Capacitive Sensor Isoelectric Point Determination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods for determining the isoelectric point of biomolecules, such as electrophoresis, are time-consuming, expensive, and require high voltages, making them inefficient and costly.

Innovation Solution

A capacitive sensor system using a substrate with a dielectric layer and an electrically conductive solution measures capacitance versus voltage curves before and after a target molecule binds to a functionalized material, allowing for the determination of the isoelectric point by extrapolating the pH value corresponding to a zero shift voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrophoresis is used to determine isoelectric point, then measurement precision is achieved, but measurement time increases to 2-16 hours

Engineering Contradiction:

Improveisoelectric point measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical electrophoresis system with a capacitive sensing system. Instead of using electric fields to separate molecules through physical movement, the invention uses capacitance measurements to detect molecular binding events, enabling rapid determination of isoelectric points without the time-consuming separation process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the measurement parameter from physical separation distance (electrophoresis) to electrical capacitance (pCap). By measuring changes in capacitance values in the pF range, the system can detect molecular binding events and determine isoelectric points much faster than traditional methods.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If high voltage electrophoresis is used, then measurement precision is improved, but energy consumption increases and cost increases

Engineering Contradiction:

Improveisoelectric point measurement accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the high-voltage electrophoresis system with a low-voltage capacitive sensing system. Instead of applying high voltages to drive molecular separation, the invention uses small voltage changes to measure capacitance variations, dramatically reducing energy consumption while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If traditional electrophoresis apparatus is used, then measurement capability is provided, but device area increases to approximately 1 square foot

Engineering Contradiction:

Improveisoelectric point measurement capabilityVSAvoidapparatus area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The invention segments the measurement function into a small, modular capacitive sensor unit rather than requiring a large electrophoresis apparatus. The sensor can be integrated into compact formats, reducing the overall device area from 1 square foot to a much smaller footprint while maintaining full measurement capability.

Inventive Principle:

Principle #1Segmentation

4Measurement precision

If traditional electrophoresis method is used, then isoelectric point determination is achieved, but the method becomes expensive

Engineering Contradiction:

Improveisoelectric point determinationVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive electrophoresis system with a cost-effective capacitive sensing system. By eliminating the need for high-voltage power supplies, large apparatus components, and complex separation chambers, the invention significantly reduces equipment cost while maintaining measurement precision for isoelectric point determination.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method is fast, inexpensive, and miniaturized, requiring low voltage and small protein sample volumes, providing a sensitive and efficient alternative for measuring isoelectric points.

Implementation Method 1

measuring a first plurality of capacitance versus voltage curves of a capacitor. The capacitor includes a substrate, a dielectric layer, and an electrically conductive solution

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9103770B2Determination of isoelectric points of biomolecules using capacitive sensors

Publication Date: 2015.08.11 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A mechanism is provided for determining an isoelectric point of a molecule. A first group of capacitance versus voltage curves of a capacitor is measured. The capacitor includes a substrate, dielectric layer, and conductive solution. The first group of curves is measured for pH values of the solution without the molecule bound to a functionalized material on the dielectric layer of the capacitor. A second group of capacitance versus voltage curves of the capacitor is measured when the molecule is present in the solution, where the molecule is bound to the functionalized material of the dielectric layer of the capacitor. A shift is determined in the second group of curves from the first group of curves at each pH value. The isoelectric point of the molecule is determined by extrapolating a pH value corresponding to a shift voltage being zero, when the shift is compared to the pH values.