Microscopic imaging tool may enable mobile disease diagnosis

Scientists from The University of Melbourne and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) have developed a low-cost microscopic imaging device small enough to fit on a smartphone camera lens, with the potential to make mobile medical diagnosis of diseases affordable and accessible. Their research has been published in the journal ACS Photonics.

The detection of diseases often relies on optical microscope technology to investigate changes in biological cells. Currently, these investigation methods usually involve staining the cells with chemicals in a laboratory environment as well as using specialised ‘phase-imaging’ microscopes. These aim to make invisible aspects of a biological cell visible, so early-stage detection of disease becomes possible. However, phase-imaging microscopes are bulky and cost thousands of dollars, putting them out of reach of remote medical practices.

The researchers are helping to miniaturise phase-imaging technology using metasurfaces, which are only a few hundred nanometres thick — about 350 times thinner than the thickness of a human hair — thus small enough to fit in the lens of a smartphone or other small camera. Lead researcher Dr Lukas Wesemann, from The University of Melbourne, said that similar to expensive phase-imaging microscopes, metasurfaces can manipulate the light passing through them to make otherwise invisible aspects of objects like live biological cells visible.

“We manufactured our metasurface with an array of tiny rods — nanorods — on a flat surface, arranged in such a way as to turn an invisible property of light, called its ‘phase’, into a normal image visible to the human eye, or conventional cameras,” Wesemann said.

“These phase-imaging metasurfaces create high-contrast, pseudo-3D images without the need for computer post-processing.”

In addition to providing resources for remote medical practices, the 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.

“Making medical diagnostic devices smaller, cheaper and more portable will help disadvantaged regions gain access to health care that is currently only available to first-world countries,” Wesemann said.

Study co-author and TMOS Chief Investigator Professor Ann Roberts said the research serves as an exciting breakthrough in the field of phase-imaging, stating, “It’s 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.”

Image credit: ©stock.adobe.com/au/Khunatorn

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