Development of Cell Surgery System on a Chip with Nanoneedle Array

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In order to realize cell surgery on a chip-based system, we have developed key devices such as a bio-microdevice actuated by piezoelectric thin film for the enhancement of cell functions (cell multiplication and gene transfer) by applying mechanical stimulation to cells and a nanoneedle array capable of introducing biomolecules of interest into living cells and the parallel extracting biomolecules expressed in the cells.First, we optimized the design of the bio-microdevice using a finite element method (FEM). The maximum displacement at the center of a silicon nitride (Si_3N_4) diaphragm (with more than 100×100 μm^2 in size) was estimated to be more than the target value of 100 nm, when a voltage of 10 V was applied to the PZT thin film actuator. Moreover, we fabricated PZT thin film to be used as an actuator by a sol-gel method, and characterized its crystallographic structure. As a result, when pyrolysis at 320℃ for 1 min and then annealed at 600℃ for 1 min in air, PZT thin films with (111) orientation were obtained.In addition, we developed a novel and simple micromachining technique for the fabrication of out-of-plane, hollow nanoneedles in array. An array of silicon dioxide (SiO_2) needles with a circler tip shape (an inner diameter of 3.5 μm, an outer diameter of 6.0 μm and a height of 45 μm) were successfully fabricated by a combination of an anisotropic deep reactive ion etching (DRIE) process for producing thorough holes into a Si substrate as a needle mold followed by wet oxidation and an isotropic XeF_2 etching process for leaving SiO_2 nanoneedle structures. In order to fabricate high-aspect-ratio microchannels and through holes in a glass substrate, a sand blasting technique using a polymer (PDMS) as a mask material, which was patterned using a thick photoresist (SU-8) as a mold, was also developed.