Nanowire arrays for trace vapor preconcentration
Inventors
Giordano, Braden C. • Pehrsson, Pehr E. • Johnson, Kevin J. • Ratchford, Daniel • Field, Christopher • Yeom, Junghoon
Assignees
Publication Number
US-11046579-B2
Publication Date
2021-06-29
Expiration Date
2031-11-10
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Abstract
Disclosed herein is a method of providing a structure having two electrodes connected by nanowires, exposing the structure to an analyte that can adsorb onto the nanowires, and passing an electrical current through the nanowires to heat the nanowires to desorb the analyte. Also disclosed herein is an apparatus having the above structure; a current source electrically connected to the electrodes, and a detector to detect the analyte.
Core Innovation
The invention disclosed presents a method and apparatus involving a structure comprising two electrodes connected by a vertical array of nanowires. This structure is exposed to a sample potentially containing an analyte capable of adsorbing onto the nanowires. Subsequently, an electrical current is passed through the nanowires, causing Joule heating, which raises the nanowires' temperature to a level sufficient for desorbing the analyte.
The disclosed structure includes the ability to form either solid or perforated top electrodes with an ordered or disordered arrangement of nanowires. The perforations in the electrode layer allow gases or liquids to flow rapidly through the electrode to the nanowire sensing region, enhancing analyte contact rate. The nanowires can be made of silicon or other materials and can have chemically selective surfaces to improve analyte retention and selectivity. The apparatus further includes a current source electrically connected to the electrodes and a detector for sensing the desorbed analyte, optionally coupled to a gas chromatograph.
Claims Coverage
The patent includes two independent claims directed to a method and an apparatus. Each claim focuses on structures with nanowires having multiple chemically selective surfaces and electrodes connected to both ends of the nanowires.
Nanowires with multiple chemically selective surfaces
The nanowires comprise two or more different chemically selective surfaces to enhance analyte specificity and adsorption properties.
Structure with electrodes contacting both nanowire ends
A structure includes a first electrode contacting one end of each nanowire and a second electrode contacting the opposite end, enabling electrical current passage for Joule heating.
Passage of electrical current to heat nanowires for analyte desorption
Application of electrical current through the nanowires to raise their temperature to desorb adsorbed analytes.
Second electrode with optional perforations
The second electrode can be perforated with controlled hole size and arrangement, enabling analyte access through the electrode to the nanowires.
Apparatus comprising nanowire structure, current source, and detector
An apparatus that includes the nanowire structure, an electrically connected current source to heat the nanowires, and a detector capable of sensing the desorbed analyte.
Detector varieties and additional chromatography
The apparatus may include detectors such as mass spectrographs, ion mobility spectrographs, fluorescence probes, microcantilevers, chemiresistors, or nanowire arrays, optionally combined with a gas chromatograph before detection.
The independent claims cover a method and an apparatus employing vertically aligned nanowires with multiple chemically selective surfaces connected between two electrodes, wherein electrical current induces Joule heating to desorb adsorbed analytes, and wherein the apparatus includes various detector configurations to detect the analytes after desorption.
Stated Advantages
The perforated top electrode enables rapid analyte flow through the electrode and nanowire array, resulting in fast response rates and high sensitivity.
Highly ordered silicon nanowire arrays allow efficient preconcentration and partial separation of trace analytes, improving sensitivity and selectivity.
The use of Joule heating provides rapid and controlled thermal desorption spectra facilitating unique analyte analysis profiles.
The approach reduces the complexity and size of traditional analytical instruments and decreases total analysis time.
Integration with various detectors, including mass spectrometry and ion mobility spectrometry, enables versatile detection methods.
Minimized eddy diffusion during desorption improves measurement precision and analyte concentration delivered to the detector.
The self-assembly fabrication method allows for scalable and reproducible formation of periodic perforations without requiring alignment, facilitating large-area manufacturing.
Documented Applications
Detection and partial separation of trace vapor explosives such as 2,4-DNT, TNT, nitrobenzene, and related compounds by preconcentration on the silicon nanowire arrays followed by thermal desorption and detection.
Non-contact or standoff sensing of trace explosives vapors in complex environments like battlefields or airports.
Integration as a front end preconcentrator for portable multichannel detectors such as mass spectrometers or ion mobility spectrometers.
Calibration of vapor detectors by delivering metered doses of vapor through controlled nanowire heating and desorption.
Gas and liquid phase sensing including detection of chemical warfare agents, toxic industrial chemicals, and chemical or biological agents employing nanowire-based sensors.
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