University of Adelaide Adelaide,
Australia

A team of researchers led by the University of Adelaide and University of Stuttgart has used 3D micro-printing to develop the world’s smallest, flexible scope for looking inside blood vessels. The camera-like imaging device can be inserted into blood vessels to provide high-quality 3D images to help scientists better understand the causes of heart attack and heart disease progression and could lead to improved treatment and prevention.

In a study published in the journal Light: Science & Applications, a multidisciplinary team of researchers and clinicians was able to 3D print a tiny lens on to the end of an optical fiber, the thickness of a human hair. 1

According to the study, the ultrathin monolithic OCT endoscope overcomes the current limitations by using two-photon polymerization to 3D print 125-m-diameter micro-optics directly onto the optical fiber (see Figure 1). “Freeform micro-optics have been created for correcting the nonchromatic aberrations of highly miniaturized probes, which cannot be fabricated using traditional techniques.

Fig. 1 - Ultrathin 3D printed endoscope design. Schematic of the 3D printed OCT endoscope inside an artery (a). Microscope image of the 3D printed off-axis freeform total internal reflection (TIR) mirror on the tip of the no-core fiber that is fusion spliced onto the light-guiding single-mode fiber (b). Optical design of the system with light exiting the single-mode fiber, expanding in the no-core fiber, being reflected and phase-shaped at the freeform mirror, passing the catheter sheath and focusing into the artery tissue (c). Photo of the 3D printed OCT endoscope, which rotates and is pulled back to accomplish full 3D OCT scanning (d). (Credit: Light: Science & Applications)

The OCT endoscope achieved a measured full width at half maximum (FWHM) focal spot size of 12.4 m and effective depths of focus (the depth range in which FWHM < 2FWHM min 29) of 760 µm (x axis) and 1100 µm (y axis). The utility of the ultrathin endoscope is demonstrated on both in situ preclinical (mouse) and ex vivo clinical (human) models of cardiovascular disease.

This scope reveals details of the tissue microarchitecture at depths not previously achieved with such small imaging probes. The researchers believe this is the smallest aberration-corrected intravascular probe to have been developed.

The imaging device is so small that researchers were able to scan inside the blood vessels of mice. Dr. Jiawen Li, coauthor and Heart Foundation Postdoctoral Fellow at the Institute for Photonics and Advanced Sensing, University of Adelaide, says that in Australia cardiovascular disease kills one person every 19 minutes.

“A major factor in heart disease is the plaques, made up of fats, cholesterol, and other substances that build up in the vessel walls,” Li says. “Preclinical and clinical diagnostics increasingly rely on visualizing the structure of the blood vessels to better understand the disease. Miniaturized endoscopes, which act like tiny cameras, allow doctors to see how these plaques form and explore new ways to treat them,” she says.

Dr. Simon Thiele, group leader, Optical Design and Simulation at the University of Stuttgart, was responsible for fabricating the tiny lens.

“Until now, we couldn’t make high quality endoscopes this small,” Thiele says. “Using 3D micro-printing, we are able to print complicated lenses that are too small to see with the naked eye. “The entire endoscope, with a protective plastic casing, is less than half a millimeter across,” he says.

The collaboration also included researchers from The South Australian Health and Medical Research Institute, The Royal Adelaide Hospital, and Monash University.

Reference

  1. Jiawen Li, et al., “Ultrathin monolithic 3D printed optical coherence tomography endoscopy for preclinical and clinical use,” Light: Science & Applications, Vol. 9, Article number: 124 (2020).

Contact Dr. Li at This email address is being protected from spambots. You need JavaScript enabled to view it.. For more information, visit here .


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This article first appeared in the September, 2020 issue of Medical Design Briefs Magazine.

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