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The influence of the mechanical bending, rolling and crimping of flexible screen-printed electrodes upon their electrical properties and electrochemical behavior has been elucidated. Three different flexible plastic substrates, Mylar, polyethylene naphthalate (PEN), and Kapton, have been tested in connection to the printing of graphite ink working electrodes. Our data indicate that flexible printed electrodes can be bent to extremely small radii of curvature and still function well, despite a marginal increase the electrical resistance. Below critical radii of curvature of ~8 mm, full recovery of the electrical resistance occurs upon strain release. The electrochemical response is maintained for submm bending radii and a 180° pinch of the electrode does not lead to device failure. The electrodes appear to be resistant to repeated bending. Such capabilities are demonstrated using model compounds, including ferrocyanide, trinitrotoluene (TNT) and nitronaphthalene (NN). These printed electrodes hold great promise for widespread applications requiring flexible, yet robust non-planar sensing devices.

Rapid detection of the hydrogen peroxide precursor of peroxide explosives is required in numerous security screening applications. We describe a highly sensitive and selective amperometric detection of hydrogen peroxide vapor at an agarose-coated Prussian-blue (PB) modified thick-film carbon transducer. The sensor responds rapidly and reversibly to dynamic changes in the level of the peroxide vapor, with no apparent carry over and with a detection limit of 6 ppbv. The remarkable selectivity of the PB-based screen-printed electrode towards hydrogen peroxide leads to effective discrimination against common beverage samples. For example, blind tests have demonstrated the ability to selectively and non-invasively identify concealed hydrogen peroxide in drinking cups and bottles. The attractive performance of the new microfabricated PBbased amperometric peroxide vapor sensor indicates great potential for addressing a wide range of security screening and surveillance applications.

A highly selective and rapid electrochemical assay of the improvised explosive urea nitrate (UN) is reported. The method involves a short ( approximately 10 s) acid-catalyzed reaction of UN with 4-nitrotoluene (NT) followed by a rapid ( approximately 2 s) square-wave voltammetric (SWV) detection of the 2,4-dinitrotoluene (DNT) product. The new protocol offers great promise for a reliable field detection of UN, with significant advantages of speed, sensitivity, portability, simplicity, and cost.

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