HKUST Engineers Achieve “Impossible” Trifecta: A Compact, Precise, and Multifunctional Biomedical Robot

Small-scale continuum robots hold promise for interventional diagnosis and treatment, yet existing models struggle to achieve compactness, precise navigation, and visualized functional treatment all in one. In a recent breakthrough, the School of Engineering of the Hong Kong University of Science and Technology (HKUST) has successfully surmounted this “impossible trinity”, paving the way for the use of robots in medical procedures within narrow, challenging channels of the human body such as the lung end bronchi and the oviducts.

Led by Prof. SHEN Yajing, Associate Professor at the Department of Electronic and Computer Engineering (ECE), the research team unveiled a novel optical fiber-based continuum robot. Their innovation accomplishes a trifecta by integrating imaging, high-precision motion, and multifunctional operation abilities – all at the submillimeter-scale.

With a slim profile of 0.95 mm created by microscale 3D printing and magnetic spray, this robot delivers competitive imaging performance and extends obstacle detection distance up to ~9.4 mm, a tenfold improvement from theoretical limits. It also showcases remarkable motion precision (less than 30 μm) and substantially widens the imaging region by ~25 times the inherent view.

“Continuum robots chart a new course for medical technology thanks to their narrow cavity-accessing ability, which brings the superiorities of quick recovery and low infection risk,” Prof. Shen explained of the background of the study.

“Up to date, the treatment of several diseases has been demonstrated using small continuum robots, such as heart disease treatment through deploying stent or electrophysiology catheter, repair of perforation of gastric and duodenal ulcers by single-port laparoscopy etc.,” he added.

Recognizing the merit of optical fiber in small-scale and media transmission, the research team proposed a magnetic-driven submillimeter soft continuum robot based on optical fiber array. This robot consists of an optical fiber array for imaging, a customized tool for implementing treatment, a submillimeter hollow skeleton produced by micro-scale 3D printing for deploying fibers or tools, and a functionalized skin for controlling.

Functionalized skin was proposed as a strategy to control the motion of the probe precisely. In an experiment, a layer of magnetic elastomer was covered on the surface by employing magnetic spray, granting the probe active steering capacity under a magnetic field while keeping almost no increase in its contour. Then, a layer of hydrogel skin was coated on the outer surface of the robot body to reduce the potential friction during surgery.

Consequently, a functionalized submillimeter probe robot with a 0.95 mm diameter was achieved with simultaneous active navigation and in situ treatment – indicating the unraveling of the “impossible trinity”.

Researchers subsequently conducted in vitro experiments inside a bronchial tree phantom and ex vivo trials in porcine lung models. They demonstrated successful interventional navigation inside constrained environments, as well as high-precision scanning imaging and various in situ treatments for pathological areas.

Prof. Shen further pointed out that this groundbreaking robot had integrated customized functionalities such as sampling, drug delivery, and laser ablation, giving it tremendous potential in clinical applications.

“Our study provides a significant solution for the development of a clinical surgical robot aimed at achieving early diagnosis and therapeutic goals in more hard-to-reach bodily regions. With continuous technological advancements, we believe that the fiberscopic robot will make greater contributions to human health in the foreseeable future,” he remarked.

As for the next step, the team plans to refine the robot’s features to fit them into practical settings.

“We aim to further optimize the design and control of the fiberscopic robot, prioritizing safety and reliability during interventional surgery. We look forward to implementing in vivo trials to demonstrate its performance in clinical scenarios,” said Dr. ZHANG Tieshan, a postdoctoral fellow at HKUST. He is one of the two co-first authors of the study, along with Dr. LI Gen, who is Prof. Shen’s former PhD student at the City University of Hong Kong. Other co-authors from HKUST include Research Assistant Professor Dr. YANG Xiong and PhD student ZHAO Haoxiang, also from the ECE Department.

Their findings have been published in Nature Communications, in a paper titled “Sub-Millimeter Fiberscopic Robot with Integrated Maneuvering, Imaging, and Biomedical Operation Abilities”.