Piezoelectric sensors and quartz crystal monitors
Inventors
Schlereth, Fritz H. • Spencer, James
Assignees
Publication Number
US-11187680-B2
Publication Date
2021-11-30
Expiration Date
2037-09-08
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Abstract
Surface modifications and improvements to piezoelectric-based sensors, such as QCMs and other piezoelectric devices, that significantly increase the sensitivity and the specificity (selectivity). These modifications can comprise mechanical and chemical changes to the surfaces of the sensors, either individually or together. For example, nanosize structures may be provided on the surface to improve sensitivity. Additionally, chemical coatings may be tethered to the surfaces, walls, or crystal to provide targeted sensitivity. Additionally, porous, layered and multiple sensor arrays may be formed to enhance sensitivity and selectivity.
Core Innovation
The invention provides surface modifications and enhancements to piezoelectric-based sensors, such as quartz crystal monitors (QCMs) and related devices, to significantly increase their sensitivity and specificity. These modifications include the introduction of nanoscale structures such as upstanding walls on sensor surfaces, as well as chemical coatings that are either individually or jointly applied. Nanosize structures, such as nanowalls, improve the sensor’s detection capabilities by enhancing physical interactions with target molecules.
To further improve selectivity, the invention introduces the use of tethered chemical linkers and functional groups, including biochemical moieties, that interact specifically with target analytes. Additionally, porous, layered, and multi-sensor array designs can be formed, which increase both the surface area and the specificity for the detection of various compounds. These mechanical and chemical surface modifications can be applied across different piezoelectric materials, including quartz and piezoelectric composite polymers.
The problem addressed by this invention is the need for greater sensitivity and specificity in piezoelectric sensor systems, which is necessary to meet the demands of new applications such as biochemical, environmental, and explosives detection, as well as intrusion detection. Existing QCM and piezoelectric sensors do not provide sufficient sensitivity and selectivity for these advanced use cases, thus novel surface engineering and functionalization approaches as described are needed.
Claims Coverage
The patent includes two independent claims, each focused on distinct inventive features regarding piezoelectric sensor structure and surface functionalization.
Piezoelectric sensor with nanoscale upstanding walls for molecule detection
A sensor comprising: - A sensing oscillator formed from a piezoelectric material having an upper surface. - A plurality of upstanding walls positioned directly on the upper surface, wherein the walls have: - Height between 100 and 1000 nanometers - Width between 100 and 500 nanometers - Length between 2 and 4 millimeters - Spaced apart by between 100 and 1000 nanometers - These walls define a volume for entrapping at least one molecule to be detected, causing collisions with the walls. - A reference oscillator coupled to the sensing oscillator, configured to detect collisions based on changes in the relative phase between the sensing and reference oscillators.
Functionalized porous piezoelectric sensor with silane-tethered functional groups
A sensor comprising: - A piezoelectric material having an upper surface that defines a plurality of pores. - A plurality of functional groups attached to the upper surface by a tether comprising a silane and located within these pores. This foundational claim covers functionalization of porous piezoelectric sensors using specific chemical tethering within the pores of the substrate.
In summary, the inventive features cover the integration of nanoscale upstanding walls for enhanced molecule detection via phase measurement, and the use of silane-tethered functional groups within porous piezoelectric materials to provide targeted analyte interaction and improved selectivity.
Stated Advantages
Significantly increases the sensitivity and specificity (selectivity) of piezoelectric-based sensors such as QCMs.
Enables differentiation between various molecular targets and tuning for sensitivity to a select group of reagents at exceptionally low concentrations.
Allows measurable frequency or phase changes due to increased residence time of target analytes, facilitating detection at very low concentrations.
Permits selective and sensitive detection of key target molecules using chemically functionalized sensor surfaces.
Provides design flexibility with three-dimensional porous and layered structures, further increasing surface area and improving both sensitivity and selectivity.
Permits rapid, inexpensive, and simple analysis of key biochemical/chemical markers at the ppb level in under 10 seconds of analytic time.
Supports robust, multi-agent capable, low-cost sensor systems suitable for operation in both gas and liquid phases under extreme environmental conditions.
Documented Applications
Dew point detection and measurement in environmental monitoring
Chemical and biomolecular detection, including detection of DNA, RNA, and related biochemical markers
Gaseous compound determination and CO2/exhaled gas detection
Medical diagnostics for early-stage medical conditions by detecting biochemical markers from breath, sweat, and body fluids
Forensic identification and rapid species identification using nucleotide and biomolecule analysis
Explosives detection and environmental monitoring
Networkable multi-agent sensor/detector systems for remote operation and automated monitoring
Automated or field analysis of suspected drug samples
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