Shielded Nanopore Read Amplifiers for Low-Capacitance Sensing
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Solution Overview
Problem
Nanopore applications face challenges in detecting small differences in ionic current due to noise peaking caused by high capacitance at the amplifier input, which limits signal-to-noise ratio (SNR) and time resolution.
Innovation Solution
The introduction of a shield situated between the sense electrode and the counter electrode, coupled to the amplifier output, which reduces parasitic capacitance by isolating the sense electrode from the counter electrode, thereby mitigating noise and improving SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard amplifier configuration is used to detect ionic current, then the detection system is simple, but high capacitance at the amplifier input causes noise peaking and degrades signal-to-noise ratio
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the sense electrode and counter electrode. This shield electrode, when held at the same potential as the sense electrode, acts as a mediator to reduce the parasitic capacitance between the sense and counter electrodes, thereby reducing noise peaking and improving the signal-to-noise ratio without fundamentally changing the amplifier configuration
2Measurement precision
If the sense electrode is positioned close to the nanopore for high signal strength, then detection sensitivity improves, but parasitic capacitance increases causing noise peaking
Solution Approach 1:
The shield electrode serves as an intermediary that allows the sense electrode to be positioned close to the nanopore for high signal strength while simultaneously reducing the harmful parasitic capacitance effect. By holding the shield at the same potential as the sense electrode, it minimizes the voltage difference across the parasitic capacitance, thereby reducing noise peaking while maintaining detection sensitivity
3Productivity
If fast translocation of molecules through the nanopore is achieved for high throughput, then productivity increases, but temporal resolution of detection deteriorates due to noise
Solution Approach 1:
The shield electrode as an intermediary reduces noise peaking by minimizing the effect of parasitic capacitance. This noise reduction enables better temporal resolution in detecting fast translocating molecules, allowing high throughput while maintaining the ability to resolve rapid molecular events through improved signal quality
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 solution significantly reduces amplifier input current noise, enhancing the signal-to-noise ratio and allowing for more accurate and rapid detection of molecules passing through the nanopore.
Implementation Method 1
the capacitance at the input to the amplifier forms a pole with the output impedance of the amplifier. High capacitance at the input to the amplifier can cause noise peaking and SNR degradations
Data Source
AI summary
Disclosed herein are systems for detecting molecules. In some embodiments, a system includes a multiplexer, a read amplifier coupled to the multiplexer, a digitizer coupled to the read amplifier, a first nanopore, a first sense electrode situated on a first side of the first nanopore, a first counter electrode situated on a second side of the first nanopore, a first shield at least partially surrounding the first sense electrode and coupled to the multiplexer, a first shield driver coupled to the first shield, drive circuitry coupled to the first sense electrode, and control logic coupled to the drive circuitry, the multiplexer, and to the digitizer. In some embodiments, the control logic is configured to control the drive circuitry and/or the multiplexer to select the first sense electrode and/or the first counter electrode, and obtain a digitized signal from the digitizer, the digitized signal representing a current through the first nanopore.