Since January 2016, FBH and eight other partners from the Research Alliance Leibniz Health Technologies are collaborating in the EXASENS project for research in on point-of-care (POC) technologies to predict and diagnose chronic inflammatory respiratory diseases such as asthma or chronic obstructive pulmonary disease, COPD. The Alliance is backed by 6.25 million Euros from the German Federal Ministry of Education and Research (BMBF).
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.
The Laser Sensors Lab and FBH are developing compact light sources as key components for the POC system, among other things, employing Shifted Excitation Resonance Raman Difference Spectroscopy (SERRDS). The diode laser modules deliver two excitation lines at 532 nm with a close spectral distance of about 10 cm-1. Applying SERRDS separates Raman signals from interfering signals such as fluorescence or ambient light. An additional requirement for the light source is rapid spectral switching between the excitation wavelengths. This, in turn, allows for much shorter measuring times and thus faster diagnoses than ever before.
The light sources are realized by single-pass frequency conversion of dual-wavelength Y-branch DBR diode lasers in ridge waveguide nonlinear crystals. This requires precise adjustments of the diode laser properties to the tolerances of the required third-party non-linear crystals. Thus, utmost precision in the waveguide design of the diode lasers and the manufacturing of the laser’s wavelength-stabilizing gratings are crucial. Additional heating elements along the grating section are installed and allow precise adjustment of the wavelength by altering the temperature of the intrinsic grating. Switching between the two wavelengths is done directly via the active gain sections.
Exasens (duration 01.12.2015 - 30.04.2019)
Funding: BMBF grant number 13N13858