Metal detectors are already available that can detect ferrous metals, but until now they have been unable to detect stainless steel - the most common material used for pharmaceutical manufacturing machinery - because it is not magnetic.
Sartorius has solved this problem by developing the Observer, a metal detector that first passes a magnetic field over the product to be tested. Stainless steel is generally not magnetic because the chromium and nickel it contains interferes with its structure.
However, the pre-magnetisation step in the Observer hikes the remnant magnetic signal in even stainless steel so that a new magnetic field sensor unit - developed by Sartorius in tandem with STL of Germany - can pick it up. This sensor can also strip out the interference caused by the aluminium, which is non-magnetic and practically transparent the Observer.
Sartorius claims that "conventional detectors that operate on the basis of electromagnetic alternating fields bump up against their limits when they encounter packaging, or parts of packaging, based on aluminium".
Andrew Hallitt, Sartorius' brand manager for checkweighing and metal detection, told In-Pharmatechnologist.com that at present only expensive X-ray machines - costing in the region of £25,000 - can be used to detect stainless steel contamination. They also require elaborate safety measures to ensure operatives are protected against radiation.
The Observer has only been launched for about a month and costs around £18,000, something of a premium over conventional metal detectors that generally cost around £10,000.
Meanwhile, the Observer can also be used to detect product flow in stainless steel pipes, opening up additional applications in the processing industries.