Wide-field computational imaging of pathology slides using lens-free on-chip microscopy

Abstract

Optical examination of microscale features in pathology slides is one of the gold standards to diagnose disease. However, the use of conventional light microscopes is partially limited owing to their relatively high cost, bulkiness of lens-based optics, small field of view (FOV), and requirements for lateral scanning and three-dimensional (3D) focus adjustment. We illustrate the performance of a computational lens-free, holographic on-chip microscope that uses the transport-of-intensity equation, multi-height iterative phase retrieval, and rotational field transformations to perform wide-FOV imaging of pathology samples with comparable image quality to a traditional transmission lens-based microscope. The holographically reconstructed image can be digitally focused at any depth within the object FOV (after image capture) without the need for mechanical focus adjustment and is also digitally corrected for artifacts arising from uncontrolled tilting and height variations between the sample and sensor planes. Using this lens-free on-chip microscope, we successfully imaged invasive carcinoma cells within human breast sections, Papanicolaou smears revealing a high-grade squamous intraepithelial lesion, and sickle cell anemia blood smears over a FOV of 20.5 mm(2). The resulting wide-field lens-free images had sufficient image resolution and contrast for clinical evaluation, as demonstrated by a pathologist's blinded diagnosis of breast cancer tissue samples, achieving an overall accuracy of ~99%. By providing high-resolution images of large-area pathology samples with 3D digital focus adjustment, lens-free on-chip microscopy can be useful in resource-limited and point-of-care settings.

Synthetic holography based on scanning microcavity

“…2,3 In microscopy, these systems were also realized in a more compact way, by developing lens-free devices to record holographic patterns. [4][5][6][7] Although the features of wide-field digital holography have confirmed this technique as a relevant tool for imaging, only recently this method has been implemented in optical scanning microscopy. 8 In the latter, named synthetic optical holography (SOH), a point detector is employed, replacing CCD cameras, in order to encode the phase across the whole image.…”

Image Processing and Cell Phone Microscopy to Analyze the Immunomagnetic Beads on Micro-Contact Printed Gratings

“…Optical micrographs were recorded using Nikon (Melville, NY, USA) microscope equipped with a charge-coupled (CCD) Cell phone microscopy is gaining in popularity due to being low cost, and the wide-spread use of cell phones [11]. Lens attachments [12,13] or lens free computational [14] strategies were developed to turn cell phones into optical microscopes. One approach is to attach a spherical ball lens to a cell phone camera to provides magnification and record microscopic images [15,16].…”

On-chip cell analysis platform: Implementation of contact fluorescence microscopy in microfluidic chips

“…On-chip imaging techniques are highly attractive, particularly in the application fields of automated systems, for high-throughput biological and medical screening due to their advantages compared with conventional tabletop-type microscopes, including (i) ease of scale-up of field of view with large numbers of pixels and smaller pixel sizes, (ii) compact hardware geometry, cost effectiveness and mass producibility, (iii) and simple usability without careful selection and focusing of the lenses. [2][3][4][5][6][7][8] Automated system using microfluidic technology has also demonstrated great potential for biological and medical analysis, 9,10 drug screening, 11,12 and cell processing. 13,14 Thus, using on-chip fluorescence imaging techniques and a microfluidic chip platform provides a fully automated system from sample handling to detect of cellular activity.…”