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We report the integration of a novel split ring resonator ( SRR ) surface mapping technique directly into an AM process to make non-destructive in-line measurements of the local relative dielectric permittivity ( ϵr ) within 3D objects as they are formed .
 resonator, surface, AM process, dielectric, 3D objects
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:
 resonator, surface, AM process, dielectric, 3D objects