Three-dimensional photonic devices fabricated by ultrafast lasers for optical sensing in lab-on-a-chip

We report on the use of femtosecond laser pulses to fabricate photonic devices (waveguides and interferometers) inside commercial CE chips without affecting the manufacturing procedure of the microfluidic part of the device. The fabrication of single waveguides intersecting the channels allows one to perform absorption or Laser Induced Fluorescence (LIF) sensing of the molecules separated inside the microchannels. Microfluidic channels, with access holes, are fabricated using femtosecond laser irradiation followed by chemical etching. Mach-Zehnder interferometers are used for label-free sensing of the samples flowing in the microfluidic channels by means of refractive index changes detection.