An agar-based on-chip neural-cell-cultivation system for stepwise control of network pattern generation during cultivation

We have developed a new type of single-cell based on-chip cell-cultivation system with an agarose microchamber (AMC) array and a photo-thermal etching module for step-by-step topographical control of the network patterns of living neural cells during long-term cultivation. The advantages of this system are that (1) it can control positions and numbers of cells for cultivation by using agar-based microchambers, and (2) it can change the neural network complexity during cultivation by photo-thermal melting a portion of agar at the focal point of a 1064 nm infrared laser beam. This laser wavelength is permeable with respect to water and agarose, and it is only absorbed at the thin chromium layer on the chromium-coated glass slide surface at the bottom of the agarose layer. With adequate laser power, we can easily fabricate narrow tunnel-shaped channels between the microchambers at the bottom of the agar layer without the complicated steps conventional microfabrication processes entail even during cultivation; we demonstrated that rat hippocampal cells in two adjacent chambers formed fiber connections through new connections between chambers after these had been photo-thermally fabricated. We also verified the fiber connection between those cells by using calcium-based fluorescent microscopy. These results indicate that this system can potentially be used for studying the complexity of neural network patterns for epigenetic memorization.