively avoids risks like excessive dehydration, structural damage, or permanent\nfunctional loss caused by overly intense driving light, ensuring sustainable and stable actuation.\nDuring actuation, the contraction amplitude of the hydrogel tentacles under 660 nm\nillumination is significantly lower than that achievable with 808 nm radiation at the same light\nintensity. This means the mechanical deformation signal from the driving light source itself is\nstrictly kept at a low level. This prevents contact with the active electrode, thus minimizing\ninterference with the overheating monitoring module and greatly improving the accuracy and\nreliability of environmental hotspot detection.\nThe 808 nm light source in our study is not used as the driving light source but as a\ndemonstration light source. Its role is to simulate the infrared radiation from typical overheating\nsources in the environment, so as to verify the robot's detection ability for such target signals.\nIn summary, our choice of 660 nm as the driving light source is based on the following key\nscientific reasons:\n1) Achieving functional decoupling by separating its spectrum from the target monitoring signal;\n2) Enabling controllable and safe driving by utilizing the moderate photothermal response of\nmaterials in this wavelength range; 3) Minimizing interference with the monitoring system due\nto its weak response characteristics.\nWe have included detailed explanations in the manuscript. We believe these additions will\neffectively address your concerns and help readers better understand the innovation and\nreliability of our design.\nThe specific revisions are as follows:\n“Here, we chose 660 nm light as the driving light source since this wavelength is different from\nthe required detection signal band. Additionally, 660 nm light irradiation causes a weak\nphotothermal response in the BP/WS moiré superlattice, leading to a slight temperature rise.\nexcessive water loss that might damage its internally stable cross-linked structure. Its weak\nresponse property also reduces the interference to the monitoring system caused by the tentacle\ncontraction induced by the driving light source.”\n3. On page 17 “This result aligns closely with the material’s light absorption spectrum\ncharacteristics (Fig. 3c)”. Fig. 3c is not the absorption spectrum. Please provide the absorption\nspectrum of BP/WS moiré superlattice in the SI.\nAfter careful review, we confirm that the original wording was indeed lacking in rigor and\nmight have caused readers to misinterpret it. We sincerely apologize for this.\nThe statement “This result aligns closely with the material’s light absorption spectrum\ncharacteristics (Fig. 3c).” This statement may cause confusion. We have made clear changes to\nthis part. Our original intention was to emphasize that the excellent photothermal response\nbehavior under 808 nm laser irradiation, shown in Fig. 3b (Temperature change curves under\nlaser irradiation of different wavelengths), is highly consistent with the material's strong\nabsorption peak at 808 nm in Fig. 2k (Material's light absorption spectrum characteristics). Fig.\n3c (Temperature change under periodic 808 nm laser irradiation) shows the remarkable\nrepeatability of photothermal conversion in the BP/WS moiré superlattice. Specifically, in the\n2\nperiodic on-off laser irradiation experiments, the temperature change trend caused by the\nphotothermal effect remains consistent.\nTo solve this problem, we have rephrased the ambiguous sentences in the original text precisely,\nplaced Fig. 3c correctly to match its description, and clearly labeled the spectral absorption\ncharacteristics (Fig. 2k). These changes ensure a clear and unambiguous presentation,\nremoving potential misunderstandings. The revised text will clearly state that the results in\nFigure 3b match the characteristics in Fig. 2k, and the content of Fig. 3c corresponds to the\nfollowing paragraph.\nMoreover, we have thoroughly reviewed the manuscript. We have carefully checked all\nstatements with figure citations to ensure their accuracy, logical consistency, and to effectively\nguide readers in understanding the figures and their relationships. Specific revisions have been\nmade at the corresponding places in the text (as cited below). We kindly ask for your review.\nFig 2k Ultraviolet-visible absorption spectra of three samples.\nFig 3b Temperature change curves under laser irradiation of different wavelength.\nFig 3c Temperature change under periodic 808 nm laser irradiation.\n“Notably, this photothermal conversion behavior is observed across multiple wavelength bands\n(Fig. 3b), with the 808 nm band being particularly prominent: the system temperature rapidly\nrises from an initial 22℃ to 51.9℃ within 600 s of irradiation, achieving a temperature\nincrease of 29.9℃. This result aligns closely with the material’s light absorption spectrum\ncharacteristics shown in Fig. 2k. Furthermore, the BP/WS moiré superlattice demonstrates\n2\nexcellent reproducibility in photothermal conversion (Fig. 3c). In periodic light-switching\nexperiments, the system responds rapidly to optical stimuli and recovers stably to the initial\ntemperature after irradiation ceases, highlighting the remarkable stability of its photothermal\neffect.”\n4. In Fig. 3a-3c, the system temperature is irradiation intensity dependent. Please provide the\nintensity value.\nResponse: We sincerely appreciate your valuable correction regarding the rigor of the\nexperimental data in Figure 3. In response to your query about the necessity of specific intensity\nvalues for the “system temperature variation with irradiation intensity” presented in Figures 3a\n- 3c, we promptly carried out a comprehensive review and made revisions.\nTo precisely quantify the correlation between light intensity and temperature response in the\nexperiments of Figure 3, we used standardized optical power density for all tests. The specific\nparameters are as follow table:\nName Description Wavelength Optical Irradiation Mode\nPower\nDensity\nFig. 3a Time-dependent thermal 808 nm 45 ± 0.5 Continuous irradiation\nimaging under mW/cm2\ncontinuous illumination\nFig. 3b Temperature response 405/550/660 45 ± 0.5 Pulsed on/off switching\nunder different /808 nm mW/cm2 (ON 650 s/ OFF 650 s)\nwavelengths with on/off\nswitching\nFig. 3c Temperature variation 808 nm 45 ± Periodic cycling (ON 650\nover four irradiation 0.5mW/cm2 s / OFF 650 s)\ncycles\nAll experiments were monitored in real-time with an optical power meter to ensure that the\nfluctuations in optical power density were within ±0.5 mW/cm2, thus eliminating the\ninterference from light intensity variations. To make it easier for readers to trace the details, we\nhave added the optical power density calibration process and key parameters to the\nexperimental methods section. Meanwhile, we have enhanced the data correlations in the main\ntext. The specific content is referenced as follows:\n“Equipment: ……Photothermal measurements were conducted using a light source with a fixed\npower density, which was calibrated to be 45.0 ± 0.5 mW/cm2 using an optical power meter\n(Model 1936-R, Newport). Unless otherwise stated, this power density was applied for all\nexperiments. The surface temperature was measured by an infrared thermal imager (Hikvision,\nP10) at a data acquisition rate of 10 Hz.”\n5. The experimental part of the article lacks many details, such as the ratio of BP/WS for the\n2\nmoiré superlattice preparation, the content of moiré superlattice in the hydrogel, which would\nfacilitate others to replicate the experiment.\nResponse: We sincerely appreciate your valuable and perceptive comments. The lack of details\nabout the preparation of the moiré superlattice and hydrogel components, which you pointed\nout, was truly an oversight on our end.\nIn accordance with your suggestion, we have comprehensively supplemented and elaborated\non the relevant content in the “Methods” section of the revised manuscript. The specific\nadditions are quoted below, and we hope this resolves your concerns.\n“Preparation of BP/WS Composites: The BP nanosheet dispersion was uniformly sprayed on\n2\nthe surface of WS nanosheets……Through a series of preliminary experiments for optimization,\n2\nthe mass ratio of BP nanosheets to WS₂ nanosheets was determined to be 1:8.\nPreparation of Anemone-like Light-driven/light-detecting Hydrogel Robots: 4.8 g of purified\nNIPAM powder, 0.12 g of TPO, and 0.13 g of BIS were taken and added with 2 mL of absolute\nethanol and 7 mL of deionized water……The substrate has a length of 20 mm, a width of 4 mm,\nand a thickness of approximately 3 mm. Each tentacle is 14 mm long and has a diameter of 2\nmm. Six tentacles in total are arranged in a 3×2 configuration. The base plate contains 7.5–8%\n(by mass) of the BP/WS molar superlattice material and 50–65% (by mass) of water. The\n2\ntentacles contain 2–3% (by mass) of the bimodal photoresponsive film and 50–65% (by mass)\nof water.”\n6. Due to the inevitable evaporation of water, especially under the stimulation of photothermal\neffects, the stability of the hydrogel robot is of utmost importance. Please provide the\ncorresponding data.\nResponse: Thank you very much for raising this crucial and insightful question. We fully\nconcur that water evaporation is a core challenge for the long-term stable operation of\nphotothermal-driven hydrogel robots, especially under repeated “light-heat” cycle stimulation.\nAlthough we presented some performance data in Fig. 5 of the original manuscript, as you\ncorrectly noted, the stability assessment was indeed not thorough and comprehensive enough.\nTo address this issue, we carried out a systematic stability evaluation of the hydrogel robot. We\nhave also added detailed experimental data and analysis to the revised manuscript. The specific\nrevisions are referenced as follows:\n(Minor adjustments have been made to the main text structure, which has led to changes in the\nimage sequence.)\n“To assess performance degradation under different conditions, we first placed tentacle\nsamples in an unencapsulated, open environment at room temperature. As shown in Fig. 4g,\nthe results showed that after 7 days, their response speed remained above 85% of the initial\nvalue. We found that the total weight loss rate was about 12% over 7 days, which closely\nmatched the performance degradation rate. This confirms that water evaporation is the main\nfactor affecting long-term performance. Fig. 4h shows the drive performance stability of the\nbase plate under continuous on-off light cycles (660 nm laser, 19 mW/cm2, 120 seconds per\ncycle). The results indicate that after 200 cycles (about 6.7 hours in total), the decay rate of the\nbase plate's bending angle was below 5%, and the response speed remained basically\nunchanged. This demonstrates that our robot has excellent cyclic operational stability and\nfatigue resistance. We mainly attribute this remarkable stability to the dense three-dimensional\nnetwork structure of the PNIPAM hydrogel, which can effectively hold a large number of water\nmolecules. Moreover, our BP/WS moiré superlattice has extremely high photothermal\n2\nconversion efficiency, lowering the energy threshold for actuation. This enables a rapid\nresponse at lower overall temperatures, thus minimizing excessive heating of the hydrogel and\nthe associated intense thermal evaporation effects.\nFig.4 g Response status of ALHR after seven days of storage.\nFig. 4 h Cyclic stability of ALHR (Illustration: the details of the initial and final parts of the\ncurve, and the schematic diagram of base plate changes with or without 660 nm drive light\nsource).”\nReviewer #2 (Remarks to the Author):\nThe manuscript fabricated BP/WS moiré superlattice via an ultrasound-assisted stacking\n2\nmethod and investigated its photothermal and photovoltaic properties. An anemone-like light-\ndriven/light-detecting hydrogel robot was prepared by compounding PNIPAM hydrogel. Under\nspecific light conditions, based on the photothermal response, the robot can move under light\ndrive and recognize infrared radiation.\n1. Generally, the manuscript emphasize on the properties of moiré superlattice. The part related\nto robot is relatively weak. The motion and sensing functions needs more investigations.\nResponse: We sincerely thank you for reviewing our work and providing valuable guidance.\nWe fully acknowledge that the current manuscript indeed devotes more space to the study of\nmoiré superlattice properties, while the sections about the motion and sensing capabilities of\nhydrogel robots are relatively weak and need further in-depth exploration.\nTo address this key concern, we have carried out systematic experimental supplementation and\ndata refinement. Specifically, we have focused on expanding the following key experimental\ndata and analyses:\n1) Evaluation of basic hydrogel properties: This includes short-term cycling stability and long-\nterm storage stability.\n2) In-depth investigation of core robotic functions: We characterized the response times and\nthermodynamic behavior of hydrogel robot under light actuation. Moreover, we quantified\nmotion performance metrics such as movement speed, displacement, and overheating detection\naccuracy.\nTo present these significant additions clearly and comprehensively, we integrated new\nexperimental data, figures, and in-depth analytical discussions into the relevant sections of the\nmanuscript. This greatly improves the information density, depth, and logical coherence of the\nrobotics section. All content has been systematically organized and incorporated into both the\nmain text and supplementary information sections to ensure completeness and traceability. In\nresponse to your observation of the structural imbalance, we have reorganized the sequence and\nplacement of figures to better highlight the innovation and key strengths of our work.\nAdditionally, we have carefully produced and included high-definition video footage showing\nthe hydrogel robot’s motion and temperature sensing capabilities. This video clearly\ndemonstrates its motion speed, responsiveness, operational state, and performance in simple\ntasks. The video file has been submitted as supplementary material. The specific supplementary\ncontent is referenced as follows:\n“To assess performance degradation under different conditions, we first placed tentacle\nsamples in an unencapsulated, open environment at room temperature. As shown in Fig.\n4g, the results showed that after 7 days, their response speed remained above 85% of\nthe initial value. We found that the total weight loss rate was about 12% over 7 days,\nwhich closely matched the performance degradation rate. This confirms that water\nevaporation is the main factor affecting long-term performance. Fig. 4h shows the\ndrive performance stability of the base plate under continuous on-off light cycles (660\nnm laser, 19 mW/cm2, 120 seconds per cycle). The results indicate that after 200 cycles\n(about 6.7 hours in total), the decay rate of the base plate's bending angle was below\n5%, and the response speed remained basically unchanged. This demonstrates that our\nrobot has excellent cyclic operational stability and fatigue resistance. We mainly\nattribute this remarkable stability to the dense three-dimensional network structure of\nthe PNIPAM hydrogel, which can effectively hold a large number of water molecules.\nMoreover, our BP/WS moiré superlattice has extremely high photothermal conversion\n2\nefficiency, lowering the energy threshold for actuation. This enables a rapid response\nat lower overall temperatures, thus minimizing excessive heating of the hydrogel and\nthe associated intense thermal evaporation effects.\nUnder illumination at a wavelength of 660 nm, the base plate undergoes a periodic\nbending–straightening cycle (Fig. 5a and Supplementary Movie 1 and 3). Specifically,\nrapid photothermal heating induces upward bending at the disk center and forward\nretraction of its rear end; upon light removal, cooling restores the structure to its\noriginal configuration. Driven by friction, the front edge advances forward, yielding\nthe morphology observed in the physical image on the left. This process exhibits\nexcellent repeatability, enabling the light-driven disk to achieve an average crawling\nspeed of approximately 2 mm/s under modulated illumination. Our ALHR demonstrates\ndistinct advantages over previously reported designs, as shown in Supplementary Table\n2. Experimental testing has confirmed that our ALHR showcases remarkable motion\nperformance. It can adapt to a wide range of media and different pipeline conditions,\nenabling efficient optical actuation and flexible locomotion (refer to Supplementary\nTable 3). In contrast, under 808 nm near‑infrared light irradiation (which mimics\nthermal radiation), the tentacle mainly undergoes a contraction-expansion cycle: light\ntriggers downward contraction, which is followed by slow recovery after illumination\nceases, as shown in the inset. Owing to its geometric constraint, this motion occurs\nprimarily along the vertical axis (Fig. 5b and Supplementary Movie 2). The described\nbehaviours were experimentally verified. During actuation, the light intensity of the\ndriving source significantly influences the locomotion speed of the disk (Fig. 5c),\nshowing a positive correlation with the former. Furthermore, the speed also increases\nwith the on‑off switching frequency of the light (Fig. 5d). Experimental measurements\nindicate that the maximum locomotion speed is attained at a frequency of 0.6 Hz.\nBeyond deformation, the tentacle’s detection functionality was also verified. We fixed\ntwo contact electrodes at a specific height on the tentacle’s base. Only when the tentacle\ncontracted under the photothermal drive of BP/WS , did the BP/WS at the top contact\n2 2\nthe electrodes, enabling rapid conduction of photogenerated carriers to transmit\nelectrical signals externally (Fig. 5e, Supplementary Movie 4 and Fig. 26). No current\nwas detected in the loop without contact, while the current magnitude varied with light\nintensity during contact. We also evaluated the spatial resolution of the temperature\ndetection system. After securing a blackbody heat source, the entire ALHR was mounted\non a precision-movable platform and translated along a straight line toward and away\nfrom the heat source. During this motion, the ALHR transitioned from the ‘non-\noverheated’ to the ‘overheated’ state at position x , where the tentacle contacted the\n1\nbottom electrode, and reverted to the ‘non-overheated’ state at position x when the\n2\ntentacle detached from the bottom electrode. This procedure was repeated 50 times. The\nspatial resolution was defined as:\n∆𝑥 = 𝑥̅̅̅−𝑥̅̅̅\n2 1\nAmong them, 𝑥̅̅̅ and 𝑥̅̅̅ represent the average values of multiple sets of test data for\n1 2\nx and x , respectively. The results show that the spatial resolution of ALHR is 2.037 m.\n1 2\nIn scenarios where overheating detection is needed in complex pipelines and similar\nenvironments, our ALHR can move flexibly under the action of light. When it senses\nnear-infrared radiation from an overheating point, it rapidly generates an electrical\nsignal, thus reporting the overheating risk to the external environment.\nFig.4 g Response status of ALHR after seven days of storage.\nFig. 4 h Cyclic stability of ALHR (Illustration: the details of the initial and final parts of the\ncurve, and the schematic diagram of base plate changes with or without 660 nm drive light\nsource).”\nFig. 5| Functional Realization and Extension of ALHR. a Real-time motion state of\nthe base plate. b Infrared-driven contraction cycle of the tentacles. c Influence of light\nintensity on the motion speeds of the base plate and tentacles. d Relationship between\nthe frequency of the driving light and the motion speed of the base plate. e Electrical\nsignals generated by the tentacles in response to heat sources with different intensities.\nf Spatial resolution of ALHR.”\n2. In Fig. 5c–f, the temperature rise and bending cycles are demonstrated, but the quantitative\nmotion performance of the robot is not analyzed. Please provide the bending angle vs.\nillumination time and movement velocity vs. power density curves to evaluate reproducibility\nand fatigue behavior.\nResponse: We sincerely appreciate your insightful comments and valuable suggestions. We\nfully acknowledge the critical issues you raised. The original manuscript did not sufficiently\ndemonstrate the motion performance of the hydrogel robot, making it difficult for readers to\ncomprehensively evaluate its performance metrics.\nTo address this, we conducted systematic supplementary experiments and quantitative analyses\nto provide a more comprehensive and intuitive basis for assessing its motion performance.\nFirst, we measured and plotted the time-dependent curves of bending angle and displacement\nat the robot’s base plate and tentacle under continuous illumination. These curves directly show\nthe robot’s dynamic response to light stimulation, its saturated bending amplitude, and response\nrelaxation characteristics. To establish a quantitative relationship between robotic motion\nefficiency and input energy, we used a laser light source with precisely adjustable power density.\nWe measured and plotted the relationship between the robot’s motion speed and incident light\npower density. This curve reveals how motion speed depends on input energy. Under fixed\npower density and illumination cycles, we performed repeated illumination-bending-light\nremoval-recovery cycles. For example, the bending angle-time curve in Fig. 5a shows high\nreproducibility across cycles, demonstrating excellent motion repeatability.\nAll newly added key quantitative curves have been carefully plotted and integrated into the\nmain figure (Fig. 5) and corresponding sections of the Supplementary Information in the\nrevised manuscript. Furthermore, we have significantly expanded the textual descriptions and\nanalysis in the main body of the manuscript, as detailed below:\n“Under illumination at a wavelength of 660 nm, the base plate undergoes a periodic\nbending–straightening cycle (Fig. 5a and Supplementary Movie 2). Specifically,\nrapid photothermal heating induces upward bending at the disk center and forward\nretraction of its rear end; upon light removal, cooling restores the structure to its\noriginal configuration. Driven by friction, the front edge advances forward, yielding\nthe morphology observed in the physical image on the left. This process exhibits\nexcellent repeatability, enabling the light-driven disk to achieve an average crawling\nspeed of approximately 2 mm/s under modulated illumination. Our ALHR demonstrates\ndistinct advantages over previously reported designs, as shown in Supplementary Table\n2. Experimental testing has confirmed that our ALHR showcases remarkable motion\nperformance. It can adapt to a wide range of media and different pipeline conditions,\nenabling efficient optical actuation and flexible locomotion (refer to Supplementary\nTable 3). In contrast, under 808 nm near‑infrared light irradiation (which mimics\nthermal radiation), the tentacle mainly undergoes a contraction-expansion cycle: light\ntriggers downward contraction, which is followed by slow recovery after illumination\nceases, as shown in the inset. Owing to its geometric constraint, this motion occurs\nprimarily along the vertical axis (Fig. 5b and Supplementary Movie 3). The described\nbehaviours were experimentally verified. During actuation, the light intensity of the\ndriving source significantly influences the locomotion speed of the disk (Fig. 5c),\nshowing a positive correlation with the former. Furthermore, the speed also increases\nwith the on‑off switching frequency of the light (Fig. 5d). Experimental measurements\nindicate that the maximum locomotion speed is attained at a frequency of 0.6 Hz.\nFig. 5| Functional Realization and Extension of ALHR. a Real-time motion state of\nthe base plate. b Infrared-driven contraction cycle of the tentacles. c Influence of light\nintensity on the motion speeds of the base plate and tentacles. d Relationship between\nthe frequency of the driving light and the motion speed of the base plate.”\n3. The XPS spectra show slight blueshifts in W 4f and P 2p peaks, which are ascribed to\n“quantum confinement and flat band formation”. However, this is speculative, and more\nevidence/discussion should be presented. Additionally, please rule out surface charging or\noxidation effects, especially considering BP’s high reactivity in air.\nResponse: We sincerely appreciate your thorough review of our work and the valuable\nfeedback you’ve provided. Your comments on the interpretation of the W 4f and P 2p peak\nshifts in the XPS spectra are both relevant and significant. Below, we address each of your\nconcerns sequentially and elaborate on our supplementary analysis and discussion.\nFirst, we’d like to clarify and emphasize the actual observations reported in our manuscript: W\n4f peak: A decrease in binding energy (red shift) was observed. P 2p peak: An increase in\nbinding energy (blue shift) was observed. In the original manuscript, we incorrectly described\nthe decrease in W 4f binding energy as a blue shift. We sincerely apologize for this\ntypographical error. In the original manuscript, our explanation was that the moiré potential\nmodulated the electron density of W atoms. The formation of a flat band enhanced electron\nlocalization, inducing a quantum confinement effect that facilitated electron movement within\nconfined orbitals. The P 2p blue shift is due to P atoms in BP acting as electron donors within\nthe heterojunction. To support our view, we tested the ultraviolet photoelectron spectra (UPS)\nof intrinsic BP, WS , and BP/WS (Supplementary Fig. 5, Supplementary Fig. 6, and Fig. 2j).\n2 2\nComparisons showed a significant downward shift in the Fermi level of the composite material\ncompared to pure WS . DFT calculations further indicated that the work function of the\n2\ncomposite material lies between those of BP and WS₂. For WS , the Fermi level shift shows\n2\nthat the moiré potential effectively modulates the potential distribution of W atoms near the\ninterface, leading to the localization of their electron cloud. When electrons are localized around\nW atoms, their shielding effect on W 4f inner-shell electrons is enhanced. According to\nCoulomb’s law, this enhanced shielding weakens the nucleus’s effective attraction to 4f\nelectrons, thus reducing their binding energy. The composite material’s work function being\nhigher than that of BP means that, in the composite, BP acts as an electron donor. By transferring\nelectrons to WS , it reduces the surface electron density, enhancing the nucleus’s electron-\n2\nbinding ability and increasing the work function compared to the intrinsic material.\nWe fully agree that surface charging effects must be excluded. During XPS testing, accumulated\npositive charges on the sample surface can cause energy loss in all emitted photoelectrons,\nresulting in an overall peak shift towards higher binding energies in the spectrum. We analyzed\nthe peak shifts of elements in the composite material: W 4f and S 2s were red-shifted, while P\n2p was blue-shifted. This asynchronous shift pattern clearly rules out surface charging\ninterference, confirming that the peak shifts are due to changes in the chemical environment.\nAdditionally, during data processing, we used the C 1s peak (284.8 eV) from contaminant\ncarbon as an internal standard for calibration to reduce surface charging effects.\nBlack phosphorus is prone to oxidation. Despite our best efforts, partial surface oxidation was\ninevitable during testing. However, as you can see, oxidation peaks for phosphorus are present\nin both the pristine material and the composite. Importantly, the intensity of these oxidation\npeaks is significantly lower in the composite (Fig. 2i). Comparing the two under the same\nconditions allows us to effectively exclude interference from oxidation peaks of the composite\nmaterials and focus on chemical state changes related to material composite formation.\nWe fully understand that the lack of clarity in the relevant sections may have confused you and\nother readers about our material properties. Therefore, we have made revisions and additions\nat the corresponding locations, as detailed below:\nFig. 2 j UPS mapping of BP/WS .\nSupplementary Fig. 6 | UPS mapping of WS .\n2\n“According to the binding energy calculation formula, the composite material (Fig. 2j) exhibits\nsignificantly higher electron binding energy compared to intrinsic BP (Supplementary Fig. 5)\nand WS₂ (Supplementary Fig. 6), indicating stronger electron binding. This modulation\nprofoundly influences the light absorption properties of the system. For WS2, the Fermi level\nshift shows that the moiré potential effectively adjusts the potential energy distribution of W\natoms near the interface, causing the localization of their electron clouds. When electrons are\nlocalized around W atoms, their shielding effect on the inner-shell electrons of W 4f is\nstrengthened. According to Coulomb’s law, this strengthened shielding weakens the nucleus’s\neffective attraction to the 4f electrons, thus reducing their binding energy. In composite\nmaterials, BP serves as an electron donor. It transfers electrons to WS2, which in turn reduces\nthe surface electron density of WS2. This enhances the ability of atomic nuclei to confine\nelectrons, leading to an increase in the work function compared to the intrinsic material.”\n4. The article compares the photodetection performance of WS and BP/WS . Why is there no\n2 2\ncomparison with standalone BP?\nResponse: Thank you very much for raising this insightful question. You pointed out that our\nstudy didn’t include pure BP as a crucial reference when comparing the photodetection\nperformance of WS₂ and BP/WS composites. This was indeed a significant oversight in our\n2\noriginal manuscript design. To address this key point, we conducted supplementary experiments\nand data analysis. Now, we have systematically and quantitatively compared the photoresponse\nperformance of pure BP material with that of BP/WS composites. Under the same experimental\n2\nconditions (including the same light source wavelength, power density, electrode configuration,\netc.), we characterized the photoresponse of pure BP devices (Supplementary Fig. 11 and\nSupplementary Fig. 12). The test results show that, compared to the BP/WS moiré superlattice\n2\ncomposite material, pure BP devices have a weaker photoresponse in multiple wavelength\nbands, and their response and recovery times are significantly longer. Moreover, the BP/WS\n2\nmoiré superlattice material has better responsivity and specific detection efficiency than pure\nBP. We have supplemented relevant details in the main manuscript and supplementary\ninformation. The specific additions are referenced as follows:\nSupplementary Fig. 11 | I-t curve of BP.\nSupplementary Fig. 12 | Responsivity and specific detectivity of BP under different\nwavelengths of illumination.\n“As elucidated by experimental data (Supplementary Fig. 9–14) and a direct comparison (Fig.\n3j), the BP/WS moiré superlattice surpasses the performance of pristine BP and WS2 in both\n2\nphotothermal conversion and photovoltaic applications, particularly under 808 nm\nillumination.”\n5. This manuscript currently limits the characterization of the robot’s photoresponse to the 365-\n808 nm range. A key question for its practical relevance is whether its functionality can be\nextended to the infrared spectrum?\nResponse: Thank you very much for your insightful and relevant question. You’ve accurately\npointed out that the key to evaluating the practical application value of this robot's optical\ndetection technology is to clarify its functional effectiveness in the infrared spectral band. In\nthe original manuscript, we specifically characterized the robot's optical response properties in\nthe 365 nm-808 nm wavelength range, which generally covers the UV-Vis-NIR spectrum.\nHowever, the characterization of the infrared band was indeed inadequate.\nTo address this core concern you raised, we conducted supplementary experimental studies to\nevaluate the robot’s photoresponse performance at the more representative 940 nm wavelength\nfor infrared applications. The supplementary experiments strictly followed the same\nexperimental conditions and testing standards used for characterizing other wavelengths in the\noriginal manuscript, ensuring the comparability and reliability of the data. Under 940 nm\nillumination, we systematically measured the robot’s I-t response curve and I-V characteristics,\nand calculated its responsivity and specific detection rate (Fig. 3e, Fig. 3f, Fig 3h, and Fig.\n3j). The results show that at the same incident light power density, the photocurrent generated\nby the robot at 940 nm is comparable to its performance at 808 nm. The calculated responsivity\nat 940 nm is of the same order of magnitude as that at 808 nm, with only a 10% difference,\nwhich strongly demonstrates the device’s high photoelectric conversion efficiency in the\ninfrared band. The detection rate at 940 nm is also highly comparable to that at 808 nm,\nindicating that the device has excellent optical detection capability in the infrared band.\nIn the main text of the manuscript, we have expanded the curves and corresponding descriptions\nin the photovoltaic performance characterization section, including I-t curves at multiple\nwavelengths, responsivity at multiple wavelengths, and relative detection rates. We hope these\nefforts will help you and other readers have a more comprehensive understanding of the\noutstanding optical detection capabilities of our robot. The specific supplementary content is\ncited as follows:\nFig.3 e-f I-V curves and I-t curve of the BP/WS .\nFig 3j Comparison of photocurrent and responsivity between the BP/WS and WS under light\n2 2\nirradiation at different wavelengths.\n“Under a bias range of -2 to 2 V, the current under illumination significantly exceeds that in\nthe dark state (Fig. 3e), confirming the material’s photoresponsive properties. Even more\nremarkable are the zero-bias experimental results (Fig. 3f): the photocurrent response exhibits\nstrong wavelength dependence, with particularly high photoelectric conversion efficiencies at\n405, 610, 808 and 940 nm, consistent with the light absorption spectrum. Notably, the 808 nm\nband generates a maximum photocurrent of 514.2 nA at zero bias, with photocurrent intensity\npositively correlated with light intensity (Fig. 3g). We also performed continuous spectral\nphotoresponse testing on the BP/WS₂ thin film(Supplementary Fig. 7). The results demonstrate\nthat the device exhibits significant photoresponse capabilities across multiple bands in the\nultraviolet, visible, and near-infrared regions, with particularly exceptional performance in the\nnear-infrared band.……As elucidated by experimental data (Supplementary Fig. 9–14)\nand a direct comparison (Fig. 3j), the BP/WS moiré superlattice surpasses the\n2\nperformance of pristine BP and WS in both photothermal conversion and photovoltaic\n2\napplications, particularly under 808 nm illumination.”\n6. Furthermore, does the robot possess broad-range photodetection capabilities, particularly\nunder low-intensity light conditions?\nResponse: As the reviewer has pointed out, the original manuscript did have deficiencies in\ncharacterizing the broadband photoresponse. Specifically, it lacked a systematic investigation\nof the photoresponse behavior across the entire UV-Vis-NIR spectrum and an evaluation of the\nspectral detection capability under low light intensity. We fully concur and have supplemented\nrelevant experimental data to improve the rigor and persuasiveness of our discussion. To\ncomprehensively assess the device’s spectral response range, we used a xenon lamp light source\ncombined with a high-precision spectrometer to perform continuous spectral photoelectric\nresponse tests on the BP/WS film in the 400 nm to 1000 nm wavelength range, with a 10 nm\n2\nstep (Supplementary Fig. 7 and Supplementary Fig. 8). The results clearly show that the device\nhas a significant photoresponse in multiple bands of the ultraviolet, visible, and near-infrared\nregions, and its performance is particularly excellent in the near-infrared band (750-1000 nm).\nThis full-spectrum detection technique operates by dispersing white light through a series of\nspectral separations, a process that inherently yields low light intensity, resulting in a power\ndensity of less than 12 mW/cm2. To address the reviewer’s concern about the low-light\ndetection capability, we carried out independent irradiation experiments at the same low power\ndensity (10 mW/cm2) using several representative marker wavelengths (405 nm, 550 nm, 660\nnm, 808 nm and 940 nm). The results indicate that even at such low illumination intensities,\nthe device maintains observable and relatively stable photoresponse signals in the near-infrared\nband. In contrast, the response signals in other tested bands are significantly weaker, falling\nbelow the effective detection threshold. This result strongly suggests that the device not only\nhas the potential for broad-spectrum optical detection but also shows unique advantages and\napplication value for infrared detection in low-light environments.\nThe supplementary experimental data and analysis mentioned above have been incorporated\nand updated in the corresponding sections of the revised manuscript and supplementary\ninformation. The specific content is cited as follows:\nSupplementary Fig. 7 | Full-spectrum response characteristics of BP/WS .\n2\nlow power conditions.\n“We also performed continuous spectral photoresponse testing on the BP/WS₂ thin\nfilm(Supplementary Fig.7). The results demonstrate that the device exhibits significant\nphotoresponse capabilities across multiple bands in the ultraviolet, visible, and near-infrared\nregions, with particularly exceptional performance in the near-infrared band. At the same low\npower density, multiple representative spectral bands (405, 532, 650, 808 and 940 nm) were\nselected for independent irradiation experiments. As shown in Supplementary Fig.8, the results\ndemonstrate that even at such low light intensities, the device maintains observable and\nrelatively stable photoresponse signals in the near-infrared band. In contrast, response signals\nin the other tested bands are significantly weaker, falling below the effective detection threshold.”\n7. The schematic in Fig. 5j shows an ALHR moving through pipes. The actual experimental\nenvironment e.g., medium, illumination, and thermal source should be presented.\nResponse: We sincerely appreciate the valuable feedback from the reviewers. The schematic\nin the original Fig. 5j was indeed too simplified and failed to properly illustrate the detailed\nexperimental conditions of the key demonstration experiment, which was to support the\nALHR’s movement within a curved pipe to detect overheating sources. This omission might\nhave led to some confusion about the experiment’s rigor and result reliability. In the revised\nmanuscript, we have systematically supplemented and refined Fig. 5j and its descriptions as\nfollows:\n(Due to the adjustments made to the image content and sequence, Fig. 5g will now correspond\nto the original Fig. 5j.）\n1) We have significantly revised Fig. 5g to increase its information content. The figure now\nclearly annotates the following core parameters: test medium (air), pipe characteristics (smooth-\nsurface plastic water pipe with bends, inner diameter 50 mm), and ambient temperature (25 °C).\nWe specified the light source type (660 nm ultra-compact laser), operating mode (periodic\nswitching illumination), power density (25 mW/cm2), and ambient light control (fully dark\nenvironment with no other light sources). We also detailed the heat source type (controllable-\ntemperature thermocouple probe), spatial layout (placed at 10 cm intervals along the pipe’s\nouter wall), and set temperature (with specific values labeled on the curve in the figure).\n2) In the “Results and Discussion” section of the main text, we added a detailed paragraph\ndescribing the experimental process shown in Fig. 5g. This paragraph elaborates on the\nexperimental setup for simulating the environment of the transformer's internal cooling oil pipes.\n3) We also evaluated the locomotion performance of the ALHR under various environmental\nconditions, including different media (air, water, and silicone oil) and diverse conduit settings.\nThe detailed results are provided in Supplementary Table 3.\nThe modifications have been specifically incorporated into the caption of Fig. 5g and\nSupplementary Table 3 in the revised version, the relevant part of the “Results and Discussion”\nsection in the main text. The specific modifications are referenced as follows:\nSupplementary Table 3 | Locomotion performance of the ALHR under various fluidic\nand pipeline conditions.\nEnvironmental\nPath Features Performance Indicators Test Results\nMedia\nAir Horizontal surface Movement speed 2 mm/s\nAir 45° sloped surface Crawling speed ~0.4 mm/s\nSilicone oil\nHorizontal surface Movement speed ~0.8 mm/s\n(100 cSt)\nWater Horizontal surface Movement speed 1.4 mm/s\nWater 45° sloped surface Crawling speed ~0.1 mm/s\n100%\nWater 90° bent pipe Passage success rate\n(10 tests)\nFig 5g Schematic diagram of the ALHR for overheating detection inside a large transformer\npipeline and its response curves near different overheating points.\n“Experimental testing has confirmed that our ALHR showcases remarkable motion\nperformance. It can adapt to a wide range of media and different pipeline conditions, enabling\nefficient optical actuation and flexible locomotion (refer to Supplementary Table 3). ……To\nverify its performance, we simulated the cooling oil lines inside a transformer using a 50-mm-\ndiameter smooth-surfaced plastic water supply pipe with an elbow. As shown in Fig. 5g, the\nwhole experiment was carried out in a dark, room-temperature atmospheric environment.\nThermocouple probes with controlled temperatures were placed every 10 centimeters to\nsimulate overheating sources, and the temperature of each thermocouple was labeled on the\ncurve.”\n\nReviewer #3 (Remarks to the Author):\nThe manuscript presents the design of a multifunctional biomimetic hydrogel robot that\nintegrates a BP/WS moiré superlattice to achieve both photothermal actuation and\n2\nphotoelectric sensing for real-time overheating detection. This concept leverages the unique\ninterlayer interactions between BP and WS₂ to enhance both photothermal and photovoltaic\nperformance, and integrates this dual-function material into a PNIPAM hydrogel to create an\nanemone-inspired light-driven robot capable of directional locomotion and infrared radiation\ndetection. The work is technically solid and represents a meaningful contribution to the\nintegration of sensing and actuation in soft robotic systems. However, the scientific novelty lies\nmore in the integration strategy and application demonstration than in a fundamental\nbreakthrough in materials science or robotic mechanisms. Moiré superlattices themselves are\nnot new, and their optoelectronic properties have been extensively reported. Thus, the\nconceptual advance of this work is largely application-driven rather than rooted in the discovery\nof new physics.\nThe abstract and introduction provide clear motivation for the need to integrate sensing and\nactuation functions in hydrogel robots and highlight the potential advantages of using moiré\nsuperlattices. However, the problem statement remains too general and does not sharply define\nthe specific performance limitations of existing soft robots that the proposed system overcomes.\nTo meet the high conceptual and scientific threshold of Nature Communications, the authors\nshould more clearly articulate the scientific and technological gap and emphasize why BP/WS\n2\nmoiré superlattice provides a distinct solution compared to existing photothermal or\nphotoresponsive materials. This will strengthen the impact narrative of the manuscript.\nThe experimental work is thorough, including extensive material characterization (XRD,\nRaman, TEM, UPS, XPS, UV-Vis) that supports the formation of the moiré superlattice. The\nperformance metrics reported such as the 72.1% photothermal conversion efficiency, 4.14 A/W\nresponsivity, and 12 × 1011 Jones detectivity, are impressive and support the claim of enhanced\noptoelectronic response. The robot demonstration is conceptually appealing, showing how the\nbase and tentacle components can respond to light and infrared stimuli, respectively. However,\nthe manuscript lacks quantitative benchmarking against state-of-the-art systems in terms of\nrobot performance. Parameters such as actuation speed, bending displacement, response time,\nspatial resolution, and robustness under prolonged operation should be evaluated and\ncompared to competing photothermal actuators. Moreover, the environmental stability and practical\nfunctionality of the robot should be further tested, especially under fluidic or more realistic\npipeline conditions.\nA significant weakness of the presentation is the absence of video demonstrations. Since the\ncore of the work involves a soft robot that moves and senses based on photothermal and\nphotoelectric cues, including high-quality supplementary videos would greatly strengthen the\nmanuscript’s impact, making the concept more intuitive and convincing. Visual content would\nalso help reviewers and readers better evaluate the claimed responsiveness and motion behavior,\nwhich is difficult to fully convey through static figures alone.\nThe discussion effectively explains the underlying mechanism of enhanced photothermal and\nphotoelectric response through DFT calculations and analysis of energy band modulation.\nHowever, it is focused mainly on material properties and less on the broader design framework\nthat this strategy enables for other multifunctional hydrogel robots. To elevate the conceptual\nweight of the work, the authors should extend the discussion to generalize this integration\nstrategy beyond BP/WS to other moiré or 2D systems, positioning it as a versatile platform for\n2\nmultifunctional soft robotics.\nThe manuscript is generally well written, but some sentences are overly long and descriptive,\nparticularly in the abstract, introduction, and conclusion. The writing should be tightened for\nclarity, and the novelty should be emphasized more directly. In addition, the title should be\nrevised to better reflect the main focus of the study. Currently, the title emphasizes the\nmoiré superlattice but does not sufficiently highlight the hydrogel robot or its application in\nreal-time thermal surveillance, which is the true strength of this work. A more application-reflective\ntitle may help align expectations and better communicate the contribution of the study.\nOverall, this is a strong applied research paper with high-quality material characterization and\na creative integration concept. However, in its current form, it may not fully meet the high\nconceptual threshold of Nature Communications. To improve its chances, the authors should:\n(i) sharpen the novelty and gap statement, (ii) provide quantitative robot performance\nbenchmarking, (iii) add video demonstrations, (iv) revise the title for clarity and accuracy, and\n(v) generalize the discussion to strengthen conceptual significance. If these revisions are made,\nthe work could be more competitive. At present, the most appropriate recommendation is major\nrevision.\nResponse: We would like to express our sincere gratitude for your comprehensive and\nhighly constructive review comments on our manuscript. We have systematically\nrevised the manuscript in accordance with all your suggestions. We are confident that\nthe revised version has significantly improved in terms of academic rigor, clarity, and\nthe presentation of its contributions. Below is a detailed point-by-point response to each\nof your suggestions along with explanations of the modifications made.\n(i) “sharpen the novelty and gap statement”\nWe are extremely grateful to you for pointing out the deficiencies in our elaboration of the\ninnovation points. This is indeed the focus of this revision. To this end, we have\ncarried out a comprehensive and intensive revision from the introduction, abstract to\nthe conclusion.\nFirst, we refined the abstract and used more forceful expressions. At the beginning of\nthe article, we clearly declared the two core innovations of this work: (1) The creative\ncombination of high-performance moiré superlattice materials and hydrogels; (2) A\nbrand - new design paradigm for multifunctional hydrogel robots.\nSecond, we completely rewrote the introduction. We weakened the background\nintroduction of the materials and strengthened the critical analysis of the existing\ntechnologies. We clearly pointed out the “key bottlenecks” in the current design of\nbiomimetic hydrogel robots (such as insufficient material performance and low\nfunctional integration). On this basis, we naturally introduced the core innovation\npoints of our work as solutions, enabling readers to clearly understand the unique value\nof this work at a glance.\nFinally, we also made a corresponding response in the conclusion section. Instead of\nmerely summarizing the results, we restated and elevated the conceptual breakthroughs\nof this work in the design paradigm and material application, emphasizing its leading\nrole in future research. The specific revised content is quoted as follows:\n“Abstract\nThe flexibility and intelligent responsiveness of hydrogel robots offer great potential for\nexploration in narrow and complex environments. However, it remains challenging to\nstably and efficiently integrate sensors with hydrogel robotic bodies. Inspired by marine\norganisms, this paper presents an anemone-like light-driven hydrogel robot (ALHR) for\ndirectional infrared radiation detection. Using the regulation of photo-generated\ncarriers by moiré superlattices and the synergistic photo-thermal-electric effects, a\nblack phosphorus/tungsten disulfide (BP/WS ) moiré superlattice was fabricated\n2\nthrough ultrasonic-assisted stacking, which shows excellent dual-mode photothermal-\nphotovoltaic conversion performance. Based on this, a composite poly(N-\nisopropylacrylamide) (PNIPAM) hydrogel was used to build the base plate and tentacle\nstructures of the ALHR. Specific illumination triggers the photothermal effect of the\nBP/WS moiré superlattice, allowing for directional movement. When the tentacles\n2\nretract and contact the bottom electrode, photocurrent signals are conducted for\ninfrared detection. The ALHR can work in specialized spatial environments, providing\na new method for early overheating fault identification. This study also proposes a\ndesign framework for multifunctional hydrogel robots. By integrating responsive units\nwith flexible substrates to achieve coupled synergistic responses, its material properties\nenable various functionalities, offering a universal platform and model for developing\nmultifunctional soft robots based on advanced low dimensional materials.\nMain\nFlexible hydrogel robots with biomimetic structures show great application potential in\ncomplex scenarios that humans can't access, like deep-sea exploration, extremely\nconfined spaces, and high-radiation environments. This is due to their excellent\nbiocompatibility, deformability, and environmental adaptability [1-4]. By integrating\nfunctional units such as sensors and actuators into hydrogel matrices to imitate the\nmorphology and behavior of natural organisms, researchers can effectively combine\nthe unique physicochemical properties of hydrogels with the excellent capabilities of\nbiological systems [5-8]. This method gives robots intelligent features like autonomous\nmobility and real-time perception, creating new opportunities for the development of\nflexible bionic robots [9-11]. However, two main bottlenecks still exist in this field. Firstly,\nthe high water content and softness of hydrogels often reduce the performance and\nstability of integrated sensors, making traditional microelectronic fabrication\ntechniques inappropriate. Secondly, current research mainly focuses on achieving\nsingle functions (such as actuation or drug delivery) and has difficulty in balancing\nrobotic mobility and sensing capabilities. Achieving the integration of actuation-\nsensing remains a very challenging task [12, 13]. Therefore, how to enhance the response\nspeed, structural stability, and sensing compatibility of hydrogel robots simultaneously\nthrough innovative material and structural design has become a crucial scientific\nproblem that needs urgent solutions in this field.\nTo tackle these challenges, exploring novel materials that combine both actuation and\nsensing functions is a key breakthrough. Among different actuation strategies, light-\ndriven actuation is regarded as an ideal option for building smart hydrogel robots. This\nis because it is non-contact, highly precise, has a rapid response, and excellent\nbiocompatibility [14-20]. Among them, poly(N-isopropylacrylamide) (PNIPAM), due to\nits excellent thermosensitive properties, has become a typical material system for\npreparing photodriven hydrogels when combined with photothermal converters [21-23].\nTraditional methods rely on complex integrated designs to couple sensing and driving\nfunctions, but this makes the system even more unstable [24, 25]. Therefore, developing\nan intrinsic, integrated material with both photothermal actuation and optoelectronic\nsensing capabilities is the fundamental solution to the sensor-hydrogel compatibility\nproblem. Our research focuses on emerging moiré superlattice materials. This periodic\nstructure, formed by stacking two two-dimensional(2D) materials with different lattice\nconstants or orientations [26, 27], provides a unique moiré potential field. This field can\neffectively adjust interlayer exciton dynamics, phonon vibration modes, and band\nstructures, offering an unprecedented platform for synergistically optimizing\nphotothermal and photovoltaic performance [28-37]. Despite the great potential of moiré\nsuperlattices, current research mainly focuses on systems such as graphene. There is\nstill limited systematic exploration of heterojunctions and their dual-function\ncharacteristics involving BP, a material with an inherently high photothermal\ncoefficient, and other 2D materials.\nThis work introduces a research paradigm advancing from novel materials to novel\ndesigns and culminating in a universal framework to realize multifunctional integrated\nhydrogel robots. At the materials level, we designed and synthesized black\nphosphorus/tungsten disulfide (BP/WS ) moiré superlattices using an ultrasonic-\n2\nassisted stacking method. The moiré potential field in this material enhances phonon-\nphoton coupling to improve photothermal conversion efficiency while simultaneously\npromoting the separation and transport of photogenerated carriers, resulting in\nexceptional dual photothermal-photovoltaic response characteristics. At the design\nlevel, inspired by sea anemone feeding behavior, we integrated the BP/WS moiré\n2\nsuperlattice with a PNIPAM flexible matrix to construct an anemone-like light-driven\nhydrogel robot (ALHR). The base plate generates photothermal effects under\nillumination to drive directional motion, while the tentacles sense infrared radiation\nand produce photocurrent signals, effectively integrating coordinated motion and\nsensing. Finally, we propose a universal strategy centered on function-oriented moiré\nsuperlattice-hydrogels, where modular integration and synergistic coupling of\nresponsive units with flexible substrates enable on-demand design of intelligent soft\nrobots with diverse sensing and actuation capabilities. This research not only provides\nnew materials and methods for high-performance integrated actuator-sensor robots but\nalso establishes a universal technical pathway and design paradigm for future\nmultifunctional soft robots based on advanced 2D materials.\nConclusion\nInspired by the biological activity patterns of sea anemones, this study developed an\nanemone-like light-driven hydrogel robot that can detect superheating, and thus\nproposed a universal fabrication strategy for multifunctional hydrogel robots.\nSpecifically, BP/WS moiré superlattice materials were first synthesized by ultrasonic -\n2\nassisted stacking. These materials have long-range periodic moiré patterns. Their\nmodulation effect causes interfacial electron rearrangement, enhances partial electron\nlocalization, and significantly affects the system's light absorption properties.\nExperiments confirmed that BP/WS moiré superlattices have improved photothermal\n2\nand photovoltaic conversion capabilities in the infrared spectrum. Based on this, we\nfully used the excellent photothermal response and specific photoconductive properties\nof the BP/WS moiré superlattice material. By integrating it as a dual-functional\n2\nmaterial for both actuation and sensing into PNIPAM hydrogel, we designed and made\nthe ALHR. Under specific illumination, this robot can move flexibly driven by light\nthrough its photothermal response and can recognize infrared radiation.\nWe further propose a fabrication framework for moiré superlattice material-hydrogel\nbased soft robots. Focusing on function-oriented material selection and inspired by\nbiomimetic structures, this approach allows the preparation of hydrogel robots with\nreplaceable modules, expandable functions, and controllable synergistic behavior. This\nprovides a general technical way and design model for the future design and fabrication\nof multifunctional soft robots based on advanced two-dimensional materials.”\n(ii) “provide quantitative robot performance benchmarking”\nWe are acutely aware that qualitative descriptions alone are insufficient to fully\nsupport our performance claims. Therefore, we have designed and conducted a series\nof systematic and multi-dimensional supplementary experiments. The aim is to provide\nyou with comprehensive and rigorous quantitative evidence from four dimensions:\nmaterial stability, motion performance, driving efficiency, and functional accuracy. We\nhave integrated these new data into the revised manuscript. The specific new additions\nare as follows:\n1) Verification of basic performance and robustness: We added long-term stability and\ncyclic fatigue tests of the materials (Fig. 4g and 4h).\n2) Benchmarking of core motion capabilities: We supplemented quantitative\nkinematic/dynamic performance tests of the robot base and tentacles under different\nenvironmental conditions (Fig. 5a and 5b, Supplementary Table 2). We also\nintroduced a direct performance comparison with representative photothermal\nactuators in the field (Supplementary Table 3). The data clearly demonstrate the\nsuperiority of our system in terms of moving speed.\n3) In-depth exploration of the driving mechanism: To reveal the internal mechanism\nof performance optimization, we added a systematic study of the key influencing\nfactors of driving performance (Fig. 5c and 5d), which provides a scientific basis\nfor subsequent performance tuning.\n4) Evaluation of functional accuracy: We supplemented the resolution test of the\nALHR (Fig. 5f) to quantitatively evaluate its upper-limit ability when performing\ntasks.\nWe believe that these newly added quantitative data not only effectively address your\nconcerns but also greatly enhance the credibility and persuasiveness of our research\nconclusions. The order of the revised figures and tables has been optimized to ensure\nthe logical presentation and readability of the data. The specific revised content is\nquoted as follows:\nFig. 4| g Response status of ALHR after seven days of storage.\nFig. 4| h Cyclic stability of ALHR (Illustration: the details of the initial and final parts\nof the curve, and the schematic diagram of base plate changes with or without 660 nm\ndrive light source).\n“As shown in Fig. 4g, the results showed that after 7 days, their response speed\nremained above 85% of the initial value. We found that the total weight loss rate was\nabout 12% over 7 days, which closely matched the performance degradation rate. This\nconfirms that water evaporation is the main factor affecting long-term performance.\nFig. 4h shows the drive performance stability of the base plate under continuous on-\noff light cycles (660 nm laser, 19 mW/cm2, 120 seconds per cycle). The results indicate\nthat after 200 cycles (about 6.7 hours in total), the decay rate of the base plate's bending\nangle was below 5%, and the response speed remained basically unchanged. This\ndemonstrates that our robot has excellent cyclic operational stability and fatigue\nresistance. We mainly attribute this remarkable stability to the dense three-dimensional\nnetwork structure of the PNIPAM hydrogel, which can effectively hold a large number\nof water molecules. Moreover, our BP/WS moiré superlattice has extremely high\n2\nphotothermal conversion efficiency, lowering the energy threshold for actuation. This\nenables a rapid response at lower overall temperatures, thus minimizing excessive\nheating of the hydrogel and the associated intense thermal evaporation effects.\nFig. 5| Functional Realization and Extension of ALHR. a Real-time motion state of\nthe base plate. b Infrared-driven contraction cycle of the tentacles. c Influence of light\nintensity on the motion speeds of the base plate and tentacles. d Relationship between\nthe frequency of the driving light and the motion speed of the base plate. e Electrical\nsignals generated by the tentacles in response to heat sources with different intensities.\nf Spatial resolution of ALHR.\nUnder illumination at a wavelength of 660 nm, the base plate undergoes a periodic\nbending-straightening cycle (Fig. 5a and Supplementary Movie 1 and 3). Specifically,\nrapid photothermal heating induces upward bending at the disk center and forward\nretraction of its rear end; upon light removal, cooling restores the structure to its\noriginal configuration. Driven by friction, the front edge advances forward, yielding\nthe morphology observed in the physical image on the left. This process exhibits\nexcellent repeatability, enabling the light-driven disk to achieve an average crawling\nspeed of approximately 2 mm/s under modulated illumination. Our ALHR demonstrates\ndistinct advantages over previously reported designs, as shown in Supplementary Table\n2. Experimental testing has confirmed that our ALHR showcases remarkable motion\nperformance. It can adapt to a wide range of media and different pipeline conditions,\nenabling efficient optical actuation and flexible locomotion (refer to Supplementary\nTable 3). In contrast, under 808 nm near‑infrared light irradiation (which mimics\nthermal radiation), the tentacle mainly undergoes a contraction–expansion cycle: light\ntriggers downward contraction, which is followed by slow recovery after illumination\nceases, as shown in the inset. Owing to its geometric constraint, this motion occurs\nprimarily along the vertical axis (Fig. 5b and Supplementary Movie 2). The described\nbehaviours were experimentally verified. During actuation, the light intensity of the\ndriving source significantly influences the locomotion speed of the disk (Fig. 5c),\nshowing a positive correlation with the former. Furthermore, the speed also increases\nwith the on‑off switching frequency of the light (Fig. 5d). Experimental measurements\nindicate that the maximum locomotion speed is attained at a frequency of 0.6 Hz.\nBeyond deformation, the tentacle’s detection functionality was also verified. We fixed\ntwo contact electrodes at a specific height on the tentacle’s base. Only when the tentacle\ncontracted under the photothermal drive of BP/WS did the BP/WS at the top contact\n2 2\nthe electrodes, enabling rapid conduction of photogenerated carriers to transmit\nelectrical signals externally (Fig. 5e, Supplementary Movie 4 and Fig. 26). No current\nwas detected in the loop without contact, while the current magnitude varied with light\nintensity during contact. We also evaluated the spatial resolution of the temperature\ndetection system. After securing a blackbody heat source, the entire ALHR was mounted\non a precision-movable platform and translated along a straight line toward and away\nfrom the heat source. During this motion, the ALHR transitioned from the ‘non-\noverheated’ to the ‘overheated’ state at position x , where the tentacle contacted the\n1\nbottom electrode, and reverted to the ‘non-overheated’ state at position x when the\n2\ntentacle detached from the bottom electrode. This procedure was repeated 50 times. The\nspatial resolution was defined as:\n∆𝑥 = 𝑥̅̅̅−𝑥̅̅̅\n2 1\nAmong them, 𝑥̅̅̅ and 𝑥̅̅̅ represent the average values of multiple sets of test data for\n1 2\nx and x , respectively. The results show that the spatial resolution of ALHR is 2.037 m.”\n1 2\nSupplementary Table 2 | Comparison with Other Light-Driven Devices.\nResponse Actuation Actuation\nMaterial Composition Reference\nWavelength Principle Velocity\nPhotothermal\nPNIPAM(BP/WS ) 660 nm 2 mm/s This work\n2\nconversion\nLCE and Sylgard 184 Self-oscillation\nNIR 6 cm/min [9]\n(candle soot) mechanism\nPVDF/ Conductive Mechano-\nMicrofiber Fabric Tape IR Photothermal 1.8 mm/s [10]\n（BP) Cooperation\nPNIPAM with Ni White-light Photothermal\n1.2 mm/s [11]\nNanowires LED conversion\nNIPAAm based the Marangoni\n795 nm 1 mm/s [12]\nEffect\nThermal\nPDMS/Graphene/Mica - expansion- 0.28 mm/s [13]\ndriven actuation\nSupplementary Table 3 | Locomotion performance of the ALHR under various fluidic\nand pipeline conditions.\nEnvironmental\nPath Features Performance Indicators Test Results\nMedia\nAir Horizontal surface Movement speed 2 mm/s\nAir 45° sloped surface Crawling speed ~0.4 mm/s\nSilicone oil\nHorizontal surface Movement speed ~0.8 mm/s\n(100 cSt)\nWater Horizontal surface Movement speed 1.4 mm/s\nWater 45° sloped surface Crawling speed ~0.1 mm/s\n100%\nWater 90° bent pipe Passage success rate\n(10 tests)\n(iii) “add video demonstrations”\nDynamic videos are an indispensable medium for vividly presenting the performance\nof complex robot systems. They can go beyond the limitations of static images and texts,\nallowing readers to directly experience the system’s dynamic response, function\nimplementation, and details in actual operation. To this end, we have carefully produced\nand submitted four high-definition demonstration videos:\nMovie 1: It shows the precise horizontal movement of the base plate driven by 660-nm\nlight.\nMovie 2: It records the reversible contraction-relaxation cycles of the tentacles under\n808-nm light illumination.\nMovie 3: It demonstrates the overall movement of the fully assembled ALHR.\nMovie 4: It focuses on the real-time detection of infrared signals and signal output by\nthe ALHR.\nAll videos are accompanied by clear English subtitles to guide the audience to quickly\nunderstand the operation background and technical highlights. These videos have been\nsubmitted as supplementary materials according to the journal’s requirements, and we\nhope they can provide you and the readers with a more three-dimensional and vivid\ncognitive experience.\n(iv) “revise the title for clarity and accuracy”\nWe are extremely grateful for your valuable suggestion regarding the precision of the\ntitle. A clear, accurate, and appealing title is crucial for the dissemination and influence\nof a paper. After careful discussion, we have adopted your advice and revised the\noriginal title “Photothermo-electro-responsive black phosphorus/WS moiré\n2\nsuperlattice propelling biomimetic hydrogel robot for thermal surveillance\" to \"Moiré\nsuperlattice-driven bionic hydrogel robot with programmable multifunctionality”.\n(v) “generalize the discussion to strengthen conceptual significance”\nWe are grateful for your insightful suggestion to enhance the conceptual significance\nof our research. This has prompted us to step out of the details of specific experiments\nand examine and distill the theoretical value of our work from a more macroscopic\nperspective. To address this, we have made a crucial expansion to the discussion section.\nAt the end of the discussion section in the revised manuscript, we have proposed and\nelaborated on a broader and generalizable design concept-the moiré superlattice\nmaterial-hydrogel-based multifunctional robot paradigm.\nSpecifically, we have constructed a function-oriented design framework. Based on a\ndeep understanding of the characteristics of moiré superlattice materials, through\ncustomized design, we can design biomimetic hydrogel robots with specific target\nfunctions.\nWe believe that the proposal of this paradigm not only elevates the significance of this\nwork but also provides a systematic and reusable methodology for the future design of\nfunctional soft robots. It connects material innovation with robot system design,\nshifting from manufacturing single-function robots to constructing a general design\nplatform, which may give rise to more innovative robot applications. The specific\nrevised content is quoted as follows:\nFig. 5| h Implementation paradigm of multifunctional hydrogel robots based on moiré\nsuperlattice materials.\nAlthough this study validates the application potential of BP/WS moiré superlattices\n2\nin constructing light-driven infrared-detecting anemone hydrogel robots, its core\nsignificance extends beyond this specific material’s performance. It lies in presenting\na universal design framework and integration strategy. This framework can be broadly\napplied to multifunctional soft robots based on diverse advanced two-dimensional\nmaterials, particularly moiré superlattice systems. As depicted in Fig. 5h, the designed\nsoft robot features two core functional units: a driving module and a sensing module.\nThe drive module must achieve controllable photothermal conversion with precise\nregulation of response intensity, speed, and spatial distribution. Integrated into a\nthermosensitive hydrogel matrix, this module induces material contraction/deformation\nthrough the photothermal effect. Material selection should prioritize moiré systems with\nhigh photothermal conversion efficiency (e.g., strongly coupled TMD heterojunctions\nand specific-angle graphene), or other 2D heterostructures suitable for flexible\nhydrogel environments (e.g., BP/Graphene, TMDs; see Supplementary Information\nTable 4). Preparation depends on achieving uniform nanomaterial dispersion within\nthe hydrogel network, ensuring interface compatibility and long-term stability,\nachievable via optimized dispersion methods.\nThe core requirements for the sensing module are efficient photoelectric detection\nwithin the target wavelength band, demanding high photoelectric conversion efficiency,\na rapid response speed, excellent wavelength selectivity, and signal stability. Integrated\nonto a flexible structure, this module must achieve a drive-contact-conduction\nsequential response. Material selection prioritizes moiré systems with high\nphotoelectric conversion efficiency and narrow or tunable response wavelengths (e.g.,\nwell-matched TMD heterojunctions, bandgap-tunable BP heterojunctions; see\nSupplementary Information, Table 4). Fabrication primarily employs interfacial\nintegration methods, with key challenges including strong adhesion between thin films\nand flexible substrates, efficient interfacial charge transport, and structural integrity.\nFunctional integration and response coordination between the drive and sensing\nmodules are central to the system design. Drawing inspiration from nature's intricate\nstructure-function synergies, efficient biomimetic structural design effectively\naddresses this challenge. Furthermore, the tailored selection of sensing materials based\non specific application requirements (e.g., environmental monitoring, drug delivery,\nenvironmental adaptation, and micro-sensing units) enables diverse signal detection\nand transmission capabilities.\nIn summary, this study achieves standardized integration of hydrogel robots through\nfunctional module decomposition and core requirement definition, guided by design\nprinciples of function-material matching, structure-function coupling, and response\nsynergy. It provides a material-agnostic, universal methodology for systematically\nintegrating the optoelectronic/photothermal properties of advanced two-dimensional\nmaterials with the flexibility, actuation, and biocompatibility of hydrogels. The\nsuccessful application of BP/WS moiré superlattices in ALHR serves as a robust\n2\ndemonstration of this framework’s efficacy and versatility. Moving forward, as more\nhigh-performance two-dimensional moiré systems are discovered, manufacturing\ntechniques advance, and hydrogel functionalization research deepens, this framework\nwill serve as a valuable catalyst for developing next-generation intelligent soft robots\nwith integrated sensing-actuation capabilities. This will advance innovations in critical\nfields including environmental monitoring, healthcare, and industrial applications.\nSupplementary Table 4 | Comparative Properties of Different Moire Superlattice\nSystems.\nName Property Reference\nTunable valley spin (g-factor), strong circular\nMoSe /WSe polarization, twist-angle dependent intensity [14]\n2 2\nmodulation and moiré-trapped valley excitons.\nBilayer 2H-\nMoiré potential confinement, valley-dependent\nMoSe /Monolayer [15]\n2\ncircular polarization and atomic registry locking.\nWSe\ndensity & magnetic-field dependence, engineering\nWSe /WS [16]\n2 2\nof spatially tailored excited states and strongly\ncorrelated exciton physics.\nAnisotropic near-field optical response, tunable\nTBG plasmonic bandgap and lithography-free [17]\nfabrication.\nElectromagnetic-hybridization-driven polariton\nTwisted α-MoO coupling, twist-angle-tunable wavefront topology [18]\n3\nand lithography-free in-situ optical field shaping.\nSuperlattice bandgap-tuned phonon-assisted\nSmall-twist-angle\nphotoresponse and broadband mid-infrared [19]\nBilayer Graphene\nbolometric effect.\nTwist-angle-driven ultra-strong phonon coupling,\nhigh-frequency phonon splitting & strain mapping,\nMoS TBL phonon hybridization in magic-angle continuum [20]\n2\nand lattice reconstruction-enabled thermal\nswitching.\nMoiré phonon band reconstruction, open-\nGraphene/h-BN boundary string vibration model and near- [21]\ndegenerate low-energy phonon modes."}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have satisfactorily addressed all questions raised by myself and the other reviewers. I recommend acceptance of this manuscript.", "reviewer_2": "The revised manuscript has greatly improved and the previous concerns have been addressed. Thus the revised manuscript can be accepted for publication.", "reviewer_3": "I appreciate the authors’ careful and thorough revision of the manuscript in response to my comments. The revised version demonstrates substantial improvement in conceptual framing, experimental rigor, and presentation quality.\nIn particular, the revised title more accurately reflects the core contribution of the work by emphasizing the hydrogel robot and its multifunctional integration, rather than focusing narrowly on the moiré superlattice material alone. The Abstract and Introduction have been significantly strengthened, with a clearer articulation of the scientific and technological gap, and a more convincing positioning of the work as an integration-driven design framework for multifunctional hydrogel robots rather than a purely materials-centric advance. This revision aligns well with the expectations for a broad-interest journal.\nThe addition of quantitative benchmarking data for robot performance including actuation speed, stability, repeatability, spatial resolution, and environmental adaptability, greatly enhances the credibility of the claims and allows meaningful comparison with existing photothermal soft robotic systems. These data address a key weakness of the original submission.\nImportantly, the inclusion of high-quality supplementary video demonstrations substantially improves the clarity and impact of the work. Given that the central contribution involves motion, actuation-sensing coupling, and real-time response, the videos are essential and effectively support the manuscript’s main claims.\nThe discussion has also been expanded to better generalize the proposed strategy beyond the specific BP/WS₂ system, framing the work as a broader platform for multifunctional soft robotics. While the advance remains application- and integration-driven rather than a fundamental discovery in moiré physics, the revised manuscript now presents a coherent, well-supported, and impactful contribution.\nOverall, the authors have satisfactorily addressed my concerns. I have no further major comments on the revised manuscript and believe it is now suitable for consideration in its current form."}, "author_response": ""}]

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