Nanogap Sensor Readout With In-Sampling Digitization
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Solution Overview
Problem
Conventional nanogap sensor systems face challenges in converting large full-scale currents to digital signals due to the need for large sampling capacitors, which occupy excessive chip surface area, and require extreme current attenuation, limiting the feasibility of implementing millions of sensors.
Innovation Solution
The proposed solution involves digitizing the signal as it is being sampled, allowing for short-term integration of a portion of the signal, reducing the size of sampling capacitors and eliminating the need for large capacitors, while also using digital counters for accumulation, which grows logarithmically with measurement time, and employing techniques like delta-sigma ADCs and relaxation oscillators to improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional nanogap sensor systems use large sampling capacitors to convert large full-scale currents to digital signals, then the conversion accuracy is improved, but the chip surface area occupied increases excessively
Solution Approach 1:
The patent segments the current conversion process into multiple stages: first converting large full-scale currents to smaller intermediate currents, then to digital signals. This segmentation allows using much smaller sampling capacitors (e.g., 100aF instead of large capacitors) while maintaining conversion accuracy through the multi-stage process.
Solution Approach 2:
The patent introduces intermediary current conversion stages with intermediate currents as mediators between the large sensor currents and the digital domain. These intermediate currents serve as bridging signals that enable accurate conversion with small capacitors, resolving the contradiction between accuracy and area.
2Adaptability or versatility
If extreme current attenuation is applied to convert large full-scale currents to digital signals, then the signal range is reduced to match ADC input requirements, but the system complexity and feasibility for large-scale sensor arrays deteriorates
Solution Approach 1:
The patent divides the attenuation function into multiple discrete current conversion stages, each handling a portion of the dynamic range. This segmentation makes the attenuation process more manageable and integrable, reducing overall system complexity while maintaining adaptability to different signal ranges.
Solution Approach 2:
The patent merges the current attenuation function with the sampling and conversion functions into an integrated current-to-digital conversion circuit. This combination eliminates separate attenuation stages, reducing system complexity while achieving the required signal range compatibility for large sensor arrays.
3Measurement precision
If large sampling capacitors are used to accurately convert large full-scale currents, then the conversion precision is improved, but the feasibility of implementing millions of sensors on a chip is reduced
Solution Approach 1:
The patent segments the conversion architecture so that each sensor channel uses a small sampling capacitor, but achieves high precision through multi-stage conversion and digital signal processing. This segmentation enables scaling to millions of sensors while maintaining conversion precision through the distributed architecture.
Solution Approach 2:
The patent replaces the traditional mechanical/electrical approach of using large physical capacitors for precision conversion with a digital-based multi-stage conversion system. This substitution enables high precision with minimal physical area, allowing massive sensor array integration on a single chip.
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 reduces the size of sampling capacitors, makes the system more viable for large-scale nanogap sensor arrays, and enhances signal-to-noise performance, enabling the manufacture and commercialization of millions of nanogap sensors.
Implementation Method 1
a relaxation oscillator, coupled to the readout input, for oscillating with an oscillation frequency indicative of the input signal
Implementation Method 2
the relaxation oscillator is a current-controlled relaxation oscillator for converting the input signal received in an analog form to a digital signal
Data Source
AI summary
Embodiments of the present disclosure relate to various methods and example systems for carrying out analog-to-digital conversion of data acquired by arrays of nanogap sensors. The nanogap sensors described herein may operate as molecular sensors to help identify chemical species through electrical measurements using at least a pair of electrodes separated by a nanogap. In general, the methods and systems proposed herein rely on digitizing the signal as the signal is being integrated, and then integrating the digitized results. With such methods, the higher sample rate used in the digitizer reduces the charge per quantization and, therefore, the size of sampling capacitors used. Consequently, sampling capacitors may be made factors of magnitude smaller, requiring less valuable space on a chip compared to sampling capacitors used in conventional nanogap sensor arrays.