Spectral Calibration for Real-Time PCR Instruments

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Solution Overview

Problem

Real-time PCR instruments face challenges in achieving reproducible Ct values due to spectral non-uniformity caused by variations in instrument sensitivity, optics, and optical paths, making it difficult to compare results across different instruments or over time.

Innovation Solution

A calibration system using a calibration plate with predetermined spectral species in each well, where the measured signal responses are compared to expected responses to generate calibration factors, which are then applied to adjust the measured signal values and compensate for differences between instruments and well positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If baseline approach is used to control Ct values, then Ct values can be controlled for a particular assay, but spectral non-uniformity between different instruments or over time cannot be compensated

Engineering Contradiction:

ImproveCt value controlVSAvoidreproducibility across instruments

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by introducing spectral calibration factors that adjust the detected signal based on the instrument's specific spectral sensitivity profile. Instead of using a fixed baseline approach, the system dynamically modifies the measurement parameters (signal intensities) according to the instrument's characteristics, enabling consistent Ct values across different instruments and over time

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by measuring the actual spectral response of each instrument using known spectral species, comparing it to expected responses, and using the derived calibration factors to correct future measurements. This closed-loop approach ensures that instrumental variations are continuously compensated, maintaining reliability across instruments

Inventive Principle:

Principle #23Feedback

2Productivity

If multiple instruments are used to measure gene expression, then measurement capacity is increased, but spectral non-uniformity causes Ct variability between instruments

Engineering Contradiction:

Improvemeasurement capacityVSAvoidCt value consistency

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent achieves universality by developing a calibration approach that works across multiple instruments with different spectral characteristics. The calibration plate with known spectral species serves as a universal reference that can be used to characterize and correct any instrument in the network, enabling consistent measurements across the entire instrument fleet

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses an intermediary approach by introducing calibration plates with known spectral species as a mediator between the instruments and the samples. These calibration plates serve as a common reference point that translates measurements from different instruments into a unified scale, enabling accurate comparison across instruments

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If spectral sensitivity varies over time on the same instrument, then instrument adaptability is reduced, but calibration can restore consistency

Engineering Contradiction:

Improvespectral sensitivity stabilityVSAvoidmeasurement reproducibility

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing spectral calibration at regular intervals or before experiments to detect and correct drift in spectral sensitivity. By proactively characterizing the instrument's spectral response using known standards, the system prevents measurement errors from accumulating, maintaining reliability even as the instrument ages

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for consistent and comparable Ct values across multiple instruments and over time, reducing the effects of spectral non-uniformity and ensuring accurate gene expression measurement.

Implementation Method 1

Each well is then exposed to at least one excitation source that causes the one or more spectral species in each of the wells to fluoresce

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS8084260B2Spectral calibration method and system for multiple instruments

Publication Date: 2011.12.27 APPLIED BIOSYSTEMS LLC

AI summary

Implementations of the present invention describe an apparatus for generating calibration factors for a spectral detector instrument. The calibration factors are derived from a calibration plate containing one or more spectral species in each well of the calibration plate. Each well is then exposed to an excitation source that causes the one or more spectral species in each of the wells to fluoresce. The signal response is measured and associated with each spectral species at each different well position in the calibration plate. Next, the measured signal response from each spectral species at each well position in the calibration plate is compared with a predetermined signal response for each spectral species. The results of this comparison can be used to determine a calibration factor for each well and spectral species to compensate for the difference between the measured signal response and the predetermined signal response.