To mimic a simplified neurocircuitry in the brain where a group of neurons receives two defined inputs (Fig. 1a), we designed a novel multi-compartmental device where the side chambers are linked with the central chamber through microchannels (Fig. 1b). We microfabricated the device using the procedure described in Methods (Fig. 1). Human iN cells29,31 derived from iPSCs were seeded into both outer and central chambers, producing cultures with normal neuronal morphology with extensive and complex branches (Fig. 2). We first evaluated difrerent center wall widths (microchannel lengths) (100 μm, 200 μm [Fig. 2a] and 500 μm [Fig. 2b]). While devices with either 200 μm or 500 μm walls were easily fabricated, those with 100 μm walls were more challenging, due to difficulty in removing un-crosslinked photoresist from the master wafer during SU-8 development. We continued experimentation with the 200 μm wall device, as it balanced successful fabrication with a shorter path for process growth into the central chamber, as compared with the 500 μm wall.
