Label-free digital cytopathology using deep-ultraviolet coded ptychography with intrinsic molecular contrast

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Project Summary / Abstract Histopathological examination of tissue is a pillar of modern medicine and biological research. Commonly used bright-field microscopy requires prior preparation of micrometer-thick tissue sections mounted on glass slides and stained with dyes, a process that takes hours or days, delaying access to critical information for interventions. This project aims to develop a new type of high-throughput digital cytopathology tool with intrinsic molecular contrast for label-free and slide-free histology. This tool will be built based on lensless high-throughput coded ptychography operated at the 260-nm and 280-nm deep ultraviolet (DUV) wavelengths. DUV light directly interacts with and is absorbed by biomolecules of nucleic acids (nucleus) and amino acids (protein) of cells. Absorption spectra are different for these two types of biomolecules. By measuring the specimen profiles at the 260-nm and 280-nm DUV wavelengths, we can recover the quantitative mass maps of cell nucleus and protein without any dye labeling. In contrast, there is no absorption for these biomolecules in the visible light regime. In the proposed DUV coded ptychography tool, we do not use any optical lens as in a conventional microscope platform. Instead, we fabricate a disorder-engineered coded layer on top of an image sensor. This coded layer serves as a large-scale scattering ‘lens’ for imaging specimens placed on top of it. When light diffracts from the tissue samples at a large angle, the coded layer redirects the diffracted light into smaller angles that are detectable by sensor pixels. As such, the otherwise inaccessible high-resolution object details can be acquired using the pixel array underneath the coded layer. Our preliminary data show that the image throughput is greater than the fastest whole slide scanner in the world: resolving 308-nm linewidth over a 240-mm2 effective field of view in 15 seconds. By using the dual wavelength DUV LEDs for sample illumination, the proposed tool will provide both phase-based quantitative morphology measurement and amplitude-based intrinsic chemical specificities for different biomolecules. It can be used for rapid onsite evaluation of cytology smear obtained from fine-needle aspirate. It can also reduce sample preparation time and provides intraoperative pathology guidance on surgical margins. The cost of the entire device will be similar to that of an iPad, making it a handheld, high-throughput ‘personal’ whole slide scanner for most individual pathologists and researchers worldwide.