Graphene DEP Sensor for Rapid Pathogen Detection

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Solution Overview

Problem

Current methods for detecting pathogenic bacteria like Salmonella spp. and E. coli are time-consuming, costly, and lack the speed and sensitivity required for hand-held systems, especially when using graphene-based sensors that rely on simple diffusion or non-selective dielectrophoresis (DEP).

Innovation Solution

A graphene-edge dielectrophoretic (DEP) sensor is developed that utilizes surface functionalization on graphene to achieve selectivity and sensitivity, allowing for the separation of DEP-attraction bias voltages from sensing bias voltages, and enabling the use of time-varying excitation for DEP attraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional graphene sensors utilize simple diffusion processes to attract particles to the surface, then the sensing mechanism is simple, but the detection speed is slow

Engineering Contradiction:

Improvedetection speedVSAvoidsensing mechanism complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by using dielectrophoresis to pre-concentrate target particles at the graphene sensor surface before detection occurs. This pre-positioning of particles through electric field manipulation accelerates the detection process significantly compared to passive diffusion, while maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #10Preliminary action

2Speed

If dielectrophoresis is used to attract particles to a region of high electric field gradient, then the particle attraction speed is fast, but selective sensing is not provided

Engineering Contradiction:

Improveparticle attraction speedVSAvoidsensing selectivity

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent applies local quality by functionalizing specific regions of the graphene surface with target-specific recognition elements. This creates localized zones of selective binding capability while using dielectrophoresis to concentrate particles globally across the sensor surface. The combination achieves both fast particle attraction and selective sensing at specific locations.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If DEP-attraction bias voltages are applied to attract particles, then particle concentration at the sensor surface is high, but the sensing signal is obscured by the large AC excitation

Engineering Contradiction:

Improveparticle concentration at sensor surfaceVSAvoidsensor response detection accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent applies periodic action by using time-varying AC excitation at specific frequencies to drive dielectrophoresis for particle concentration, then switching to DC or low-frequency measurement modes to detect the sensor response. This temporal separation of particle attraction and signal measurement allows high particle concentration to be achieved without obscuring the sensing signal.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12325031B2Graphene-based dielectrophoresis sensor and method

Publication Date: 2025.06.10 REGENTS OF THE UNIVERSITY OF MINNESOTA

AI summary

A dielectrophoretic (DEP) sensor includes a graphene electrode adjacent a channel for confining a target particle in a liquid, a surface probe attached to a surface of the graphene electrode, the surface probe having a selective reaction with the target particle, and a voltage source electrically connected to the graphene electrode and configured to apply a voltage to the graphene electrode to cause DEP trapping of the target particle at the graphene electrode.