English
norskBlar i forfatter "Jayakumar, Nikhil"
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Characterization of Liposomes Using Quantitative Phase Microscopy (QPM)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-21)The rapid development of nanomedicine and drug delivery systems calls for new and effective characterization techniques that can accurately characterize both the properties and the behavior of nanosystems. Standard methods such as dynamic light scattering (DLS) and fluorescent-based assays present challenges in terms of system’s instability, machine sensitivity, and loss of tracking ability, among ... -
Demystifying speckle field interference microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-27)Dynamic speckle illumination (DSI) has recently attracted strong attention in the feld of biomedical imaging as it pushes the limits of interference microscopy (IM) in terms of phase sensitivity, and spatial and temporal resolution compared to conventional light source illumination. To date, despite conspicuous advantages, it has not been extensively implemented in the feld of phase imaging due ... -
High-throughput spatial sensitive quantitative phase microscopy using low spatial and high temporal coherent illumination
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-04)High space-bandwidth product with high spatial phase sensitivity is indispensable for a single-shot quantitative phase microscopy (QPM) system. It opens avenue for widespread applications of QPM in the field of biomedical imaging. Temporally low coherence light sources are implemented to achieve high spatial phase sensitivity in QPM at the cost of either reduced temporal resolution or smaller field ... -
Label-free imaging on waveguide platform with enhanced resolution and contrast
(Conference object; Konferansebidrag, 2021)Chip-based Evanescent Light Scattering (cELS) utilizes the multiple modes of a high-index contrast optical waveguide for near-field illumination of unlabeled samples, thereby repositioning the highest spatial frequencies of the sample into the far-field. The multiple modes scattering off the sample with different phase differences is engineered to have random spatial distributions within the integration ... -
Label-free super-resolution optical microscopy
(Doctoral thesis; Doktorgradsavhandling, 2024-02-06)To see structures well below 200 nm using visible light, super-resolution techniques have been developed. Most of these techniques rely on fluorescence labelling or use of artificial materials to go beyond the Abbe limit. Therefore, achieving super-resolution in the label-free regime is the problem that is being addressed in this thesis. In this work, high-index contrast dielectric waveguides are ... -
Multi-moded high-index contrast optical waveguide for super-contrast high-resolution label-free microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-20)The article elucidates the physical mechanism behind the generation of superior-contrast and highresolution label-free images using an optical waveguide. Imaging is realized by employing a high index contrast multi-moded waveguide as a partially coherent light source. The modes provide near-field illumination of unlabeled samples, thereby repositioning the higher spatial frequencies of the ... -
On-chip TIRF nanoscopy by applying Haar wavelet kernel analysis on intensity fluctuations induced by chip illumination
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-09)Photonic-chip based TIRF illumination has been used to demonstrate several on-chip optical nanoscopy methods. The sample is illuminated by the evanescent field generated by the electromagnetic wave modes guided inside the optical waveguide. In addition to the photokinetics of the fluorophores, the waveguide modes can be further exploited for introducing controlled intensity fluctuations for exploitation ... -
Sampling moiré method: a tool for sensing quadratic phase distortion and its correction for accurate quantitative phase microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-24)The advantages of quantitative phase microscopy (QPM) such as label-free imaging with high spatial sensitivity, live cell compatibility and high-speed imaging makes it viable for various biological applications. The measurement accuracy of QPM strongly relies on the shape of the recorded interferograms, whether straight or curved fringes are recorded during the data acquisition. Moreover, for a ... -
A transparent waveguide chip for versatile total internal reflection fluorescence-based microscopy and nanoscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-20)Total internal reflection fluorescence (TIRF) microscopy is an imaging technique that, in comparison to confocal microscopy, does not require a trade-off between resolution, speed, and photodamage. Here, we introduce a waveguide platform for chip-based TIRF imaging based on a transparent substrate, which is fully compatible with sample handling and imaging procedures commonly used with a standard ...
