# On-Chip Polarization Light Microscopy

## TL;DR

This paper introduces a compact on-chip polarization light microscopy system for analyzing birefringent materials, suitable for point-of-care diagnostics.

## Contribution

A novel semiconductor-based platform for quantitative polarization light microscopy is developed for portable and non-contact imaging.

## Key findings

- The on-chip system achieved micrometer-scale spatial resolution for polarization imaging.
- The platform successfully visualized Euglena gracilis and detected Monosodium Urate crystals.
- Negative birefringence of crystals was observed, aiding in gout diagnosis.

## Abstract

Polarization light microscopy (PLM) enables detailed examination of birefringent materials and reveals unique features that cannot be observed under non-polarized light. Implementation of this technique for quantitative PLM (QPLM) assessment of samples is challenging and requires specialized components and equipment. Here, we demonstrate QPLM on a semiconductor imaging chip that is suitable for point-of-care/need applications. A white LED illumination was used with crossed polarizers and a full wave plate to perform on-chip, non-contact-mode QPLM. Polarization complexity is probed by assessing the multispectral phase shift experienced by white light through the distinct optical paths of the sample. This platform can achieve micrometer-scale spatial resolution with a Field of View determined by the size of the semiconductor sensor. Visualization of a biological sample (Euglena gracilis) was demonstrated, as well as the detection of Monosodium Urate crystals, where the presence of negative birefringence of crystals in synovial fluid is important for the diagnosis of gout.