Preparation and optimization of biomimetic materials simulating solar spectrum reflection characteristics of natural leaves

Abstract

Solar spectrum reflection characteristics of natural leaves are caused by the absorption and scattering processes of incident radiation in the leaves. To realize hyperspectral camouflage in the background of vegetation, two types of biomimetic materials are prepared. One type utilizes Cr 2 O 3 particles to simultaneously simulate the absorption characteristics in the visible light band and the scattering characteristics in the solar spectrum band and is named as COG-BM. The other type contains chlorophyll and TiO 2 particles to simulate the absorption and scattering characteristics in the above two bands, respectively, and is named as CH/TD-BM. The measured results show that both can simulate the solar spectrum reflection characteristics of the leaves approximately. In order to optimize the bionic performance, the reflectance predicting model was constructed with Lorenz-Mie scattering and four-flux theories. The simulation results show that with the increase in particle volume fraction, the reflectance of COG-BM in the visible light band is maintained at almost the same level as that of the leaves because of the simultaneous increase in absorption and scattering coefficients. Nevertheless, the reflectance of CH/TD-BM increases significantly, because the absorption coefficient of CH/TD-BM is constant with the increase in the particle volume fraction, and the scattering coefficient enhances remarkably. More interestingly, with the increase in particle size, the near-infrared plateau of COG-BM and CH/TD-BM is closer to horizontal, exhibiting greater similarity to the natural leaves. Moreover, the water absorption characteristics at 1450 and 1940 nm become more significant with the increase in water content.

Programmable Microfluidics for Dynamic Multiband Camouflage

“…The micro uidic textiles was demonstrated for ground hyperspectral camou age in the solar radiation spectrum in 300-2500 nm 34 . As a common ground vegetation with complex optical characteristics 35 , natural leaves were taken as the background (Supplementary Note 3).…”

One-step preparation of Cr2O3-based inks with long-term dispersion stability for inkjet applications

“…[20][21][22] This makes Cr 2 O 3 a proper pigment to simulating the solar spectrum reflection characteristic of green leaf for camouflage purpose. 23 Since Cr 2 O 3 coatings exhibits high reflectance in whole near infrared (NIR) region that carry 51% of solar energy, it has the potential to be utilized as coloured radiative coolers which can reduce solar heating and improve appearance simutaneously. 24,25 Applying the inkjet printing technology with Cr 2 O 3 being the pigments can significantly simplify the process from designing to coating a new camouflage pattern and reduce the cost.…”

“… 20–22 This makes Cr 2 O 3 a proper pigment for simulating the solar spectrum reflection characteristic of green leaves for camouflage purpose. 23 Since Cr 2 O 3 coatings exhibit high reflectance in the whole near-infrared (NIR) region that carry 51% of solar energy, it has the potential to be utilized as coloured radiative coolers, which can reduce solar heating and improve appearance simultaneously. 24,25 …”

Emulating Solar Spectral Reflectance of Natural Leaf with Bionic Leaf Prepared from 4A Zeolite-Derived Ultramarine Green Pigment

“…The solar spectral reflectance characteristics of natural leaves have been widely reported in previous literature [ 1 , 3 ]. The solar spectral reflectance of three different green leaves is shown in Figure 1 .…”

“…On the other hand, for composite coating, Gao et al [ 11 ] prepared a biomimetic material comprising of a hygroscopic material and Cr 2 O 3 to counter the hyperspectral detection through the simulation of the solar spectral reflection of a natural leaf. Furthermore, Xu et al [ 3 ] reported two types of biomimetic materials, whereby one utilized Cr 2 O 3 particles, while the other contained chlorophyll and TiO 2 particles. The results showed that both biomimetic materials were able to emulate the solar spectral reflectance characteristics exhibited by the leaf.…”