Exploring the nooks and crannies of the body’s organs seems fodder for a sci-fi movie. Yet, an international team of researchers and engineers has made this a reality — and it’s set to change the way we see human diseases.

A new study, published in the prestigious journal Light: Science & Applications, outlines how the team developed the world’s tiniest endoscope.

Lead author Dr Jiawen Li is an associate investigator and Heart Foundation Postdoctoral Fellow at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) at the University of Adelaide. She says, ultimately, the endoscope will help clinicians better understand the causes and progression of various diseases.

At the heart of the endoscope is a tiny 3D printed lens on the end of an optical fibre, as thin as a single human hair. With a protective catheter sheath, the entire device is less than half a millimetre wide. This means it can safely fit inside a narrow artery.

‘We used the technology to take 3D scans of atherosclerotic plaques inside blood vessel walls,’ Dr Li said. ‘These are a common cause of heart attacks.’

The images Dr Li and the team received were of a higher quality than what is possible from the fibre-optic tools currently used for preclinical and clinical cardiovascular disease diagnostics. And because the tool is so small, it’s less likely to cause any damage to the body.

While smaller endoscopes were always necessary for these diagnostics, the problem previously was how to make a smaller lens. It was next to impossible to create a hair-sized device with all the complicated optics inside, so the team turned to 3D microprinting.

‘To shrink it using traditional manufacturing methods caused a lot of problems with the blurring of images. They weren’t high quality,’ Dr Li said. ‘What’s nice with 3D microprinting is you can print whatever shape you want on such a tiny scale.’

Jiawen Li holding a 3D printed probe. Credit: Dr Shikui Yao.

Within the team are world leaders in 3D printing from the University of Stuttgart. They worked with Dr Li to print complicated lenses only a few hundred microns in diameter. The end result is not only a tiny endoscope but one that captures clear, sharp images.

In Australia 157 people are hospitalised every day due to heart attacks. Around one in 10 of these people are likely to be readmitted for a second one within a year. The endoscope can help detect and prevent these secondary heart attacks by assessing plaque in the arteries after the initial attack.

The CNBP team of engineers, physicists, cardiologists and biologists also hope the technology can help a wider range of patients by detecting other conditions such as lung cancer.

‘The endoscope can fit into the small branches of airways without causing damage,’ Dr Li said.

It could also help develop better drugs and treatments, or guide stents into arteries.

The next steps to move the tool past a proof of concept are further studies and to closely examine how diseases progress.

‘We want to give people the opportunity to receive the best treatment by helping doctors to see the disease more clearly,’ Dr Li said. ‘The technology could help save a patient’s life.’

Source: ARC Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide


Journal: Light: Science & Applications

DOI: 10.1038/s41377-020-00365-w

Publication Title: Ultrathin monolithic 3D printed optical coherence tomography endoscopy for preclinical and clinical use.

Authors: Jiawen Li, Simon Thiele, Bryden C. Quirk, Rodney W. Kirk, Johan W. Verjans, Emma Akers, Christina Bursill, Stephen J. Nicholls, Alois M. Herkommer, Harald Giessen, Robert A. McLaughlin.

Abstract:

Preclinical and clinical diagnostics increasingly rely on techniques to visualize internal organs at high resolution via endoscopes. Miniaturized endoscopic probes are necessary for imaging small luminal or delicate organs without causing trauma to tissue. However, current fabrication methods limit the imaging performance of highly miniaturized probes, restricting their widespread application. To overcome this limitation, we developed a novel ultrathin probe fabrication technique that utilizes 3D microprinting to reliably create side-facing freeform micro-optics (<130 µm diameter) on single-mode fibers. Using this technique, we built a fully functional ultrathin aberration-corrected optical coherence tomography probe. This is the smallest freeform 3D imaging probe yet reported, with a diameter of 0.457 mm, including the catheter sheath. We demonstrated image quality and mechanical flexibility by imaging atherosclerotic human and mouse arteries. The ability to provide microstructural information with the smallest optical coherence tomography catheter opens a gateway for novel minimally invasive applications in disease.

Link: https://www.nature.com/articles/s41377-020-00365-w

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