Fabrication of ultrafloppy single-crystal silicon cantilever for magnetic resonance imaging

We have proposed a fabrication method of the ultrafloppy single-crystal silicon cantilever and evaluated their mechanical properties under several conditions. A spring constant of the fabricated cantilever was less than 0.0001 N/m and minimum detectable force was around 10^-16 N at room temperature. With them, we performed the measurement of the vacuum dependent and temperature dependent. First the change of a quality factor was measured as a function of vacuum. A big increase of the quality factor is observed in a range of 1 to 0.1 Pa. The quality factor these cantilever are very high (Q=68840+/-1184) in a high vacuum. In the second experiment we measured the temperature dependent of the resonance frequency and the internal friction. By decreasing the operating temperature, the resonance frequency is slightly increased due to the change of Young´s modules. The internal friction is observed the minimum at 20K and the maximum at 160K. The best sensitivity is achieved at 20K, where a factor of 10 is compared to room temperature