Silicon Nanowire Vertical Arrays with Porous Top Electrodes for Trace Vapor Preconcentration and Partial Separation

B. Giordano, P. Pehrsson, K. Johnson
U.S. Naval Research Laboratory,
United States

Keywords: preconcentration, separation, trace

Summary:

Commercial Off the Self (COTS) technologies for chemical vapor detection of trace analytes in complex, unknown background environments, often underperform with respect to sensitivity and selectivity. We have developed a chemical preconcentrator based on a Silicon Nanowire Vertical Array with a Porous Top electrode (SiN-VAPOR) that will immediately improve COTS chemical vapor detectors. The array has a modular format which first preconcentrates trace chemical vapors such as explosives, CWA, opioids, and TICs, and then serially releases them by Joule heating. This approach greatly increases the downstream sensitivity of small, handheld chemical sensors by 1) increasing the amount of analyte delivered in a given time, and 2) expanding the detector’s data dimensionality by metered delivery of collected vapors using temperature-based desorption. Analyte discrimination may be further improved by selective functionalization of multiple nanowire arrays, i.e. a matrix of arrays. The desorption profiles from each component are analyzed using software to maximize information extraction. The nanowire arrays are small, light, fast, and have a low power budget, making them well-suited as the drop-in front end of existing detector technologies such as IMS and portable MS.