Nanochannel Fabrication via Narrow Trench Patterning
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Solution Overview
Problem
Current DNA sequencing methods face challenges in fabricating nanochannels and electrode gaps small enough to allow single DNA strand passage, leading to high costs and low speeds, with existing MEMS and nanofabrication methods being inadequate for creating the required structures.
Innovation Solution
A method involving a two-stage narrow trench patterning process and thermal re-flow to create nanochannels with electrode gaps as small as 1 nm, using suspended electrodes and shear actuators to achieve the necessary dimensions for effective DNA sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional MEMS and nanofabrication methods are used to fabricate nanochannels and electrode gaps, then device fabrication can be performed with existing technology, but the resulting structures are too large to allow single DNA strand passage and achieve effective DNA sequencing
Solution Approach 1:
The fabrication process is divided into two distinct stages: first forming trenches in a sacrificial layer to define the nanochannel path, then forming electrodes in separate trenches that intersect the nanochannel. This segmentation allows each structure to be optimized independently for the required sub-10 nm dimensions while using conventional lithography tools.
Solution Approach 2:
A sacrificial layer (such as silicon dioxide or polymer) is used as an intermediary material to define the nanochannel geometry during fabrication. The sacrificial layer is patterned with trenches, then replaced with conductive material to form electrodes. This intermediary approach enables precise nanochannel formation without requiring direct patterning of the final structure at such small dimensions.
2Measurement precision
If electrode gaps are made small enough (sub-nanometer to 1 nm) to detect DNA signals effectively, then DNA sequencing sensitivity is improved, but fabrication precision requirements become extremely high
Solution Approach 1:
The electrode gap dimensions are predetermined by the trench width in the sacrificial layer before electrode fabrication. By carefully controlling the sacrificial layer trench dimensions using conventional lithography and etching, the final electrode gap is pre-established at the correct sub-nanometer scale, eliminating the need for post-fabrication adjustment and reducing manufacturing precision requirements during electrode formation.
Solution Approach 2:
The nanochannel geometry defined in the sacrificial layer serves as a template or copy that guides the formation of the electrode structures. The electrode trenches are patterned to intersect the sacrificial layer trenches at specific locations, copying the spatial arrangement needed for DNA translocation and signal detection without requiring direct measurement at the final nanometer scale.
3Productivity
If nanochannels are made long and narrow to guide single DNA strands, then sequencing effectiveness is improved, but fabrication difficulty increases significantly
Solution Approach 1:
The sacrificial layer self-organizes into the desired nanochannel pattern through conventional lithography and etching processes. Once the sacrificial trenches are formed, they automatically define the long and narrow nanochannel geometry needed for DNA guidance. The subsequent electrode formation process simply fills these pre-defined spaces, allowing the structure to self-assemble into the final complex configuration without additional complex fabrication steps.
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
Enables fast and low-cost genome, transcriptome, and proteome sequencing by providing a device capable of guiding single molecule DNA through a long, narrow nanochannel with a tunneling current electrode gap small enough to detect DNA signals effectively, addressing the technical challenges of device fabrication and sequencing efficiency.
Implementation Method 1
shrinking the first trench using a thermal re-flow process
Data Source
AI summary
Apparatus and methods relating to DNA sequencing are provided. In one embodiment, a DNA sequencing device includes a nanochannel having a width that is approximately 0.3 nm to approximately 20 nm. A pair of electrodes having portions exposed to the nanochannel may form a tunneling current electrode (TCE) with an electrode gap of approximately 0.1 nm to approximately 2 nm, and more particularly about 0.3 nm to about 1 nm. In one embodiment, at least one of the pair of electrodes is formed as a suspended electrode. An actuator may be associated with the suspended electrode to displace it relative to the other electrode. In various embodiments, the nanochannel and/or the electrodes may be formed using thermal reflow processes to reduce the size of such features.