Integrated photonics enables sensitive and label-free optical biosensors for the detection of chemical and
biological substances and is therefore promising for future lab-on-chip solutions. In this article we present
our current development of silicon nitride based integrated photonic biosensing devices working at telecom
wavelengths. Our approach of three-port based interferometric sensing circumvents the issues of conventional
Mach-Zehnder interferometers, providing a constant sensitivity, and allowing to use a fixed wavelength sensing
scheme. Preliminary experimental results show that the fabricated devices work as expected from simulations.