Principles for Measurement of Chemical Exposure Based on Recognition-Driven Anchoring Transitions in Liquid Crystals
Rahul R. Shah,*
Nicholas
L. Abbott
The competitive binding of a molecule forming a liquid crystal and
a targeted analyte to a common molecular receptor presented at a solid
surface possessing nanometer-scale topography is used to trigger an
easily visualized surface-driven change in the orientation of a
micrometer-thick film of liquid crystal. Diffusion of the targeted
analyte from atmosphere to surface-immobilized receptor across the
micrometer-thick film of liquid crystal is fast (on the order of
seconds), and the competitive interaction of the targeted analyte and
liquid crystal with the receptor provides a high level of tolerance to
nontargeted species (water, ethanol, acetone, and hexanes). Systems
that provide parts-per-billion (by volume) sensitivity to either
organoamine or organophosphorus compounds are demonstrated, and their
use for imaging of spatial gradients in concentration is reported. This
approach does not require complex instrumentation and could provide the
basis of wearable personalized sensors for measurement of real-time and cumulative exposure to environmental agents.
Department of Chemical Engineering, University of Wisconsin,
Madison, WI 53706, USA.
*
Present address: 3M Center, 3M Corporation, St. Paul, MN 55144, USA.
To whom correspondence should be addressed. E-mail:
abbott{at}engr.wisc.edu
