7403
These results provide a first step in using 3D printing techniques to optimize and integrate piezoelectrets into parts , allowing a useful new electroactive functionality for additive manufacturing .
 concept or principle: step; manufacturing process: 3D printing; material: piezoelectrets; concept or principle: electroactive functionality; manufacturing process: additive manufacturing
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: 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} 
 Entities: step, 3D printing, piezoelectrets, electroactive functionality, additive manufacturing 
Answer:
 concept or principle: step; manufacturing process: 3D printing; material: piezoelectrets; concept or principle: electroactive functionality; manufacturing process: additive manufacturing