Planar Electro-diffusion Bio-molecule Charge Detection
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Solution Overview
Problem
Current methods for electrical detection of bio-molecules are limited by electrolyte screening, requiring small pore sizes for effective detection, which complicates fabrication and restricts sensitivity to close proximity of bio-molecules to sensing elements, hindering single-molecule analysis and ensemble average signal detection.
Innovation Solution
The use of micro-machined channels and electro-diffusion ionic current flow to detect bio-molecule charges through long-range electrostatic interactions, allowing for enhanced sensitivity and compatibility with conventional manufacturing processes, and incorporating AC modulation and lock-in techniques for improved sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If translocation of bio-molecules through nanometer-size ion channels is used for detection, then single bio-molecule analysis capability is achieved, but fabrication complexity increases and sensitivity is limited to close proximity only
Solution Approach 1:
The patent transitions from three-dimensional nanopore structures requiring complex fabrication to planar two-dimensional sensor arrays that can be manufactured using standard semiconductor processes. The detection surface is extended laterally rather than relying on vertical pore depth, enabling single-molecule sensitivity without nanometer-scale pore fabrication.
Solution Approach 2:
The patent replaces mechanical translocation through physical nanopores with electrical field-based detection on a planar surface. Instead of forcing molecules through narrow channels, charged molecules are detected electrically as they pass near the sensor surface during electrophoresis, substituting mechanical confinement with electrical sensing.
2Measurement precision
If small pore sizes are used for bio-molecule translocation detection, then single molecule analysis is enabled, but manufacturing difficulty increases significantly
Solution Approach 1:
The patent creates sensor arrays that can detect multiple types of charged bio-molecules (DNA, RNA, proteins) using the same planar electrode structure. The universal planar detection surface replaces specialized nanopore geometries, allowing a single manufacturing process to produce sensors for diverse molecular targets without requiring different pore sizes or shapes.
Solution Approach 2:
The patent changes the detection parameter from physical pore diameter (nanometer scale) to electrical field interaction distance (micrometer scale). This parameter transformation allows detection of single molecules through longer-range electrostatic interactions, enabling standard semiconductor fabrication to produce sensors with sufficient resolution without nanometer-scale precision requirements.
3Measurement precision
If electrostatic interaction detection is used without electro-diffusion, then detection is limited by Debye screening length, but adding electro-diffusion ionic current flow enhances sensitivity beyond screening limits
Solution Approach 1:
The patent introduces ionic current flow as an intermediary mechanism that mediates between the charged bio-molecules and the sense electrodes. The electro-diffusion current acts as a carrier that transmits charge information over distances beyond the Debye screening length, enabling long-range detection without requiring the molecules to be in direct contact with the electrode surface.
Solution Approach 2:
The patent employs AC modulation of the ionic current to enhance detection sensitivity. By applying periodic voltage modulation and using lock-in detection techniques, the system can extract weak charge signals from the ionic current background, improving signal-to-noise ratio and enabling detection beyond the conventional Debye screening limit.
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 enables detection of bio-molecule charges beyond the Debye screening length, facilitating single-molecule level analysis with reduced fabrication complexity and improved sensitivity, suitable for low-cost, point-of-care medical diagnostics.
Implementation Method 1
the detection of bio-molecule charges based on their long-range electrostatic interaction
Implementation Method 2
enhanced detection of charges of bio-molecules traversing a channel... by exploiting electro-diffusion ionic current flow
Implementation Method 3
first and second biasing electrodes... configured for enhanced ionic current flow
Data Source
AI summary
According to one aspect, the disclosure is directed to an example embodiment in which a circuit-based arrangement includes a circuit-based substrate securing a channel, with an effective width that is not limited by the Debye screening length, along a surface of the substrate. A pair of reservoirs are included in or on the substrate and configured for containing and presenting a sample having bio-molecules for delivery in the channel. A pair of electrodes electrically couple a charge in the sample to enhance ionic current flow therein (e.g., to overcome the electrolyte screening), and a sense electrode is located along the channel for sensing a characteristic of the biological sample by using the electrostatic interaction between the enhanced ionic current flow of the sample and the sense electrode. Actual detection occurs by using a charge-signal processing circuit to process the sensed charge signal and, therefrom, provide an output indicative of a signature for the bio-molecules delivered in the channel.