CAB and PS performed literature review and contributed in writing the first draft of the manuscript. VJ and SF wrote the section on PDMS-related materials and manufacturing techniques. HT, FN, TK and KY wrote the sections on agar-microstructure technology and directed neuronal networks. SEL and CR performed literature review and contributed in writing the electrophysiological parts of the review. KY and HJH designed, edited and revised the final manuscript. All authors read and approved the final manuscript.
