Templated nanostructure sensors and methods of manufacture
Inventors
Biaggi-Labiosa, Azlin M. • Hunter, Gary W.
Assignees
National Aeronautics and Space Administration NASA
Publication Number
US-11192780-B1
Publication Date
2021-12-07
Expiration Date
2033-03-07
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Abstract
A microsensor and its method of manufacture are disclosed based on templated metal or metal oxide nanostructures. The microsensor includes an electrode that in one embodiment may be configured as a first sawtooth patterned electrode having a series of first peaks and first valleys and a second electrode that by be configured as a second sawtooth patterned electrode having a series of second peaks and second valleys where the second peaks generally align with the first peaks of the first electrode. A plurality of templated metal or metal oxide nanostructures connect on one side to the first electrode and on another side to the second electrode, where an electrical property of the microsensor changes in response to exposure to an environment to be monitored.
Core Innovation
The invention concerns a microsensor and methods of manufacture based on templated metal or metal oxide nanostructures. The microsensor includes electrodes configured in patterns, such as sawtooth patterns, between which templated nanostructures are aligned and electrically connected. These nanostructures have crystal patterns and morphological properties imprinted from a sacrificed structural template, forming a sensor whose electrical properties change in response to environmental exposure.
The problem addressed is improving the control of structural and morphological properties of metal oxide and metal nanostructures to produce improved chemical sensor systems. Existing metal oxide sensors, though sensitive, often operate at high temperatures and face challenges in fabricating nanostructures with controlled morphology and alignment for enhanced sensing. The invention seeks to develop sensors that are small, low cost, easy to batch fabricate, have low power consumption, and reduced operational temperatures with increased sensitivity and selectivity.
Claims Coverage
The patent includes two independent claims detailing the microsensor structure and composition. The main inventive features relate to the templated nanostructures, electrode patterns, and the sensor's functional responses.
Microsensor structure with templated nanostructures
A microsensor comprising a first and second electrode deposited onto a substrate, with templated nanostructures aligned between electrode tips. These nanostructures electrically connect opposing electrodes and are buried by a top electrode. The nanostructures comprise metal oxide precipitates with crystal patterns and interior morphology imprinted from a sacrificed template, where crystallite size is less than twice the depletion layer depth, enabling sensing via changes in electrical properties upon environmental exposure.
Sawtooth patterned electrodes for nanostructure alignment
The first and second electrodes are patterned and aligned with each other, comprising sawtooth patterns whose peaks align such that templated nanostructures are positioned between the tips of these sawtooth patterns, enhancing nanostructure alignment and sensor performance.
Templated nanostructures from sacrificial templates on alumina substrates
Microsensors having tin oxide and other metal oxide templated nanostructures formed using sacrificial structural templates like multiwalled carbon nanotubes on alumina substrates, where the templated nanostructures retain the morphology and crystal patterns of the template for improved sensing.
The claims collectively cover a microsensor design leveraging templated metal oxide nanostructures electrically connected between patterned electrodes on substrates. The use of templated nanostructures with precise morphology imprinted from sacrificial templates, alignment via sawtooth electrode patterns, and sensor operation based on changes in electrical properties upon exposure to selected contaminants constitute the core inventive aspects.
Stated Advantages
Low power consumption due to operation at room temperature without heating requirements.
Small sensor size and low weight enabling miniature form factors.
Simple batch fabrication using microfabrication techniques and dielectrophoresis for alignment, allowing high yield and low cost.
Increased sensitivity resulting from templated nanostructures having large surface area and porosity which enable gas molecules to interact with both inner and outer surfaces.
Robust structure with stable long-term sensor performance demonstrated through extended testing.
Documented Applications
Environmental monitoring of gases including methane, hydrogen, hydrocarbons, nitrogen oxides, fluorines, chlorines, ammonia, hydrazine, and formaldehyde.
Explosive gas monitoring.
Detection of biological agents and biological molecules such as cells, viruses, or proteins.
Sensing in both air and aqueous environments.
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