Step S100: Prepare a sol-gel substr

Step S100: Prepare a sol-gel substrate containing SERS active gold and fix it on the inner wall of a glass vial. In specific implementation, gold metal particles are encapsulated in a porous glass structure, and the fixed glass sol-gel as a thin film (attached to the inner wall of the vial) is optically transparent and porous, containing gold metal dispersed therein nanoparticles, these nanoparticles are clusters of fractal aggregates with an average size between 10 and 200 nm; and can use passive diffusion force to make liquid samples flow into the sol-gel substrate for detection and identification. The liquid is flowed into the vial with a dropper.