Scientists are about to turn your smartphone into a tool that can diagnose diseases such as malaria, making mobile medical diagnostics affordable and accessible to remote areas such as third world countries and outback Australia.

Currently, disease diagnostics usually requires chemical staining of cells and bulky and expensive microscopes that perform a process referred to as phase imaging. These microscopes cost thousands of dollars, putting them out of reach of remote medical practices. As a result, early stage detection is often not possible, leading to more severe illness and increased death rates. In 2020, there were an estimated 627,000 deaths caused by malaria, with 96% of those coming from the African region, where advanced medical diagnostics is hard to come by.

Research published today in ACS Photonics by researchers at the University of Melbourne and TMOS, an Australian Research Council-funded research centre, is helping to miniaturize technology that makes invisible aspects of biological cells visible using metasurfaces, which are only a few hundred nanometres thick and thus small enough to be included in the lens of a smartphone. This future technology would allow mobile devices such as a smartphone to investigate biological specimens in a way not possible previously.

In addition to providing resources for remote medical practices, this new technology could one day lead to at-home disease detection, where the patient could obtain their own specimen through saliva or a pinprick of blood, and then transmit an image to a laboratory anywhere in the world. The lab could then analyse and diagnose the illness.

Lead researcher, Lukas Wesemann, says “making medical diagnostic devices smaller, cheaper and more portable will help disadvantaged regions gain access to healthcare that is currently only available to first world countries. This is why we go into science—to help change the world.”

TMOS Chief Investigator Ann Roberts says “This is an exciting breakthrough in the field of phase-imaging and just the tip of the iceberg in terms of how metasurfaces will completely reimagine conventional optics and lead to a new generation of miniaturised devices.”

For more information about this research, please contact connect@tmos.org.au

Real-Time Phase Imaging with an Asymmetric Transfer Function Metasurface

Lukas Wesemann, Jon Rickett, Timothy J. Davis, and Ann Roberts

ACS Photonics, 30th April 2022

The conversion of phase variations in an optical wavefield into intensity information is of fundamental importance for optical imaging including the microscopy of biological cells. Recently, meta-optical devices have demonstrated all-optical, ultracompact image processing of optical wavefields but are limited by their symmetric optical response to amplitude and phase gradients. Here, we describe a metasurface that exploits photonic spin–orbit coupling to create an asymmetric optical transfer function for real-time phase imaging. We demonstrate experimentally the effect of the asymmetry with the generation of high contrast pseudo-3D intensity images of phase variations in an optical wavefield without the need for post-processing. This non-interferometric method has potential applications in biological live cell imaging and real-time wavefront sensing.