Organic laser source enables disposable biosensors

Organic laser
Cheap, disposable organic biosensors such as blood glucose measurement strips are already helping to make medical tests affordable. The integration of a signal amplifier made of organic materials with a conventional organic laser source, devised by scientists of the Karlsruher Institut für Technologie (KIT), develop a perspective for a new class of cost-effective biosensors.

The first ever integration of a laser source with an organic amplifier on a silicon-based photonic chip is not only a remarkable achievement in the area of nanoelectronics, it also creates an enormous potential for cost-effective biosensors that can be used in near-patient testing, much like today’s disposable blood glucose test strips that can be used without any effort for sterilisation.

“This is the first ever implementation of an organic laser on a silicon photonics chip”, says Christian Koos a researcher at the KIT institutes for photonics and quantum electronics as well as at the institute for microstructure technology. “The most striking benefit of lasers is that they can be manufactured in large quantities at low cost. In the long run, a price of a few euro cents per laser is perceivable”.

A major challenge during the implementation of organic microchips poses the requirement of integrating multiple different components on a common substrate at low cost. Since several of years it is possible to manufacture optical components based on silicon. These so-called silicon photonics utilises advanced microelectronics manufacturing processes and thus makes it possible to produce sophisticated photonic components in large quantities and at low cost. These sub-micron components suit very well for the implementation of compact biosensors. However, it hitherto was not possible to implement light sources on such chips because silicon is not a good light emitter; it has a poor efficiency and tends to generate more heat than light.

The KIT researchers therefore have developed a new class of infrared laser sources. They combined silicon-based nano-scale waveguides with a polymer to which an organic pigment has been added. The operating energy for this “organic” laser source is fed from above, vertically to the chip area, by means of a pulsed light source. The laser light created this way is coupled directly into a silicon nanoscale waveguide. The researchers were able to generate a pulsed laser at a