Hair cells that respond to movements of a surrounding medium are the mechanoreceptors commonly found in creatures. A lot of filiform hairs function as a sensory system for raider detections and communications in life. An analysis has been conducted in order to investigate the behavior of a flexible filiform hair for the development of a biomimetic hair cell sensor. The forces acting on the hair are due to drag, vorticity diffusion and added mass of a surrounding flow. In the transient analysis, the flow is assumed as an oscillating flow on a substrate at low or moderate frequencies. The lower order in the normal modes plays the most dominant role in characterizing the hair cell behavior. It is easy to understand the dynamics of the artificial hair cell sensor by comparing the magnitude of generalized coordinates and their phase diagrams. It is found that the elastic modulus and the geometric parameters such as length and diameter of the sensory hair determine the mechanical sensitivities and responses in the oscillating flow. By manipulating them appropriately, the displacement, velocity, and acceleration can be controlled and measured in a wide range of frequencies.