Dielectric sensing for sample characterization
Inventors
Suster, Michael • Mohseni, Pedram • Maji, Debnath • Stavrou, Evi • Gurkan, Umut
Assignees
Case Western Reserve University • US Department of Veterans Affairs
Publication Number
US-11058316-B2
Publication Date
2021-07-13
Expiration Date
2037-01-17
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Abstract
As one example, a fluid monitoring apparatus includes a dielectric microsensor that includes a capacitive sensing structure integrated into a microfluidic channel. The microfluidic channel includes a fluid input to receive a sample volume of a sample under test (SUT). A transmitter provides an input radio frequency (RF) signal to an RF input of the microsensor. A receiver receives an output RF signal from the microsensor. A computing device computes dielectric permittivity values of the SUT that vary over a time interval based on the output RF signal. The computing device may determine at least one permittivity parameter based on the computed dielectric permittivity values over at least a portion of the time interval.
Core Innovation
The invention relates to dielectric sensing to determine properties of a sample by using a dielectric microsensor that includes a capacitive sensing structure integrated into a microfluidic channel. The microfluidic channel includes a fluid input to receive a sample volume of a sample under test (SUT). A transmitter provides an input radio frequency (RF) signal to an RF input of the microsensor, and a receiver receives an output RF signal. A computing device computes dielectric permittivity values of the SUT that vary over a time interval based on the output RF signal and determines at least one permittivity parameter based on the computed values.
Typical dielectric spectroscopy (DS) systems are large and expensive, which limits their use. The problem being addressed is the need for a low-cost, portable, and rapid technique to perform dielectric spectroscopy measurements with small sample volumes to characterize molecular and cellular properties of biological or other samples. The invention aims to provide a microsensor and associated system that allows rapid, high-throughput, low-cost DS measurements using microfluidic channels with volumes less than about 10 µL.
The system includes a sensor interface with a transmitter and receiver to provide and receive RF signals through a DS sensor apparatus, which contains the sample in a microfluidic channel. Impedance measurements are used to calculate dielectric permittivity over time, which is then analyzed to extract parameters such as time to peak dielectric permittivity (TPEAK), difference between peak and plateau permittivity values, and slope characteristics. These parameters correlate to properties of the SUT such as anticoagulation and platelet function in blood samples. The microsensor can be disposable and removably connected to allow reusing the apparatus for multiple samples.
Claims Coverage
The patent includes 2 independent claims related to a dielectric spectroscopy sensing system and a method for dielectric permittivity measurement. The claims cover innovative sensor apparatus configuration, system integration, and permittivity parameter analysis.
Dielectric spectroscopy sensing system with modular sensor interface electronics
A dielectric spectroscopy sensing system comprising a housing with sensor interface electronics including an RF transmitter and receiver electrically connected to mating sensor contacts of a dielectric spectroscopy sensor apparatus configured to receive a sample under test (SUT). A computing device within the housing determines dielectric permittivity parameters based on impedance characteristics measured over a time interval when the sensor apparatus containing the SUT is connected.
DS sensor apparatus with microfluidic channel and capacitive sensing electrodes
The DS sensor apparatus includes a first and opposing second surface defining a microfluidic sample volume less than about 10 μL, with an inlet for sample entry, first and second sensing electrodes on the first surface spaced apart, and a floating electrode on the opposing second surface, forming a capacitive sensing structure inside the microfluidic channel.
Electrical coupling structure enabling removable modular connection
The DS sensor apparatus is modular and removably replaceable relative to the housing, with specific electrical contacts coupling sensor electrodes to the RF transmitter and receiver contacts in the housing to facilitate plug-and-play replacement.
Sensor interface electronics integrated with RF signal amplification and filtering
Sensor interface electronics include circuitry within an integrated circuit to amplify and filter the RF signal provided to the RF receiver, to accurately measure transmission characteristics related to the SUT's complex impedance.
Computing device programmed to analyze dielectric permittivity parameters over time
The computing device analyzes dielectric permittivity values over at least a portion of the measurement time interval to determine parameters such as time to reach peak dielectric permittivity (TPEAK), difference between peak and plateau permittivity, and slopes of permittivity changes, relating to properties of the SUT like coagulation and platelet function, especially for blood samples.
Method of measuring and analyzing dielectric permittivity of SUT
A method comprising attaching the sensing apparatus to a housing with sensor interface system, providing an input RF signal, receiving an output RF signal representing impedance of the SUT in the sensing apparatus, computing dielectric permittivity values over a measurement interval, and analyzing these values to determine dielectric permittivity parameters indicative of properties of the SUT.
The claims collectively cover a portable DS system with modular DS sensor apparatus having a microfluidic capacitive sensing structure, integrated sensor interface electronics with RF transmission and reception, a computing device analyzing permittivity parameters over time for sample characterization, and methods for performing these measurements and analyses.
Stated Advantages
Enables rapid, high-throughput, and low-cost dielectric spectroscopy measurements using microfluidic volumes less than about 10 μL.
Provides portable, low-power device configurations suitable for point-of-care applications.
Allows analysis of time-based dielectric permittivity parameters that correlate to molecular and cellular properties of samples, such as anticoagulation and platelet function in blood.
Supports use of disposable, removable microsensors enabling reuse of the monitoring apparatus without contamination.
Exhibits improved sensitivity in detecting coagulation-related properties compared to conventional assays like aPTT and PT.
Documented Applications
Chemical analysis of oil in the petroleum industry.
Analysis of substances for security or defense purposes.
Soil moisture monitoring in agriculture.
Fermentation monitoring during alcoholic beverage production.
Food quality and safety monitoring.
Drug development in the pharmaceutical industry.
Label-free, non-destructive real-time characterization of biological and biochemical samples in the biomedical field.
Assessment of anticoagulation properties and platelet function in blood samples for clinical diagnostics and therapeutic monitoring, including efficacy evaluation of anticoagulants such as target-specific oral anticoagulants.
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