Portable impedance based chemical sensor
Inventors
Hauser, Adam • Soliz, Jennifer Rose • Ranjit, Smriti
Assignees
University of Alabama at Birmingham UAB • US Army Edgewood Chemical and Biological Center • Government of the United States of America
Publication Number
US-12111278-B2
Publication Date
2024-10-08
Expiration Date
2039-04-30
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Abstract
An apparatus for sensing a target analyte includes a sensing material of a baseline composition. The sensing material is in electrical communication with an alternating energy input across the sensing material at a first frequency. The sensing material is configured to be placed within an environment such that an exposed state is in communication with a concentration of a target analyte proximate the sensing material, and wherein the target analyte changes at least one compositional property of the baseline composition. An impedance detection device is connected to a sensing circuit and receives an output from the sensing material, the output exhibiting a respective impedance value of the sensing material corresponding to the input for the first frequency. The respective impedance value is dependent upon the concentration of the target analyte in the environment and the first frequency.
Core Innovation
The invention relates to an apparatus for sensing a target analyte using a sensing material having a baseline composition. This sensing material is in electrical communication with an alternating energy input, such as AC voltage or current, applied across the material at a first frequency. The sensing material is placed within an environment so that an exposed portion interacts with a concentration of the target analyte. The presence of the analyte changes at least one compositional property of the sensing material's baseline composition, altering its impedance value for the applied frequency.
The apparatus includes an impedance detection device connected to a sensing circuit that receives an output from the sensing material. This output exhibits an impedance value that varies depending on the concentration of the target analyte and the frequency of the input signal. This impedance change reflects changes in the sensing material due to analyte presence and concentration. This approach enables frequency-dependent impedance spectroscopy (FDIS) to selectively detect target analytes in various environmental conditions.
The problem addressed is that current chemical sensing technologies are typically bulky, expensive, or lack selectivity, often providing a single measurement insufficient for detecting multiple target analytes simultaneously. Existing devices like mass spectrometry or electronic noses using DC resistivity are either too large or suffer from environmental interference and poor selectivity. There is a significant need for portable, selective chemical sensors that can rapidly identify multiple analytes with improved sensitivity and operate safely in diverse and even hazardous environments.
Claims Coverage
The claims disclose one independent claim and several dependent claims relating to a sensing apparatus with specific compositions and methods to detect target analytes via impedance changes.
Sensing material composition with dopant for selectivity
The apparatus includes a sensing material comprising a baseline metal hydroxide or mixed metal hydroxide composition doped with specific dopants (e.g., CoCl2, CuS2, FeCl3, lanthanide salts) which react with the target analyte to impart selectivity.
Electrical communication with AC energy input and impedance detection
The sensing material is connected to an energy source applying an AC voltage or current at a first frequency, with an impedance detection device measuring the material's output impedance value that depends on the dopant, analyte concentration, and frequency.
Structural features enabling analyte interaction
The sensing material structure, including thickness and bond angles, facilitates a reaction with the dopant that changes the composition and is reflected in the impedance measurement.
Frequency spectrum scanning and threshold impedance changes
The energy source can scan across a frequency spectrum, with changes in impedance relative to a baseline profile exceeding a threshold indicating analyte presence and allowing tuning of selectivity and sensitivity via the threshold value.
Hydrophobic and nonpolar sensing materials
The sensing material can be hydrophobic and nonpolar to reduce interference and improve selectivity for target analytes.
Use of specific materials including graphene oxide and porous films
The sensing material includes films that may be porous and may comprise materials such as graphene oxide to enhance analyte adsorption and impedance response.
The claims collectively focus on a sensing device with a doped metal hydroxide-based material that reacts chemically to target analytes, with associated circuitry applying and measuring AC impedance across frequencies to identify analyte presence and concentration, emphasizing structural and material features that allow selective and sensitive detection through impedance changes.
Stated Advantages
Provides portable, selective identification of various target analytes in different environments using a single sensor material.
Improves sensitivity and selectivity by using frequency-dependent AC impedance measurements rather than DC, thereby reducing environmental interference.
Enables rapid detection with reaction times on the order of one second or less.
Allows non-contact chemical detection enhancing user safety, particularly for hazardous substances like fentanyl analogs.
Miniaturizable design suitable for integration with flexible, wearable, or transparent substrates and use with smartphone interfaces and networked systems.
Documented Applications
Rapid, non-contact detection of airborne chemical agents including fentanyl and fentanyl analogs for defense and law enforcement.
Detection of explosives, chemical weapons, industrial toxins, and narcotics in environmental monitoring and security scenarios.
Use in medical, life sciences, and industrial chemistry for on-site chemical sensing and diagnostic applications.
Integration with smartphones and wireless communication for remote monitoring and Internet-of-Things implementations.
Adaptations for aqueous environments such as water treatment facilities and blood testing by controlling sensor layer and circuit parameters.
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