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The rat hippocampal cells were selected as model to study the interaction between the neural cells and silicon substrates using atomic force microscopy (AFM). The hippocampal cells show tight adherence on silicon wafers with nano-scale surface topograph. The lateral friction force investigated by AFM shows significant increase on the boundary around the cellular body. It is considered to relate to the cytoskeleton and cellular secretions. After ultrasonic wash in ethanol and acetone step by step, the surface of silicon wafers was observed by AFM sequentially. We have found that the culture leftovers form tight porous networks and a monolayer on the silicon wafers. It is concluded that the leftovers overspreading on the silicon substrates are the base of cell adherence on such smooth inert surfaces.

Electron holography was applied to study the microstructure evolution of magnetic tunnelling junctions (MTJs) CoFe/AlO(x)/Co annealed at different temperatures. A mean inner potential barrier was observed in the as-deposited MTJ sample, while it was changed to a potential well after a 200 degrees C or a 400 degrees C annealing. It is suggested that the oxygen atoms were redistributed during the annealing, which left metallic atoms acting as acceptors to confine the electrons, leading to the decrease of the potential of the AlO(x) barrier layer. The results suggest that the electron holography may be a useful tool for the study of the microstructure of amorphous materials.

Electron holography (EH) in a field emission gun transmission electron microscope has been used to profile the inner potential V 0 across CoFe/AlO x /Co magnetic tunneling junctions (MTJs). The spatial dimension of the AlO x barrier layer can be accurately determined from the phase profile at the tunneling junctions. The EH results show unambiguously that the potential jump across the CoFe/AlO x interface is smaller than that across the Co/AlO x interface, which results in asymmetrical barriers in the MTJs. The inner potential difference and the asymmetrical barrier were discussed based on the different oxidation statuses between Co/AlO x and CoFe/AlO x interfaces.

The adherence and viability of central neural cells (substantia nigra) on a thin layer of SiO 2 on Si wafers with different surface roughness were investigated. Variable roughness of the Si wafer surface was achieved by etching. The nano-scale surface topography was evaluated by atomic force microscopy. The adherence and subsequent viability of the cells on the wafer were examined by scanning electron microscopy (SEM) and fluorescence immunostaining of tyrosine hydroxylase (TH). It is found that the surface roughness significantly affected cell adhesion and viability. Cells survived for over 5 days with normal morphology and expressed neuronal TH when grown on surfaces with an average roughness (Ra) ranging from 20 to 50 nm. However, cell adherence was adversely affected when surfaces with Ra less than 10 nm and rough surfaces with Ra above 70 nm were used as the substrate. Such a simple preparation procedure may provide a suitable interface surface for silicon-based devices and neurones or other living tissues.

The adherence and subsequent viability of central neural cells (substantia nigra) on silicon wafers with different surface roughness conditions were investigated. Various roughness conditions of the silicon wafer were achieved by etching at different times. The topography was evaluated by AFM. Primary neurons were obtained from Wistar rats. The adherence and subsequent viability of the cells on the wafer were examined by scanning electronic microscopy and fluorescence immunostaining of tyrosine hydroxylase. It is found that the surface roughness affects significantly cell adhesion and viability. Cells can survive for over 5 days on the surface with average roughness in the range 20–70 nm. Such a treatment may provide a new method to make a mild interface of silicon-based electronic devices and neurons as well as other living tissues.