Journal Article

Valve controlled fluorescence detection system for remote sensing applications

James, T. D., Krauss, T. F., Scullion, M. G., Ashok, P. C., Di Falco, A., Dholakia, K.

2011

Overview

We demonstrate a microfluidics-based fluorescence detection device where the filters, source, detector, and electronically controlled valves are embedded into a Polydimethylsiloxane (PDMS)-based microfluidic chip. The device reported here has been specifically designed for chlorophyll a fluorescence sensing in autonomous systems, such as oceanic applications. In contrast to a monolithic approach, the modular approach made the fabrication of this device simpler and cheaper. For fluorescence detection, an InGaN/GaN LED is used as the excitation source to specifically excite chlorophyll a; a metal-dielectric Fabry–Perot filter was used to extinguish out-of-band excitation. A simple Si photodiode is used as detector and provided with a thermally evaporated CdS emission filter to block the excitation source. This filter combination provides an excellent solution to the difficult problem of combining high-rejection excitation and emission filters in an integrated thin-film format. Furthermore, the metal-dielectric filter provides a much broader angular response than a comparable multilayer Bragg mirror, which is a key advantage in the integrated format. We use a novel paraffin wax-based valve design affords low power single-use actuation, between 0.5 and 1 J per actuation and withstands 0.6 bar differential pressure, which provides better performance than its previously reported counterparts. The remote valve-controlled operation of the fluorescence detection system is demonstrated, illustrating the measurement of a chlorophyll a solution, with a detection limit of 340 μM and subsequent valve-controlled flushing of the measurement reservoir.

• Publisher: Springer-Verlag,Springer,Springer Nature B.V
• Subject: Analytical Chemistry / Biological and medical sciences / Biomedical Engineering and Bioengineering / Biosensors / Biotechnology / Chlorophyll / Emissions / Engineering / Engineering Fluid Dynamics / Fabrication / Filters / Fluorescence / Fundamental and applied biological sciences. Psychology / Methods. Procedures. Technologies / Nanotechnology and Microengineering / Remote sensing / Research Paper / Thin films / Various methods and equipments