Key Preparation Technology Of SPM Probe And Studies On Silver/Graphene Nanocomposites

An artisan must first sharpen his tools if he is to do his work well.With the continuous advancement of nanocomposites,higher requirements have been put forward for the related characterization tools of nanocomposites and the method for nanocomposites preparation.Scanning probe microscopy(SPM)is a key characterization tool for nanocomposites,and its resolution is almost relying on the morphology of the probe.Only by improving the fineness of the probe can the structure of the composites be better characterized.In the preparation of nanocomposites,it is hoped that a new technology can realize the one-step preparation of nanocomposites based on the existing experimental methods.Laser technology,as a relatively simple,green and efficient micromachining technology,makes the one-step preparation of nanocomposites possible.In this paper,the preparation of SPM probes related to nanocomposites characterization and the one step preparation of silver/graphene nanocomposites by laser micromachining technology were studied,mainly including the following contents:(1)Double-electrolytes etching method was used to fabricate high yield ultrasharp Scanning Tunnel Microscopy(STM)tungsten probes.Through the work on the electrochemical etching parameters,the optimized etching parameters were obtained.Under this condition,the tip curvature radius of the sharpest probe is?8nm.The success rate of probe(radius?10nm)is 63.5%.These probes own the ability of stably obtaining atomic resolution STM images.Furthermore,a model of artificial neural network(ANN)was built by the method of machine learning to predict probe feature under different experimental conditions.This model shows a great predictable performance that the correlation factors R between predict data and experimental data are all over 0.85.Garson algorithm was used to analyses the relative importance of every etching parameter on tip feature.Importance analyses indicate that the length of tungsten wire below the liquid lamellae is the most important parameter to obtain ultrasharp STM tungsten probes in double-electrolytes etching method.(2)Scanning Electrochemical Microscope(SECM)probe with platinum wire as ultra-micro disk electrode(UMDE)was prepared by P-2000 Laser Based Micropipette Puller instrument.A system optimization on the experimental parameters was conducted.The success rate of the probe preparation was improved by the precise control of the heating time required for the laser to seal the platinum wire and the improvement of the experimental procedure of the encapsulation of platinum wire inside the glass micropipette.In addition,by controlling the thickness of the glass that seals the platinum wire,the SECM probes with platinum UMDE directly exposed were obtained.Moreover,all the UMDE diameters are within hundreds of nanometers,the minimum UMDE size is about 79nm.(3)Via the combination of laser ablation technique and laser-induced graphene technique,silver/graphene nanocomposite materials were prepared in one step.Based on the advantages of laser direct writing that can realize the direct forming of various patterns,flexible nanocomposite material electrode was prepared.The flexible electrode can realize strain sensing and used for gesture recognition.