Methods for fabricating microfluidic structures

The present invention relates generally to optical devices and, more particularly, to a microfluidic device defined by a plurality of parallel, elongate channels for containing a sample and optical apparatus for irradiating a sample in the channels and measuring absorption of the sample and diffraction of electromagnetic radiation by the system for sensor and modulation applications. A system is provided for positioning separate portions of a sample in elongate, parallel channels of a sample chamber and to irradiate a sample in the chamber to create a diffraction pattern where the sample and chamber differ in refractive index. The system also can measure absorption of electromagnetic radiation by a sample in the chamber, and can measure the absorption simultaneously with measurement of diffraction by the sample.