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Impedance measurements made on the thermoplastic filaments demonstrate that the copper-based filament had an impedance similar to a copper PCB trace at frequencies greater than 1 MHz .
 Impedance measurements, thermoplastic filaments, filament, copper
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:
 Impedance measurements, thermoplastic filaments, filament, copper