Apparatuses, systems, and methods for sample testing

A sample testing device comprising:

• a substrate layer defining a bottom surface of the sample testing device;
• a waveguide disposed on the substrate layer and comprises at least one reference channel and at least one sample channel;
• and
• a processor configured to align a laser source to the waveguide by causing the laser source or an optical element from which a laser emitted by the laser source is refracted or reflected to move in a vertical dimension until detecting a change in a back-reflected power from a surface of the waveguide.