Quantum cascade lasers ‘can detect falsified drugs’

Researchers at the Fraunhofer Institute in Germany have developed a miniaturised quantum cascade laser (QCL) device that could provide a new, no-contact way of rapidly distinguishing falsified from genuine medicines.

The matchbox-sized unit has already showed its security potential in the rapid detection of explosive or toxic substances – at a distance of several metres – and Fraunhofer is in the process of seeking out industry partners to develop that commercial application. At the same time, it is assessing QCL for pharmaceutical applications, including not only detection of counterfeits but also monitoring the quality of medicines during manufacturing.

The semiconductor-based infrared laser technology comes from a tie-up between Fraunhofer’s Dresden-based Institute for Photonic Microsystems IPMS – which has been working on the detector component of the device – and its Institute for Applied Solid State Physics which developed the tunable laser chips.

The premise behind the device is that virtually every chemical absorbs light in the mid-infrared wavelength range (4-10μm), and their absorption bands are “as characteristic as a fingerprint in humans”, according to the institute, which notes it can be used to identify solids, liquids and gases. Each scan only takes a few milliseconds, so it can operate at real-time production speeds.

It is possible to differentiate various drugs – Fraunhofer has already tested with aspirin and acetaminophen – from other substances such as glucose by simply illuminating tablets with the laser. A detector receives the backscattered light and the resulting absorption bands are evaluated by a computer and cross-referenced with a database.

“If we irradiate a substance with a specific light source, we receive a very characteristic backscattering signal,” says Dr Ralf Ostendorf, head of the semiconductor laser unit at Fraunhofer. “The mid-infrared spectrum (MIR) is particularly well-suited for an unambiguous identification of substances.”

The technology has already been incorporated in a handheld device for hazardous substance detector that Fraunhofer is hoping to develop for use by enforcement agencies, and a similar unit could be developed to help identify falsified medicines in the field, for example by customs agents.

Using such a device may make it possible in future to identify some substances that at the moment require time-consuming laboratory analysis, says Ostendorf.

Initial talks have already taken place to develop the system for pharmaceutical applications. “In a next step, we want to use our sensors to detect individual substances in a drug mixture,” he notes.