Asymmetric microchannels in PDMS chips provide another way for creating unidirectional axon connectivity. Peyrin et al. recently described reconstruction of oriented cortico-striatal neuronal networks in “axon diode” microfluidic chambers composed of funnel-shaped microchannels [75]. The axon diode chip provides an important development, as it is a batch-producible device for creation of highly ordered neuron connection architectures in vitro.
