On-the-flow absorption and refractive index measurements in a microfluidic device
Conferences & Talks

• Markus Beck
• Peter Kiesel
• Joerg Martini
• Noble Johnson

BIOS 2009 (part of SPIE Photonics West) -- Microfluidics, BioMEMS, and Medical Microsystems

24 January 2009 - 29 January 2009
San Jose, California, USA

description

In conventional absorption spectroscopy the detection of small absorption changes requires a long interaction length, typically on the order of the absorption length, and therefore large sample volumes. In a lab-on-a-chip approach, the interaction length must be prolonged inside the device. We enhance the sensitivity with a Fabry-Pérot etalon inside a microfluidic channel. While the changes of the refractive index result in a shift of the Fabry-Pérot peak position, absorption within the optical cavity is causing a change of the amplitude and the width of the modes. The method is insensitive to intensity variations outside the fluidic channel since the transmitted light also provides the referencing signal.