Soft Capsule Magnetic Millirobots for Region-Specific Drug Delivery in the Central Nervous System

Lamar O Mair; Georges Adam; Sagar Chowdhury; Aaron Davis; Dian R Arifin; Fair M Vassoler; Herbert H Engelhard; Jinxing Li; Xinyao Tang; Irving N Weinberg; Benjamin A Evans; Jeff W M Bulte; David J Cappelleri

doi:10.3389/frobt.2021.702566

Soft Capsule Magnetic Millirobots for Region-Specific Drug Delivery in the Central Nervous System

Front Robot AI. 2021 Jul 22:8:702566. doi: 10.3389/frobt.2021.702566. eCollection 2021.

Authors

Lamar O Mair¹, Georges Adam², Sagar Chowdhury^{1

2}, Aaron Davis², Dian R Arifin^{3

4}, Fair M Vassoler⁵, Herbert H Engelhard^{6

7}, Jinxing Li⁸, Xinyao Tang¹, Irving N Weinberg¹, Benjamin A Evans⁹, Jeff W M Bulte^{3

4

10}, David J Cappelleri^{2

11}

Affiliations

¹ Weinberg Medical Physics, Inc., North Bethesda, MD, United States.
² Multi-Scale Robotics and Automation Lab, School of Mechanical Engineering, Purdue University, West Lafayette, IN, United States.
³ Russel H. Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
⁴ Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
⁵ Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, United States.
⁶ Affiliated Neurosurgery Corporation, Chicago, IL, United States.
⁷ Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States.
⁸ Department of Biomedical Engineering, Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, United States.
⁹ Department of Physics, Elon University, Elon, NC, United States.
¹⁰ Departments of Oncology, Biomedical Engineering and Chemical and Biomolecular Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
¹¹ Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States.

Abstract

Small soft robotic systems are being explored for myriad applications in medicine. Specifically, magnetically actuated microrobots capable of remote manipulation hold significant potential for the targeted delivery of therapeutics and biologicals. Much of previous efforts on microrobotics have been dedicated to locomotion in aqueous environments and hard surfaces. However, our human bodies are made of dense biological tissues, requiring researchers to develop new microrobotics that can locomote atop tissue surfaces. Tumbling microrobots are a sub-category of these devices capable of walking on surfaces guided by rotating magnetic fields. Using microrobots to deliver payloads to specific regions of sensitive tissues is a primary goal of medical microrobots. Central nervous system (CNS) tissues are a prime candidate given their delicate structure and highly region-specific function. Here we demonstrate surface walking of soft alginate capsules capable of moving on top of a rat cortex and mouse spinal cord ex vivo, demonstrating multi-location small molecule delivery to up to six different locations on each type of tissue with high spatial specificity. The softness of alginate gel prevents injuries that may arise from friction with CNS tissues during millirobot locomotion. Development of this technology may be useful in clinical and preclinical applications such as drug delivery, neural stimulation, and diagnostic imaging.

Keywords: alginate microcapsule; drug delivery; magnetic millirobot; rotating magnetic fields; surface walkers.

Grants and funding

R01 DK106972/DK/NIDDK NIH HHS/United States