Multi-layer Micro-porous Biosensor with Size-Selective Pores
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Solution Overview
Problem
Existing biosensing methods using porous microstructures face challenges in accurately detecting biomolecules in noisy environments and accounting for signal drift due to thermal fluctuations and changes in sample composition, particularly requiring sensitive equipment and failing to effectively differentiate between molecules based on size.
Innovation Solution
A multi-layer micro-porous thin film structure is developed, where the top layer has larger pores to accept a first molecule of interest and the second layer has smaller pores to accept a second, smaller molecule, producing multiple superimposed interference patterns that can be resolved using Fourier transform analysis, allowing for specific and nonspecific binding detection and correction for matrix effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer porous microstructure is used for biosensing, then the device complexity is reduced, but the measurement precision and ability to discriminate between molecules of different sizes deteriorates
Solution Approach 1:
The single porous layer is segmented into multiple porous layers with different pore sizes. Each layer is designed to accommodate specific size ranges of biomolecules, enabling size-based discrimination. The first porous layer has larger pores for larger molecules while the second porous layer has smaller pores for smaller molecules, creating a hierarchical separation structure.
Solution Approach 2:
Different regions of the porous structure are given different local properties through varying pore sizes in different layers. The first porous layer has larger average pore sizes optimized for accepting larger biomolecules, while the second porous layer has smaller average pore sizes optimized for smaller biomolecules, creating spatially differentiated selective permeability.
2Device complexity
If traditional optical sensing methods are used, then the equipment requirements are reduced, but the reliability and sensitivity in noisy environments deteriorates
Solution Approach 1:
The porous microstructure acts as an intermediary element that converts molecular presence into optical interference pattern changes. The Fabry-Perot interferometer structure mediates between the biomolecules and the detection system, transforming subtle molecular interactions into measurable optical signals that are less susceptible to environmental noise.
Solution Approach 2:
The patent replaces direct mechanical or electrical sensing with optical interferometric sensing. The Fabry-Perot interferometer uses optical waves instead of mechanical transducers or electrical sensors, providing a non-contact measurement method that is inherently more reliable in noisy environments while maintaining high sensitivity.
3Measurement precision
If porous microstructures are used for biosensing, then the sensitivity is improved, but the measurement precision deteriorates due to signal drift from thermal fluctuations and sample composition changes
Solution Approach 1:
The patent implements a reference interferometer that provides a feedback mechanism for compensating drift. By having a reference arm that experiences similar environmental conditions but does not interact with the sample, the system can subtract reference signals from sample signals, effectively compensating for thermal fluctuations and sample composition changes.
Solution Approach 2:
A reference interferometer is created as a copy of the sample interferometer setup. The reference interferometer replicates the optical path and detection characteristics but without the sample interaction, serving as a baseline that copies the environmental effects so they can be subtracted from measurements.
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 precise discrimination and detection of biomolecules based on size, effectively correcting for signal drift and matrix changes, enhancing sensitivity and reducing equipment requirements compared to traditional methods.
Implementation Method 1
Porous microstructures have been demonstrated to produce characteristic spectral interference patterns. The interference based sensing is largely impervious to less complex optical sensing and detection methods.
Implementation Method 2
chemical or biomolecule detection can be based on changes in the spectral interference pattern that results from the reflection of white light at the interfaces above (air or solution) and below a porous silicon layer
Implementation Method 3
Porous silicon films with a distribution of pore diameters in the x-y plane (parallel to the surface of the wafer) have been demonstrated as size-exclusion matrices to perform an on-chip determination of macromolecule dimensions.
Implementation Method 4
Biomolecule penetration into the pores of porous Si layers, driven either by nonspecific adsorption or by specific binding (to an antibody, for instance)
Implementation Method 5
producing multiple superimposed interference patterns that can be resolved using Fourier transform analysis
Data Source
AI summary
A preferred embodiment biosensor is a multi-layer micro-porous thin film structure. Pores in a top layer of the micro-porous thin film structure are sized to accept a first molecule of interest. Pores in a second layer of the micro-porous thin film structure are smaller than the pores in the top layer and are sized to accept a second molecule of interest that is smaller than the first molecule of interest. The pores in the second layer are too small to accept the first molecule of interest. The pores in the top layer and the pores in the second layer are sized and arranged such that light reflected from the multi-layer micro-porous thin film structure produces multiple superimposed interference patterns that can be resolved. In preferred embodiments, the multi-layer micro-porous thin film structure is a porous silicon thin film multi-layer structure formed on a silicon substrate, such as a silicon wafer. Specific and nonspecific binding can be detected with biosensors of the invention. The position of peaks in the Fourier transform of the reflection spectrum and the shift in peak amplitudes can be used to determine the presence and quantity of targeted biological molecules of interest.