Scientists build motion detector that can ‘see’ through metal

Using powerful acoustic sensors, scientists believe they can detect movement through metal walls. The system must be used, among other things, to detect stowaways on boats and trucks.

The system was developed by Starmark, a scientific development company headquartered in San Diego, MIT Technology Review reports. They decided to develop a way to detect movement on the other side of a metal wall. Previously there were no good solutions for this. Starmark developed a system with acoustic sensors that are significantly more powerful than conventional models.

Various options were tried, but in the end the researchers proved to be able to achieve their goal with a fairly simple system that works with a 9-volt battery. Simply put, it works by hitting a metal disc with a hammer, which emits a specific frequency. By mounting the device on a metal wall, the signals can cross over to the other side. Reflections of those signals are then collected again.

It is possible to detect movement on the other side of the wall because reflected signals that do not change, and thus belong to stationary objects, are filtered out. Only if change, and therefore movement, is detected is this made clear by the device. The system developed by Starmark is so sensitive that it can even detect breaths on the other side of a metal wall.

In the future, such motion detectors should be used on ships and trucks. Specifically, it is intended that stowaways are found, who secretly try to get a lift, in order to enter a country for example. Incidentally, practical tests must first be carried out before the system can actually be deployed.