Environmental sensors with optical metasurfaces

Abstract

A sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition; a substrate, the sensing material superposed on the substrate; a metasurface, the metasurface superposed on the substrate, the metasurface being coupled to the sensing material such that an optical response of the metasurface changes in response to the change in at least one of refractive index and geometry as a function of an environmental condition of the sensing material.

Description

ENVIRONMENTAL SENSORS WITH OPTICAL METASURFACESRELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of United States patent application no. 63 / 535,810, “Environmental Sensors With Optical Metasurfaces” (filed August 31, 2023). All foregoing applications are incorporated herein by reference in their entireties for any and all purposes.GOVERNMENT RIGHTS

[0002] This invention was made with government support under 1941529 awarded by the National Science Foundation. The government has certain rights in the invention.TECHNICAL FIELD

[0003] The present disclosure relates to the field of nanostructures and to the field of sensors.BACKGROUND

[0004] Existing remote environmental sensors can be significant in cost and also require power. Further, in some instances, such sensors cannot be placed directly on what the user seeks to be measured - as an example, rather than being placed directly on leaves, existing leaf sensors are instead placed nearby to the leaves of interest, which placement results in the omission of critical leaf-specific information like transpiration and effects of different leaf surface hydrophilicities. Additionally, current remote sensing methods such as hyperspectral imaging and LIDAR cannot directly detect plant stressors such as humidity, leaf temperature, and transpiration rate. Accordingly, there is a long-felt need in the art for improved remote sensors, in particular sensors that can be placed directly on what is sought to be measured.SUMMARY

[0005] In meeting the described long-felt needs, the present disclosure provides, inter alia, low-cost, passive environmental sensors that can be easily deployed and measured using existing farm infrastructure and ground and aerial robots. The sensors can be based on optical metasurfaces and adaptive polymers that respond to local environmental conditions.

[0006] Metasurfaces are designed to exhibit high quality factor (Q) resonances, using design parameters such as material system, geometry, and arrangement. These metasurfaces are integrated with adaptive polymers whose refractive index and / or geometry is a function of local environmental conditions such as, for example, humidity, temperature, presence of Volatile Organic Compounds (VOCs) and toxins, which in turn enables sensing. The integrated sensors can be optimized to achieve the desired operating wavelength in the visible, near infrared (NIR) or short-wave infrared (SWIR), and sensitivity to desired target measurands.

[0007] Colorimetric sensors based on optical metasurfaces are designed to exhibit high figure of merit (FOM) in the visible, NIR, and / or SWIR with adaptive polymers that respond to relevant environmental conditions. Metasurface design parameters such as material system, geometry, and arrangement can be optimized to achieve the desired operating wavelength and sensitivity of the sensor.

[0008] In one aspect, the present disclosure provides a sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition; a substrate, the sensing material superposed on the substrate; a metasurface, the metasurface superposed on the substrate, the metasurface being coupled to the sensing material such that an optical response of the metasurface changes in response to the change in at least one of refractive index and geometry as a function of an environmental condition of the sensing material.

[0009] Also provided is a sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition, the sensing material being disposed between a first mirror and a second mirror, the first mirror and the second mirror defining a cavity therebetween, at least one of the first mirror and the second mirror being a permeable mirror, and the sensing component being arranged such that material that permeates thepermeable mirror contacts the sensing material; and a substrate, the sensing material being superposed over the substrate, and the sensing component being configured as a Fabry - Perot interferometer.

[0010] Further provided is a system, comprising: a sensing component according to the present disclosure; and a detector, the detector configured to collect a signal of the sensing component that related to a response by the sensing component to an environmental condition.

[0011] Additionally disclosed is a method, comprising: monitoring a signal from a sensing component according to the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes can represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various aspects discussed in the present document. In the drawings:

[0013] FIG. 1 A. (Parts A-G) Cross-section schematics of metasurface sensor architectures with (1) - Sensing Material (SM), (2) - Metasurface pattern, (3) - Waveguide, (4) substrate (which can be an adhesive material - AM). (C) and (D) show architectures where the sensing material can be combined with or possess additional functionality as the adhesive material or the waveguide. (F) Cross-section schematic of a Fabry-Perot sensor schematic with (5,6) - mirror layers whose thickness can be tuned to allow for transmission of reflected light from within the sensing material (1) cavity. (G) Example architecture in which the metasurface pattern and waveguide are combined (2, 3) and the sensing material and waveguide (1, 3) are also combined and are superposed on substrate (4), which can be an adhesive material.

[0014] FIG. IB. (Parts A-E) provide exemplary top views of metasurface patterns showing (2) - Metasurface pattern, (3) - Waveguide. Optionally, the waveguide is not present, and the metasurface rests directly on the substrate.

[0015] FIG. 2. Multiple sensors integrated on a single substrate for an optical nose.

[0016] FIG. 3. Photograph of a colorimetric sensor on a peanut plant leaf. Optical response from the sensor is probed by cameras on drones or ground robots. Inset: schematic and features of the flexible and passive / battery-free leaf sensor, (b) Sensor attachment to corn leaf.

[0017] FIG. 4. Variation of metasurface material, pitch and geometry enables spectral tunability of the optical response of the metasurfaces. Multiple sensors with exemplar modification of geometry to tune resonant wavelengths of individual metasurfaces, where (1) is an array of circular pillars with a diameter ranging from 20 nm - 500 nm, and pitch ranging from 30 nm to 1000 nm.

[0018] FIG. 5: (a) Quality factor (Q), Sensitivity (S), modulation strength (A / ?) and FIG. of Merit (FOM) defined for reflectance (or transmission) spectra of colorimetric sensors, (b-e) Schematic of a pillar for different metasurface designs, and simulations of resonances for arrays of structures where the metasurface response operates on (b) plasm onic resonances from Au nanopillar arrays, (c) Fano resonances from Au double- nanorod arrays, (d) Mie resonances from TiCh nanopillar arrays, and (e) quasi -guided modes based on TiCh nanopillar arrays coupled to TiCh waveguides.

[0019] FIG. 6. Humidity Dependent Response of Plasmonic Metasurfaces Embedded into Chitosan, (a) change in resonance of the metasurface due to Chitosan coating, (b) Resonance shift between wet (at 0 min), and dry (at 180 min) states of the Chitosan sensor, (c) Resonance shift between wet and dry states at various environmental conditions.

[0020] FIG. 7. FDTD simulations for TiCh nanocrystal-based metasurfaces, showing (a) effect of changing refractive index of the substrate on resonant wavelength of the metasurface, (b) effect of changing pitch of nanostructures along x- and y-directions on resonant wavelength, and (c) effect of changing refractive index of a layer between metasurface pillars and waveguides on resonant wavelength.

[0021] FIG. 8: Chitosan film molding for improved leaf adhesion and flexibility.

[0022] FIG. 9A provides reflectance spectra of high-aspect ratio / high-index nanocrystal-based optical metasurfaces where A / ? is the modulation strength of the resonance. The inset shows a photograph of the nanocrystal-based metasurface printed on a flexible substrate and a scanning electron micrograph of the printed structures that give rise to the resonances observed.

[0023] FIG. 9B illustrates RH-dependent resonance of a chitosan-TiCh nanocrystal composite metasurface fabricated on glass (black) and Chitosan (blue) for high sensitivity sensors.

[0024] FIG. 9C illustrates the refractive index of chitosan-TiCh nanocrystal composites, showing enhanced refractive indices at low concentration and enabling nanocrystal-based metasurfaces with high FOM via improvements in S and AR. In the pore filling regime, chitosan polymer fills in the air interstices between nanocrystals, thereby increasing the effective refractive index (RI) of the composite. At higher concentrations of polymer, the polymer dominates over the nanocrystals, leading to lower effective RI of the composite.

[0025] FIG. 9D illustrates substrate adhesion to citrus leaves, where the upper image shows a substrate made of PDMS, and the lower image shows a substrate made of ethyl cellulose.

[0026] FIG. 9E: Tracking of leaf wetness showing an expected spectral shift relative to a nearly constant RH environment. The spectral resonance of the sensor placed on a leaf immediately after it is cut is tracked over time, showing a shift in the wavelength of the peak, likely due to moisture absorption from leaf transpiration, at nearly constant environmental relative humidity. The image shows the sensor on the leaf being interrogated by a spectrometer.

[0027] FIG. 10A provides an exemplary method of fabricating components according to the present disclosure. As shown, one can use direct nanocrystal imprinting to fabricate a nanocrystal-based metasurface on a polymer substrate.

[0028] FIG. 10B provides (upper row of images) images of TiCh nanocrystal inks in various solvents, including water, a-terpineol, and UV-curable ink; and (lower row of images) imprints of these inks on various substrates.

[0029] FIG. 10C provides SEM images of imprinted structures without and with a residual layer. The residual layer is comprised of TiCE nanocrystals, similar to the metasurface, and acts as a waveguide, where guided mode resonances within the waveguide couple to the overlaying metasurface and scatter into free space, forming high Q quasi guided mode resonances. Optical transmission spectra of the imprinted structures without (green) and with (pink) a residual layer, and simulations of structures with a residual layer (red) show the Q-factor of resonances for an example device according tothe present disclosure. In the lower images, the simulation shows field maps showing the confinement of the electric dipole within the waveguide and scattering of the light via the coupled pillar structures. The experimental plot shows high Q resonances of imprinted metasurfaces, with transmission (lower line at left) and hyperspectral reflection, plotted as (1 -refl ection) for comparison (upper line at left).

[0030] FIG. 11 A provides example illustrations of the integration of moisture sensitive polymer into components according to the present disclosure. As shown in the upper left image, a component can comprise a metasurface (which can itself comprise TiChnanocrystals) disposed on a substrate of chitosan / glycerol. As shown in the middle image, a component can include a metasurface that comprises a composite of TiCh nanocrystals and adaptive polymer, which metasurface is disposed on a glass substrate. As shown in the right image, a component can comprise a composite - in this instance, TiCh nanocrystals and an adaptive polymer - disposed on an adaptive polymer substrate. These schematics show different sensor architecture options for integrating adaptive polymers into the metasurfaces to improve the sensitivity of the sensor through increasing the resonance wavelength shift with changes in relative humidity (RH). The measured changes in resonance shifts with RH show a 11.7nm shift with adaptive polymers as a substrate, 21.7nm shift when the adaptive polymer is mixed into the metasurface, and a 36nm shift when the adaptive polymer mixed into the metasurface is printed on an adaptive polymer substrate. These architectures provide multiple methods of integrating adaptive polymers into the metasurfaces.

[0031] FIG. 1 IB illustrates the effect of polymer concentration on sensing performance. As shown, resonance position (left image) and resonance shift (right image) can vary with polymer concentration. With regard to the left image showing resonance position as the humidity is cycled between 5% and 80%, the maximum resonance shift can be controlled by tuning the amount of mixed polymer in concentrations ranging from 0% to 30% resulting in resonance shifts ranging from 4nm up to 22nm.

[0032] FIG. 11C illustrates the effect of sensor orientation on sensor response. As shown, a sensor responds to moisture changes on one side of the sensor, dependent on substrate permeability. This can be used, for example, for selective sensing of transpiration over environmental humidity. When the sensor metasurface is separated from the leaf surface by a non-permeable substrate, the sensor does not shift in resonanceposition to changes in leaf transpiration, as seen by the overlaying resonance position in both dry and wet states when the sensor is face up (away from leaf surface). When the sensor faces the leaf surface, it responds to changes in moisture as shown by the 1 Inm shift in resonance position.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0033] The present disclosure may be understood more readily by reference to the following detailed description of desired embodiments and the examples included therein.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0035] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0036] As used in the specification and in the claims, the term "comprising" can include the embodiments "consisting of' and "consisting essentially of.” The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named ingredients / steps and permit the presence of other ingredients / steps. However, such description should be construed as also describing compositions or processes as "consisting of' and "consisting essentially of' the enumerated ingredients / steps, which allows the presence of only the named ingredients / steps, along with any impurities that might result therefrom, and excludes other ingredients / steps.

[0037] As used herein, the terms “about” and “at or about” mean that the amount or value in question can be the value designated some other value approximately or about the same. It is generally understood, as used herein, that it is the nominal value indicated±10% variation unless otherwise indicated or inferred. The term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about” or “approximate” whether or not expressly stated to be such. It is understood that where “about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0038] Unless indicated to the contrary, the numerical values should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0039] All ranges disclosed herein are inclusive of the recited endpoint and independently of the endpoints. The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and / or values.

[0040] As used herein, approximating language can be applied to modify any quantitative representation that can vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not be limited to the precise value specified, in some cases. In at least some instances, the approximating language can correspond to the precision of an instrument for measuring the value. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” can refer to plus or minus 10% of the indicated number. For example, “about 10%” can indicate a range of 9% to 11%, and “about 1” can mean from 0.9-1.1. Other meanings of “about” can be apparent from the context, such as rounding off, so, for example “about 1” can also mean from 0.5 to 1.4. Further, the term “comprising” should be understood as having its open-ended meaning of “including,” but the term also includesthe closed meaning of the term “consisting.” For example, a composition that comprises components A and B can be a composition that includes A, B, and other components, but can also be a composition made of A and B only. Any documents cited herein are incorporated by reference in their entireties for any and all purposes.

[0041] Any embodiment or aspect provided herein is illustrative only and does not limit the scope of the present disclosure or the appended claims. Any part or parts of any one or more embodiments of aspects can be combined with any part or parts of any one or more other embodiments or aspects.

[0042] The disclosed sensors can be fabricated using large-area patterning techniques to form nanostructured metasurfaces over very large areas. These plasmonic and dielectric metasurfaces exhibit sharp and distinct resonating features. The resonant wavelength of the metasurface is highly dependent on the dielectric function of the environment and the exact geometry of the array. A shift in the characteristic resonance of the metasurface that is within the visible, near-infrared (NIR; 740 and 1400 nm wavelength), or shortwave infrared (SWIR; 1400 - 3000 nm wavelength) can be detected and therefore, can be used to sense a target variable. This mechanism can be effected (without a power supply or battery) via interrogation of the sensor surface using appropriate visible, NIR, and SWIR cameras. Free-standing films of the sensor are created by integrating the metasurfaces with adhesive composites. The sensors can, for example, be applied to leaf surfaces for precision agriculture applications to provide growers with tools to improve irrigation regimes and disease management. It should be understood, however, that the disclosed sensors can be adhered to other surfaces besides leaves, including, for example, fruits, packaging, structures, vehicles, signs, roadways, and the like. The disclosed sensors can also be in contact with soil, as a further example of a medium that can be sensed using the disclosed technology.

[0043] Metasurface Sensor Architectures for Environmental Sensing

[0044] The disclosed technology provides sensor architectures, designs, and fabrication schemes for colorimetric sensors for environmental sensing using optical detectors. Sensor materials and fabrication schemes are described to enable biodegradable, biocompatible, low-cost, scalable, and high-throughput manufacturing while maintaining optimal sensor performance. The low-cost and passive (no onboard power source) features of these sensors can enable high volume and large area sensor deployment, enablingunprecedented spatiotemporal data resolution. These sensors can be used in various applications including internet of things (loT) for sensing crop health, food spoilage by integration into food packaging, local environmental sensing in manufacturing facilities, integrated sensors in robotics, smart skin, and the like.

[0045] For an example application in loT for precision agriculture, leaf sensors are described. Leaf sensors are an important part of the sensor suite being developed for precision agriculture. Drought often can lead to decreased crop yield and increased stress. Heightened leaf temperature is a common response to drought and can be used to isolate stressed individuals. In addition to drought stress, there is an increased likelihood of disease in plants with wet surfaces which can lead to reduced yields or plant loss. As a result, monitoring of leaf temperature and moisture is critical for ensuring crop success.

[0046] Current leaf moisture sensors cost ~$100 per sensor, require power, and are often not directly placed on leaf surfaces. They are instead placed in the vicinity of leaves to mimic leaf surface moisture, resulting in the omission of critical leaf-specific information like transpiration and effects of different leaf surface hydrophilicities. In contrast, our colorimetric sensors enable remote monitoring of plant moisture and temperature at the canopy level which can be used to identify early signs of crop stress, thereby improving crop yield and resiliency. Current remote sensing methods such as hyperspectral imaging and LIDAR cannot directly detect plant stressors such as humidity, leaf temperature, and transpiration rate. Remote sensing of these stressors will allow for the isolation of crop stress prior to undesirable outcomes such as reduced crop yield and crop disease. Further, sensor data can be used to reduce fungicide use in integrated disease management by detecting plant-level infection.

[0047] This invention describes low-cost, biodegradable, and passive colorimetric sensors capable of remote sensing of crop conditions at the leaf level to help mitigate crop stress. Sensor data collected by cameras mounted on existing farm infrastructure or on aerial or ground-based robots is used to improve modeling approaches to link leaf temperature and wetness to the onset of drought stress and disease. This approach will provide growers with tools to improve water utilization and disease management.

[0048] The development of these types of sensors allows for continuous sensing of parameters critical to leaf success without the need of an external power supply orvoltage. The scalability of this fabrication approach allows for bulk manufacturing of these sensors. Furthermore, their colorimetric properties will allow for remote sensing platforms to detect many of these sensors at once.

[0049] Colorimetric optical sensors that adhere to the surfaces of leaves are developed by embedding high quality factor metasurfaces into select adaptive polymers which are biocompatible, biodegradable, and can change their properties depending on target variables to be measured, such as moisture temperature, VOCs and toxins. A shift in the transmission or reflection resonances of the device is observed as a color change. The sensors are designed to reflect / transmit light at wavelengths that can be detected by detection systems such as visible-NIR RGB, multispectral and / or hyperspectral cameras, while accounting for the optical properties of leaves they are placed on. The data from the sensors can improve development of models that correlate leaf wetness and temperature with the onset of plant diseases and water deficit stress.

[0050] Sensor materials and fabrication schemes are developed to ensure biodegradable, biocompatible, low-cost, scalable, and high-throughput manufacturing. The sensors are designed to be:

[0051] - flexible and structured for good contact with leaf surfaces

[0052] - biodegradable and biocompatible so they do not need to be retrieved from the field

[0053] - passive, requiring zero power

[0054] - low cost, using fabrication methods such as large area imprint lithography and solution-based coating techniques

[0055] - highly reflective, promising signal communication with cameras deployed on farm equipment or aerial and ground robots

[0056] - deployable at -10,000 sensors per acre for unprecedented spatiotemporal data, while being biodegradable to avoid retrieval of deployed sensors from the field

[0057] - tailorable to degrade within or as much as one growing season

[0058] FIG. 1 A provides example sensor architectures of such sensors, where the sensor comprises one or more of (1) an optional sensing polymer, (2) metasurface pattern, (3) optional waveguide, and (4) substrate with optional Adhesive Polymer (AP). Thesensor can be placed on the adaxial or abaxial surface of the leaf, and the sensor can be placed such that the sensing polymer (1) or the substrate (4) is in contact with the leaf.

[0059] With regard to FIG. 1 A(A), a device can include a metasurface 2 having a sensing / adaptive polymer 1 superposed thereover; the adaptive polymer 1 can contact the metasurface 2. The metasurface 2 can be superposed on a waveguide 3; the waveguide 3 can contact the metasurface 2, as shown. A substrate 4 can support the adaptive polymer 1, the metasurface 2, and the waveguide 3; the substrate can contact the waveguide 3. Without being bound to any particular theory or embodiment, this embodiment can be used to assess environmental conditions in the environment above adaptive polymer 1, as environmentally-caused changes in the adaptive polymer can be detected by monitoring metasurface 2. Substrate 4 can be impermeable. Substrate 4, however, can also be permeable, which in turn allows for monitoring of the environment proximate to the substrate. As but one example, if substrate 4 is water-permeable, water can permeate through substrate 4 to waveguide 3, and water-driven changes in waveguide 3 and / or adaptive polymer 1 can be detected through monitoring of metasurface 2. An adhesive spacer can be placed between substrate 4 and the location of sensor application; such an adhesive spacer can help to secure the sensor in place.

[0060] Without being bound to any particular theory or embodiment, environmentally-caused changes in the adaptive polymer (for example, a swelling or contraction, a change in dielectric constant / refractive index) can result in a detectable change in the metasurface, for example a change in the geometry of the metasurface, a change in the refractive index of the metasurface, a change in in the dielectric constant of the metasurface, and the like. By monitoring a color or other property of the metasurface, one can then correlate a change in that property to a change in the environment surrounding the sensor device.

[0061] With regard to FIG. 1A(B), metasurface 2 is superposed on waveguide 3. Waveguide 3 is in turn superposed over adaptive polymer 1, and adaptive polymer 1 is superposed over substrate 4. Without being bound to any particular theory or embodiment, this embodiment can be used to assess environmental conditions in the environment above metasurface 2 and polymer 1, as environmentally -caused changes in the adaptive polymer 1 can be detected by monitoring metasurface 2.

[0062] Regarding FIG. 1A(C), metasurface 2 is superposed on waveguide 3. Waveguide 3 is in turn superposed over adaptive polymer 1 and substrate 4; as shown, the adaptive polymer 1 and substrate 4 can be integrated together. In this way, changes in the environment proximate to polymer 1 / substrate 4 will manifest via changes in adaptive polymer 1, and such changes can further manifest in waveguide 3. By virtue of its contact and communication with waveguide 3, metasurface 2 will evidence changes taking place in the structures beneath, and by monitoring changes in metasurface 2, one can assess changes in the environment proximate to polymer 1 / substrate 4.

[0063] Regarding FIG. 1 A(D), metasurface 2 is superposed on waveguide 3 / adaptive polymer; as shown, the waveguide 3 and adaptive polymer can be integrated together. As described elsewhere herein, substrate 4 can be permeable; in some embodiments, substrate 4 can be impermeable.

[0064] Regarding FIG. 1 A(E), a device can be free of a waveguide structure - as shown, metasurface 2 can be superposed on adaptive polymer 1, and adaptive polymer 1 can be superposed on substrate 4, without the presence of a separate waveguide. Without being bound to any particular theory or embodiment, adaptive polymer can be disposed on metasurface 2, as shown in FIG. 1(A), such that adaptive polymer “fills in” spaces between structures of the metasurface.

[0065] FIG. 1 A(F) provides a further embodiment of the disclosed technology. As shown, one can place two mirrors 5 and 6 that sandwich adaptive polymer 1; this can effectively create a filter where certain colors are trapped in the cavity formed between the mirrors, and only specific colors can escape. Depending on the dimensions (swelling of sensing material, also refractive index), once can tune the cavity color. It can be preferred to construct the device such that at least one of mirrors 5 and 6 is permeable so that adaptive polymer 1 can receive the measurand (for example, humidity or temperature) being monitored. The adaptive polymer 1 can be sensitive to, for example, temperature, humidity, a chemical or biological agent, and the like.

[0066] FIG. 1 A(G) provides a further embodiment of the disclosed technology. As shown, metasurface 2 and waveguide 3 can be integrated together, and adaptive polymer 1 and waveguide 3 can be integrated together; the foregoing can be superposed on substrate 4. As described elsewhere herein, substrate 4 can be permeable; in some embodiments, substrate 4 can be impermeable.

[0067] As shown in FIG. 11 A, in some embodiments, a metasurface can be disposed on an adaptive polymer (left hand image column). A metasurface can comprise, for example, TiCh, although this is not a requirement, as a metasurface can comprise other nanocrystals. As shown in the middle image column of FIG. 11 A, an adaptive polymer can be incorporated into the metasurface; as shown, a metasurface can include TiCh and an adaptive polymer. Such an integrated metasurface can be disposed on a substrate; glass is a non-limiting example of such a substrate. As shown in the right-hand image column of FIG. 11 A, a metasurface can include TiCh and an adaptive polymer. Such an integrated metasurface can be disposed on an amount of adaptive polymer; chitosan is a non-limiting example of such an adaptive polymer.

[0068] Multiple sensors can be integrated into a single device, where different areas of the sensor are comprised of multiple metasurface patterns and adaptive polymers to create an “optical nose” capable of sensing multiple target measurands in the same sensor.

[0069] Alternatively, multiple sensors can be placed next to each other on the leaf as opposed to being integrated on the same substrate. Further, a metasurface pattern can be included in the optical nose as an imaging standard for sensor calibration at the leaf level. FIG. 2 shows an example of a top-down view of an optical nose comprising six sensors integrated on a substrate.

[0070] Examples of surfaces on which the sensors can be placed include the abaxial or adaxial surface of a leaf, stem of a plant, surface of a fruit, and the like.

[0071] Fabrication of sensors can be performed by thin-film deposition of relevant materials on a substrate, using techniques such as ink-jet printing, screen printing, imprinting, physical vapor deposition, chemical vapor deposition, spin coating, dropcasting, and the like. Nanofabrication of metasurface structures on top of the substrate can be performed using methods such as nanoimprint lithography, photo- or e-beamlithography, laser writing, thin-film patterning, deposition, etching, and the like. Adaptive polymers can be deposited by thin-film deposition methods including ink-jet printing, drop- and blade-casting, spin-coating, as well as pick-and-place techniques to integrate sensors fabricated using multiple materials and methods onto a single substrate to create an integrated sensor.

[0072] Further, cost-effective solution-processing techniques can be used for fabrication by using nanoparticle (which can be nanocrystal) dispersions and mixtures with sensing materials. Nanoparticles and polymers can be used for low-cost coating, printing and imprinting techniques.

[0073] FIG. 3 shows an example of the sensor deployed on corn leaves in a field. Effects of the sensor on leaf health including gas transport, transpiration, stomatai behavior, and leaf growth was examined. A preliminary test where the sensors were left on a peanut plant leaf for 7 days did not visibly show changes to the leaf. Sensor deployment tests include characterization of leaf health below the sensor prior to and during sensor placement, and after the sensor is removed.

[0074] The sensors can be imaged using, for example, RGB cameras, hyperspectral cameras, multispectral cameras, VIS / NIR / SWIR cameras, spectrometers, and the like.

[0075] Imaging the sensors after attaching them to leaves requires imaging the leaves at various angles depending on leaf movement due to growth / wind, along with sensor placement on the top / underside of the leaf. Detection systems such as cameras are placed on detection platforms such as drones, farm equipment including tractors and irrigation system pivots, ground robots and the like. This requires maneuvering the camera on board the detection platform, or establishing the correlation between angle of sensor and color, so that plant health information can be isolated from sensor angle.

[0076] Imaging the leaves at various angles depending on leaf movement due to growth / wind, along with sensor placement requires maneuvering the camera on the detection platform, or establishing correlation between angle of sensor and color, so that plant health information can, in some instances, be isolated from sensor angle.

[0077] A. Adaptive Polymers

[0078] Adaptive polymers change their optical and / or mechanical properties on exposure to environmental stimuli. For instance, an adaptive polymer exposed to moisture from air can swell or shrink and change its refractive index. Adaptive polymers can change their properties due to multiple stimuli (e.g. some hydrogels respond to changes in pH, moisture, and temperature), which may make changes in the optical signature hard to interpret. Sensor system designs with multiple sensors (or arrays of sensors) with different polymers can be used to improve sensitivity and selectivity to multiple stimuli. Forapplications in leaf sensors, measurement of changes in humidity, leaf transpiration, temperature, VOCs, and toxins can be used to determine plant health and the onset of plant diseases.

[0079] Moisture-sensitive adaptive polymers include synthetic and natural hydrogels, chitosan, silk and cellulose; example synthetic hydrogels are found in J. Appl. Polym. Sci. 2021, 138 (19), 50376. Chitosan is a semicrystalline biopolymer that is biocompatible, biodegradable, and nontoxic. Chitosan is also a superabsorbent hydrogel that can expand up to 300% of its original volume. Its dielectric properties also change as a function of its water content, which makes the material useful to couple to the metasurfaces to achieve moisture sensing.

[0080] Moisture-sensitive materials can also include mixtures of nanomaterials with polymers to adjust their refractive index to improve sensor properties. Open polymer networks (i.e. foams) can also be used to increase the tunable range of refractive index of the polymers.

[0081] Temperature-sensitive polymers include hydrogels, poly(N- isopropylacrylamide) (PNIPAM) and hydroxypropyl cellulose.

[0082] VOC-sensitive polymers include polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), and poly(3,4-ethylenedioxythiophene) (PEDOT), and their modifications with metals and metal oxides. Further, selectivity can be improved by integrating with metal oxide nanoparticles (e.g., nanocrystals) that can also comprise the metasurface patterned features.

[0083] Specific target-molecule sensitive polymers can be made using techniques such as molecular imprinting.

[0084] Multi-stress sensors can be fabricated by integrating multiple stimuli - responsive polymers to create an “optical nose” to detect various target measurands (FIG. 2).

[0085] B. Metasurface

[0086] The sensor design consists of two main components: a metasurface and an adaptive polymer. Metasurface design parameters such as material system, geometry, and arrangement, along with the dielectric properties of the polymer, determine the operating wavelength and the sensitivity of the sensor.

[0087] When these metasurface designs are embedded into adaptive polymers that change their physical properties in response to some variable, the optical response of the metasurface also changes. These changes can be measured in both reflection and / or transmission using a spectrometer or camera that can capture how the base response of the device changes as a function of time. This transient response provides insight into the response time of the sensor, the steady state behavior, and the spectral range of operation. These parameters allow for determination of the local environment around the sensor and by extension the leaves of the crops.

[0088] The optical metasurfaces can be made of the following materials:

[0089] Plasmonic

[0090] Dielectric

[0091] Hybrid (Plasmonic and Dielectric)

[0092] The metasurfaces can be designed to exhibit the following resonance modes:

[0093] Leaky Cavity Modes

[0094] Quasi-Bound-In-Continuum (QBIC) Modes (it should be understood that Quasi Guide Mode resonance is a subset of QBICs)

[0095] Polarization Selective Modes

[0096] The metasurfaces are fabricated using one or more of the following techniques:

[0097] Thin film deposition - sputtering, ALD, CVD, Ebeam deposition, spincoating, drop- and blade-casting, doctor-blading

[0098] Patterning - photolithography, ebeam lithography, nanoimprint lithography, screen printing

[0099] Etching - wet chemical etch, plasma etch

[0100] Nanoparticle patterning

[0101] Electroplating

[0102] Self Assembly

[0103] Templated Assembly

[0104] While most colorimetric sensors use Au and / or Ag plasmonic nanostructures due to their stability and resonances in the visible spectrum, sensors for precision agriculture, food monitoring, implantable health monitoring applications and thelike, need to be biodegradable, biocompatible and low cost. Metals such as Cu, Al, Ni, Ti can be used; one can also use doped semiconductor oxides and chalcogenides (for example, Al-doped ZnO, In-doped SnO2, copper sulfide, and In-doped CdO); one can also use TiO2, ZrO2, ZnO, Si, Ge, GaAs, perovskites and other semiconductors, including such materials with high values of the optical refractive index.

[0105] In one example of sensor fabrication, passive, biodegradable sensors were designed to exhibit high-Q and high Figures of Merit (FOM). To ensure scalable nanofabrication of sensors at low cost, imprint lithography can be used to fabricate a wide range of geometries and to integrate a large library of materials. Solution-processible nanoparticle inks (which can include nanocrystals) are imprinted to create the resonating nanostructures in a single process step, further reducing sensor cost. In conjunction, various metasurface material systems and designs were explored using simulations, while maintaining fabrication constraints, and validated experimentally. Sensors were characterized for peak shifts and color changes in response to changes in humidity.

[0106] Metasurface geometries preferably have a lateral resolution of 100 nm or higher to ensure ease of fabrication using imprinting methods for fabrication. The metasurface response can be tuned by tailoring the size, shape and composition of the pillar, as well as the pitch and motif of the array for an example geometry of pillars (FIG. 4). This can also be extended to holes and other geometries as shown in FIG. IB.

[0107] We designed sensors with metasurfaces composed of metallic and dielectric components that operated based on plasmonic, Mie, Fano, and QBIC resonances (FIG. 5). To compare the various metasurface options, we define a figure of merit (FOM) for the sensor as the product of the Quality factor (Q) of the metasurface, the relative resonant frequency shift of the sensor (i.e. Sensitivity, S), and the modulation strength of the resonance (A / ?) (see FIG. 5a). FIG. 5 shows a schematic and sensor performance for the various metasurface designs.

[0108] Plasmonic metasurfaces, composed of arrays of metallic nanostructures, suffer from ohmic losses in the visible spectrum, which cause peak broadening and decrease the quality factor (Q) of the metasurface. However, due to high field enhancement at the metal-environment interface they have high sensitivity to changes in the refractive index of their environment. Alternatively, dielectric metasurfaces are explored, which have high refractive indices (allowing them to strongly couple to light)and low losses within the visible. When dielectric nanostructures are patterned into subwavelength periodic arrays, the solutions to Maxwell’s equations are known as Mie resonances. FDTD simulations were used to evaluate metallic and dielectric nanostructure arrays of various geometries. Circular pillar arrays made of Au (FIG. 5b) result in plasmonic resonances, while those made of TiCh result in dielectric Mie resonances (FIG. 5d). Sharp Fano resonances are observed with rectangular double nanorod arrays made of Au (FIG. 5c), and sharp quasi guided mode resonances are observed for circular TiCh pillars on a waveguide layer made of TiCh (FIG. 5e). Further, FIG. 5d also shows an increase in the resonant amplitude for taller TiCh pillars, which motivates increasing the aspect ratios for nanoparticle-imprinted features. To increase the sharpness of the resonance peaks, the metasurface is designed to produce Fano type resonances. Fano type resonances emerge from a coupling / interference between a continuum of scattering states and discrete scattering states to form quasi bound states in the continuum (QBIC). This coupling results in resonances with very high Q-factors which are promising for sensing applications.

[0109] In FIG. 6, a plasmonic metasurface is combined with Chitosan to detect changes in humidity. Optical transmission measurements showed plasmonic resonances which were strong, reasonably sharp and that fell within the visible spectrum for both Au and Ag nanostructured metasurfaces. The Au also showed a redshifted resonance compared to the Ag due to its slightly higher free electron density. Chitosan was then synthesized and used to encapsulate the metasurface. FIG. 6 shows how the response of a Chitosan coated Au plasmonic sensor changes with respect to humidity.

[0110] In another example, Fabry -Perot (FP) sensors are fabricated using Chitosan and thin metallic mirrors. These sensors can also be made in large areas and they showed distinct color changes as a function of moisture content. By patterning the top mirror, or creating a porous nanoparticle-based top mirror (which can include nanocrystalline nanoparticles) and allowing for more moisture diffusion pathways, a high uniform colorimetric sensor can be achieved.

[0111] C. Waveguide

[0112] The integration of adaptive polymers with optical metasurfaces opens up a litany of possibilities with regards to device design and architecture. FIG. 7 below provides three examples of device architectures within the category of QBIC metasurfacesthat require a waveguiding layer. TiCh is used as the dielectric material and the responsive layer (labelled as sweeping layer) represents an arbitrary adaptive polymer whose refractive index changes in response to some variable. The operating principle of these devices is the confinement of light within a high refractive index medium (the waveguide), and the coupling of light using a grating (pillars) which allows specific wavelengths to be scattered out into free space. Consequently, it is possible for these devices to act as sensors by modulating:

[0113] i) the waveguide resonance

[0114] ii) the grating periodicity

[0115] iii) the coupling between the waveguide and the grating.

[0116] FIG. 7a shows the example of the first case where the waveguide resonance is modulated. The pillars rest on top of the waveguide and the pillar -waveguide structure rests on top of a layer that can change its refractive index. FDTD was used to simulate how changing the refractive index of the underlying layer would affect the spectral position of the ED and MD resonances. It was calculated that a change in the substrate refractive index from 1.3 to 1.7 resulted in a red shift of the ED and MD peaks by ~60 nm and ~50 nm, respectively. When the refractive index was above 1.7, the resonances were no longer observable due to the inability of the waveguide to confine the propagating light. The ability of a waveguide to confine light is strongly dependent on having the smallest critical angle possible where the critical angle is dependent on the ratio of the environmental refractive index to the waveguide refractive index given by theequation sin(0c) = - — — . If the refractive index of the environment can be^waveguide modulated ie. the environment is the adaptive polymer, the critical angle changes thereby modulating the guided mode within the waveguide and changing the spectral position of the resonance.

[0117] The grating that is coupled to the waveguide also plays a role in the optical characteristics of the device (FIG. 7b). The periodicity of the grating determines the spectral position of the in-plane diffraction orders of the grating known as Rayleigh- Woods anomalies (RA) which then affect the spectral position of the ED and MD resonances. The spectral position of these RAs for a rectangular grating is given by =axand ayare the periods in the respective x and y directions, 1 and mare integers, and n is the refractive index of the environment.

[0118] D. Adhesive Polymer

[0119] Deployment and attachment of the sensors to plant leaves distributed throughout the field is challenging. Designing interfaces for the sensors that allow attachment of the sensor to the leaf without damaging the plant is a key challenge as an adhered sensor can limit transport through the leaf surface and induce mechanical stress. Additionally, the adhesive must be robust enough to accommodate leaf deformation due to plant growth and environmental induced swelling and drying and remain functional over multiple deformation cycles. Furthermore, the attachment mechanism must be rapid and simple to facilitate broad sensor deployment.

[0120] The attachment mechanism between the sensor and leaf must allow for efficient moisture and heat exchange to allow for sensing, must not damage the plant, and facilitate easy rapid deployment in the field.

[0121] To realize optimal adhesion, the modulus of the adhesive polymer must be low so as to be able to conform to the surface texture of the leaves. To achieve this within the requirement of biodegradability, we provide a composite chitosan based adhesive polymer. Additives, such as glycerol, were added to chitosan to improve polymer flexibility and adhesion (FIG. 8). Polymers containing a mixture of chitosan, glycerol showed higher optical transparency.

[0122] To further improve adhesion, the chitosan and glycerol containing polymer was cast on a micropatterned film to create adhesive surfaces inspired by microfibrils on gecko feet. 5 wt% glycerol and Chitosan mixture were poured into micropillar-structure molds, forming an adhesion-enhanced substrate film.

[0123] Other substrate materials include cellulose, silk, wax, poly (glycerol sebacate) (PGS), polyurethane and the like. They can be made porous to improve gas permeability of the polymers, and their degradability can be tailored by modifying the composition and synthesis conditions of the polymers.

[0124] We fabricated moisture-sensitive metasurfaces on custom flexible substrates made of different thicknesses of ethyl cellulose and PDMS optimized for both sensor nanoimprinting and leaf adhesion. Sensors transferred to citrus leaves in the lab showed differing rates of moisture permeability based on substrate material and thickness,as measured through porometry of the leaf through the sensor. Differential sensing of leaf wetness and local environmental humidity was realized by changing the metasurface orientation towards and away from the leaf. Abaxial leaf attachment proved to show higher leaf wetness due to the larger numbers of stomates, as benchmarked by porometry measurements.

[0125] Aspects

[0126] The following Aspects are illustrative only and do not limit the scope of the present disclosure or the appended claims. Any part or parts of any one or more Aspects can be combined with any part or parts of any one or more other Aspects.

[0127] Aspect 1. A sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition; a substrate, the sensing material superposed on the substrate; a metasurface, the metasurface superposed on the substrate, the metasurface being coupled to the sensing material such that an optical response of the metasurface changes in response to the change in at least one of refractive index and geometry as a function of an environmental condition. Such an environmental condition can be, for example, a condition of an environment to which the sensing material is exposed.

[0128] In some non-limiting embodiments, the sensing material is integrated into the metasurface. FIG. 11 A depicts such an embodiment, as shown in the middle image column and the right-hand image column of that figure, a metasurface can include a sensing material incorporated therein; as shown, such a metasurface can include nanocrystals (which can be TiCh nanocrystals in some instances) and the sensing material (which can be chitosan, in some instances). The metasurface can be disposed on a substrate that is comparatively inert - such as glass, polydimethyl siloxane (PDMS), and poly (glycerol sebacate) (PGS) - but this is not a requirement. As shown, the metasurface can be disposed on a sensing material, which sensing material can be the same as the sensing material incorporated into the metasurface. This too, however, is not a requirement, as a sensing material incorporated into a metasurface need not be identical to the sensing material on which the metasurface is disposed or superposed.

[0129] Aspect 2. The sensing component of Aspect 1, wherein the metasurface comprises any one or more of a plasmonic metasurface and a dielectric metasurface.

[0130] Aspect 3. The sensing component of any one of Aspects 1-2, wherein the metasurface comprises a structure comprising a plurality of nanoparticles associated together.

[0131] Aspect 4. The sensing component of any one of Aspects 1-3, wherein the metasurface comprises a structure having a characteristic dimension in the range of from about 5 nm to about 500 nm.

[0132] Aspect 5. The sensing component of any one of Aspects 1-4, wherein the metasurface is configured to exhibit any one or more of Leaky Cavity Modes, Quasi - Bound-In-Continuum (QBIC) Modes, and Polarization Selective Modes.

[0133] Aspect 6. The sensing component of any one of Aspects 1-4, wherein the sensing material comprises a polymer, and optionally wherein the sensing material comprises a plurality of polymers. In some embodiments, the sensing material can include any one or more of a mixture of polymers, a mixture of polymers and nanoparticles, and a mixture of polymers and dyes.

[0134] Aspect 7. The sensing component of Aspect 6, wherein the polymer comprises any one or more of a moisture-sensitive polymer, a temperature-sensitive polymer, and an analyte-sensitive polymer.

[0135] Aspect 8. The sensing component of Aspect 7, wherein the temperaturesensitive polymer comprises any one or more of a hydrogel, poly(N-isopropylacrylamide) (PNIPAM) and hydroxypropyl cellulose.

[0136] Aspect 9. The sensing component of Aspect 7, wherein the moisturesensitive polymer comprises any one or more of a hydrogel, chitosan, and cellulose.

[0137] Aspect 10. The sensing component of Aspect 7, wherein the analytesensitive polymer comprises any one or more of polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), and poly(3,4-ethylenedioxythiophene) (PEDOT).

[0138] Aspect 11. The sensing component of any one of Aspects 1-10, wherein the substrate comprises any one or more of silicon and silicon dioxide (SiCL). It should be understood that the substrate can also be a polymer, which may or may not be water- permeable and gas-permeable, and / or which is flexible, which has adhesive properties, which is biodegradable and / or biocompatible.

[0139] Aspect 12. The sensing component of any one of Aspects 1-11, wherein the sensing material (a) surmounts the metasurface, or (b) is incorporated into the metasurface, or both (a) and (b).

[0140] Aspect 13. The sensing component of any one of Aspects 1-12, wherein the sensing material and substrate are integrated with one another in a layer.

[0141] Aspect 14. The sensing component of any one of Aspects 1-11, further comprising a waveguide.

[0142] Aspect 15. The sensing component of Aspect 14, wherein the waveguide is coupled to any one or more of the metasurface and the sensing material.

[0143] Aspect 16. The sensing component of any one of Aspects 14-15, wherein the sensing material and waveguide are integrated with one another in a layer.

[0144] Aspect 17. The sensing component of any one of Aspects 14-16, wherein the metasurface surmounts the waveguide. The metasurface can be at least partially covered by the waveguide, and can accordingly be completely covered by the waveguide, in some embodiments.

[0145] Aspect 18. The sensing component of any one of Aspects 1-17, further comprising an adhesive layer configured to maintain the sensing component in position.

[0146] Aspect 19. The sensing component of any one of Aspects 1-18, wherein the sensing component is characterized as biodegradable. The sensing component can also be any one or more of gas-permeable, water-vapor-permeable, or otherwise configured such that the sensing component does not substantially affect the environment it is sensing (e.g., a leaf).

[0147] Aspect 20. A sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition, the sensing material being disposed between a first mirror and a second mirror, the first mirror and the second mirror defining a cavity therebetween, at least one of the first mirror and the second mirror being a permeable mirror, and the sensing component being arranged such that material that permeates the permeable mirror contacts the sensing material; and a substrate, the sensing material being superposed over the substrate, and the sensing component being configured as a Fabry - Perot interferometer.

[0148] Aspect 21. The sensing component of Aspect 20, wherein one or more of the first mirror and the second mirror is patterned. It should be understood that a patterned mirror is optional.

[0149] Aspect 22. The sensing component of Aspect 21, wherein the substrate is permeable. A substrate (which can be adhesive) can also contact a plant.

[0150] Aspect 23. A system, comprising: a sensing component according to any one of Aspects 1-22; and a detector, the detector configured to collect a signal of the sensing component that related to a response by the sensing component to an environmental condition.

[0151] Aspect 24. The system of Aspect 23, wherein the sensing component is a sensing component according to any one of Aspects 1-19.

[0152] Aspect 25. The system of any one of Aspects 23-24, wherein the signal is a signal from the metasurface.

[0153] Aspect 26. The system of Aspect 25, wherein the signal is a change in reflected color.

[0154] Aspect 27. The system of Aspect 26, wherein the signal is in the visible spectrum, the NIR spectrum, the SWIR spectrum, or other detectable spectrum. The signal can be one that is matched with what a detector can measure.

[0155] Aspect 28. The system of Aspect 23, wherein the sensing component is a sensing component according to any one of Aspects 20-22.

[0156] Aspect 29. The system of Aspect 28, wherein the detector collects a signal emitted from the cavity.

[0157] Aspect 30. The system of any one of Aspects 23-29, wherein the sensing component contacts a plant.

[0158] Aspect 31. The system of Aspect 30, wherein the sensing component is adhered to a leaf.

[0159] Aspect 32. The system of any one of Aspects 23-29, wherein the sensing component is characterized as a colorimetric sensor.

[0160] Aspect 33. A method, comprising: monitoring a signal from a sensing component according to any one of Aspects 1-22.

[0161] Aspect 34. The method of Aspect 33, further comprising relating the signal to an environmental condition proximate to the sensing component.

[0162] Aspect 35. The method of Aspect 34, wherein the environmental condition is a condition of a plant with which the sensing component is engaged.

[0163] Aspect 36. The method of Aspect 34, wherein the environmental condition is any one or more of an atmospheric condition or a plant output condition, for example, a leaf transpiration, a leaf temperature, or volatile organic compounds emitted by the leaf / plant.

[0164] Aspect 37. The method of Aspect 34, wherein the environmental condition is the presence of an analyte.

[0165] Aspect 38. The method of any one of Aspects 33-37, wherein the signal is detectable in any one or more of the visible, near-infrared (NIR), and shortwave infrared (SWIR) ranges.

[0166] Aspect 39. The method of any one of Aspects 33-38, further comprising relating the signal to at least one of an estimated condition and a predicted condition of a plant.

[0167] Aspect 40. The method of any one of Aspects 33-39, further comprising any one of constructing a model and training a model based on the signal.

Claims

What is Claimed:

1. A sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition; a substrate, the sensing material superposed on the substrate; a metasurface, the metasurface superposed on the substrate, the metasurface being coupled to the sensing material such that an optical response of the metasurface changes in response to the change in at least one of refractive index and geometry as a function of an environmental condition.

2. The sensing component of claim 1, wherein the metasurface comprises any one or more of a plasmonic metasurface and a dielectric metasurface.

3. The sensing component of any one of claims 1-2, wherein the metasurface comprises a structure comprising a plurality of nanoparticles associated together.

4. The sensing component of any one of claims 1-2, wherein the metasurface comprises a structure having a characteristic dimension in the range of from about 5 nm to about 500 nm.

5. The sensing component of any one of claims 1-2, wherein the metasurface is configured to exhibit any one or more of Leaky Cavity Modes, Quasi -Bound-In- Continuum (QBIC) Modes, and Polarization Selective Modes.

6. The sensing component of any one of claims 1-2, wherein the sensing material comprises a polymer, and optionally wherein the sensing material comprises a plurality of polymers.

7. The sensing component of claim 6, wherein the polymer comprises any one or more of a moisture-sensitive polymer, a temperature-sensitive polymer, and an analyte-sensitive polymer.

8. The sensing component of claim 7, wherein the temperature-sensitive polymer comprises any one or more of a hydrogel, poly(N-isopropylacrylamide) (PNIPAM) and hydroxypropyl cellulose.

9. The sensing component of claim 7, wherein the moisture-sensitive polymer comprises any one or more of a hydrogel, chitosan, and cellulose.

10. The sensing component of claim 7, wherein the analyte-sensitive polymer comprises any one or more of polypyrrole (PPy), poly aniline (PANI), polythiophene (PTh), and poly(3,4-ethylenedioxythiophene) (PEDOT').

11. The sensing component of any one of claims 1-2, wherein the substrate comprises any one or more of silicon and silicon dioxide (SiCh).

12. The sensing component of any one of claims 1-2, wherein (a) the sensing material surmounts the metasurface, or (b) the sensing material is incorporated into the metasurface, or both (a) and (b).

13. The sensing component of any one of claims 1-2, wherein the sensing material and substrate are integrated with one another in a layer.

14. The sensing component of any one of claims 1-2, further comprising a waveguide.

15. The sensing component of claim 14, wherein the waveguide is coupled to any one or more of the metasurface and the sensing material.

16. The sensing component of claim 14, wherein the sensing material and waveguide and integrated with one another in a layer.

17. The sensing component of claim 14, wherein the metasurface surmounts the waveguide.

18. The sensing component of any one of claims 1-2, further comprising an adhesive layer configured to maintain the sensing component in position.

19. The sensing component of any one of claims 1-2, wherein the sensing component is characterized as biodegradable.

20. A sensing component, comprising: a sensing material, the sensing material exhibiting a change in at least one of refractive index and geometry as a function of an environmental condition, a the sensing material being disposed between a first mirror and a second mirror, the first mirror and the second mirror defining a cavity therebetween, at least one of the first mirror and the second mirror being a permeable mirror, and the sensing component being arranged such that material that permeates the permeable mirror contacts the sensing material; and a substrate, the sensing material being superposed over the substrate, and the sensing component being configured as a Fabry -Perot interferometer.

21. The sensing component of claim 20, wherein one or more of the first mirror and the second mirror is patterned.

22. The sensing component of claim 21, wherein the substrate is permeable.

23. A system, comprising:a sensing component according to any one of claims 1 or 20; and a detector, the detector configured to collect a signal of the sensing component that related to a response by the sensing component to an environmental condition.

24. The system of claim 23, wherein the sensing component is a sensing component according to claim 1.

25. The system of any one of claims 23-24, wherein the signal is a signal from the metasurface.

26. The system of claim 25, wherein the signal is a change in reflected color.

27. The system of claim 26, wherein the reflected color is in the visible spectrum, the NIR spectrum, or the SWIR spectrum.

28. The system of claim 23, wherein the sensing component is a sensing component according to claim 20.

29. The system of claim 28, wherein the detector collects a signal emitted from the cavity.

30. The system of claim 23, wherein the sensing component contacts a plant.

31. The system of claim 30, wherein the sensing component is adhered to a leaf.

32. The system of claim 23, wherein the sensing component is characterized as a colorimetric sensor.

33. A method, comprising: monitoring a signal from a sensing component according to any one of claims 1 or 20.

34. The method of claim 33, further comprising relating the signal to an environmental condition proximate to the sensing component.

35. The method of claim 34, wherein the environmental condition is a condition of a plant with which the sensing component is engaged.

36. The method of claim 34, wherein the environmental condition is an atmospheric condition or a plant output condition.

37. The method of claim 34, wherein the environmental condition is the presence of an analyte.

38. The method of claim 33, wherein the signal is detectable in any one or more of the visible, near-infrared (NIR), and shortwave infrared (SWIR) ranges.

39. The method of claim 33, further comprising relating the signal to at least one of an estimated condition and a predicted condition of a plant.

40. The method of claim 33, further comprising any one of constructing a model and training a model based on the signal.

41. The system of claim 23, wherein the sensing component is a sensing component according to claim 20.