Perforated contact electrode on vertical nanowire array
Inventors
In, Hyun Jin • Field, Christopher • Pehrsson, Pehr E.
Assignees
Publication Number
US-10167192-B2
Publication Date
2019-01-01
Expiration Date
2031-11-10
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Abstract
Disclosed herein is a structure having: a support, a plurality of nanowires perpendicular to the support, and an electrode in contact with a first end of each nanowire. Each nanowire has a second end in contact with the support. The electrode contains a plurality of perforations. The electrode contains a plurality of perforations. Also disclosed herein is a method of: providing the above support and nanowires; depositing a layer of a filler material that covers a portion of each nanowire and leaves a first end of each nanowire exposed; depositing a plurality of nanoparticles onto the filler material; depositing an electrode material on the nanoparticles, the ends of the nanowires, and any exposed filler material; and removing the nanoparticles and filler material to form an electrode in contact with the first end of each nanowire; wherein the electrode contains a plurality of perforations.
Core Innovation
The invention describes a structure comprising a support, an array of nanowires perpendicular to the support, and an electrode in contact with the first end of each nanowire, where the electrode contains multiple perforations. Each nanowire has a second end contacting the support. The electrode's perforations form open spaces normal to the support, allowing a straight-line path completely through the electrode.
The invention addresses the challenge in sensor devices of making electrical connections to each nanowire in a vertical nanowire array while enabling rapid analyte access to the nanowire tips. Existing methods do not achieve a porous or perforated electrode with controllable hole size and distribution over nanowire arrays. This structure overcomes limitations by providing perforated electrodes, especially with periodic and well-defined hole arrays, facilitating rapid gas or liquid flow to the sensing nanowires underneath while maintaining electrical contact.
Also disclosed are methods to fabricate such perforated electrodes via depositing filler material over the nanowires leaving their tips exposed, placing nanoparticles onto the filler to define hole locations, depositing electrode material over nanoparticles, wire tips, and exposed filler, then removing the nanoparticles and filler to create the perforated electrode. The perforation properties including pitch and diameter can be controlled by adjusting nanoparticle size and etching parameters. The structure and method benefit sensor performance by maximizing gas flow and electrical contact in massively parallel arrays of vertical nanowires.
Claims Coverage
The patent contains two independent claims covering the structure with perforated electrodes and a method of measuring electrical property changes upon exposure to a sample. The following inventive features are identified from these claims.
Structure with perforated electrode in contact with vertical nanowires
A structure comprising a support, a plurality of nanowires perpendicular to the support with each nanowire's second end contacting the support; and an electrode in contact with the first end of each nanowire; wherein the electrode contains a plurality of perforations forming open spaces that pass completely through the electrode normal to the support.
Sensor using the structure to measure electrical property changes
A sensor comprising the above structure and a meter coupled to measure an electrical property of the structure, enabling detection of changes when exposed to a sample.
Method of detecting analytes via electrical measurement
A method comprising providing the above structure, exposing it to a sample, and detecting any change in an electrical property of the structure.
The independent claims cover both the novel perforated electrode structure on vertical nanowire arrays and its application as a sensor through electrical property measurements, including the method of detecting analytes by observing changes upon exposure.
Stated Advantages
The perforated electrode allows rapid gas or liquid flow through the electrode and nanowire array, improving sensor response speed and sensitivity.
The self-assembled close-packed nanosphere method enables automatic formation of periodic perforations without complex alignment, scalable to large areas or entire wafers.
The massively parallel vertical nanowire configuration connected via the perforated electrode minimizes noise sources such as 1/f noise, enhancing signal-to-noise ratio and measurement reliability.
The porosity of the top electrode layer facilitates uniform analyte exposure to all nanowires, reducing diffusion-limited response times and improving detection at low analyte concentrations.
Documented Applications
Gas and liquid phase sensing for detection of chemical warfare agents, explosives, chemical or biological agents, and toxic industrial chemicals using electrical measurement changes in the nanowire array sensor.
Sensitive detection of nitrogen dioxide and ammonia in humidified air at ppb concentration levels for environmental monitoring.
Use in field-deployable sensors that are selective, sensitive, miniature, fast, low power, and suitable for complex environments such as battlefields or airports.
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