Formation and propagation of cracks in concrete structure are one of the earliest symptoms threatening durability and reliability of the structure. Existing solutions for crack monitoring are expensive and incapable of large scale deployment. In this paper, existing solutions targeting crack monitoring application are analyzed and new wireless sensor is proposed by harvesting ambient energy and hence providing a longer life time. In order to monitor crack, our proposed sensor is required to physically cross the crack and attached to the concrete surface on one end while the other end is placed on rubber pad. With the change in crack width, there is a proportional relative displacement in the concrete surface under sensor and this relative displacement is computed by acquiring sequential images of concrete surface and processing through digital signal processor. Moreover, In order to efficiently utilizing harvested energy, energy aware task management is adopted to accomplish tasks. As compared to existing solutions, this solution offers low power, longer lifetime and large scale deployment capability.