Mobile microrobots for bioengineering applications

Abstract

Untethered micron-scale mobile robots can navigate and non-invasively perform specific tasks inside unprecedented and hard-to-reach inner human body sites and inside enclosed organ-on-a-chip microfluidic devices with live cells. They are aimed to operate robustly and safely in complex physiological environments where they will have a transforming impact in bioengineering and healthcare. Research along this line has already demonstrated significant progress, increasing attention, and high promise over the past several years. The first-generation microrobots, which could deliver therapeutics and other cargo to targeted specific body sites, have just been started to be tested inside small animals toward clinical use. Here, we review frontline advances in design, fabrication, and testing of untethered mobile microrobots for bioengineering applications. We convey the most impactful and recent strategies in actuation, mobility, sensing, and other functional capabilities of mobile microrobots, and discuss their potential advantages and drawbacks to operate inside complex, enclosed and physiologically relevant environments. We lastly draw an outlook to provide directions in the veins of more sophisticated designs and applications, considering biodegradability, immunogenicity, mobility, sensing, and possible medical interventions in complex microenvironments.

Self‐Folded Hydrogel Tubes for Implantable Muscular Tissue Scaffolds

“…Recently, considerable interest has been given to the development of shape‐changing and self‐folding 3D systems, which can undergo a morphological transformation from an initial 2D shape to a prescribed 3D one in response to an external trigger . Programming chemical and physical properties of materials can enable smart programmable material systems with embedded structural and functional information, and engineering an overall material response . Design and creation of such well‐controlled, complex structures that morph to predetermined shapes could offer great promise for applications in tissue engineering, drug delivery, sensing, and soft robotics …”

Hydrodynamic Impedance Correction for Reduced‐Order Modeling of Spermatozoa‐Like Soft Micro‐Robots

“…[1,2] A large body of experimental efforts has been demonstrated in the literature in recent years on how to employ or mimic the spermatozoa in order to utilize plane wave propagation for micro-robotic actuation; [3][4][5][6][7] however, comprehensive theoretical models date back to the early 1950s. [1,2] A large body of experimental efforts has been demonstrated in the literature in recent years on how to employ or mimic the spermatozoa in order to utilize plane wave propagation for micro-robotic actuation; [3][4][5][6][7] however, comprehensive theoretical models date back to the early 1950s.…”

3D-Printed Biodegradable Microswimmer for Drug Delivery and Targeted Cell Labeling

“…In contrast to other untethered power transfer alternatives, such as light and chemical signals, magnetic fields are able to safely penetrate biological tissues and other materials (12). To rotate the double helix, rotating magnetic fields are needed, which then create a torque on the microswimmer through a magnetic axis defined perpendicular to the helical axis.…”

“…The advances and evolution of untethered mobile robots, whose overall size is down to around a single cell, can further leverage minimally invasive medicine by providing an unprecedented direct access and precise control in deep and delicate body sites, such as the central nervous system, the circulatory system, the fetus, and the eye (3)(4)(5)(6)(7)(8). Recent progress along this line has already resulted in a number of synthetic and biohybrid microrobotic designs with intriguing functionalities toward their use in various body sites (9)(10)(11)(12).…”