IR for medical applications

Light plays an extremely important role in all aspects of medicine. Looking beyond the visible spectrum, infrared can also play an important role, measuring the things we cannot see with the human eye.

A group from Frankfurt Johann Wolfgang Goethe-University, Germany, has developed a method of glucose detection based on photothermal deflection.

A pulsed Quantum Cascade Laser (QCL) is used on the skin, and due to the LWIR absorption characteristics of glucose, the skin absorbs a certain amount of light; heating it up. This energy is transferred to a prism via contact, changing the refractive index and hence the total internal reflection. A spectrum can then be taken by tuning the QCL over a wide range giving the concentration of glucose present in the blood. The goal is to create a non-invasive blood-glucose monitoring system, avoiding the need for diabetic patients to draw blood.