Disturbance Signal in Atomic Force Microscope Based Microinjection Detection

The determination of microinjection volumes has received extensive attention in genetic and cell engineering. A new method for measuring the injection volumes is reported. The measurement is achieved by detecting the deflection of cantilever effected by the gravity of injected liquid, based on atomic force microscope (AFM) with nanometer resolution. The detecting system is sensitive to microvibration and the reliability of measuring result is remarkably influenced by disturbance. Disturbance factors are analyzed in droplet detection, a suppression device is adopted to suppress medium and high frequency disturbance, it has been observed that small swinging of suspension isolation system in horizontal direction cannot be ignored. In order to suppress the influence of this kind of low frequency for super micro-injection detection in the research, a liquid attenuator is designed and the horizontal and rotation damping are increased to improve isolation performance effectively. Detection experiment on picoliter-level injection is carried on and result indicates that ultra micro injection detection based on the atomic force microscope can realize 10-30 pL micro injection detection.