Miniaturized TGS CMOS Chip Without Optical Filters
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Solution Overview
Problem
Current third-generation sequencing (TGS) technologies rely on ultra-thick optical-density filters to achieve high signal-to-noise ratios, which restricts the miniaturization of CMOS chips and increases sequencing costs.
Innovation Solution
The development of a miniaturized TGS CMOS chip that eliminates the need for optical-density filters by using a substrate with a photodetector, waveguide, and nanowell array, where the photodetector includes a photoactive layer with a specific bandgap range and the waveguide transmits long-wavelength light that is converted to short-wavelength light by fluorescently-labeled nucleotides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ultra-thick optical-density filter is used to achieve high signal-to-noise ratio, then the signal quality is improved, but the device size and fabrication cost increase
Solution Approach 1:
The patent changes the fundamental parameter of light detection by using a photodetector with a specific bandgap (1.5-2.5 eV) that is sensitive to short-wavelength light (400-800 nm) but insensitive to long-wavelength light (800-1600 nm). This parameter change eliminates the need for ultra-thick optical-density filters, enabling pixel size reduction while maintaining high signal-to-noise ratio through intrinsic optical filtering rather than extrinsic filter layers.
2Measurement precision
If an ultra-thick optical-density filter is used to eliminate excitation light interference, then the signal quality is improved, but the device complexity and fabrication cost increase
Solution Approach 1:
The patent extracts and removes the optical-density filter component from the traditional TGS device structure. Instead of using a thick multi-film filter (OD > 6, thickness > 10 μm), the invention uses a photodetector with inherent spectral selectivity that naturally filters out long-wavelength excitation light, simplifying the device structure and reducing fabrication complexity while maintaining signal quality.
Solution Approach 2:
The patent replaces the mechanical/optical filtering system (thick multi-film filters) with an electronic/optoelectronic system (photodetector with specific bandgap). The photodetector's inherent spectral response provides the filtering function that was previously achieved through physical filter layers, substituting a complex optical-mechanical structure with a simpler electronic detection mechanism.
3Ease of manufacture
If a small-pixel-size imaging system is used to reduce sequencing cost, then the cost is reduced, but the resolution and signal detection capability deteriorate
Solution Approach 1:
The patent changes the photodetector's spectral response parameters by selecting materials with specific bandgaps (1.5-2.5 eV) that create an intrinsic cutoff at long wavelengths. This parameter change enables the photodetector to reject excitation light interference even at small pixel sizes, maintaining resolution and signal detection capability while enabling cost reduction through miniaturization.
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 allows for a significant reduction in pixel size and module thickness, reducing fabrication costs and enabling high-resolution, cost-effective third-generation sequencing without the issues of optical crosstalk.
Implementation Method 1
The nanowell array is loaded with fluorescently-labeled nucleotides that convert the long-wavelength light to short-wavelength light with a wavelength of 400 nm to 800 nm
Implementation Method 2
The first photodetector includes a first photoactive layer with a first bandgap smaller than photon energy of the short-wavelength light and larger than the photon energy of the long-wavelength light
Data Source
AI summary
An optical device is provided. The optical device includes a substrate, a first photodetector, a waveguide and a nanowell array. The first photodetector is disposed on the substrate. The waveguide is disposed on the first photodetector. The waveguide is in contact with the first photodetector or apart from the first photodetector by a color filter array which is in contact with the waveguide and the first photodetector. The nanowell array is disposed on the waveguide. There is no multi-film filter in the optical device.