Methods and compositions for detecting analytes
Inventors
Pierson, Shad • Meehan, Timothy D. • Montgomery, Kyle William • Wade, Daniel J. • Sustarich, Jess M. • Lord, Brenna Hearn • Chiarello, Ronald Phillip
Assignees
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Publication Number
US-11465141-B2
Publication Date
2022-10-11
Expiration Date
Abstract
The present application is generally directed to systems, methods, and devices for diagnostics for sensing and/or identifying pathogens, genomic materials, proteins, and/or other small molecules or biomarkers. In some implementations, a small footprint low cost device provides rapid and robust sensing and identification. Such a device may utilize microfluidics, biochemistry, and electronics to detect one or more targets at once in the field and closer to or at the point of care.
Core Innovation
The invention relates to a system for detecting a target agent using an assay cartridge and a reader device that performs an amplification process in a test well and applies electrical excitation to electrodes in the cartridge. The cartridge includes an excitation electrode and a sensing electrode, and the sensing electrode provides a signal that represents the excitation current after attenuation by at least the sample within the test well. The reader device decomposes the signal into a resistance component and a reactance component, enabling analysis of the reactance during amplification.
During the amplification process, the reader device analyzes the reactance component to determine whether a signal cliff indicative of a positive sample including the target agent occurred during at least a portion of the duration of the amplification process. The signal cliff represents a change in the reactance during a window of time. In response to determining that the signal cliff occurred, the system outputs a positive test result, and in response to determining that the signal cliff did not occur, the system outputs a negative test result.
The disclosure further frames the platform as an amplification-based diagnostic approach that monitors nucleic-acid amplification using contactless electrical sensing, including frequency-dependent capacitively coupled contactless conductivity detection and impedance sensing approaches. The described architectures include a disposable fluidics cartridge and reader device with sample introduction and pneumatic fluidics, and the described electrode and reader electronics support heating, excitation, electrode interfacing, signal processing, and data processing to call results using the reactance signal cliff.
Claims Coverage
The provided claim coverage centers on electrode-based impedance/reactance analysis during an amplification process in an assay cartridge, including determination of a signal cliff indicative of a positive sample during a defined time window. Independent claim content is supported by four inventive features, with additional dependent limitations refining signal analysis and target selection.
Assay cartridge and amplification in a test well with excitation and sensing electrodes
An assay cartridge with a test well containing an excitation electrode and a sensing electrode, the test well configured to contain a sample comprising the target agent undergoing an amplification process.
Reader device heater and electrical excitation during amplification
A reader device including a region to receive the assay cartridge, a heater positioned to heat the assay cartridge in use within the cavity, and a processor configured to cause the heater to heat the assay cartridge to a predetermined temperature for performing the amplification process and to provide an excitation current to the excitation electrode for at least a portion of the duration of the amplification process.
Reactance/resistance decomposition and signal acquisition from sensing electrode
Receiving a signal from the sensing electrode representing the excitation current after attenuation by at least the sample within the test well, decomposing the signal into a resistance component and a reactance component, and analyzing the reactance component.
Signal cliff detection in reactance during amplification to output positive or negative
Determining whether a signal cliff indicative of a positive sample including the target agent occurred during at least the portion of the duration of the amplification process, where the signal cliff represents a change in the reactance during a window of time, and outputting a positive test result if the signal cliff occurred or a negative test result if the signal cliff did not occur.
Memory-based expected signal-cliff characteristics
The system further analyzes the reactance component by having a processor access predetermined expected signal-cliff characteristics stored in memory.
Window-of-time constrained signal-cliff prediction
The predetermined expected signal-cliff characteristics include a time window during the duration of the amplification process in which the signal cliff is predicted to occur.
Threshold slope constraint for reactance signal cliff
The predetermined expected signal-cliff characteristics define a threshold slope for a curve of the reactance component based on reactance values sampled over at least part of the amplification process duration.
Nyquist-criterion sampling and in-phase/out-of-phase processing for impedance decomposition
The system decomposes a sampled impedance signal into resistance and reactance by sampling faster than the Nyquist frequency, separating the sampled impedance into in-phase and out-of-phase components, and calculating the resistance from the in-phase component and the reactance from the out-of-phase component.
Viral target-agent category selection
The detection method uses a target agent selected from viral nucleic acid, viral capsid protein, viral structural protein, viral glycoprotein, viral membrane fusion protein, viral protease, or viral polymerase.
Overall, the claim coverage focuses on impedance-based detection during amplification using a cartridge with excitation and sensing electrodes, reader-side heating and excitation, decomposition of the sensed signal into resistance and reactance, and a reactance signal cliff decision that drives positive/negative outputs during amplification. Dependent claims further refine this by using memory-stored expected characteristics, including time-window prediction and threshold slope, and by narrowing impedance decomposition to Nyquist-criterion sampling and in-phase/out-of-phase processing.
Stated Advantages
Enables positive versus negative test calling based on a reactance signal cliff indicative of a positive sample during an amplification process.
Provides an electrical sensing approach (impedance/reactance analysis) for detecting target agent amplification outcomes rather than relying on optical/fluorescence approaches.
Documented Applications
Diagnostic detection of a target agent in a sample undergoing an amplification process using an assay cartridge and reader device, including nucleic-acid amplification monitoring.
Detection of viral-related targets, using target-agent selection among viral nucleic acid, viral capsid protein, viral structural protein, viral glycoprotein, viral membrane fusion protein, viral protease, or viral polymerase.
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