A self-excited micro cantilever biosensor actuated by PZT using the mass micro balancing technique

A micro biosensor, which can be applied to a Lab-On-a-Chip (LOC), is developed in order to detect biomaterials such as protein or DNA. The biomaterials are detected by mass micro-balancing technique, which measures the change of the resonant frequency of the sensor structure. The sensor structure consists of a micro cantilever actuated by piezoelectric PZT film. The PZT film is designed to act as both a sensor and an actuator. The geometry of the micro cantilever is determined so as to maximize the sensitivity of the sensor, and environmental effects such as added mass effect in liquid are also considered in the structural analysis. The micro cantilever is 100 μm in length, 30 μm in width and 5 μm in thickness, and the PZT film thickness and length are 2.5 and 50 μm, respectively. The first resonant frequency of the PZT micro cantilever is 1.2 ∼ 1.3 MHz. Lastly the fabricated micro-biosensor using the self-excited PZT-micro cantilever is tested by detecting the human insulin-anti human insulin binding protein, the poly T-sequence DNA, the K20-Thiol DNA and the K40-Thiol DNA in air.