Monday, June 18, 2007 - 9:40 AM
The Kestrels (Boise Centre on the Grove)

Field portable electrochemical sensor for uranium and other actinides in aqueous samples

Noah Minskoff, Boise State University, Boise, ID and Dale D. Russell, Boise State University, Boise, ID.

A rugged, solid state field portable sensor for water-borne actinide species has been demonstrated with 10 part-per-trillion detection limit for UO22+ ion. A semiconductive polymer is prepared with selective binding sites, calix-6-arene (C[6]A). These chelating rings have high formation constants with actinide ions having the form MO22+ or MO2+, where M is the actinide metal. The binding site specificity for actinide ions largely excludes chemical interferences such as other heavy metal ions, and preconcentrates the actinide species on the polymer. When actinide ions bind into the polymer, they can be detected by the redox properties of the actinide metal itself, or by changes in the electronic or electrochemical properties of the polymer. Two detection modes have been demonstrated. In one mode, a cyclic voltammogram is recorded in which the potential of electron transfer is correlated to the identity of the actinide species present, and the current of the peak(s) correlates to concentration (s). In the second mode, the actinide-binding polymer is coated onto the gate of a field effect transistor (FET). In operation, as actinide ions bind to the polymer, the gate potential changes thus changing the source-drain current correspondingly. Both detection systems are housed in a single package for hand-held or autonomous deployment. The power requirement is very low (~ 9 volts), and signal transmission is possible for remote applications or long term in-situ deployment. The entire sensor weighs less than a kilogram, including power supply, control electronics, data collection and signal transmission systems.