Nanoimprint Lithography: Toward Functional Photonic Crystals

Lova, Paola; Soci, Cesare

doi:10.1007/978-3-319-16580-6_9

Cited by 9 publications

(5 citation statements)

References 153 publications

(166 reference statements)

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“…For this reason, all-polymer DBR can be called Flory–Huggins photonic sensors (FHPSs) . Then, the choice of suitable polymers as active media makes them efficient detectors for the label-free identification of a variety of analytes in the vapor phase, and allows to extend the method to a large amount of chemical species, including water, toxic, and carcinogenic volatile organic compounds and even perfluorinated species, ,,− paving the way for a new generation of disposable photonic sensors with novel capabilities and broad band selectivity.…”

Section: Introductionmentioning

confidence: 99%

Flory–Huggins Photonic Sensors for the Optical Assessment of Molecular Diffusion Coefficients in Polymers

Lova

Manfredi

Bastianini

et al. 2019

ACS Appl. Mater. Interfaces

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The lack of cost-effective systems for the extensive assessment of air pollutants is a concern for health and safety in urban and industrial areas. The use of polymer thin films as labelfree colorimetric sensors featuring specific interactions with pollutants would then represent a paradigm shift in environmental monitoring and packaging technologies, allowing to assess air quality, formation of byproducts in closed environment, and the barrier properties of the polymer themselves. To this end, all-polymer distributed Bragg reflectors promises reliable transducers for chemical stimuli, and effective colorimetric label-free selective detectors. We show selectivity attained by specific interaction of the polymeric components with the analytes. Such interactions drive the analyte intercalation trough the polymer structure and its kinetics, converting it in a dynamic optical response which is at the basis of the Flory-Huggins photonic sensors. Additionally, we demonstrate that such optical response can be used to esteem the diffusion coefficients of small molecules within the polymer media via simple UV-Vis spectroscopy retrieving data comparable to those obtained with state of the art gravimetric procedures. These results pave the way to an innovative, simple, and lowcost detection method integrable to in-situ assessment of barrier polymers used for the encapsulation of optoelectronic devices, food packaging, and goods storage in general. Currently, barrier properties of polymer thin films to vapors and gas are assessed via gravimetric 1 and pressure decay methods, 2-4 or by optical techniques based on microscopy 5 and infrared absorption, 6 which remained substantially unchanged for the last few decades. These methods need dedicated equipment and cannot be performed in-situ. In this scenario, research for new low-cost, simpler, and portable technologies to gather lab-on-chip devices is strongly pursued. In these regards, sensors based on the optical response of polymer distributed Bragg reflectors (DBR) represent a possible revolution in the field due to the high responsivity to analytes in the vapor phase. 7-9 DBRs are planar photonic crystals made of media with different refractive index stacked to form a dielectric lattice. The interaction between light and DBRs induces frequency regions where light propagation is forbidden. These frequencies are called photonic band gaps (PBGs), and are easily detectable via simple reflectance or transmittance spectroscopy. 10 In analogy with the energy-gap of semiconductors, the PBG properties depend on the lattice structure. Then, dielectric contrast among the lattice components, lattice parameters, and the number of layers affect the optical features generated by the DBR photonic structure. 11 Intuitively, a perturbation of

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Section: Introductionmentioning

confidence: 99%

Flory–Huggins Photonic Sensors for the Optical Assessment of Molecular Diffusion Coefficients in Polymers

Lova

Manfredi

Bastianini

et al. 2019

ACS Appl. Mater. Interfaces

Self Cite

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“…These systems exploit the intrinsic response to the analytes of an active material. In this regards, photonic crystal based optical sensors are largely investigated thanks to low fabrication costs and ease of integration in lab-on-a-chip devices. − Photonic crystal sensing relies on the optical response generated by the variation of effective refractive index ( n eff ) and periodicity of a dielectric lattice. , These variations can be induced by the intercalation of an analyte within the structure and in principle, allow selective colorimetric responses . Indeed, highly permeable porous lattices such as synthetic opals, − porous inorganic − and hybrid distributed Bragg reflectors (DBRs) have been widely investigated as colorimetric detectors for gas and vapor organic pollutants.…”

Section: Introductionmentioning

confidence: 99%

Label-Free Vapor Selectivity in Poly(p-Phenylene Oxide) Photonic Crystal Sensors

Lova

Bastianini

Giusto

et al. 2016

ACS Appl. Mater. Interfaces

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160

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The lack of sensors for low cost, extensive, and continuous detection of vapor pollutants is a serious concern for health and safety in industrialized urban areas. Colorimetric sensors, such as distributed Bragg reflectors made of polymers, could achieve this task thanks to their low cost and easy signal transduction but are typically affected by low vapor permeability and lack of selectivity without chemical labeling. Here we demonstrate all-polymer Bragg multilayers for label-free selective detection of organic volatile compounds. The system exploits the ability of amorphous poly(p-phenylene oxide), PPO, to uptake large amount of guest molecules and to form cocrystalline phases with distinct optical properties. Bragg stacks embedding PPO active layers show selective colorimetric response to vapors of carbon tetrachloride and aromatic homologues, which can be revealed by the naked eye.

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“…In this respect, a simple method for the assessment of air containing volatile PFCs using cost-effective sensors is of great importance. Optical and chromatic measurements constitute a class among simple methods and has been demonstrated in a variety of structures including molecular systems, photonic crystals, , and liquid crystalline nanostructures. − In particular, polymer dielectric mirrors (or distributed Bragg reflectors, DBR) proved to be a reliable and low-cost platform for colorimetric sensing for both organic and inorganic analytes in the vapor phase. − These devices are made of polymer layers having a different refractive index periodically alternated to generate dielectric submicrometric lattices. The interaction between light and these dielectric lattices, which are also known as monodimensional or planar photonic crystals, induces frequency regions forbidden to photon propagation.…”

Section: Introductionmentioning

confidence: 99%

Colorimetric Detection of Perfluorinated Compounds by All-Polymer Photonic Transducers

et al. 2018

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We report on the highly sensitive optical and colorimetric detection of perfluorinated compounds in the vapor phase achieved by all-polymer dielectric mirrors. High optical quality and uniformly distributed Bragg reflectors were fabricated by alternating thin films of poly( N -vinylcarbazole) and Hyflon AD polymers as high and low refractive index medium, respectively. A new processing procedure has been developed to compatibilize the deposition of poly( N -vinylcarbazole) with the highly solvophobic Hyflon AD polymer layers to achieve mutual processability between the two polymers and fabricate the devices. As a proof of principle, sensing measurements were performed using the Galden HT55 polymer as a prototype of the perfluorinated compound. The Bragg stacks show a strong chromatic response upon exposure to this compound, clearly detectable as both spectral and intensity variations. Conversely, Bragg mirrors fabricated without fluorinated polymers do not show any detectable response, demonstrating that the Hyflon AD polymer acts as the active and selective medium for sensing perfluorinated species. These results demonstrate that organic dielectric mirrors containing perfluorinated polymers can represent an innovative colorimetric monitoring system for fluorinated compounds, suitable to improve both environmental safety and quality of life.

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Nanoimprint Lithography: Toward Functional Photonic Crystals

Cited by 9 publications

References 153 publications

Flory–Huggins Photonic Sensors for the Optical Assessment of Molecular Diffusion Coefficients in Polymers

Flory–Huggins Photonic Sensors for the Optical Assessment of Molecular Diffusion Coefficients in Polymers

Label-Free Vapor Selectivity in Poly(p-Phenylene Oxide) Photonic Crystal Sensors

Colorimetric Detection of Perfluorinated Compounds by All-Polymer Photonic Transducers

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