Single Particle Detector Using the Evanescent Field of a Silicon Nitride Waveguide

The interaction between analytes and the evanescent field of a waveguide can be exploited for highly sensitive measurement devices, which find already wide usage as chemical and biological sensors. Based on this sensor principle, we designed a single particle detector, featuring a silicon nitride waveguide with sub-micron dimensions, a diode laser, and a photodetector. The first prototype provides single counting efficiency for PSL spheres down to a diameter of 200 nm.