Demonstration of a microfluidic polarimeter

Traditional methods of detecting chiral molecules, such as optical rotation are not suitable for miniaturization, since, the magnitude of the rotation of polarization scales down linearly with the optical path length of the device. Since the origin of optical activity is due to difference of refractive indices between the two circularly polarized states of light, it is possible to detect chiral media by measuring the dependence of the angles of refraction on the polarization state of the incident light. This however is a weak effect and hence requires sensitive optical detection schemes, based on novel polarization modulation techniques. The device can be scaled down for applications involving small sample volumes. Fabrication details of a prototype microfluidic device are described.