Research On The Fabrication Of Bionic Micro/Nano Structures For Flexible Enzyme-Free Glucose Sensor

Flexible non-enzymatic glucose sensors have attracted widespread attentions due to their importance and potential applications in clinical diagnosis,flexible wearable devices,and implanted devices in vivo.At present,there are still major problems in preparing flexible enzyme-free glucose sensors with low detection limits,high stability and high sensitivity at low cost,which hindering their practical application.At the same time,the bionic micro-nano hierarchical structure was gradually discovered and applied by researchers due to its large specific surface area,and its potential application in flexible enzyme-free glucose sensors should not be underestimated.We have found micro-nano hierarchical structures based glucose sensors have the best electrochemical performance compared with other structures through simulation.Based on the analysis above,we have proposed new processes for the fabrication of flexible bionic micro-nano hierarchical structures using nano-bionic foam and ginkgo biloba as templates,focusing on the factors that affecting the formation of micro-nano hierarchical structures during fabrication.The fabricated flexible glucose sensors exhibit excellent performance.The main contents are as follows.Firstly,we have compared the electrochemical performances of enzyme-free glucose sensors based on planar,square microstructures,semi-circular microstructures,triangular microstructures and micro-nano hierarchical structures by Comsol simulation.The results show that the enzyme-free glucose sensor based on the micro-nano hierarchical structures has best electrochemical performance of fastest response speed,largest cyclic voltammetric current and minimal electron transfer resistance.The best performance should attribute to the shortest electron transmission path of micro-nano hierarchical structure caused by the large effecitve surface area.On the basis,we have proposed a new process to fabricate micro-nano hierarchical structures based on nano-bionic foam template.Nano-bionic foam is cost-effective and has a porous network.In this study,a nano-sponge foam is introduced when coating the silver film on the surface of silicon pyramid microstructures to obtain nano-porous silver film.The silver microstructure is then etched with the porous silver film as catalyst,thus stable silicon micro-nano hierarchical structures are obtained.The porous silver film has better catalytic activity and is able to discharge gas easily,which are beneficial for the formation of silicon micro-nano hierarchical structures.The effect of porous silver film thickness on the hierarchical structures has been studied.Flexible PDMS micro-nano structure was fabricated with the above structures as template by soft lithography,and the Pt/Au/PEDOT:PSS film was integrated as a conductive layer.Ni O nanofilm was electrodeposited and used as a reaction layer to fabricate the flexible enzyme-free glucose sensor.Due to the large specific surface area of the micro-nano hierarchical structures,the flexible enzyme-free glucose sensor shows high sensitivity(0.9773 m A·m M^-1·cm^-2),high linearity（0.9979）,low operating voltage（0.50 V）,low detection limit（0.371μM）and good anti-interference properties.In addition,we have also proposed a low-cost fabrication strategy of bionic micro-nano hierarchical structure with the ginkgo leaf as template.The characteristics of the micro-nano hierarchical structures of the pristine surface of Ginkgo biloba were analyzed at first.The effects of fabricating parameters such as the Ginkgo biloba types,mold release temperature and time on the PDMS micro-nano hierarchical structures have been studied.A Pt/Au/PEDOT:PSS film was integrated on the surface of the fabricated micro-nano hierarchical structures as conductive layer.And Ni O nanofilm was electrodeposited and acted as reaction layer for the flexible enzyme-free glucose sensor.The results show that the flexible enzyme-free glucose sensor exhibits excellent performance,with high linearity（0.9993）,high sensitivity(0.7413 m A·m M^-1·cm^-2),low operating voltage（0.55 V）,low detection limit（0.329μM）and good anti-interference.