(Received September 19, 2002; accepted for publication January 30, 2003)
Multichannel 5 ×5-site Si microprobe electrode array has been developed for neural activity recording. Si microprobes were fabricated successfully at predetermined sites on a chip using Au dots and Si2H6 gas source molecular beam epitaxy (GS-MBE), a method based on vapor-liquid-solid (VLS) growth. Selective VLS Si growth allowed the design of three-dimensional (3D) microprobes with 40 µm spacing in a 5 ×5 array. The diameter and the length of the Si probe can be widely changed by changing the Au dot size and the Si growth time, respectively. In addition, the circular-cone-shaped Si probe has a shape suitable for penetration into neural tissues, and can be realized by increasing growth pressure. The mechanical strength of the Si probe was evaluated with observation of its bending and penetration into a gelatin membrane, which indicated that the Si probes are strong enough to withstand the application. Signal recording with the same amplitude as neural activity was also performed using the fabricated Si probe array chip. These results confirm that high-density neural signals from neural tissues can be obtained with the multichannel 3D VLS Si microprobe array chip.