Label-free video-rate micro-endoscopy through flexible fibers via Fiber Bundle Distal Holography (FiDHo)

Real-time holographic lensless micro-endoscopy through flexible fibers via Fiber Bundle Distal Holography (FiDHo)

10.21203/rs.3.rs-528386/v1 ◽

2021 ◽

Author(s):

Noam Badt ◽

Ori Katz

Keyword(s):

Three Dimensional ◽

Phase Shifting ◽

Tissue Imaging ◽

Label Free ◽

Deep Tissue ◽

Optical Elements ◽

Full Field ◽

Low Coherence ◽

Flexible Fibers ◽

Deep Tissue Imaging

Abstract Fiber-based micro-endoscopes are a critically important tool for minimally-invasive deep-tissue imaging. However, the state-of-the-art micro-endoscopes cannot perform three-dimensional imaging through dynamically-bent fibers without the use of bulky optical elements such as lenses and scanners at the distal end, increasing the footprint and tissue-damage. Great efforts have been invested in developing approaches that avoid distal bulky optical elements. However, the fundamental barrier of dynamic optical wavefront-distortions in propagation through flexible fibers, limits current approaches to nearly-static or non-flexible fibers. Here, we present an approach that allows holographic 3D bend-insensitive, coherence-gated, micro-endoscopic imaging, using commercially available multi-core fibers (MCFs). We achieve this by adding a miniature partially-reflecting mirror to the distal fiber-tip, allowing to perform low-coherence full-field phase-shifting holography. We demonstrate widefield diffraction-limited reflection imaging of amplitude and phase targets through dynamically bent fibers at video-rates. Our approach holds potential for label-free investigations of dynamic samples

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Label-free, mass-sensitive single-molecule imaging using interferometric scattering microscopy

Essays in Biochemistry ◽

10.1042/ebc20200023 ◽

2020 ◽

Author(s):

Nikolas Hundt

Keyword(s):

Single Molecule ◽

Cellular Systems ◽

Single Molecule Imaging ◽

Label Free ◽

Measurement Sensitivity ◽

Mass Distributions ◽

Quantitative Measurements ◽

Contrast Mechanism ◽

Cellular Components ◽

Scattering Signal

Abstract Single-molecule imaging has mostly been restricted to the use of fluorescence labelling as a contrast mechanism due to its superior ability to visualise molecules of interest on top of an overwhelming background of other molecules. Recently, interferometric scattering (iSCAT) microscopy has demonstrated the detection and imaging of single biomolecules based on light scattering without the need for fluorescent labels. Significant improvements in measurement sensitivity combined with a dependence of scattering signal on object size have led to the development of mass photometry, a technique that measures the mass of individual molecules and thereby determines mass distributions of biomolecule samples in solution. The experimental simplicity of mass photometry makes it a powerful tool to analyse biomolecular equilibria quantitatively with low sample consumption within minutes. When used for label-free imaging of reconstituted or cellular systems, the strict size-dependence of the iSCAT signal enables quantitative measurements of processes at size scales reaching from single-molecule observations during complex assembly up to mesoscopic dynamics of cellular components and extracellular protrusions. In this review, I would like to introduce the principles of this emerging imaging technology and discuss examples that show how mass-sensitive iSCAT can be used as a strong complement to other routine techniques in biochemistry.

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A microfluidic device with integrated impedance detection for λ-DNA

MRS Proceedings ◽

10.1557/proc-773-n6.5 ◽

2003 ◽

Vol 773 ◽

Cited By ~ 1

Author(s):

Myung-Il Park ◽

Jonging Hong ◽

Dae Sung Yoon ◽

Chong-Ook Park ◽

Geunbae Im

Keyword(s):

Microfluidic Device ◽

Electrochemical Impedance ◽

Direct Detection ◽

Full Potential ◽

Label Free ◽

Buffer Solution ◽

Detection Systems ◽

Significant Difference ◽

Detection Of Biomolecules ◽

Impedance Magnitude

AbstractThe large optical detection systems that are typically utilized at present may not be able to reach their full potential as portable analysis tools. Accurate, early, and fast diagnosis for many diseases requires the direct detection of biomolecules such as DNA, proteins, and cells. In this research, a glass microchip with integrated microelectrodes has been fabricated, and the performance of electrochemical impedance detection was investigated for the biomolecules. We have used label-free λ-DNA as a sample biomolecule. By changing the distance between microelectrodes, the significant difference between DW and the TE buffer solution is obtained from the impedance-frequency measurements. In addition, the comparison for the impedance magnitude of DW, the TE buffer, and λ-DNA at the same distance was analyzed.

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