Research Alliance Leibniz Health Technologies

Prediction or early detection of acute, attack-like exacerbations by telemedicine-capable POC diagnosis systems could reduce the necessity for intensive medical measures and also improve prognoses. The ultimate goal is to have POC systems readily available for rapid intervention in acute situations, for individualized treatment, and for closely networked monitoring of disease progression and treatment, thereby significantly helping to improve quality of life.

Compact light sources for the POC system

FBH is developing the necessary compact light sources, and thus a key component, for the POC system which, among other things, employs Shifted Excitation Resonance Raman Difference Spectroscopy (SERRDS). The diode laser modules, which emit at 532 nm wavelength, deliver two excitation lines at a close spectral distance of about 10 cm^-1. When measuring two Raman spectra with excitation wavelengths at this distance, Raman signals can be separated from interfering signals such as fluorescence or ambient light. A particular requirement for the light source, which is only about half the size of a box of matches, is rapid spectral switching capability for the excitation wavelength. This, in turn, allows for much shorter measuring times and thus faster diagnoses than ever before.

SERRDS requires precise adjustment of the properties of two active components in the system: the diode laser as pump light source, and the crystal for non-linear frequency conversion. Because such SHG crystals are third-party components, the diode laser must be precisely adjustable to accommodate any manufacturers’ tolerances in the crystals. This demands utmost precision in the manufacture of the wavelength-stabilizing grating and in the lateral design of the waveguide in the semiconductor chip. Heating elements are also installed to allow precise adjustment of the wavelength by altering the temperature of the grating section. Switching between the two wavelengths is done directly via the active gain section.

The Alliance is backed by 6.25 million Euros from the German Federal Ministry of Education and Research (BMBF).

Among other things, the project aims to translate the method of integral field spectroscopy, which was born from astrophysics and is normally used to study large areas of the night sky, to biomedical imaging applications.

Raman-based diode lasers for tissue diagnostics

In this project, FBH is again developing the Raman-based diode lasers optimized for tissue diagnosis, as an important centerpiece of the system. The challenge lies in combining the high laser powers required for imaging with the spectral characteristics needed for spectroscopy and SERRDS. At the same time, the maximum permissible radiation doses must not be exceeded. FBH is therefore taking two approaches: it is developing a light source of 785 nm wavelength and up to 4 watt output power, plus a second beam source in the blue-green spectral range of 457 nm wavelength – a frequency range in which strong fluorescence occurs. This light source should be suitable for the SERRDS method and thus allow the separation of Raman signals and fluorescence for the imaging method as well.

The overall project started in 2016 and is planned to run for three years with approximately one million Euros in funding from the Leibniz competition.