Abstract: A compact collision detector can be configured for low power operation to facilitate collision avoidance. In one embodiment, a nanoscale collision detector can be based on a photodetector, stacked on top of a non-volatile and programmable memory architecture that imitates the escape response of LGMD neuron at a frugal energy expenditure of few nanojoules (nJ) and at the same time can offer orders of magnitude benefit in device footprint (e.g. by having a relatively small size). Embodiments of the collision detector can be utilized in smart, low-cost, task-specific, energy efficient and miniaturized collision detection systems configured for collision avoidance.