Abstract: An accelerometer assembly and its method of operation. The accelerometer assembly is designed to be very low cost and robust. This enables the accelerometer assembly to be used in traditionally inexpensive consumer products. The accelerometer assembly uses one or more molded elastomeric structures. Each of the elastomeric structures has a flexible neck section and a head section that is supported by the flexible neck section. The head section of the elastomeric structure is placed between a light source and a photodetector. The head section partially obscures the photodetector from the light source. As the elastomeric structure experiences acceleration forces, the neck section flexes and the head section moves. This varies the degree in which the head section obscures the photodetector. The amount of light detected by the photodetector, therefore, becomes a measure of changing acceleration forces.