Untethered shape-changing devices in the gastrointestinal tract

ABSTRACT

Introduction

Advances in microfabrication, automation, and computer engineering seek to revolutionize small-scale devices and machines. Emerging trends in medicine point to smart devices that emulate the motility, biosensing abilities, and intelligence of cells and pathogens that inhabit the human body. Two important characteristics of smart medical devices are the capability to be deployed in small conduits, which necessitates being untethered, and the capacity to perform mechanized functions, which requires autonomous shape-changing.

Areas covered

We motivate the need for untethered shape-changing devices in the gastrointestinal tract for drug delivery, diagnosis, and targeted treatment. We survey existing structures and devices designed and utilized across length scales from the macro to the sub-millimeter. These devices range from triggerable pre-stressed thin film microgrippers and spring-loaded devices to shape-memory and differentially swelling structures.

Expert opinion

Recent studies demonstrate that when fully enabled, tether-free and shape-changing devices, especially at sub-mm scales, could significantly advance the diagnosis and treatment of GI diseases ranging from cancer and inflammatory bowel disease (IBD) to irritable bowel syndrome (IBS) by improving treatment efficacy, reducing costs, and increasing medication compliance. We discuss the challenges and possibilities associated with ensuring safe, reliable, and autonomous operation of these smart devices.

KEYWORDS:

• Extended drug release
• oral delivery of biologics
• monoclonal antibodies
• targeted delivery
• microrobots
• minimally invasive surgery
• capsule endoscope
• ingestible electronics

Article highlights

• Current trends, such as capsule endoscopy and active matter therapeutics, point to the convergence of surgical and diagnostic tools with drug delivery devices.

• Shape-changing devices can emulate the autonomy and mechanical features of GI-resident organisms.

• Evidence shows that shape-changing and self-latching microdevices, such as theragrippers, can enhance the efficacy of extended drug delivery.

• The untethered shape-changing devices capable of tissue penetration improve the bioavailability of macromolecules and biologics via the GI tract.

• Untethered devices can access hard-to-reach conduits and operate in large numbers for localized treatments.

• Multimodal shape-changing devices capable of performing surgical or diagnostic functions (e.g., imaging, sensing, sampling, and patching) and drug delivery are gaining attention.

Declaration of interest

Johns Hopkins University has filed patents related to self-folding, microgrippers, theragrippers, and related technologies with either D. H. Gracias or F. M. Selaru or both. Under an option to license agreement between Kley Dom Biomimetics, LLC and the Johns Hopkins University, D. H. Gracias and the Johns Hopkins University are entitled to royalty distributions related to these technologies described in the study. This arrangement has been reviewed and approved by Johns Hopkins University in accordance with its conflict-of-interest policies. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The authors acknowledge funding from the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award Number R01EB017742. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.