4357
Tests were performed with a simple bang-bang controller test setup and a mass spectrometer , and the existence of the coating was confirmed with scanning electron microscope imaging .
 simple, controller, coating, scanning electron microscope, imaging
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 simple, controller, coating, scanning electron microscope, imaging