High-resolution Hydrogel Nanostructures And Their Application In Tunable Nanophotonic Device

Organic materials own the advantages of biocompatibility,flexibility and easy-access.Therefore,the extensive research on the nanostructures of such materials have been carried out by scientists,and the study of organic nanostructure in nanophotonics is developing quickly.At present,multi-band responsive,real-time tunable,dynamically controllable nanophotonic structures and devices is are desirable for practical application.However,the nanofabrication technique of tunable polymer materials is limited,which cannot be evaporated or deposited.Compared with tunable inorganic materials,polymer films are generally formed through coating,or self-assembly,and realizes limited performance.Therefore,whether the active organic nanostructures and the tunable photonic structure can be realized have become a new challenge in application research.In this paper,we found that polyvinyl alcohol(PVA)can be used to form high-resolution hydrogel nanostructures by electron beam lithography,and then the photonic structure with dynamic tunability can be achieved.Based on this,the main work of this paper is as follows:(1)We have demonstrated that PVA can be used as a negative resist for electron beam lithography,with the highest resolution at 50 nm half-pitch.In addition,the near-field infrared spectrum showed that the hydrophilic groups of PVA remained stable after electron beam exposure.Therefore,PVA still showed rapid response to humidity changes after patterning.We have established an aqueous nano-patterning process including dissolution,spin coating and development.This process is friendly to the manufacture of organic devices.This high-resolution nanopatterning technology based on polyvinyl alcohol is helpful for the design and realization of hydrogel-related nanodevices in the future.(2)We have achieved the humidity-responsive photonic structure by based on PVA hydrogel nanodots array on aluminum film.Due to the limitation of the secondary electron scattering mechanism,simply increasing electron beam exposure dose cannot achieve the designable nanodot size.Here,we developed a low-voltage exposure mechanism to suppress the scattering range of secondary electrons in the depth direction,and controlled nanodot size effectively by exposure dose.It is proved that the spectral response of hydrogel nanostructures in multi-band can be controlled by applied humidity,and the scattering resonance is red shifted with the increased humidity.As the application,the rapid response of PVA nanostructures to humidity can be applied in the anti-counterfeiting.This provides a new idea for dynamic control of nanostructured materials.