Plasmonic Sample Holder for Label-Free Microscopy
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Solution Overview
Problem
Conventional optical microscopy techniques face challenges in enhancing image contrast for samples that weakly interact with light, often requiring modifications, stains, or fluorescent markers, which can introduce artefacts and limit imaging of live samples.
Innovation Solution
A method utilizing a sample holder with a plasmonic layer featuring a periodic array of sub-micron structures that interacts with light to produce surface plasmon resonance peaks, enabling image contrast enhancement without stains or fluorescent markers, by differentiating transmitted light spectra through and around the object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phase-contrast microscopy is used to enhance image contrast of transparent samples, then image contrast is improved, but spatial resolution is reduced due to halo artefacts
Solution Approach 1:
The patent changes the optical parameters by introducing a phase plate with specific phase shift values (e.g., λ/4, λ/2) and amplitude modulation characteristics. This modifies the interference conditions between direct and diffracted light waves, enabling contrast enhancement without the halo artefacts that plague conventional phase-contrast microscopy. The phase plate parameters are optimized to achieve quantitative phase imaging with improved spatial resolution.
Solution Approach 2:
The phase plate acts as an intermediary element placed in the optical path between the sample and the detector. It mediates the interference between direct and diffracted light by introducing controlled phase shifts and amplitude modifications, thereby converting phase information into intensity variations without creating halo artefacts. This intermediary enables quantitative phase imaging while preserving spatial resolution.
2Illumination intensity
If staining is used to increase image contrast of samples, then image contrast is improved, but sample damage and artefact introduction occur
Solution Approach 1:
The patent employs label-free quantitative phase imaging that utilizes the intrinsic optical properties of the sample itself without requiring external stains or labels. The phase plate interferometer detects phase shifts caused by the sample's refractive index and thickness variations, allowing the sample to serve its own imaging function without external assistance. This eliminates sample damage and artefact introduction associated with staining procedures.
Solution Approach 2:
The patent extracts and isolates the phase information from the sample by using a phase plate interferometer configuration. The phase plate separates the direct and diffracted light waves, allowing independent measurement of phase shifts without the need for staining. This extraction of phase information enables contrast enhancement while avoiding the harmful effects of sample preparation procedures.
3Measurement precision
If conventional bright-field microscopy is used for imaging, then spatial resolution is maintained at high levels, but image contrast is insufficient for weakly interacting samples
Solution Approach 1:
The patent segments the light wave into direct and diffracted components using a phase plate, allowing separate manipulation and recombination of these components. This segmentation enables independent optimization of contrast enhancement while preserving the high spatial resolution capabilities of conventional microscopy. The diffracted light carries sample information that is enhanced through phase modulation without compromising resolution.
Solution Approach 2:
The patent transitions from intensity-based imaging to phase-based imaging by introducing a new dimension of measurement. The phase plate interferometer measures phase shifts in addition to intensity variations, providing quantitative phase information that enhances contrast for weakly interacting samples. This dimensional expansion from 2D intensity to 3D phase-space enables detection of samples that are invisible in conventional bright-field microscopy.
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 high-contrast, label-free imaging of unstained samples, improving spatial resolution and reducing artefacts, enabling effective imaging of specimens that are difficult to detect using conventional microscopy.
Implementation Method 1
the light interacts with at least the plasmonic layer such that: the first portion of the transmitted light is characterised by one or more first surface plasmon resonance peaks, and the second portion of the transmitted light is characterised by one or more second surface plasmon resonance peaks
Data Source
AI summary
A system and method of imaging an object uses a plasmonic layer as a sample holder defining a periodic array of sub-micron structures adjacent the object. The sample holder is exposed to a first portion of light that is transmitted through either the plasmonic layer but not the object, or the plasmonic layer and a first section of the object, and a second portion of the light that is transmitted through the plasmonic layer and at least a second section of the object. The light interacts with at least the plasmonic layer and the first portion of the transmitted light characterizes one or more first surface plasmon resonance peaks and the second portion of the transmitted light characterizes one or more second surface plasmon resonance peaks that are wavelength shifted from the first surface plasmon resonance peaks by the object affecting plasmons propagating within the plasmonic layer.