Fabrication Of Silicon Dioxide Photonic Crystals And Research On Electrical Response Properties

In nature,some organisms use their skin as an interface with the outside world,sensing the environment and releasing bioelectric signals to change the color of their skin for purposes such as camouflage,courtship,and communication.Inspired by color-changing organisms in nature,researchers have developed stimulus-responsive photonic crystals that can change their structural color in response to external stimuli.Among all types of responsive photonic crystals,electric field-responsive photonic systems have the widest range of applications because they can be patterned at the pixel level on a microscale.However,their applications are limited by their angle-dependency and slow response time.Moreover,structural deformations in photonic films can lead to color non-uniformity in photonic crystal materials.Drawing inspiration from this phenomenon,researchers in recent years have developed stimulus-responsive photonic crystals that can change their structural colors in response to external stimuli.Among all types of responsive photonic crystals,electrically responsive photonic systems have the broadest range of applications because they can be pixelated at the microscale.However,their applications are limited by angle dependence and slow response times.Additionally,structural defects in photonic films can cause color non-uniformity in photonic crystal materials.To address these issues,this paper employed the St（?）ber method to prepare uniform and monodisperse SiO₂photonic crystals of varying sizes,which were then compounded with the high polymers ETPTA and PEGPEA.The resulting electrically responsive photonic crystal systems were fabricated on both hard ITO conductive glass and soft rGO/PDMS conductive material substrates.To fill the defects in the artificial photonic crystals and improve the stability and conductivity of the system,the researchers also included black rGO.The influence of rGO and IL content on the electrically responsive photonic crystal system was investigated using SEM,TEM,FTIR,and confocal microspectroscopy.The main research findings are as follows:（1）Electric field responsive photonic crystal inks,referred to as"e-ink",were formulated by dispersing SiO₂colloidal microspheres in ETPTA-PC/rGO with high concentration.It was found that the e-ink has good sensitivity and stability to electric field and can achieve high saturation color adjustment.the introduction of ETPTA makes it possible to instantly fix the photonic structure and color under any electric field,while the introduction of rGO plays a key role in improving the color saturation,stability and sensitivity to electric field.The photoelectric properties of 0.05 mg,0.25 mg and 0.5 mg rGO e-ink were characterized and tested with rGO content as a variable.The e-ink containing 0.25 mg rGO achieved a fast response of 40 s at safe voltages of 3.5 V and below,and the performance remained stable during repeated cycling tests with power on.Due to the unique mechanical color-changing behavior of the photonic structure under controlled voltage,this dynamic change in structure and color pattern is promising for applications in interactive electronic devices like color ink screens.（2）Self-assembly of SiO₂photonic crystals in PEGPEA and photopolymerization to form structurally colored films with structural colors.In addition,human motion monitoring PEGPEA/SiO₂-rGO/PDMS,which can be applied to the skin,was prepared using rGO-doped PDMS pure black flexible film as a substrate,combined with PEGPEA/SiO₂,and imparted conductivitybyinfiltratingitwith1-ethyl-3-methylimidazoline bis（trifluoromethylsulfonyl）imide（IL[EMIm][TFSI]）photonic crystal flexible film.By optimizing the IL content,a dual response of the photoelectric signal to stress was achieved.In the optical,mechanical,and electrical property tests,the best performance of the flexible PEGPEA/SiO₂-rGO/PDMS photonic crystal films prepared from SiO₂photonic crystals with a concentration of 0.05 g/ml and a particle size of 230 nm and treated in IL[EMIm][TFSI]for2 s was achieved.When the strain range was 0%to 60%,the visualized ion skin sensor showed an advanced visual interaction sensing capability with force-changing sensitivity（GF）≈2.5,Δλ≈160nm andΔλ≈160nm,and mechanical stability.