| With excellent sensitivity,reproducibility and stability,dynamic surface-enhanced Raman spectroscopy（Dynamic Surface Enhanced Raman Spectroscopy,D-SERS）has been widely used in drug detection,pesticide residue and biomedicine.During the D-SERS detection process,the laser is manually adjusted to focus the focus position to obtain a stronger SERS signal.But at present,the effective"hot spot"duration of nano-sol formation in traditional D-SERS detection is generally only ten seconds,and the time is very short,so it is impossible to obtain the best spectrum by manual focusing.At the same time,the existing automatic focusing methods rely on expensive instruments and complex algorithms,which are not suitable for D-SERS detection.Therefore,in view of the problems in the D-SERS detection process:（1）Lack of stable hot spots formed by nano sols;（2）Lack of simple autofocus judgment method for D-SERS detection;（3）There is no detection device suitable for D-SERS autofocus in the market at present.In view of the above problems,according to the characteristics of D-SERS detection,a method of obtaining stable dynamic hot spots based on temperature control is designed,and a hill-climbing algorithm based on spectral intensity is proposed as the discrimination method of automatic focusing.A D-SERS detection device integrating temperature control system and automatic focusing algorithm is constructed,which realizes the acquisition of stable hot spots and automatic focusing of laser in the D-SERS detection process.Research mainly in the following three areas:（1）A method of forming and maintaining hot spots of nano-sol based on temperature control is designed,which realizes stable and long-term hot spots acquisition in the process of D-SERS detection.According to the characteristics of hot spots formed by sol volatilization,the methods of increasing the temperature in the early stage,accelerating the formation of hot spots,decreasing the temperature in the later stage and prolonging the duration of hot spots were adopted.By fitting the elliptic curve of the outline during the evaporation of nano-sol droplets at different temperatures,the height change of droplets was calculated,so as to control the evaporation rate of sol and realize the acquisition of stable dynamic hot spots.The experimental results show that effective hot spots begin to appear in about 3 minutes and last for 5 minutes.（2）An autofocus method based on spectral intensity and optimized hill climbing algorithm is proposed.Aiming at the problem of automatic focusing based on the combination of high-precision images and complex algorithms,on the basis of obtaining stable hot spots,the spectral intensity is changed by slightly changing the focus position,and then the spectral intensity is judged by using the optimized mountain climbing algorithm,so as to determine the focus position by using the maximum spectral intensity and realize automatic focusing.The optimized mountain climbing algorithm adopts the method of striding moment first and then fine focusing,which avoids the interference of local maximum in traditional mountain climbing algorithm.（3）An auto-focusing system is built,which integrates data processing module based on temperature control hotspot module and hill climbing algorithm.The temperature control platform is used to heat up and cool down,and the continuous and stable hot spots are obtained.The distance between the laser and the droplet is adjusted by a high-precision stepping motor,and the real-time spectrum is captured and collected.Then,by calling the dynamic link library,the communication between the computer and the hardware and software modules is realized,and the function of the whole system is realized.Experiments show that the detection effect of this method is better than the traditional manual focusing method,and its detection limit can reach 10-9 M and when the integration time is 0.5 s,the focusing duration can reach 9 s,thus realizing simple and fast automatic focusing in D-SERS detection. |
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