Self-regulating and self-oscillating metal-organic framework hybrid plasmonic metasurfaces

Domain: physics
Published: 2025-11-24
Editorial outcome: major_revision

Abstract
Metal-organic frameworks (MOFs) offer remarkable chemical versatility, structural diversity, and, in some cases, stimuli-responsiveness. In the latter case, they typically rely on external inputs to trigger these changes. In contrast, living systems possess the ability to internally self-regulate and autonomously adapt their properties without external intervention, utilizing internal feedback mechanisms. To fill this gap, we develop a MOF-based metasurface that exhibits autonomous optical self-regulation, dynamically adjusting light absorption in response to varying incident light intensity. This device integrates colloidal MOFs with a plasmonic metasurface to create a thermo-optical negative feedback mechanism based on vapor sorption in and out of the colloidal MOF device. The self-regulation process is dynamic, leading each MOF/antenna unit to exhibit self-oscillatory behavior in the presence of a constant external energy input, analogous to a light-fueled nanoscale steam engine. This proof-of-concept highlights the potential of harnessing MOFs and sorption processes for designing metasurfaces for adaptable optical applications. It also represents a first step toward the design of materials integrating feedback mechanisms and internal clocks paving the way for a new generation of porous materials with life-like autonomy.

Introduction
Autonomous self-adaptation and self-regulation are unique features that typically distinguish living from artificial materials. A key to autonomous behavior is the ability to integrate internal self-regulation and program dynamic actions over time, with spontaneous oscillations being a common example1. Biological self-regulation and self-oscillations are programmed at the molecular level and orchestrated through complex networks of chemical reactions and internal feedback mechanisms2,3. Developing artificial materials with life-like behaviors has long been a dream in materials science4–6. Artificial chemical systems exhibiting self-regulation7 and, in some case self-oscillatory behavior have been synthesized and used to study out-of-equilibrium reaction-diffusion systems8,9 or induce spontaneous self-assembly10,11, motion of hydrogels12, or supramolecular systems13,14 in liquid solution. Spontaneous oscillations have also been achieved in colloidal solutions through spontaneous aggregation and disaggregation mediated by chemical reactions15,16 or plasmonic heating in liquid suspensions17. Recent astonishing examples of autonomous motions have been reported in devices made of liquid crystals or hydrogels for robotic applications18–23. Expanding the concepts of self-regulation to other families of materials, such as porous materials, could one day enable the design of programmable self-regulating porous devices capable of adapting autonomously to perturbations or be programmed in time24. This would open up completely new functionalities for a number of applications related to porous materials, such as (electro)catalysis, gas capture, thermal or optical management, and sensing25,26. Due to their chemical versatility and structural diversity, porous materials such as metal–organic frameworks (MOFs) represent an ideal playground in the search for new adaptive materials27. MOFs can host gas molecules and, due to their tailored porosity, enables control of matter and heat exchanges. This is a fundamental feature in many living systems; for example, plant leaves are capable of self-adjusting water content by stomatal pore opening or closure28. MOFs also offer key advantages in constructing composites and sophisticated devices; they can now be synthetized and shaped in a myriad of forms such as nanoparticles, films or patterns enabling their integration into optical devices29–31. However, programming autonomous responses in MOF materials requires a conceptual shift in how we conceive responsive porous-based materials. Unlike classical “stimuli-responsive” porous materials32,33, self-regulating systems do not require any external control to switch states; rather, they adapt and evolve spontaneously under constant external perturbation. For instance, an optical self-regulating porous material would adapt its light absorption to counterbalance light irradiation, reminiscent of the functionality of the human eye34. More ambitiously, engineering such a process would allow the emergence of MOF-based materials programmed over time24, for instance exhibiting spontaneous oscillations similar to those observed in living systems.

To fill this gap, we design a plasmonic metasurface coupled with MOFs that presents a thermo-optical self-regulating behavior. MOF hybrid plasmonic materials have been previously used for sensing, nanomedicine or catalytic applications as summarized in Supplementary Table 1. In this study, we introduce a previously unexplored and unique functionality of MOF-hybrid plasmonic materials that exploits the temperature-induced sorption behaviors of colloidal assembly of MOFs interconnected with plasmonic antennas to integrate an internal negative feedback mechanism and induce optical self-regulation. Interestingly, we show that this thermo-optical-sorptive process is dynamic: each individual MOF/antenna system exhibits self-oscillatory behavior in presence of constant external energy input, working as a light-fueled nano-steam engine.

Results
Design of the MOF plasmonic metasurface integrating a negative feedback mechanism
The self-regulating device, illustrated in Fig. 1, is able to adapt its optical properties (optical absorptivity) to the incoming light intensity. Its design requires the integration of a thermo-optical negative feedback mechanism that we devised by coupling two materials characterized by crossed sensing/actuating responsiveness. First, a plasmonic metasurface made of an array of antennas35,36, as illustrated in Fig. 1b, capable of optical sensing and efficient thermal heating in presence of a continuous flow of energy (laser at 850nm in our case). The photoheating capability of each plasmonic antenna depends on its absorptivity, usually quantified through the wavelength-dependent absorption coefficient that defines the local fraction of incident light intensity that is absorbed by the material37. The heat generation (Q) in plasmonic antenna due to absorbed light can be described by:

Q = \alpha I_0 (1)

where Q is the heat generated per unit volume, \alpha is the absorptivity of the antennas and I_0 is the intensity of the incident light. Second, a colloidal MOF film that “senses” the temperature by inducing an optical change. The process is mediated by condensation/evaporation of a liquid/vapor phase. In our case, the colloidal MOFs are constituted by ZIF-8 colloidal films in the presence of isopropyl alcohol (IPA) vapor31. The simple functioning of this thermo-optical layer is schematized in Fig. 1b: cooling down the film, the IPA condensates into the porosity. The porous film fulfilled with IPA is in the so-called “Full” (F) state; at low temperatures the refractive index of the ZIF-8 film (n_ZIF-8) is high. Conversely, when heating the film, desorption takes place leading to an “Empty” (E) state and a decrease in the refractive index of the ZIF-8 film.

The operation of the self-regulated layer is shown in Fig. 1c,d. The plasmonic antenna is coupled with the ZIF-8 layer; in presence of vapor, the system is in the “Full” state and the plasmonic antenna exhibit a longitudinal surface plasmon resonance corresponding to a peak at \lambda_SP(F). When applying a laser at wavelength matching the \lambda_SP(F), the system is able to adapt its response to the power of the incoming laser. At low laser power, the plasmonic absorption causes only a limited local heating of the particle and of the surrounding ZIF-8 layer. The system remains close to the “Full” state with a high absorptivity. Conversely, when increasing the laser intensity, the temperature rises and desorption occurs; this step is accompanied by a decrease in refractive index of the ZIF-8 (n_ZIF-8 \downarrow); the plasmon absorption peak is gradually blue-shifted toward the \lambda_SP(E), out of the “excitation window”. This shift results in a decrease of absorptivity at the wavelength of the laser. Increasing the incoming light power, the MOF plasmonic metasurface will absorb less light, converting less energy into heat, and thus result in lower plasmonic heating efficiency. The composite metasurface ultimately behaves as a homeostat at the nanoscale capable of counterbalancing the effect of the incoming light reducing its absorbed intensity, Fig. 1e, as well as the resulting generated heat with respect to a non self-regulating antenna as shown in Fig. 1f.

Fabrication of the device and in situ single-antenna analysis
The fabrication of such self-regulating metasurface requires a very strict calibration and interconnection of its components. For the colloidal ZIF-8 film, the main requirement was a film with a very high porous volume to induce a large variation of refractive index (and thus \Delta\lambda_SP) as a function of the temperature. From a practical point of view, ZIF-8 colloids are convenient because they can be applied directly onto plasmonic materials at room temperature, forming films of optical quality and can easily be dissolved (with acetic acid) and re-applied if necessary. The SEM micrograph in Fig. 2a displays a cross-section view of ZIF-8 colloidal film obtained after synthesis and deposition. The film is composed of nanoparticles having an average size of 40nm and has a thickness of around 200nm. The crystallinity of the material was first confirmed by X-ray diffraction as shown in Fig. S1. The thermo-optical response of the ZIF-8 colloidal film in the presence of IPA vapors was tested by in situ ellipsometric thermo-porosimetry38. Figure 2b illustrates the adsorption and desorption isobars carried out in presence of a constant relative vapor pressure of IPA = 0.7 P/P_0 (20°C) and expressed as the evolution of refractive index (at 700nm) as a function of the temperature of the film. At T = 120°C, the colloidal film presents a low refractive index of 1.22 suggesting that the film is “empty” (E). Decreasing the temperature, we observed an increase in refractive index around 90°C corresponding to IPA filling of the ZIF-8 microporosity. At 60°C the porosity of the MOF itself is filled (state called “MF”) but not the inter-particle voids. Further cooling leads to the capillary condensation of IPA molecules in the mesopores formed by inter-particle voids. At room temperature (20°C) the whole film is in the Full state (F) corresponding to a refractive index of 1.475 By heating back, the process is reversible. The films present a hierarchical porosity (interparticle + intraparticle) ensuring a porous volume of 63% inducing a refractive index variation of around 0.25 between the (F) and the (E) states as detailed in Fig. S2 and in agreement with previous reports31. Importantly, the sorption transition between the F and MF states presents a hysteresis as displayed in the inset of Fig. 2b.

For the design of the plasmonic metasurface, we choose an isotropic Au antennas because of their narrow plasmon resonance, their refractive index sensitivity and their photothermal capability39. The size of the antenna was optimized to align \lambda_SP aligned with our light source (laser at 850nm) in the “full porosity” (F) configuration. We designed the antenna by optical simulation starting from the value of refractive index of ZIF-8 in Fig. 2b as detailed in Figs. S3 and S4. The antennas were made by electron beam lithography by preparing arrays with different sizes as detailed in Fig. S5. The optimized Au nanoantenna array is a squared pattern of 100\mu m \times 100\mu m on glass. Figure 2c displays a SEM image of 120nm long antennas (width 30nm and 20nm height). They are organized in a periodic array with a periodicity of 1\mu m (surface density 1 per \mu m^2), a distance sufficient to make behave the antennas as optically and electronically isolated units. To probe the optical response (scattering) of the full array and of each individual antenna, we performed hyperspectral microscopy in dark-field mode40–42 as shown in the micrographs in Fig. 2d. The scattering spectra of the full array and that of an individual antenna, plotted in Fig. 2e, both shows a plasmonic peak around 745nm. By analyzing the hyperspectral micrograph of the full array shown in Fig. 2f we could map the position of the peak position over the full array of 10,000 antennas. The color-map in Fig. 2g indicates the position of the plasmonic scattering across the whole array; 97% of the sample consists of plasmonic antenna with peak centered at 745 \pm 10nm, confirming the spectral “homogeneity” of the plasmonic array from a spectral viewpoint.

The plasmonic metasurface on glass has been covered by spin-coating deposition with a 200nm ZIF-8 colloidal layer, as determined by ellipsometry. The optical response of each individual antenna in presence of IPA vapors was probed by in situ hyperspectral microscopy customized with an environmental chamber in dark-field mode as shown in Fig. 3a,b. The hyperspectral micrograph in Fig. 3c displays the scattering signal of several individual plasmonic antenna covered by the ZIF-8 layer. During the experiment, the relative vapor pressure was progressively increased from 0 to 0.75 while recording the scattering spectra of each individual antenna. The evolution of the scattering intensity during adsorption of one individual antenna as function of the wavelength is reported in a 2D plot in Fig. 3e. This adsorption isotherm at the single antenna level is highlighted with the dotted line. The curve exabit two main red-shifts during vapor sorption: (i) from 788 to 805nm due to IPA uptake into the microporosity of the ZIF-8 colloids (E \rightarrow MF) and (ii) from 805 to 850nm due to IPA uptake in the interparticle porosity (MF \rightarrow F). The scattering curves corresponding to the three states (E), (MF) and (F) are displayed in Fig. 3d. As expected, the plasmonic antennas are sensitive to the refractive index of the surrounding ZIF-8 in the vicinity of the Au particles. This sensitivity is higher in the vicinity of the tip of the anisotropic antenna as confirmed by the local enhancement of electric field obtained by simulation of Fig. 3f. In addition, the simulation clearly indicates that, antenna spaced 1000nm do not exhibit coupling effect and behave as optically individual antennas. We then calculated the scattering spectra starting from the refractive index of the ZIF-8 layer in Fig. 2b. The simulated spectra shown in Fig. 3g are in good agreement with the experimental results; these first results confirm that the scattering curve for this antenna in the “F” state is centered around 850nm, the wavelength of our laser source, meeting the main requirement for obtaining the self-regulating device.

Self-regulating metasurface
We then tested the capabilities of the MOF plasmonic metasurface to modulate its adsorption when exposed to monochromatic light. To do so, we used a microscope equipped with a NIR-sensitive camera and with the environmental chamber as described above. In addition, we exposed the surface to an 850nm laser through the dark-field condenser in order to simultaneously irradiate and image the scattering evolution of the sample (Fig. 4a). More specifically, we imaged and quantified the scattering intensity at 850nm (I_850nm) of the array as a function of the incoming laser intensity (I_laser)42. The intensity-based plasmonic signal, was determined by following the evolution of the scattering intensity normalized by the incoming laser intensity. As plotted in Fig. S6, following the evolution of antenna’s scattering intensity provides a direct insight on the evolution of the absorptivity as demonstrated by simulations in Fig. S7. To validate the concept illustrated in Fig. 1, two experiments were conducted, in presence of IPA vapor and without vapors as shown in Fig. S6. In absence of vapor, the normalized I_850nm / I_laser ratio remains constant upon increasing the laser intensity. Indeed, in this configuration the material is in the (E) state, it is not self-regulating and the absorptivity \alpha remains constant. Instead, when adding IPA vapor with a vapor pressure of 0.7 P/P_0, the material is initially in the (F) state with a plasmonic peak centered around 850nm. In this configuration, the normalized I_850nm / I_laser ratio decreases when increasing the laser power because of the shift of the plasmonic peak induced by the heating confirming the self-regulation properties as envisioned in Fig. 1. More precisely, Fig. S6 indicates that the MOF plasmonic metasurface is able reduce the scattering and absorptivity by 60% when the laser intensity is increased from 0.05 to 3.9 W cm^-2. Based on these data, we can estimate the extent of desorption and the local temperature as a function of the incoming laser power (Fig. S8). The analysis shows that increasing the laser intensity from 0.05 to 3.9 W cm^-2 leads to an estimated temperature rise of about 6.8°C. Under our irradiation conditions (up to a maximum 3.9 W cm^-2), the system transitions from the (F) state to the (MF) state. Higher temperatures required to reach the fully empty (E) state (up to ~110°C) are not achieved under our experimental conditions, due to both the limited laser power and the self-regulating nature of the device, which reduces light absorption at higher intensities. The self-regulating response of the system is not uniform across the entire temperature range, but instead exhibits distinct regions of enhanced sensitivity. This behavior can be analyzed by calculating the derivative of the scattering signal at 850nm with respect to temperature. As shown in Fig. S9, the highest sensitivity occurs between 22°C and 27°C, corresponding to the transition from the Full (F) to the MOF-filled (MF) state. A second, less intense sensitivity peak is observed between 80°C and 100°C, associated with the transition from the MF to the E state. These findings suggest that the self-regulating effect is most efficient within the 23–27°C window. Importantly, the sensitivity profile is strongly influenced by the adsorption/desorption dynamics within the porous layer. As a result, the system’s operating range can be readily tuned by altering the porosity characteristics, the chemical nature of the vapor, or the vapor concentration (P/P_0), offering flexibility for application-specific optimization. We explored the possible effect of the vapor pressure. As demonstrated by in situ ellipsometry experiments conducted at different vapor pressures (0.5, 0.7, and 0.9), vapor pressure systematically shift the sorption equilibrium (Fig. S10). Specifically, higher vapor pressures delay desorption, thereby shifting the thermo-optical response of the MOF layer toward higher temperatures, while lower vapor pressures produce the opposite effect. This behavior indicates that maintaining a controlled vapor pressure is essential for reliable device operation. At the same time, this variability presents a significant opportunity: by adjusting the vapor pressure, one can, in principle, dynamically tune the temperature range over which the device exhibits its large self-regulating response.

Self-oscillatory behavior: nano “steam-engines”
The next step was to investigate the dynamics of this self-regulation process. To do so, we examined the evolution of plasmonic scattering over time for both the array, Fig. 4a, and at the single antenna level. Specifically, Fig. 4b shows a micrograph of the scattering signal (at 850nm) from the plasmonic antennas covered by the ZIF-8 layer. We first analyzed the dynamic response of the full array, Fig. 4d. Consistent with Fig. S6, increasing the laser intensity leads to a decrease in normalized scattering. When the laser power is kept constant, the scattering value remains steady, showing no notable dynamic response. In reality this seemingly steady response results from the averaged dynamic contributions of each individual antenna as shown in Video 1. When examining the temporal response of a single antenna, we observed, in some cases, marked oscillatory signals in the scattering intensity in presence of constant light input, as shown in Fig. 4c for a representative antenna. The time evolution of normalized scattering of a typical single antenna under different light irradiations is displayed in Fig. 4e.

For each laser intensity, the scattering intensity periodically fluctuates around an equilibrium state. To rule out the possibility that the observed oscillatory behavior was due to artifacts, we challenged our experiment by conducting it without vapor and without the 850nm laser (by using a white light instead). In both cases, no oscillations and no collective fluctuations were observed (this aspect will be further discussed later on).

We then conducted a detailed image analysis to reveal the dynamic behaviors of each individual ZIF-8/antenna on the array for different irradiation conditions. To do so, we developed an automatic procedure to track and analyze the dynamic evolution of each antenna. As discussed in SI, we ranked the ZIF-8/antennas based on the frequency and “quality” of their oscillations, with periodic oscillations considered of high quality. For clarity, we mainly discuss here with the case of a laser intensity of 2.4 W/cm^2. Considering the full array (Fig. 5a and Fig. S11), a variety of behaviors were observed. As seen in Video 1, while most of the antennas oscillate, no collective synchronous behavior is observed. At first glance, some antennas oscillate periodically, others oscillate only slightly or randomly not necessary depending on their locations. In addition, different antennas oscillate at different frequencies as shown in Figs. S12, 13 and 14. For instance, the similar oscillatory behavior of three ZIF-8/antennas, named A, B and C is shown in Fig. 5c. The three antennas, which are not located close to each other, exhibit a similar frequency but are not at all in phase (Fig. S15). We then investigated the oscillatory behavior of neighboring antennas that are close to each other. Figure 5b shows the evolution of the normalized scattering intensity at 850nm as a function of time for a series of ZIF-8/antennas located on the same row. The 2D plot demonstrates that the antennas exhibit spontaneous fluctuations in scattering intensity. However, these fluctuations are neither in phase nor collective.

To further investigate the possible origin of these different oscillatory behavior, we performed an in-depth spectroscopic mapping at the single antenna level of the metasurface covered with ZIF-8 and in the presence of IPA vapor. While bare antennas exhibit homogeneous optical behavior (Fig. 2), the presence of ZIF-8 and vapor induces a certain variation in the scattering response of neighboring antennas (Fig. S16). The ZIF-8 film consists of randomly stacked colloidal particles. Given that the antennas are particularly sensitive to refractive index changes at their extremities (as shown in Fig. 3), the non-uniform distribution of ZIF-8 and condensed vapor results in variations in absorptivity (\alpha) at 850nm and different local heating that is responsible for the oscillatory process. This unintended variability can be seen as an advantage to support our approach as it provides an additional evidence that the oscillations are not due to artifacts. For instance, possible fluctuations in vapor pressure or in incident light intensity would result in a simultaneous variation of the scattering intensity for all the antennas. Instead, these results indicate that each individual ZIF-8/antenna composite behaves as an individual oscillator, as illustrated in Fig. 5d. These observations also confirm that by controlling the optical properties and the porous medium, different oscillatory behaviors can be obtained.

The different oscillatory behaviors also suggests that thermo-optical process occurs at the single antenna level with very low thermal interaction with neighboring antennas. To support this hypothesis, we performed thermal simulations of two antennas acting as local photo-heaters under continuous light irradiation (Fig. 5e). As an example, we simulated a local temperature increase of 6.8°C, in agreement with the value determined above. Figure 5f shows the temperature profile at the glass surface (z = 0) along the x-axis; the temperature rise is located in the close vicinity of the antenna with a very low heating between the antenna.

The possible mechanism at the heart of this “time-programmed” behavior is analogous to an nanometric steam engine and is illustrated conceptually in Fig. 6a. We can describe the self-regulating system with a “seesaw” analogy, where the two extreme cases are represented by the (F) and (E) states, characterized by the plasmonic curves. When the laser is applied, local heating results in a new equilibrium position (green curves) characterized by lower absorptivity. In this configuration, the system is not steady but dynamically self-regulates between two intermediate states (green curves) by alternating partial adsorption and desorption of IPA into/from the ZIF-8 layer (Fig. 6c). This periodic process results in shifts of the plasmonic band peak between the two states and consequently, in oscillations in the scattering intensity as shown in Fig. 6b.

The oscillatory behavior is due to the presence of a sorption hysteresis between the F and MF states (Fig. 2b). In addition, there is a time delay between the fast plasmonic heating (microseconds) and the slower adsorption/desorption response (seconds), with time constants that we have experimentally determined, as discussed in Figs. S19 and S20.

To explore a possible mechanism underlying the self-oscillatory behavior, we employed simulation based on a simple hysteresis-based model grounded in the experimentally determined kinetic parameters and hysteresis behavior of the MOF layer. This model allows us to explore the influence of various parameters, in particular the shape of the hysteresis curve and laser intensity on the oscillation dynamics (SI). As shown in Fig. 6d, we modeled our system using a hysteresis curve in which the absorptivity (at 850nm) decreases with temperature, consistent with the results in Fig. 2b and Fig. S8c. As shown in Fig. 6e, the analysis displays an oscillatory behavior in absorptivity with a period of around 45 seconds, which is comparable to our experimental observations. The system demonstrates absorptivity oscillation that results from an elliptical loop in the hysteresis curve, capturing the delayed transitions between heating and cooling states that drive the self-oscillatory behavior. The shape and path of this hysteretic loop has thus impact the frequency of the oscillation. To further explore that, we performed the same analysis using hysteresis curves with identical threshold temperatures but varying steepness parameters (\beta), Fig. 6f, which control how sharply the adsorption and desorption transitions occur (as defined in Supporting Information Fig. S21). This variation can be describe porous networks with different pore size distribution: monodisperse pores lead to sharper transitions, while a polydisperse distribution results in broader, less abrupt changes43. As shown in Fig. 6g, the frequency of the oscillation increasing for sharper hysteresis. Similarly, as shown in Fig. S22, broader hysteresis results in a larger loop and a decrease of the frequency (no oscillation are observed for no hysteresis or very narrow hysteresis). This simple analysis suggests that by varying the sorption properties and optical response of the porous media, different oscillatory behaviors can be achieved. This may further explain why heterogeneous packing of ZIF-8 on the antenna leads to variations of photo-heating and sorption profile and thus oscillatory behavior as discussed in Fig. 5.

Finally, the effect of light intensity was examined. Observations on selected antennas (Fig. 6b), suggest that increasing the light intensity may induce a higher oscillation frequency. We performed simulations with increasing light intensity, as shown in Fig. S23. Interestingly, we confirmed that the oscillation frequency increases with light intensity until the absorptivity reaches a low value, where the steepness of the hysteresis decreases, causing the oscillations to slow down and then stop.

Methods
Fabrication of the colloidal ZIF-8 films
The colloidal ZIF-8 solution was synthesized following the procedure detailed in the literature, with slight modifications to the protocol originally reported by Cravillon et al.50. To prepare the solution, 1.47g (4.94 mmol) of Zn(NO_3)_2·6H_2O was dissolved in 100 mL of methanol. This solution was then mixed with 3.24g (39.46 mmol) of 2-Methylimidazole, which had been previously diluted in 100 mL of methanol. The mixture was allowed to cool and was gently stirred. Within seconds, the solution turned turbid. After 7 min, the mixture was centrifuged multiple times to separate the nanoparticles from the dispersion. The resulting nanoparticles were then diluted with methanol and spin-coated onto the antenna sample.

Fabrication of the Au plasmonic array
The fabrication of plasmonic metasurface was carried out using electron beam lithography (EBL). Initially, the quartz substrate underwent nitrogen plasma treatment to clean the surface and enhance adhesion. Following this, a copolymer layer of EL12 (MMA(8.5)MAA) was spin-coated with a thickness of 55nm, and then pre-baked at 160°C for 10 min. Subsequently, a layer of PMMA A2 was spin-coated to a thickness of approximately 50nm and also pre-baked at 160°C for 10 min.

To facilitate the (EBL) process, a 20nm layer of aluminum was deposited via e-beam evaporation. The substrate was then exposed to a 100 KeV electron beam. Post-exposure, the aluminum layer was removed using a 0.25M NaOH solution. The development of the PMMA/MMA layers was achieved by immersing the substrate in a solution of Methyl isobutyl ketone and IPA (1:3) for 30s, followed by rinsing in IPA for another 30s.

For the final metal deposition, a thin layer of 1nm germanium and 20nm gold was evaporated using e-beam evaporation. The lift-off process was performed in an SVC-14 stripper at 80°C to remove the remaining resist and leave behind the patterned nanoantennas. A final oxygen plasma treatment was conducted to remove any residual resist.

Characterization methods
Scanning electron microscopy (SEM) imaging was performed with SU-70 Hitachi FESEM, equipped with a Schottky electron emission gun51. Powder X-Ray diffraction was carried out using a D8 Advance diffractometer (Bruker), equipped with a Cu anode (K\alpha1 = 1.54056 Å and K\alpha2 = 1.54439 Å) and a 200 channels LynxEye detector.

In situ environmental spectroscopic thermo-ellipsometry
The ZIF-8 films were characterized using a UV-visible-NIR Woollam spectroscopic ellipsometer (SE) operating from 240 to 1700nm. This ellipsometer features a programmable heating stage (ranging from -80°C to 600°C) and an environmentally controlled chamber, allowing precise control of the films’ local environment in terms of vapor pressure52. Data measurement and analysis were conducted using CompleteEASE software, which involved fitting the raw data curves with a Cauchy model for non-absorbing materials. A mass flow controller (SOLGELWAY) managed the vapor P/P_0 by combining two gas flows: (i) dry air flow with solvent P/P_0 = 0, and (ii) air flow that passed through a bubbler containing liquid isopropyl alcohol (IPA) P/P_0 = 1.

In situ hyperspectral microscopy
The spectral imaging was performed by a Cytoviva hyperspectral microscopy (HIS) system in dark-field mode. The scattered light from the nanoantennas was collected using a 10 or 100x objective with an exposure time of 0.25s.

The resulting hyperspectral image was analyzed using ENVI software, extracting the scattering spectrum for each pixel.

Single antenna porosimetry
To performed the single antenna porosimetry, we integrated a closed environmental chamber at the HIS equipped with a gas flow and humidity controller (SOLGELWAY) and a temperature-controlled platform (Linkam Scientific)53,54. Hyperspectral analysis was acquired with an acquisition time of 0.250s at each vapor pressure that we varied between 0 and 70°C maintaining IPA partial pressure P/P_0 of 0.7.

Light-driven self-regulation and self-oscillations
To investigate the self-regulation capabilities we employed the dark-field microscope with a continuous 850nm laser (Changchun New Industries Optoelectronics Tech. Co.) in place of a white light source55. We used the 10x and 50x objectives to analyze the response of the full array and at the single antenna level respectively. Before every experiment, we first conducted measurements at lower laser power levels (with negligible heating) to establish the baseline and we kept all parameters constant (relative pressure at 0.7), to verify the absence of external fluctuations. Then, we systematically increased the laser power, recording the images and videos that stem from the changes in scattered laser intensity.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "In this manuscript, the authors present an interesting work that integrates Metal-Organic Frameworks (MOFs) with plasmonic metasurfaces to achieve autonomous optical self-regulation. The observed self-oscillatory behavior at the single-antenna level is particularly noteworthy. However, several issues need to be addressed before the manuscript can be considered for publication.\n1. The introduction lacks sufficient discussion of prior research in related fields, particularly in self-adaptation and self-regulation systems. Key information, such as evaluation metrics for self-regulation systems and existing challenges in the research field, is absence. A more thorough comparison with relevant literature would highlight the paper’s novelty and provide clearer insights into the current state of research.\n2. Like the negative feedback mechanisms of living systems, the dynamic range in the proposed system have not been explored. For instance, what is the minimum temperature change (sensitivity) that the system can respond to? Additionally, if the temperature exceeds a certain threshold (e.g. maximum laser power), does the system continue to function effectively?\n3. The self-oscillatory behavior and optical self-regulation described in the paper appear to rely on a stable external energy input. However, the long-term stability and sustainability of the system under continuous operation are not discussed. Furthermore, the potential impact of environmental factors, such as temperature fluctuations and humidity changes, on system performance remains unexplored.\n4. As discussed in Figure 5, “different antennas exhibit a similar frequency but are not at all in phase”, which is somewhat unclear, given that the external stimulus (laser with the same intensity) should be the uniform across all units. Could this discrepancy be attributed to fabrication errors, such as the random distribution of the ZIF-8 colloidal film? A detailed discussion of the phenomenon is necessary, which is crucial for achieving better control over the self-oscillatory fluctuations.\n5. More specific applications can be discussed, for instance, optical manipulation (Appl. Phys. Rev. 9, 031303 (2022)), information processing (Nature Communications 15 (1), 9658, (2024)), and others.\n6. It’s recommended that the authors pay more attention to enhancing the quality of the figures. The text is currently too small and difficult to read, and the overall aesthetics of the figures could be improved. These issues should be addressed to enhance the readability and clarity of the graphical content.", "reviewer_2": "In this manuscript, the authors report pioneering research on self-regulating adsorption and desorption of isopropanol and unique oscillation phenomena by combining adsorption/desorption characteristics in porous MOF thin films with local heating by plasmonic antennas. The oscillation phenomenon that occurs due to the coupling of changes in the plasmon resonance frequency caused by changes in the dielectric constant accompanying the adsorption and desorption of molecules (isopropanol) exhibit high novelty and is expected to be developed for various applications in the future. Since an important and highly novel discovery has been reported, it is appropriate to accept the paper after addressing the comments below.\n・ The introduction contains almost no background information on the MOF-Plasmonic array system used in this study. It is requested to add that the information on previous research using the MOF(porous materials)-plasmonic antenna system and the circumstances that led to the concept of this study.\n・ It is reported in the manuscript that the temperature change due to plasmonic heating is 6.3 degree C. The temperature change seems to be very small. It is necessary to show that the temperature dependence of the transition between the F-MF-E states of MOF (not just the relative temperature change) occurs under the temperature change estimated for the plasmonic heating in the experimental environment.\n・ A quantitative description of the oscillation frequency of plasmon scattering is required (around 50 s?), and additional information is needed on the factors that determine the oscillation frequency and the possibility of modulation.", "reviewer_3": "The paper by Amyar and coworkers deals with developing a self-oscillatory system based on thermoplasmonics and MOF components. The authors have proposed a conceptually fresh framework with the potential for fundamental studies of non-linear nanosystems and for developing nanodevices relevant to several sectors. The manuscript, presented data, and discussion do not meet the level of Nature Communication at the present stage. Nevertheless, with further work, the manuscript can be reconsidered for publication.\n1. The authors claim to have no control over the oscillation dynamics (frequency). This is a rather disappointing statement since a potential reader would expect to see the control of system dynamics. Laser power is a straightforward parameter one can think of, but the author made an explicit statement that indicated precisely the opposite. A qualitative inspection of Figure 4 e and f suggests that increasing the power density from 0.5 to 3.8 W/cm2 changes the oscillation frequency of scattering intensity accordingly. I suggest performing experiments for power densities in a forward and backward scan, maintaining the longer measurement time at each power density. One should expect a reversible change in the frequency of scattering intensity oscillations.\n2. A fundamental requisite for self-oscillations is a temporal delay between positive and negative feedback mechanisms to avoid a steady state trap. For the oscillation to be feasible in the present system, there should be a delay between reversible plasmon band shift and solvent sorption/desorption in the MOF upper layer. Additional experiments dealing with kinetic analysis of sorption/desorption under temperature change and dynamics of plasmon band shift upon refractive index change should be provided.\n3. Phase plot. Authors could estimate the temperature near the plasmonic heat source. That is, it seems that upon changing the amount of sorbed solvent in MOF, the temperature near the plasmonic heater changes because of a scattering band shift. If such a statement is valid, then additional data analysis is needed. For example, one could expect a graphical representation of the relationship between the change of scattering and local temperature.\n4. Collective heating. The whole discussion is built on the statement that collective heating of the plasmonic metasurface is negligible. Considering previous works by Baffou (ACSNano 2023 or textbook by the same author), one can argue that collective heating can dominate the temperature that rules solvent dynamics in the MOF layer, especially when the metasurface is subjected to uniform illumination.\n5. Figure 2b: what is the difference between the blue and red lines? Labels are needed.\n6. Figure 3 d and e: These two subplots show the same data. One of them could be moved to SI.\n7. English needs further editing."}, "author_response": "We would like to thank the Reviewers for the time spent to evaluate our work and for their feedback and constructive comments. We did our best to provide additional data and to revise the manuscript according to their comments. Please find hereafter our point-by-point response; in addition the modifications in the manuscript are highlighted in yellow.\n__________________________________________________________________________________________\nReviewer #1 (Remarks to the Author):\nIn this manuscript, the authors present an interesting work that integrates Metal-Organic Frameworks (MOFs) with plasmonic metasurfaces to achieve autonomous optical self-regulation. The observed self-oscillatory behavior at the single-antenna level is particularly noteworthy.\nRESPONSE: we thank the referee for the positive feedback. Below we address the remaining questions.\nHowever, several issues need to be addressed before the manuscript can be considered for publication.\n1. The introduction lacks sufficient discussion of prior research in related fields, particularly in self-adaptation and self-regulation systems. Key information, such as evaluation metrics for self-regulation systems and existing challenges in the research field, is absence. A more thorough comparison with relevant literature would highlight the paper’s novelty and provide clearer insights into the current state of research.\nRESPONSE: We appreciate the reviewer’s insightful comment regarding the comparison with other self-regulating systems. While several such systems have been reported, direct comparisons are not straightforward due to the diverse nature of their self-regulation mechanisms. For example, it is inherently difficult to directly compare a chemo-mechanical negative feedback system with one based on thermo-optical feedback, as the underlying physical principles differ significantly. That said, we have identified and analysed some of the most relevant examples of thermo-optical self-regulating systems, particularly those in which a temperature change induces an optical response that counteracts the initial perturbation.\nACTION TAKEN to address this point: we have added a comparative table in SI (Figure S24) summarizing key thermo-optical self-regulating systems. The table includes information on the materials used, feedback mechanisms, incident light wavelength (when applicable), operational temperature range, corresponding optical response, and thermo-optical sensitivity.\nFurthermore, we have expanded the discussion section to include this discussion, highlighting how our approach fits within and advances the current state of the art: \n“The self-regulating performance of our metasurface can be compared to other self-regulating systems reported in the literature. Focusing specifically on devices that are based on thermo-optical negative feedback, such as a homeostatic photonic device,43 liquid crystal elastomers,19 or materials based on phase transitions44 like VO₂,45 all these systems are designed to respond to temperature increases with an opposite optical response as summarized in Figure S24. The mechanisms of feedback; the functioning conditions and the type of optical response absorptivity, emissivity, transmittance) differ among these approaches and each approach comes with its own advantages and limitations. However, one useful comparison metric is the thermo-optical sensitivity, defined as the ratio between the relative change in the optical property and the corresponding temperature range over which the change occurs. In general one of the main challenge is have this value the highest possible in the temperaure range of interest. In this context, even though a direct comparison is not straightforward, our MOF plasmonic metasurface exhibits a significantly higher sensitivity to temperature changes in the range close to ambient temperature (60% decrease in absorptivity heating from 20 to 26.8°C).\n2. Like the negative feedback mechanisms of living systems, the dynamic range in the proposed system have not been explored. For instance, what is the minimum temperature change (sensitivity) that the system can respond to? Additionally, if the temperature exceeds a certain threshold (e.g. maximum laser power), does the system continue to function effectively?\nRESPONSE: Thank you for your valuable comment. The reviewer is absolutely right that the self-regulating response of the system deserves deeper discussion. In our case, the thermo-optical sensitivity is not constant across the full temperature range. We performed an additional analysis ot evaluate this parameter. This sensitivity can be quantified by calculating the derivative of the scattering evolution at 850 nm with respect to temperature (see Fig S9. a). This is shown in Fig. S9b and c, where two main sensitivity peaks can be identified.\nThe maximum sensitivity under our experimental conditions occurs between 22 °C and 27 °C, which corresponds to the transition between the Full (F) and MOF-filled (MF) states. In this case the maximum sensitivty is 0.5 °C-1 a an extremely high value as already discussed in the previous question. A second, less pronounced peak is observed between 80 °C and 100 °C, corresponding to the MF–Empty (E) transition.\nThese results indicate that the self-regulating effect is optimized to operate most effectively in the 23–27 °C range. However, we emphasize that this response and the range depends on the adsorption/desorption conditions within the porous layer. The system can be readily adapted to extend or shift the sensitivity range by modifying the porosity characteristics, the nature of the vapor, or its concentration (P/P₀) as we will discuss in the next response.\nACTION TAKEN : the new Figure S9 is added in SI. In addition the following paragraphs are added in the manuscript. « The self-regulating response of the system is not uniform across the entire temperature range, but instead exhibits distinct regions of enhanced sensitivity. This behavior can be analyzed by calculating the derivative of the scattering signal at 850 nm with respect to temperature. As shown in Figure S9b, the highest sensitivity occurs between 22 °C and 27 °C, corresponding to the transition from the Full (F) to the MOF-filled (MF) state. A second, less intense sensitivity peak is observed between 80 °C and 100 °C, associated with the transition from the MF to the Empty (E) state. These findings suggest that the self-regulating effect is most efficient within the 23–27 °C window. Importantly, the sensitivity profile is strongly influenced by the adsorption/desorption dynamics within the porous layer. As a result, the system’s operating range can be readily tuned by altering the porosity characteristics, the chemical nature of the vapor, or the vapor concentration (P/P₀), offering flexibility for application-specific optimization. »\n3. The self-oscillatory behavior and optical self-regulation described in the paper appear to rely on a stable external energy input. However, the long-term stability and sustainability of the system under continuous operation are not discussed. Furthermore, the potential impact of environmental factors, such as temperature fluctuations and humidity changes, on system performance remains unexplored.\nRESPONSE: We thank the reviewer for the insightful comment. As correctly noted, the self-oscillatory behavior and optical self-regulation demonstrated in our system currently depend on stable environmental conditions, particularly with respect to temperature and vapor pressure.\nThe effect of temperature on the refractive index evolution and thermo-optical sensitivity of the MOF layer has been discussed in our previous response. Here, we would like to expand on the influence of vapor pressure, which plays a central role in governing the sorption–desorption equilibrium and, consequently, the dynamic behavior of the system.\nTo address this point, we conducted additional in situ ellipsometry experiments using an environmental chamber equipped with a heating stage and vapor pressure control. These experiments were designed to measure the temperature-dependent evolution of the refractive index under three different vapor pressure conditions: 0.5, 0.7, and 0.9 P/P0.\nThe results clearly show that vapor pressure fluctuations shift the desorption curve: at higher vapor pressure, desorption occurs at higher temperatures, extending the device’s sensitivity range to higher temperatures ; at lower vapor pressure, the opposite occurs: desorption shifts to lower temperatures shifting the sensitivity range downward. Importantly, this finding not only highlights the need for vapor pressure stability to ensure consistent operation, but also reveals a valuable opportunity: by intentionally tuning the vapor pressure, it becomes possible to dynamically adjust the thermal sensitivity range of the device. This simple principle adds a layer of versatility to the porous system that can’t be achieved by other thermo-optical materials (phase changing materials such as VO2).\nACTION TAKEN : the new Figur S10 is added in SI. The following discussion is added in the main text : « We explored the possible effect of the vapor pressure. As demonstrated by in situ ellipsometry experiments conducted at different vapor pressures (0.5, 0.7, and 0.9), vapor pressure systematically shift the sorption equilibrium (Figures S10. Specifically, higher vapor pressures delay desorption, thereby shifting the thermo-optical response of the MOF layer toward higher temperatures, while lower vapor pressures produce the opposite effect. This behavior indicates that maintaining a controlled vapor pressure is essential for reliable device operation. At the same time, it presents a significant opportunity: by adjusting the vapor pressure, one can dynamically tune the temperature range over which the device exhibits its large self-regulating response.“\n4. As discussed in Figure 5, “different antennas exhibit a similar frequency but are not at all in phase”, which is somewhat unclear, given that the external stimulus (laser with the same intensity) should be the uniform across all units. Could this discrepancy be attributed to fabrication errors, such as the random distribution of the ZIF-8 colloidal film? A detailed discussion of the phenomenon is necessary, which is crucial for achieving better control over the self-oscillatory fluctuations.\nRESPONSE : Thank you for your insightful comment regarding the phase mismatch among different antennas shown in Figure 5. You rightly point out that, under uniform external input, one would expect a more homogeneous response. Following your suggestion, we conducted a more in-depth analysis to evaluate whether local inhomogeneities (fabrication errors ?) and variations in optical conditions could explain the observed variability in oscillatory response. Specifically, we adapted the experiment based on in situ hyperspectral microscopy to perform spectroscopy at the single antenna level of the metasurface covered with ZIF-8 and in the presence of IPA vapor. This allows mapping not only the scattering reponse at a single wavelength (as in the first version of the manuscript) but also the « optical homogeneity » between antennas.\nOur findings, now reported in the revised manuscript, indicate that while bare antennas exhibit homogeneous optical behavior (Figure 2), the presence of ZIF-8 and vapor induces significant variation in the scattering response of neighbor antennas. This is now shown in this new Figure S16 as follows.\nThis new figure reports the optical response of individual antennas on a single line (Figure S16a) in presence of ZIF-8 colloidal film and vapor. The corresponding scattering spectra from multiple antennas along the line, shown in Figure b, reveal that the scattering respinse is not homogenous. A selection of different antennas is presented in Figure 5c. The red vertical line in panels (c) and (d) indicates the 850 nm excitation wavelength, highlighting how variations in scattering near this wavelength can influence local absorption and heating. Figure S16(d) illustrates the spatial distribution of scattering intensity at 850 nm, measured from several antennas across the line. The variation in intensity values suggests non-uniform optical behavior among the antennas.\nThis supports the Reviewer's hypothesis that the random distribution of ZIF-8 in the composite material is responsible for the observed variability in dynamic response. Indeed, the ZIF-8 film consists of randomly stacked colloidal particles, leading to non-uniform contact with each antenna. During capillary condensation, the local distribution of ZIF-8 particles and IPA liquid becomes further inhomogeneous across the sample. As shown in Figure 3, the antennas are particularly sensitive to refractive index changes at their extremities. Therefore, the non-uniform distribution of ZIF-8 and condensed vapor likely leads to antenna-specific variations in absorption at 850 nm (the laser wavelength), which in turn results in different local heating and oscillatory behavior.\nThis additional analysis allows us to better explain why the antenna are not oscillating in phase. Additionally, this unintended variability is actually an advantage to support our approach, as (i) it provides an additional evidence that the oscillations are not due to artifacts and (ii) it suggests that, by tuning the sorption and optical properties, different oscillatory behaviors can be obtained.\nA more detailed dynamic analysis, supported by numerical simulations, is provided in our response to Reviewer 3.\nACTION TAKEN: The analysis and the new Figure S16 is added in SI, the discussion is added in the main manuscript “ To further investigated the possible origin of these different oscillatory behavior, we performed a spectroscopic mapping at the single antenna level of the metasurface covered with ZIF-8 and in the presence of IPA vapor. While bare antennas exhibit homogeneous optical behavior (Figure 2), the presence of ZIF-8 and vapor induces a certain variation in the scattering response of neighboring antennas (Figure S16). The ZIF-8 film consists of randomly stacked colloidal particles. Given that the antennas are particularly sensitive to refractive index changes at their extremities (as shown in Figure 3), the non-uniform distribution of ZIF-8 and condensed vapor results in variations in absorption at 850 nm and different local heating that is resposible for the oscillatory process. This unintended variability can be seen as an advantage to support our approach as it provides an additional evidence that the oscillations are not due to artifacts. For instance, possible fluctuations in vapor pressure or in incident light intensity would result in a simultaneous variation of the scattering intensity for all the antennas. Instead, these results indicate that each individual ZIF-8/antenna composite behaves as an individual oscillator, as illustrated in Figure 5(d). These observations also indicate that by controlling the optical properties, different oscillatory behaviors can be obtained. »\n5. More specific applications can be discussed, for instance, optical manipulation (Appl. Phys. Rev. 9, 031303 (2022)), information processing (Nature Communications 15 (1), 9658, (2024)), and others.\nRESPONSE : we thank the reviewer for the suggestion, the references have been added.\n6. It’s recommended that the authors pay more attention to enhancing the quality of the figures. The text is currently too small and difficult to read, and the overall aesthetics of the figures could be improved. These issues should be addressed to enhance the readability and clarity of the graphical content.\nRESPONSE : following the Reviewer’s suggestion we have modified some Figures (Figure 3, 4, 5 and 6) to improve their readability and clarity.\n__________________________________________________________________________________________\nReviewer #2 (Remarks to the Author):\nIn this manuscript, the authors report pioneering research on self-regulating adsorption and desorption of isopropanol and unique oscillation phenomena by combining adsorption/desorption characteristics in porous MOF thin films with local heating by plasmonic antennas. The oscillation phenomenon that occurs due to the coupling of changes in the plasmon resonance frequency caused by changes in the dielectric constant accompanying the adsorption and desorption of molecules (isopropanol) exhibit high novelty and is expected to be developed for various applications in the future. Since an important and highly novel discovery has been reported, it is appropriate to accept the paper after addressing the comments below.\nRESPONSE : we thank the reviewer for recognizing the novelty of our work.\nThe introduction contains almost no background information on the MOF-Plasmonic array system used in this study. It is requested to add that the information on previous research using the MOF (porous materials)-plasmonic antenna system and the circumstances that led to the concept of this study.\nRESPONSE : We thank the reviewer for the reccomandation. Indeed there is a relevant state of the art on so called « MOF hybrid plasmonic materials » that needs to be discussed.\nACTION TAKEN :\n1) To clearly position this work in the state of the art, we introduce the term « hybrid » when refering to our materials in the title, and in the text.\n2) The following sentence is added in the text « MOF hybrid plasmonic materials have been previously used for sensing, nanomedicine or catalytic applications as summarized in Table 1 in SI. In this study, we introduce a previously unexplored and unique functionality of MOF-hybrid plasmonic materials…”\n3) We provide in SI a table describing the state of the art\n・ It is reported in the manuscript that the temperature change due to plasmonic heating is 6.3 degree C. The temperature change seems to be very small. It is necessary to show that the temperature dependence of the transition between the F-MF-E states of MOF (not just the relative temperature change) occurs under the temperature change estimated for the plasmonic heating in the experimental environment.\nRESPONSE : Thank you for your valuable comment. As correctly pointed out, the temperature increase due to plasmonic heating is estimated to be 6.8 °C. The evolution of the optical properties of the MOF as a function of temperature is shown in Figure 2b, where it is evident that this temperature range (from approximately 20 °C to 27 °C) corresponds to the transition from the fully loaded (F) state to the medium-filled (MF) state.\nWe agree that achieving the fully empty (E) state would require a significantly higher temperature, up to around 110 °C. However, under our experimental conditions, the system does not reach such high temperatures for two main reasons: (1) the incident laser power is limited, and (2) most importantly, this reflects the core of our approach, the device is self-regulating, meaning that as the laser power increases, the material absorbs less light due to its intrinsic optical response, thus preventing further heating.\nACTION TAKEN : the following text is added : « Under our irradiation conditions (up to a maximum 3.9 W cm-2), the system transitions from the (F) state to the (MF) state. Higher temperatures required to reach the fully empty (E) state (up to ~110 °C) are not achieved under our experimental conditions, due to both the limited laser power and the self-regulating nature of the device, which reduces light absorption at higher intensities »\n・ A quantitative description of the oscillation frequency of plasmon scattering is required (around 50 s?), and additional information is needed on the factors that determine the oscillation frequency and the possibility of modulation.\nRESPONSE : Thank you for your insightful comment. The oscillation frequency is determined by several factors, the most important being the characteristic time of vapor uptake, which is on the order of tens of seconds and represents the « slowest » process. This aspect is discussed in the response of a comment/suggestion of Reviewer 3 concerning the temporal delay. Additionally, the presence and nature of the hysteresis in the adsorption/desorption process also play a crucial role in defining the frequency and its modulation.\nACTION TAKEN : This aspect is now thoroughly discussed in Section 2.4 where we include kinetic experiments, simulations that provide a quantitative description of the oscillatory behavior, as illustrated in the new Figure 6.\n__________________________________________________________________________________________\nReviewer #3 (Remarks to the Author):\nThe paper by Amyar and coworkers deals with developing a self-oscillatory system based on thermoplasmonics and MOF components. The authors have proposed a conceptually fresh framework with the potential for fundamental studies of non-linear nanosystems and for developing nanodevices relevant to several sectors. The manuscript, presented data, and discussion do not meet the level of Nature Communication at the present stage. Nevertheless, with further work, the manuscript can be reconsidered for publication.\nWe sincerely thank the reviewer for their thoughtful feedback and constructive suggestions.\nWe acknowledge that further clarification and quantitative support were needed, particularly regarding the oscillation dynamics. Since comments 1 and 2 are closely related, we have provided a combined and detailed response addressing both aspects adding new kinetic analysis and simulations to strengthen the scientific discussion.\n1. The authors claim to have no control over the oscillation dynamics (frequency). This is a rather disappointing statement since a potential reader would expect to see the control of system dynamics. Laser power is a straightforward parameter one can think of, but the author made an explicit statement that indicated precisely the opposite. A qualitative inspection of Figure 4 e and f suggests that increasing the power density from 0.5 to 3.8 W/cm2 changes the oscillation frequency of scattering intensity accordingly. I suggest performing experiments for power densities in a forward and backward scan, maintaining the longer measurement time at each power density. One should expect a reversible change in the frequency of scattering intensity oscillations.\n2. A fundamental requisite for self-oscillations is a temporal delay between positive and negative feedback mechanisms to avoid a steady state trap. For the oscillation to be feasible in the present system, there should be a delay between reversible plasmon band shift and solvent sorption/desorption in the MOF upper layer. Additional experiments dealing with kinetic analysis of sorption/desorption under temperature change and dynamics of plasmon band shift upon refractive index change should be provided.\nRESPONSE : We thank the reviewer for these insightful and important comments.\nIndeed our statement about ‘no control over the oscillation dynamics’ was not accurate. We carried out a further analysis of our experimental data and confirm that, as indicated by the reviewer and shown in (the previous) Figure 4 (e), an increase in oscillation frequency can be observed with increasing laser intensity for several antennas. As indicated in the response of Reviewer 1, from the new experiments, we realized also that the variability in oscillatory respose can be explained by the local heterogenieites in ZIF-8 packing.\nTo achieve control, understanding the origin of the oscillation dynamics is essential. We also acknowledge the importance of identifying the temporal delay and kinetic conditions that give rise to self-oscillations to ultimately control them.\nACTION TAKEN\nThe following experiments and analysis have been made :\n1) Kinetic analysis\nWe have performed new experiments of both plasmonic heating rate and adsorption/desorption rate in the MOF layer, which allowed us to estimate the characteristic timescales of the involved processes. These measurements confirm the presence of a significant temporal delay between the fast plasmonic heating and the slower adsorption/desorption response, which is further influenced by the intrinsic hysteresis of the MOF.\nIn the first experiment, we focused on the plasmonic heating rate. We simulated the transient thermal behavior of plasmonic gold nanoantennas subjected to localized photothermal excitation. The heat dissipation dynamics were modeled using a lumped capacitance approach, assuming that the temperature within the gold volume remains spatially uniform during heating due to its high thermal conductivity.\nIn this case, the plasmonic heating is very fast with a time constant of 63 µs.\n2) Dynamic simulation\nTo study the oscillatory dynamics the reviewer suggested performing longer experiments at variable light intensity. Despite our efforts, carrying out longer experiments was experimentally challenging at such a high magnification, as it requires maintaining focus and avoiding drift or vapor pressure drops. In addition, the antenna samples were partially damaged after multiple runs and cannot be refabricated exactly in the same way. Producing an identical system is challenging, time-consuming, and costly, since fabrication requires state-of-the-art electron beam lithography facilities.\nNevetheless, to answer to the reviewer’s questions, we carried out dynamic simulations to describe the oscillatory dynamics, that provide an even more complete understanding on the system.\nBased on experimental kinetic parameters and hysteresis behavior of the MOF layer, we developed a simple hysteresis-based model that reproduces the self-oscillatory behavior. This model allows us to systematically explore the influence of various parameters, in particular laser intensity and hysteresis shape, on the oscillation dynamics.\nWe considered our system as a material whose optical absorptivity depends on temperature, with a hysteretic response and a finite time constant (sorption time constant) governing its evolution. In particular, the absorptivity exhibits different transition thresholds during heating and cooling due to the hysteresis of the F to MF states reported in Figures 2.\nPhysical Model : The system under consideration consists of a material with an initial absorptivity, which absorbs optical power from a constant incident optical flux. The temperature of the material changes as a result of both the absorption of incident optical power and thermal dissipation to the environment. The material is assumed to be in thermal equilibrium with the surroundings, and the thermal behavior of the system is modeled using differential equations derived from energy conservation principles.\nGoverning Equations : The thermal behavior of the system is modeled by two coupled differential equations: one for the temperature, T(t) and one for the absorptivity, α(t). These equations describe the evolution of temperature and absorptivity over time based on the incident power, the thermal dissipation, and the feedback between temperature and absorptivity.\nThe rate of change of temperature, dT/dt is given by the following equation derived from energy conservation:\nwhere:\no Pin is the incident optical power,\no α(t) is the time-dependent absorptivity of the material.\no k is the thermal dissipation coefficient,\no Tenv is the ambient temperature\no C is the heat capacity of the material.\nThe absorptivity, α(t), evolves over time as a function of temperature. A sigmoid function is used to model the temperature-dependent change in absorptivity with different transition thresholds and steepness for heating and cooling phases. The absorptivity evolves with a delayed relaxation toward this equilibrium value with a characteristic time constant t (20s as determined experimentally).\nwhere mode switches between heating and cooling depending on the sign of the temperature derivative, enforcing the hysteresis. The absorptivity follows different paths during heating and cooling phases, with transitions occurring at specific threshold temperatures.\n• Heating Phase: When the system is in the heating mode, the absorptivity increases as the temperature rises.\n• Cooling Phase: When the system switches to cooling mode (due to a decrease in temperature), the absorptivity decreases as the temperature drops.\nThe temperature dependence of absorptivity was modeled using sigmoidal functions to capture the smooth yet sharp transition between low and high absorptivity states near threshold temperatures. These functions provide a convenient phenomenological description of hysteresis by defining separate transition branches for heating and cooling.\nFor each mode (heating or cooling), the equilibrium absorptivity is given by:\nwhere:\n• a min and max are the lower and upper bounds of absorptivity.\n• Tth is the threshold temperature at which the transition occurs.\n• β is a steepness parameter controlling how sharply the transition happens.\nAs shown in the Figure above, for the simulation we used values transition thresholds, β , a min and max and time constant determined experimentally. For the other parameter values (heat capacity, dissipation coefficient, incident power) we imposed physically reasonable values to explain the observed experimental behavior. The ultimate goal is to propose a mechanism and gain indications about the influence of various parameters.\nThe results are shown in the new Figure 6 (d-g) and in SI.\nAs shown in Figure 6(e), the analysis displays an oscillatory behavior in absorptivity with a period of around 45 seconds, which is comparable to our experimental observations. The system demonstrates absorptivity oscillations that results from an elliptical loop in the hysteresis curve, capturing the delayed transitions between heating and cooling states that drive the self-oscillatory behavior. The shape and path of this hysteretic loop has an thus impact the frequency of the oscillation. To further explore that, we performed the same analysis using hysteresis curves with identical threshold temperatures but varying steepness parameters (b). This variation can be describe porous networks with different pore size distribution: monodisperse pores lead to sharper transitions, while a polydisperse distribution results in broader, less abrupt changes. (Ceratti et al Nanoscale 2015). As shown in Figure 6(g), the frequency of the oscillation increasing for shaper hysteresis.\nSimilarly, as shown in Figure S22, broader hysteresis results in a larger loop and a decrease of the frequency . No oscillations are observed for no hysteresis or very narrow hysteresis, suggesting the importance of the presence of the hysteresis.\nThis simple analysis suggests that by varying the sorption properties and optical response of the porous media, different oscillatory behaviors can be achieved. This may further explain why heterogeneous packing of ZIF-8 on the antenna leads to variations in oscillatory behavior as discussed in Figure 5 and the response to Reviewer 1.\nFinally, the effect of light intensity was examined. As pointed out by the reviewer, observations on selected antennas (Figure 6(b), indicates that increasing the light intensity results in a higher oscillation frequency. We performed simulations with increasing light intensity, as shown in new Figure S23. Interestingly, we confirmed that the oscillation period decreases with light intensity until the absorptivity reaches a low value, where the steepness of the hysteresis decreases, causing the oscillations to slow down and then stop.\nMODIFICATIONS ON THE MANUSCRIPT: all the data and the technical discussion provided above are now included in the manuscript (new Figure 6) and in SI. We also provided a new section in the manuscript “5. Discussion” to discuss the oscillatory behaviour (based on Figure 6) by providing insights and perspectives on how to control the oscillatory behaviour.\n3. Phase plot. Authors could estimate the temperature near the plasmonic heat source. That is, it seems that upon changing the amount of sorbed solvent in MOF, the temperature near the plasmonic heater changes because of a scattering band shift. If such a statement is valid, then additional data analysis is needed. For example, one could expect a graphical representation of the relationship between the change of scattering and local temperature.\nRESPONSE : thank you for the suggestion. The evolution of the scattering intensity (at 850 nm) as fonction of the temperature is reported hereafter.\nACTION TAKEN : the plot is now added in SI and refered in the main text when discussing the thermal sensitivity of the metasurface.\n4. Collective heating. The whole discussion is built on the statement that collective heating of the plasmonic metasurface is negligible. Considering previous works by Baffou (ACSNano 2023 or textbook by the same author), one can argue that collective heating can dominate the temperature that rules solvent dynamics in the MOF layer, especially when the metasurface is subjected to uniform illumination.\nRESPONSE : We appreciate the remark that is important. We believe the Reviewer is referring to the seminal work by Baffou et al., ACS Nano 2013, Photoinduced Heating of Nanoparticle Arrays, which we cited in the first version of the manuscript as reference 39. Our findings are consistent with Baffou’s work. As shown in Figure 2(b) of the ACS Nano 2013 paper, plasmonic particles spaced 500 nm apart behave as individual hot spots, with very little temperature increase between them. In our case, the antennas are spaced 1 μm apart, an even larger distance, which explains the very low collective heating effect that we determined by thermal simulation (Figure 4).\nHowever, we agree that our initial statement claiming that collective heating is negligible may not be entirely accurate. To better support this discussion, we performed additional thermal simulations by varying the distance between the antennas.\nACTION TAKEN : the plot is now added in SI and discussed in the main text. We toned down the « no thermal coupling » statement by replacing with ‘the temperature rise is located in the close vicinity of the antenna with a very low heating between the antenna‘ . In addition we discussed the thermal coupling in the discussion section to open persoective for achieving a collective oscillatory response.\n5. Figure 2b: what is the difference between the blue and red lines? Labels are needed.\nRESPONSE : Thank you for spotting this. The curves refer to heating and cooling processes\nACTION TAKEN : the label was added in Figure 2b\n6. Figure 3 d and e: These two subplots show the same data. One of them could be moved to SI.\nRESPONSE : Thank you, yes indeed this is the same set of data. We remove the previous Figure 3e from the new Figure 3 that was simplified to improve the clarity (as requested by Reviewer 1).\n7. English needs further editing.\nRESPONSE : the text was doublechecked and revised to improve the English and correct the mistakes.\nWe would like to thank the Reviewers once again for their comments and suggestions.\nPlease find hereafter our response.\n__________________________________________________________________________________________\nReviewer #1 (Remarks to the Author):\nI am happy with the revision. Recommend its publication.\nResponse : We would like to thank again the reviewer.\nReviewer #2 (Remarks to the Author):\nThe manuscript has been appropriately revised and addresses the points raised by the reviewers. The novelty of the manuscript, the self-regulating adsorption and desorption of isopropanol and unique oscillation phenomena by combining adsorption/desorption characteristics in porous MOF thin films with local heating by plasmonic antennas, is high, and it is supported by sufficient theoretical background. I recommend that this manuscript is accepted for publication in Nature Communications in the present form.\nResponse : We would like to thank again the reviewer.\nReviewer #3 (Remarks to the Author):\nI want to thank the authors I appreciate their efforts to improve the manuscript. The modeling of the oscillations provides valuable insight into the system's properties and suggests potential future directions for enhancing the oscillator's performance. In principle, I recommend accepting the paper for publication.\nResponse : We would like to thank again the reviewer and the for the suggestions.\nBefore finalizing, I would like to mention four minor points for the Authors to consider:\n1. To model the self-oscillatory system, the authors used a simple hysteresis-based model developed from experimental data on the kinetic parameters and hysteresis behaviour of the MOF layer. It is not immediately clear where in the manuscript the hysteresis data for the MOF are located. Presumably, it is Figure 2b. If so, I suggest the authors enhance this figure by adding an inset that clearly shows the hysteresis, helping readers understand the hysteretic behaviour of MOF dynamics from the start.\nResponse : thank you for the suggestion. The inset have been added in Figure 2(b) and refered in the text from the begininng of the discussion.\n2. In Figure 6d, the Authors should indicate which lines represent cooling and heating, either by labelling or using arrows on the blue and red lines to show the direction of the hysteresis.\nResponse : the labels have been added\n3. In Figures S22 and S23, the arrows on the heating and cooling directions should be indicated.\nResponse : the arrows have been added\n4. The sections \"Discussion\" and \"Conclusions\" should be merged since the text in both sections is somewhat repetitive.\nResponse : according to the journal’s guidelines only the discussion section is included now."}, {"round": 2, "reviewer_comments": {"reviewer_1": "I am happy with the revision. Recommend its publication.", "reviewer_2": "The manuscript has been appropriately revised and addresses the points raised by the reviewers. The novelty of the manuscript, the self-regulating adsorption and desorption of isopropanol and unique oscillation phenomena by combining adsorption/desorption characteristics in porous MOF thin films with local heating by plasmonic antennas, is high, and it is supported by sufficient theoretical background. I recommend that this manuscript is accepted for publication in Nature Communications in the present form.", "reviewer_3": "I want to thank the authors I appreciate their efforts to improve the manuscript. The modeling of the oscillations provides valuable insight into the system's properties and suggests potential future directions for enhancing the oscillator's performance. In principle, I recommend accepting the paper for publication. Before finalizing, I would like to mention four minor points for the Authors to consider:\n1. To model the self-oscillatory system, the authors used a simple hysteresis-based model developed from experimental data on the kinetic parameters and hysteresis behaviour of the MOF layer. It is not immediately clear where in the manuscript the hysteresis data for the MOF are located. Presumably, it is Figure 2b. If so, I suggest the authors enhance this figure by adding an inset that clearly shows the hysteresis, helping readers understand the hysteretic behaviour of MOF dynamics from the start.\n2. In Figure 6d, the Authors should indicate which lines represent cooling and heating, either by labelling or using arrows on the blue and red lines to show the direction of the hysteresis.\n3. In Figures S22 and S23, the arrows on the heating and cooling directions should be indicated.\n4. The sections \"Discussion\" and \"Conclusions\" should be merged since the text in both sections is somewhat repetitive."}, "author_response": ""}]

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