Currently, there are dozens of types of linear accelerometers, most of which use solid materials as the "detection mass," or mass block. However, solid mass blocks generate strong inertial forces under large impacts (or high overloads), causing the sensor to malfunction. Therefore, their application in high-impact (or high-overload) situations is limited.
To overcome the aforementioned shortcomings of existing linear accelerometers, a novel linear accelerometer has been developed. This sensor uses gas instead of solid as the mass, thus avoiding the generation of large inertial forces by the mass. This novel linear accelerometer possesses unparalleled advantages over other sensors, including simple structure, low cost, and high reliability. Notably, it can still function after withstanding a high impact of 1600 μg.
Hot air rises and cold air sinks—a phenomenon we frequently observe in daily life. For example, a candle burning in still air rises due to the buoyancy of the high-temperature gas around the flame, while cold air continuously replenishes it from below, creating a long, thin flame—this is natural convection. Gas linear acceleration sensors utilize this phenomenon, based on the theory of "natural convection" in fluid mechanics. Natural convection is relative to forced convection. Forced convection relies on fans, pumps, etc., to induce fluid flow; natural convection is the convective flow that exists within a fluid even without forced velocity. It is the flow generated by the gravitational field acting on fluids with a density gradient. The speed of natural convection is generally much lower than that of forced convection. Therefore, the role of natural convection is often overlooked. However, under certain conditions, natural convection can play a decisive role. The conditions for natural convection in gas are the presence of a gravitational field and a density gradient in the gas. In fact, besides a gravitational field, overload acceleration or specific force can also induce natural convection. Gas linear acceleration sensors utilize the natural convection caused by overload acceleration to detect linear acceleration.
