Method and apparatus for detecting an analyte
Inventors
Allendorf, Mark D. • Hesketh, Peter J.
Assignees
National Technology and Engineering Solutions of Sandia LLC • Sandia National Laboratories
Publication Number
US-8065904-B1
Publication Date
2011-11-29
Expiration Date
2028-06-12
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Abstract
We describe the use of coordination polymers (CP) as coatings on microcantilevers for the detection of chemical analytes. CP exhibit changes in unit cell parameters upon adsorption of analytes, which will induce a stress in a static microcantilever upon which a CP layer is deposited. We also describe fabrication methods for depositing CP layers on surfaces.
Core Innovation
The invention describes the use of coordination polymers (CP) as coatings on microcantilevers to detect chemical analytes. The CP coatings exhibit changes in their unit cell parameters when adsorbing analytes. These changes induce stress in a static microcantilever on which the CP layer is deposited, thereby enabling detection of the analytes. The invention also includes fabrication methods for depositing CP layers on surfaces.
The problem being solved addresses the need for sensors capable of detecting molecular species at very low concentrations. Prior art microcantilever sensors use polymer coatings or other materials but lack the enhanced sensitivity that CP coatings can provide due to their structural flexibility and large changes in lattice dimensions upon adsorption. Existing nanoporous materials like zeolites do not exhibit the reversible and significant structural changes that CP materials do.
CP coatings on microcantilevers offer potential advantages such as large stress-induced signals caused by adsorption, owing to the pronounced changes in lattice dimensions of CPs. Additionally, some CP materials have very high surface areas, enhancing sorption capacities. The chemical nature of CPs can be tailored for selectivity and adsorption properties by altering linking molecules, metal centers, and pore geometry. Furthermore, effective mechanical linkage between the CP crystals and the microcantilever substrate can be achieved by covalent bonding schemes to ensure effective stress transfer.
Claims Coverage
The patent includes multiple independent claims covering sensing devices and methods involving microcantilever structures coated with coordination polymers (CP) or covalent organic frameworks (COF) for chemical analyte detection.
Sensing device using a microcantilever with CP coating causing strain upon analyte absorption
A sensing device comprises a microcantilever structure with a continuous or discontinuous absorbent crystalline layer made of a coordination polymer (CP) coating. The CP has a crystal lattice that changes dimensions when it absorbs a chemical analyte, inducing strain in the microcantilever and signaling the analyte's presence.
Sensing device using a microcantilever with covalent organic framework coating causing strain upon analyte absorption
A sensing device comprises a microcantilever structure with a continuous or discontinuous absorbent crystalline layer made of a covalent organic framework having a crystal lattice. The lattice changes dimension upon analyte absorption, causing strain in the microcantilever to indicate analyte presence.
Method of detecting a chemical species using a CP-coated microcantilever with piezoresistive sensing
The method involves providing a microcantilever with a piezoresistive element electrically connected to a resistance sensing meter, applying a continuous or discontinuous CP coating with a porous crystalline lattice to a major portion of the microcantilever surface, and exposing it to an environment containing the chemical species. The CP lattice dimension changes upon absorption, causing microcantilever strain and altering piezoresistor resistance to signal presence.
Method of detecting a chemical species using a covalent organic framework-coated microcantilever with piezoresistive sensing
This method entails providing a microcantilever with a piezoresistive element, applying a continuous or discontinuous covalent organic framework coating with a porous crystalline lattice on the surface, then exposing it to the chemical species. Changes in lattice dimension upon absorption cause strain and subsequent resistance change in the piezoresistive element, signaling the analyte.
The independent claims cover sensing devices incorporating microcantilevers coated with CP or COF materials that induce strain upon analyte absorption, and corresponding detection methods utilizing piezoresistive sensing to signal the presence of chemical species. The claims focus on the structure of the coatings, their interaction with analytes, and the resulting strain-induced detection mechanism.
Stated Advantages
CP coatings induce large stress signals due to significant lattice dimension changes upon adsorption, enhancing sensor sensitivity compared to polymer coatings.
CP materials can have very high surface areas (up to 6000 m²/g), enabling highly effective sorption of molecular species.
The chemical and structural properties of CPs can be tailored by varying linkers, metal centers, and pore geometry to achieve desired chemical selectivity and adsorption characteristics.
Strong covalent bonding between CP crystals and the microcantilever surface ensures effective mechanical linkage and stress transmission, improving sensor response.
Documented Applications
Detection of molecular species at very low concentrations in gaseous or liquid environments.
Use in sensors to detect trace material from surrounding air or liquid solutions.
Detection of various gases including water vapor, carbon dioxide, methanol, ethanol, carbon monoxide, nitric oxide, nitrous oxide, organic amines, and organic compounds containing NO2 groups.
Customization of CP coatings for use in dry atmospheres or aqueous/humid media depending on stability, such as using IRMOF-1 for gases in dry atmospheres or HKUST-1 for aqueous environments.
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