Measuring the thickness of the coating layer in nanoparticles requires the use of advanced instruments and techniques. The following are possible measurement methods:

Transmission Electron Microscope (TEM): This is a microscope that utilizes high-density electron beams to observe and measure the structure and properties of nanoparticles. For the measurement of the thickness of the coating layer, TEM can determine its thickness by observing the cross-sectional image of the particles.

Scanning Electron Microscope (SEM): This microscope can also observe and measure the structure and properties of nanoparticles. Unlike TEM, SEM uses an electron beam instead of a transmitted electron beam. By using SEM, cross-sectional images of samples can be prepared to determine the thickness of the coating layer.

X-ray photoelectron spectroscopy (XPS): XPS can perform chemical analysis of surfaces. By analyzing the X-ray spectrum of the particle surface, the composition and thickness of the coating layer can be determined.

Nanomechanical measuring instrument: This instrument can use a pressure probe to measure the length, height, and thickness of particles.

These instruments require professional knowledge and skills to operate. Therefore, if you need to perform particle characterization, please consider consulting a professional laboratory or expert.