Color and monochrome lensless on-chip imaging of Caenorhabditis elegans over a wide field-of-view

Abstract

We demonstrate color and monochrome on-chip imaging of Caenorhabditis elegans samples over a wide field-of-view using incoherent lensless in-line holography. Digital reconstruction of the recorded lensless holograms rapidly creates the C. elegans images within <1 s over a field-of-view of >24 mm 2 . By digitally combining the reconstructed images at three different wavelengths (red, green and blue), color images of dyed samples are also acquired. This wide field-of-view and compact on-chip imaging modality also permits straightforward integration with microfluidic systems.Caenorhabditis elegans (C. elegans) has been extensively studied as a model organism to better understand the underlying mechanisms of various human diseases. 1 It has several important features that justify this widespread use. First, C. elegans is easy to culture in laboratory environments, growing and reproducing rapidly and cost-effectively. Further, it is a transparent, optically accessible organism with well developed nervous and reproductive systems, intestine, skin and muscles. As a result, high-throughput phenotypical characterization of C. elegans samples, which primarily involves optical imaging in the form of conventional microscopy, has led to important discoveries in biomedical research and specifically in drug discovery, significantly impacting genetics, 2 oncology 3 and neurobiology. 4,5 Motivated by these advances, various high-throughput platforms were demonstrated for phenotypical screening of this model organism. [6][7][8][9] In these existing systems, phenotype characterization relies on conventional lens-based light microscopy, which has a limited imaging field-of-view, despite the use of bulky and expensive objective-lenses.Here we demonstrate color and monochrome on-chip imaging of C. elegans samples using an alternative optical microscopy platform that is especially suitable for high-throughput screening applications, also offering straightforward integration with microfluidics. When compared to the state of the art, our approach does not utilize any lenses, lasers or other bulky optical components or any mechanical scanning, making it highly compact and simple to use. Our on-chip imaging approach is based on incoherent lensless in-line holography 10 (see Fig. 1) which provides a significantly larger field-of-view (FOV), permitting simultaneous imaging of C. elegans samples over an area of >24 mm 2 , i.e., ~10 fold larger than a typical 10× objectivelens FOV. Digital reconstruction of the recorded lensless holograms rapidly creates the C. elegans images within less than 1 s; and by digitally combining these reconstructed images at three different wavelengths (red, green and blue) color images of the samples that are labeled with functional dyes are also acquired. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript requires almost no sensitive optical alignment, making it quite easy to operate, even for nontechnical personnel. Through its integration with micro-fluidic systems, this lensle...

Quantitative phase imaging by wide field lensless digital holographic microscope

“…The pixel size limited resolution restricts the applications for only telemedicine and for resource limited setting. The so called pixel-super resolution approaches are possible solutions to increase the resolution [16][17][18]. The development in the manufacturing of sensors with smaller pixel size will further extend it applications fields.…”

“…This requires a microscope objective and mechanical alignment components. The group of Aydogan Ozcan proposed a new lensless digital holographic microscope which is capable of imaging samples with a field of view corresponding to the entire sensor active area with a resolution in the order of the pixel size of the sensor [1], [14][15][16][17][18].The main key concepts of this setup in contrast to the well-known lensless systems are the use of an LED with a pinhole of size ~ 50-100 µm as point source to achieve a high throughput and the placing of the sensor chip closer to the sample.…”

Thin wetting film lensless imaging

“…This technique has been successfully applied to image eukaryote cells with dimensions ranging from 10 µm (with blood cell, red blood cell, platelet, etc. [3]) to 500 µm (C. elegans [4]). Prokaryote cells, e.g.…”

“…Compared to long-established microscopy techniques, lensless imaging [1][2][3][4] combines the advantage of imaging a ultralarge FOV ranging from mm 2 to cm 2 and allowing embedded portable system with low power consumption. This technique has been successfully applied to image eukaryote cells with dimensions ranging from 10 µm (with blood cell, red blood cell, platelet, etc.…”

Field-portable lensfree holographic color microscope for telemedicine applications

“…Additionally, color has a psychological effect as cytotechnologists and physicians are trained to observe samples in color. Previous methods to render a color image in holographic imaging (lensfree or lens-based) result in aberrated images that exhibit a 'rainbow' like color noise [28]- [30]. These previous approaches captured three high-resolution holograms each taken by a different illumination wavelength [typically red, green and blue (RGB)], and super-imposing them into a final RGB image, which exhibited rainbow like color artifacts that are spatially super-imposed on the object features.…”