Modification of polystyrene surface by negative ion implantation for improving and patterning attachment properties of neurons was investigated. This modification technique is required for artificial formation of neural network with neuron cells and for development of “bio-interface” between vital neural system and external silicon circuit. Silver-negative ions were implanted into various kinds of polystyrene surfaces through a mask with slit array of 60μm in width and 4 mm in length with 60μm spacing. In the cell culture of PC-12h (rat adrenal pheochromocytoma) cells with the ion-implanted polystyrenes, PC-12h cells attached and neurites extended only on the ion-implanted regions of untreated polystyrene dishes (NTPS) and spin-coated polystyrene (SCPS). This means that pattering ion implantation is able to make patterning treatment both of cell attachment and neurites extension properties.
In order to discuss mechanisms of hardness enhancement of Al/TiN multilayered thin films, elastic and plastic deformation behaviors of the multilayered films have been investigated by using dissipated and elastic energies evaluated from a load-displacement curve of nanoindentation. The Al/TiN multilayered films were deposited by dc magnetron sputtering. Thickness of Al layers was varied from 3 to 100 nm, and that of TiN layers was varied from 16 to 500 nm in correspondence with the variation in the number of layers from 60 to 2. A hardness enhancement by up to 10% compared to a monolithic TiN film was observed for a 20-layerd film with an Al layer thickness of 10 nm and a TiN layer thickness of 50 nm. A minimum dissipated energy was observed for a film with Al layer thickness of 5 or 10 nm. In contrary, elastic energy showed a maximum for the film. The reduction in the dissipated energy for a film with a thin Al layer implies that the pinning effect for propagation of dislocations at an interface between Al and TiN layers suppresses plastic deformation, resulting in the enhancement in microhardness.
We developed an electron diffractometer (ED) using an amplified metal-oxide-semiconductor (MOS) imager (AMI) overlaid with electron-bombarded amorphous silicon (a-Si). The gain of ED-AMI is 3500 at 20 kV. The gain is under unity below 2 kV because of the penetration loss of the Al layer. The fixed pattern noise (FPN) is below the detection limit. Although the SN ratio of the conventional instruments is 21.3 dB at 73 nA diffraction current, the SN ratio of ED-AMI becomes 47.3 dB. The SN ratio in this device is 26.0 dB larger than the conventional value, and is suitable for the detection of fast weak structural change such as in an amorphous material.