Paper Research Articles

Preparation and Biological Activity Studies of Octenyl Succinic Anhydride Starch-Based Emulsions Containing Natural Essential Oils and Their Components

In this study, clove essential oil (CL), eugenol (EU), and cinnamaldehyde (CI) were immobilized in starch sodium octenyl succinate (SSO) using an emulsification method. The main characteristics, stability, and biological properties of the prepared emulsions were established. Particle size analyses using dynamic light scattering showed that the smaller droplets were characteristic of emulsions containing CI (205–218 nm) and EU (181–236 nm), while the largest droplets were determined for CL emulsions (293–348 nm). Moreover, the highest antioxidant activity was determined for CL (79–83%) and EU (80–88%) emulsions, while CI emulsions showed the greatest antibacterial activity. The obtained emulsions were applied to the paper sheets and the bioactive properties of coated paper were studied. Evaluation of antioxidant properties revealed that high antioxidant activity reaching 76–92% and 87–91% was characteristic of coatings containing CL and EU, respectively. Meanwhile, coatings containing CI showed quite low antioxidant activity (4–9%) but demonstrated the greatest antimicrobial effect on Gram-negative and Gram-positive bacteria as well as yeasts. Hence, CL and EU emulsions could be used as effective natural antioxidants, whereas CI emulsions could be applied as an antimicrobial agent on cellulose-based substrates for a wide range of human health protection applications.

Liquid penetration in hydrophobised cellulose based sheets

AbstractControlling the liquid transport within cellulose-based materials is crucial for numerous applications, including printing, bio-assays, packaging, and cleaning. To control liquid transport and quality, post-processes such as calendering, a way of compressing and smoothen the paper using hard pressure rollers, and hydrophobisation, are commonly employed. To understand how these processes influence liquid uptake, this study uses an Ultra-Fast Imaging (UFI) NMR method to analyse moisture profiles during liquid uptake in various cellulose-based paper sheets with diverse levels of hydrophobisation and calendering. It is demonstrated that calendering decreases penetration speed and increases swelling. The reduction in penetration speed could be linked to a decrease in permeability upon calendering, as measured by the Gurley air permeance. Additionally, it is observed that hydrophobisation delayed and slowed down liquid uptake in the paper samples, and, in extreme cases, completely altered the liquid uptake phenomena. With substantial hydrophobisation, liquid penetration no longer proceeded with a well-defined liquid front but exhibited huge levels of fingering. Furthermore, is was observed that within highly hydrophobised paper, fibres were first prewetted, initiating a first swelling, before the pores between fibres could be filled. Subsequently, water could enter the pores between, allowing fibre bonds to be broken, leading to a second swelling of the paper sheet. The improved understanding will contribute to better control of the flow within cellulose-based materials, benefiting applications such as printing, packaging and microfluidics.

Edible Paper Sheets from Alternanthera philoxeroides and Hypophthalmichthys molitrix: Smart Biomass Valorization

Alternanthera philoxeroides and Hypophthalmichthys molitrix offer significant nutritional benefits. This study evaluates the proximate composition, amino acid profile, GC-MS analysis, FT-IR spectroscopy, SEM and EDX, and color values of edible paper sheets (EPSs) derived from Alternanthera philoxeroides incorporating different levels of Hypophthalmichthys molitrix flesh. The protein content in the EPSs varied based on fish flesh incorporation, peaking at 52.66% in Ap100/Hm300 (Non-boil). Protein and carbohydrate contents showed an inverse correlation across EPSs, with the highest carbohydrate content of 60.89% in sample Ap400/Hm0 (Boil). Lipid content was also found to correlate with H. molitrix flesh content in EPSs, ranging from 1.59% to 18.41%. Amino acid analysis identified 11 types, with methionine as the most prevalent, followed by leucine, phenylalanine, and lysine. GC-MS analysis revealed 51 bioactive compounds, including carbonic acid, hentriacontane, and various fatty acids. FT-IR analysis showed characteristic bonds, while color analysis displayed L* values ranging from 24.37 to 30.97. SEM analyses depicted the microstructure, surface view, and elemental composition of the EPSs, and EDX showed an abundance of Ca, N, K, O, C, Mg, Na, P, Cl, Mn, and Fe. Therefore, EPSs prepared from A. philoxeroides and H. molitrix could offer a promising approach for effectively utilizing aquatic biomass and providing both plant and animal nutrients to consumers.

Influence of density and chemical additives on paper mechanical properties

AbstractIn this work we have investigated the effect of surface modification of fibres on the overall mechanical properties of high-density papers. Paper sheets were prepared by a combination of heat-pressing and polyelectrolyte Layer-by-Layer (LbL) modification of different softwood fibres. LbLs of Polyallylamine Hydrochloride (PAH) and Hyaluronic Acid (HA) were adsorbed onto unbleached kraft fibres and bleached Chemo-ThermoMechanical Pulp (CTMP) to improve the strength of the fibre–fibre joints in papers made from these fibres. Additionally, different sheet-making procedures were used to prepare a range of network densities with different degrees of fibre–fibre interaction in the system. The results demonstrate that interfacial adhesion within fibre–fibre joints plays a pivotal role in the network's performance, even at higher paper densities. Hygroexpansion measurements and fracture zone imaging with Scanning Electron Microscopy (SEM) further support the claim that stronger interactions between the fibres allow for a better utilisation of the inherent fibre properties. Surface treatments and network densification significantly improved the paper sheets' mechanical properties. Specifically, LbL-treatments alone increased specific stiffness up to 60% and specific strength by over 100%. This improvement is linked to the build-up of residual stresses during drying. Due to a high interaction between the fibres during water removal the fibres become constrained, leading to increased stretching of fibre segments. Strengthened fibre joints intensify this constraint, further increasing the stretch and, consequently, the paper's strength.

In-situ synthesis and binding of silver nanoparticles to dialdehyde and carboxylated cellulose nanofibrils, and active packaging therewith

AbstractThe present work reveals the potential application of dialdehyde and carboxylated nanocellulose for the in-situ reduction of Ag+ and immobilization as silver nanoparticles (AgNPs) on cellulose surfaces. Tollens’ reagent (Ag(NH3)2OH) at concentrations ranging from 5·10–3 to 10–1 M was incorporated in both dialdehyde cellulose (DAC) and dialdehyde-modified TEMPO-oxidized cellulose nanofibers (DA-TOCNFs). The results showed that DA-TOCNFs facilitated faster reduction of Ag+ and effective immobilization of AgNPs on the nanocellulose surface. The resulting suspensions exhibited stability and demonstrated strong antimicrobial activity against Bacillus subtilis when coated on paper surfaces. Importantly, the coated papers did not show significant silver migration to food simulants B (3 vol% acetic acid) and D1 (ethanol/water mixture, 50 vol%), indicating the potential of these suspensions for active food packaging. The advantages of using DA-TOCNFs over DAC were attributed to their higher cationic demand and ζ-potential, resulting in a higher density of binding sites. Moreover, the charged and entangled network of DA-TOCNFs allowed for the individualization of AgNPs, unlike DAC, where some agglomerations were observed. Overall, this study presents an improved single-step process for the synthesis of AgNPs on nanocellulose surfaces, highlighting their potential for safe and high-performance applications in food packaging. Paper sheets coated with nanocellulose/AgNPs suspensions fully inhibited the growth of B. subtilis, at least for one month after coating, and caused damage to their cell membranes. This research provides a one-pot facile route to fabricating hybrid nanocellulose/AgNPs systems, stable in water, and may be used directly as a coating layer for board and paper active packaging with little or even undetectable release of Ag.

The Ultra Ganges Mission Activities and Impact on the Press in Pre-Modern China

Before the Opium War, Protestant missionaries to China took the Ultra Ganges Mission as a link, and carried out a series of literal missionary activities, and set up missionary stations and printing presses, church schools, and Chinese and foreign-language newspapers and magazines in the South Seas and in China's Canton and Macao, etc. The newspapers founded under the guidance and support of the Ultra Ganges Mission introduced the Western newspaper concepts and newspaper editing and printing techniques into China, cultivated the early Chinese newspaper group, and laid the material and human resource foundation for the Chinese to imitate foreign newspapers and run their own newspapers after the Opium War. By analyzing the historical facts about the establishment of modern Chinese and foreign newspapers and magazines by the Ultra Ganges Mission, this essay demonstrates how the foreign newspapers in China in the first half of the 19th century promoted and influenced the emergence and development of the modern newspaper industry in China.

Sustainable metal-organic framework based paper sheet as wallpaper for passive indoor moisture control

Passive indoor moisture control is a meaningful way to reduce HVAC operation and improve building energy efficiency. Metal-organic frameworks (MOFs) have been considered one of the most promising sorbent materials for passive indoor moisture control. However, the powder form of MOF is challenging to use in the built environment. Typical shaping methods like pellets, beads, and coating can lead to problems like partial pore blocking, insufficient mechanical stability, amorphization, and low material utilization. Here, we report a new sustainable MOF paper sheet comprising 25% cellulosic fibers and 75% MOF MIL-100(Fe) powder. The porous polymer matrix provides good support and fixation for MOF particles, so it’s more applicable in the built environment. The crystalline and pore structure characteristics of the MOF in the membrane are well preserved. Hydro characteristic test results show that MIL-100(Fe) paper sheet has high water vapor uptake, S-shape isotherm, mild regeneration condition, and high MBV. Then, a numerical model was developed to calculate the relation between a material’s MBV and its thickness. MIL-100(Fe) paper sheet with the most efficient thickness was applied as wallpaper in a building energy simulation model. The simulation result shows that the MIL-100(Fe) paper sheet is promising for passive indoor moisture control. It can remove about 45%-55% of the latent cooling load in most European climate types.

Accuracy of hygro-expansive curl predictions for paper sheets based on homogenised 2D and 3D network representations

Paper, a porous-fibrous network, is made up of hydrophilic fibres, which are notably susceptible to deformations due to variations in moisture content. The response of paper sheets to full or partial wetting, based on the water-induced fibre swelling, has mostly been predicted in the past using highly idealised two-dimensional network geometries. The purpose of the present paper is to establish how precisely the two-stage process of determining effective hygro-expansivity under uniform wetting by a two-dimensional model followed by bending analysis using a continuum model predicts the curl of a fully three-dimensional network. In the present multi-scale modelling work, the moisture-induced homogenised sheet scale curl, derived from hygro-elastic deformations using non-uniform moisture profiles, is analysed based on an idealised non-woven three-dimensional fibrous network finite element model. First, the effective paper sheet swelling properties, derived computationally for the uniform wetting condition, are compared with analytically homogenised hygro-elastic properties. Whereas the analytically predicted elastic modulus has an inaccuracy of only ∼5%, the hygro-expansivity coefficient is over-predicted by roughly a third for a network with straight fibres. The difference is smaller if waviness of the fibres and wrap-around in the fibre bonds are taken into account. Fibre alignment turns out to have little influence. Subsequently, paper sheet curl predictions made by the analytical model are compared with that computed from the three-dimensional network model. The inaccuracy of the fully analytical model, based on the two-dimensional network description, relative to the fully detailed three-dimensional computational model with straight fibres is on the order of 40%–50%. The fidelity of the simple model is primarily constrained by the inaccuracy of the effective hygro-expansion coefficient. If the expansivity extracted from the three-dimensional simulations under uniform wetting is inserted, the inaccuracy drops to less than 10%. The continuum bending description hence performs adequately, provided it is based on a reliable estimation of the uniform expansion behaviour of the material.

Artists, papermakers, and the future

This editorial considers three groups of individuals and how they often find themselves following common ways of thinking. Artists, especially those who become well known, are hard workers and somewhat stubborn. Once they have found a type of paper that works well for them, they tend to develop loyalty to it, regardless of what the label on the ream wrap may say. Papermakers, ancient and modern, likewise have tended to stick with practices that are convenient to them at the moment, whether or not they contribute to archival quality. Fortunately, the transition to alkaline papermaking practices means that modern printing papers tend to last a lot longer. Increasing knowledge of the importance of acid-free paper, as well as the principles of sustainability, are making positive contributions to our ongoing cultural heritage, at least to the part of that heritage that is related to cellulosic materials.

Polymer 3D printing: global research trends

Purpose This study aims to identify research trends and technological evolution in the polymer three-dimensional (3D) printing process that can effectively identify the direction of technological advancement and progress of acceptance in both society and key manufacturing industries. Design/methodology/approach The Scopus database was used to collect data on polymer 3D printing papers. This study uses bibliometric approach along with network analytic techniques to identify and discuss the most important countries and their scientific collaboration, compares income groups and analyses keyword trends. Findings It was found that top research production results from heavy investments in research and development. The USA has the highest number of papers among the high-income countries. However, scientific production in the other two income groups is strongly dominated by China and India. Keyword analysis shows that countries with lower incomes in certain areas, such as composite and bioprinting, have fallen behind other groups over time. International collaborations were suggested as mechanisms for those countries to catch up with the current research trends. The evolution of the research field, which started with a focus on 3D printing processes and shifted to printed part designs and their applications, was discussed. The advancement of the research topic suggests that translational research on polymer 3D printing has been led mainly by research production from higher-income countries and countries with large research and development investments. Originality/value Previous studies have conducted performance analysis, science mapping and network analysis in the field of 3D printing, but none have focused on global research trends classified by country income. This study has conducted a bibliometric analysis and compared the outputs according to various income levels according to the World Bank classification.

The influence of activated carbon fiber paper structure on adsorption performance of cyclohexane

Activated carbon fibers paper (ACFP), made through wet-laid technology, had exhibited promising adsorption performance compared with granular and powdered activated carbon. This study prepared activated carbon fibers papers with different fibrous structures and investigated the dynamic adsorption performance of thin-layered ACFP against cyclohexane gas. The effects of inter-fiber pore size, dilution degree of activated carbon fibers, and porosity of the paper sheet on the adsorption performance were explored. The Bed Depth Service Time (BDST) model was employed for fitting and calculation, and the Flowdict module in Geodict software was used to analyze the flow field within the paper sheet. The results indicated that the inter-fiber pore size variation of ACFP had no significant effect on its adsorption breakthrough curve against cyclohexane gas. However, as the dilution degree of activated carbon fibers in the ACFP increased, the breakthrough time prolonged, and the adsorption utilization efficiency of activated carbon fibers continuously improved. Furthermore, decrease of ACFP porosity significantly impaired the adsorption performance. When the porosity decreased from 95.4 % to 91.4 %, the breakthrough adsorption capacity decreased from 134 mg/g to 95 mg/g, and the critical bed thickness increased from 0.029 cm to 0.044 cm.

ALTERNATIVE METHODOLOGY SIMULATING CAMERA LUCIDA FOR DRAWING MICROSCOPIC IMAGES

The camera lucida is an ancient equipment that is still used today to illustrate images through a microscope and stereomicroscope. Although it is not an overly expensive equipment, it can be inaccessible to some laboratories, and it has certain drawbacks that can be easily overcome with current technology. This work aimed at developing and testing a technique to replace the camera lucida. To this end, a microscope, a smartphone, a computer with a printer, and a light table made with low-cost materials were used, whose construction schemes are detailed in this work. A micrograph was obtained with the smartphone positioned in the microscope eyepiece. The micrograph was printed on an A4 paper sheet that was adhered to the light table, and, over the image, was placed a second paper sheet. With the light table turned on, the printed image became clearly visible on the blank paper sheet by transparency and could then be easily drawn. It is concluded that the technique described here allows excellent results, being an efficient alternative to the camera lucida in optical equipment.

Regression modelling strategies for projected and sustainable kraft pulping of wheat straw

The demand for paper and paper-based packaging has seen a massive increase in past years, resulting in accelerated deforestation to meet the rising demand, negatively impacting the environment, and there is a need to look towards different non-woody raw materials. Kraft pulping (KP) is widely used in paper making, for which the chemical dose, temperature, time, and energy required must be optimized, for which many insignificant experimental trials are performed. An effort is made to solve this problem by developing the regression equations with the help of Excel using One Factor at a Time Analysis (OFAT), followed by carrying out design of experiments (DoE) using orthogonal approach and regression analysis in Minitab software. Life cycle Assessment (LCA) using the Open-LCA software estimates the effect of chemicals and energy required during pulping on human health, ecosystem quality, and resource depletion. Using regression analysis, the equations for predicting kappa number, yield (%), total energy consumed, and mechanical properties of the paper sheet showed a good fit with an R2 value in the range of 0.90–0.99. Apart from that, the mechanical properties, namely tensile index (41.43 Nm/g), tear index (6.96 mN m2/g), bending stiffness (0.5 mN m), and burst index (3.92 kPa m2/g) of the unbeaten sheet, were determined experimentally at optimized conditions. Based on the Open-LCA result, the optimized pulping conditions had less impact on human health, ecosystem quality, and resource depletion. Industries can use the model to predict the values of kappa number, yield, mechanical properties, and energy consumption without performing optimization experiments that may impact the industry's economy to a greater extent.

Cellulose nanowhiskers‐reinforced polymer nanofibers for photoresponsive authentication

AbstractThe objective of the current study is to develop novel photochromic polyurethane (PUR) nanofibrous films supported with cellulose nanowhiskers (CNW) and immobilized with nanoparticles of alkaline‐earth doped aluminate (NAEA) using the highly efficient and low‐cost solution blowing spinning (SBS) technique. CNW revealed a crystal diameter of 4–8 nm, and a crystal length of 55–105 nm. The solution blown spun nanofibers exhibited diameters of 250–450 nm. In order to prepare a transparent film, CNW and NAEA must be dispersed efficiently in the PUR composite. When supported with CNW, the efficiency of PUR nanofibrous films was strengthened. Cellulose paper sheets were coated with the colorless NAEA/CNW@PUR films to emit a green light at 518 nm upon excitation at 365 nm as proved by photoluminescence spectra. The prepared nanofibrous films exhibited efficient optical photochromic characteristics for potential security encoding applications. The nanofibers‐coated papers showed high photochromic reversibility without fatigue. The current approach can be reported as an efficient technology for authentication of commercial products.

Polylactic‐Acid Having MoS2 Particles for Reversible Bilayer Actuators

AbstractPolylactic acid (PLA) composites having 1 wt% of MoS2 particles are prepared by solvent (SM) and melt mixing (MM) methods and their main thermal and mechanical properties are characterized. Coated films from SM samples and 3D‐printed filaments from MM samples are tested as active layers in reversible bilayer actuators using a paper sheet as a passive layer. The thermal properties depend on the method used to prepare the composites with MM samples presenting a cold crystallization and a glass transition during the first and second heating and SM samples displaying a standard melt process during the first heating and a small cold crystallization and a glass transition during second heating. Regarding the stiffness, MoS2 increases this property confirming its reinforcement effect. Both kinds of bilayers show reversible actuation under heating either by putting the actuator on a hot plate or by remotely irradiating the sample with near‐infrared light (NIR). Under NIR, the 3D printed composites present a much higher actuation. The higher remote actuation in composited bilayers is explained by the NIR light absorption of the MoS2 photoactive particles. This actuator can be used for the design of a smart façade or blind that closes under NIR stimulus.

Hybrid nanogels and their roles in eliminating soot stains from historical paper manuscripts

Soot stain from diverse sources is the most common stain that stains historical paper documents found in libraries, museums, and storage facilities. It is believed to be one of the types of deterioration that arises from the contact between stains and paper sheets. Therefore, in the present work, the effectiveness of the synthesized hybrid nanogel consisting of carbopol and nanoparticles (NPs) of ZnO, TiO2, or Fe3O4, in low and high-viscosity forms, for eliminating soot stains from historical paper manuscripts was conducted. The prepared hybrid nanogels were characterized utilizing the TEM, AFM, XRD, DLS, and Zeta Potential techniques. Following preparation, the soot-stained paper samples were heated to 105 °C for 6 days, a process known as accelerated thermal aging. Surface morphology, mechanical properties and the color change of the paper samples were investigated. The prepared hybrid nanogel had a spherical shape with well-defined edges and uniform size, with an average particle diameter ranging from 30 to 35 nm. There was no significant NPs agglomeration seen, suggesting uniform dispersion in the carbopol matrix. Additionally, the prepared gels' crystal structure and phase purity were revealed by the XRD analysis results. Paper fibers were visible in some parts of the treated sample with TiO2/carbopol hybrid nanogel at high-viscosity before aging. Cleaning soot-stained paper samples using high-viscosity Fe3O4/carbopol hybrid nanogel is more successful than using low-viscosity nanogel. the sample treated with high-viscosity ZnONPs/carbopol hybrid nanogel produced the highest total color differences (ΔE) (26.17). The paper sample treated with high-viscosity ZnO/carbopol hybrid nanogel exhibited the maximum tensile strength (61.8 N/mm2) and elongation at break (1.174%). The evaluation of the paper samples both before and after the cleaning process revealed that, the treatment with high-viscosity ZnO/carbopol hybrid nanogel gave the best results in removing soot stains from stained paper samples.

Improving the Mechanical Strength of Paper Sheets Made from Phosphorylated Fibers Through the Use of Forming Agents

ABSTRACT The fabrication of paper or cardboards sheets with phosphorylated pulp fibers has proven to be a difficult task using traditional papermaking techniques. This problem is mainly attributed to the very high anionic charge of phosphorylated fibers. In the present work, we propose the use of cationic polymers as a neutralizing agent to attenuate the detrimental effect of the very high anionic charge of phosphorylated fibers and to promote the formation of microflocs that can be agglomerated into a uniform sheet with sufficient strength. The results obtained show that using positively charged retention agents significantly improves the sheet formation. The Kaptra formation index (KFI) was reduced from 133 to 17, which is a very good value when compared to unmodified kraft pulp fibers, which have a formation index of 35. The addition of cationic polymeric additives during the preparation of phosphorylated fiber sheets resulted in an improvement of mechanical properties over unmodified kraft pulp fibers, especially for tensile energy absorption and elongation. This study demonstrates that the use of cationic retention agents reduces the impact of the charge of the phosphorylated fibers on the overall sheet quality.

The object of the composition of the criminal - punishable act under the criminal legislation of the Republic of Poland

The article is devoted to highlighting the essence and content of the object of the criminal offense under Polish criminal law. Issues related to the classification of the object of the composition of a criminally punishable act, its practical significance and the content of the concept of similarity of criminally punishable acts are analyzed. The author focuses on the fact that it is not necessary to confuse the object of a criminally punishable act with an executive object. For example, if someone falsifies a document by scratching out certain words from its text and writing others, then the executive object here will be a sheet of paper on which he performs his actions. Instead, the object of a criminally punishable act, and, accordingly, the legal good protected by the law (and at the same time the good protected by Article 270 of the Criminal Code of the Republic of Poland) is the authenticity of the document. The article also draws attention to the fact that in some articles of a special part of the Criminal Code, when describing a criminally punishable act, the object of protection is also indicated, for example, in Art. 189 of the Criminal Code of the Republic of Poland lists freedom as a legal good among the signs. which is protected by this norm. However, most often the object of a criminally punishable act does not belong to its legally prescribed features.In the article, the author also emphasizes that the object of a criminally punishable act is also of significant importance in determining the similarity of criminally punishable acts, in particular, for the application of norms on recidivism. According to § 2 of Art. 115 of the Criminal Code, similar criminally punishable acts are criminally punishable acts that belong to the same type.

Industrial hemp hurd processing for microcrystalline cellulose production and its usage as a filler in paper

This article substantiates the possibilities of replacing commercial wood with raw materials made from industrial hemp hurd (hemp-woody core) for the production of unbleached and bleached paper pulps. A comparative analysis of the mechanical characteristics of sheets of paper prepared in the Rapid-Köthen apparatus and obtained from pulp obtained from commercial wood and hemp-woody core (HWC) was undertaken. The objective of this study was to determine the effect of mechanical refining of a pulp on the production of microcrystalline cellulose (MCC) from HWC. It was shown that an increase in the pulp refining degree from 15 °SR to 83 °SR led to a decrease in the degree of polymerisation of MCC from 272 to 75, the hydrochloric acid concentration from 73 to 45.63 g/L, and the hydrolysis time from 120 min to 60 min. With the addition of 5% MCC obtained from hemp-woody core, the mechanical properties of laboratory paper sheets from HWC were improved until they met ISO 12625-4-2017 (2017) requirements for NS-2. The results obtained support using hemp-woody core for the production of MCC.

Terahertz stretchable metamaterials with deformable dolmen resonators for uniaxial strain measurement.

In this study, we propose a terahertz stretchable metamaterial that can measure uniaxial strain. Gold dolmen resonators formed on a sheet of polydimethylsiloxane (PDMS) is deformed by strain, and its resonance peak exhibits the gradual decrease in reflectance without a frequency shift, which is suitable for imaging applications at a single frequency. The metamaterial was designed by mechanical and electromagnetic simulations and fabricated by microfabrication including a transfer process of gold structures from a glass substrate to a PDMS sheet. By measuring the reflectance and observing the deformation under different strains, the reflectance decrease was obtained at 0.292 THz despite the appearance of wrinkles on gold structures. Linear response and repeatability up to 20% strain were also confirmed. Furthermore, the strain measurement through a sheet of paper was demonstrated, suggesting that our method can be applied even in situations where opaque obstacles in the visible region exist.