**4.2.2 Neural network by microfluidic technique**

In this experiment,, we made a big progress on microfluidic technique by re-designing the parameters and enhancing the photoresist coating thickness of the Cr template. After 7 days in culture, poly-l-lysine and laminin+polyethyleneimine were found to be formed more complete and clearer flow patterns by the application of microfluidic technique. On LN group, neurons were easy to cluster into clumps when channel width was 150μm,almost overshadowed flow pattern itself; On PEI group, even though the flow patterns are more complete, the neurites extend short and cannot constitute a connection between some cells

Application of Soft Lithography and Micro-Fabrication on Neurobiology 33

sufficiently. When the channel spacing of 300μm, LN + PEI group of cells in the liquid injection port at the distribution, flow pattern clear, but the group off between individual cells, so that flow interruption. Identified with immunocytochemical staining, we found that most of the MAP-2 positive neural cells from the striatum cultured on the flow pattern were

Observing the fine structure of the intercellular on PLL group under scanning electron microscopic in Fig. 20, most of the neural cell bodies were found adhere to the flow pattern and majority of neurites are constrained within the width of the channel to grow following the orientation of flow channels. It is still visible that a few neuronal cell bodies deviate from the flow patterns slightly or adhere on the blank between two lines by local amplification. By observing the cross-linked region off low channel, we can see two endings of neurites

Fig. 20. Neurons from the striatum and the substantial nigra on PLL microfluidic patterns

In summary, this study based on previous work improve the microfluidic technique, evaluate the influence of two different soft lithography, the micro-contact printing and microfluidic technique on various interface materials for the construction of neural network. Our future work can be divided into two levels. On the one hand continue to look for the intersection of microelectrode array and the micro-fabrication technology, trying to make cell grow in accordance with patterns of MEA electrode nodes. On the other hand, need to further improve the characteristics of electrode materials, enhance biocompatibility under the premise of improving signal-to-noise ratio and without adding resistance, do good to

The application of the micro-fabrication on microelectrode array may open up a broader platform of the technique for neurochip research and provide new ideas for the treatment of various injuries in the central nervous system. Ultimately, the combination both can achieve position fixing between neurons and electrodes precisely, to make the system as a real sensor, be able to accept electrical stimulation or chemical stimulation and record their signals, to analysis the transfer process of neural network information, and apply to drug

YN Xia, Whitesides G. M. (1998). Soft lithography. *Angewandte Chemie-International Edition*,

also labeled with GABA, as shown in Figure 19.

seem to have varicose, swelling structure liking synapse.

(a)x250 bar=100μm (b)x1000 bar=10μm (c)x10000 bar=1μm

the survival of neurons and neurite extension.

Vol.37, No5, pp. 551-575.

screening of related diseases.

**6. References** 

under SEM.

**5. Conclusion** 

(a)chemical synapse structure x40000 bar=0.5μm (b)electrical synapse structure x60000 bar=0.2μm

Fig. 18. Under TEM, synapse like structure between neurons from the striatum and the substantial nigra on PEI patterns

(a) LN group, width of lines 150μm, (b) PLL group, width of lines 150μm (c) PEI group, width of lines 200μm , (d) LN+PEI group, width of lines 300μm bar=200μm

Fig. 19. Immunofluorescent image of anti-GABA (green fluorescence) +anti-MAP2 (red fluorescence) labelled striatal neurons cultured for 7 days on different substrates by microfluidic technique x100

sufficiently. When the channel spacing of 300μm, LN + PEI group of cells in the liquid injection port at the distribution, flow pattern clear, but the group off between individual cells, so that flow interruption. Identified with immunocytochemical staining, we found that most of the MAP-2 positive neural cells from the striatum cultured on the flow pattern were also labeled with GABA, as shown in Figure 19.

Observing the fine structure of the intercellular on PLL group under scanning electron microscopic in Fig. 20, most of the neural cell bodies were found adhere to the flow pattern and majority of neurites are constrained within the width of the channel to grow following the orientation of flow channels. It is still visible that a few neuronal cell bodies deviate from the flow patterns slightly or adhere on the blank between two lines by local amplification. By observing the cross-linked region off low channel, we can see two endings of neurites seem to have varicose, swelling structure liking synapse.

(a)x250 bar=100μm (b)x1000 bar=10μm (c)x10000 bar=1μm

Fig. 20. Neurons from the striatum and the substantial nigra on PLL microfluidic patterns under SEM.
