Pittcon 2012 - Bioanalytical Microfluidics and Emerging Nanotechnologies - Abstract 4
This session was webcast at Pittcon 2012 in Orlando, Florida on Monday, March 12, 2012.
TITLE: Immunoassay Signal Amplification Using 2-Dimensional Paper Networks
SPEAKER: Paul Yager
ABSTRACT OVERVIEW: We are working to combine the sophistication of the microfluidic circuit with the pump-free simplicity of capillary flow in what we are calling Microfluidics 2.0. Under support of an NBIB ARRA grant, we have been focusing on development of sophisticated but disposable 2-dimensional porous (or paper) networks (2DPNs) that allow programmed sequential delivery of an arbitrarily large set of reagents to specific sites on the devices. By limiting the devices as much as possible to single layer of porous material (plus an injection-molded housing), cost can be extremely low.
As a first challenge, we are targeting a high-value application—the development of multiplexed immunoassays that are made more sensitive than conventional lateral flow devices by performing chemical and biochemical amplification. The first challenge was to develop design tools for 2DPNs based on computation fluid dynamics. These have led to some simple design rules for controlling flow rates in the 2D structures. The next challenge was to develop methods for monitoring flow in the opaque 2DPN matrix, in which PIV techniques cannot be used. Two methods use optical absorbance or fluorescence to monitor the movement of a band of chemicals through the otherwise highly scattering matrix. Another challenge was to control the starting and stopping of fluid flows without conventional valves. Three methods for such control have been developed that cover most needs for these systems.
Using these tools, we have demonstrated a simple 2DPN design that allows automated instrument-free sequential delivery of reagents in a format ideally suited to inexpensive disposables, and have extended this to amplification chemistries, achieving much higher sensitivity without the need for a specialized reader.