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Multi-photon polymerization , like the so-called direct laser writing ( DLW ) technique allows for flexible additive manufacturing of three-dimensional ultra-precise structures on the micro- and nanoscale .
 polymerization, direct laser writing, additive manufacturing, three-dimensional, micro-
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:
 polymerization, direct laser writing, additive manufacturing, three-dimensional, micro-