Design and preparation of the composite film of SiO2 inlaying RGO and its enhanced electro-wetting performance
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The SiO2 composite film embedded with good conductor reduced graphene oxide (RGO) is designed based on the space charge polarization induced by the electromagnetic induction, and subsequently prepared using a simple sol–gel and spin-coating method. On one hand, the embedded RGO particles in SiO2 coating form large amount of heterogeneous interfaces and supply amounts of free charges. When the voltage is applied, the free charges are immediately driven to be accumulated these heterogeneous interfaces by the electromagnetic induction. Then, the space charge polarization induced by the electromagnetic induction is produced and increases the dielectric constant of the film. Also, the electromagnetic induction ensures the fast response of the space charge polarization, and further decreases the relaxation time of EWOD response obviously. On the other hand, the embedment of good conductor of RGO particles also greatly decreases the effective thickness of the SiO2 film. All these results greatly increase the capacitance of dielectric layer and further enhance EWOD performance, which are verified by the measured and calculated capacitance of the RGO@SiO2 composite film.
The authors are grateful to the support of the National Natural Science Foundation of China (Grant No. 11464041, 11864035, 11474231).