A microrobotic system guided by photoacoustic computed tomography for targeted navigation in intestines in vivo

Abstract

Recently, tremendous progress in synthetic micro/nanomotors in diverse environment has been made for potential biomedical applications. However, existing micro/nanomotor platforms are inefficient for deep tissue imaging and motion control in vivo. Here, we present a photoacoustic computed tomography (PACT)–guided investigation of micromotors in intestines in vivo. The micromotors enveloped in microcapsules are stable in the stomach and exhibit efficient propulsion in various biofluids once released. The migration of micromotor capsules toward the targeted regions in intestines has been visualized by PACT in real time in vivo. Near-infrared light irradiation induces disintegration of the capsules to release the cargo-loaded micromotors. The intensive propulsion of the micromotors effectively prolongs the retention in intestines. The integration of the newly developed microrobotic system and PACT enables deep imaging and precise control of the micromotors in vivo and promises practical biomedical applications, such as drug delivery.

Multigear Bubble Propulsion of Transient Micromotors

“…We studied the behavior of Mg-based transient micromotor with hydrophilic (titanium dioxide) and hydrophobic (parylene) insulating shells [31]. A typical micromotor is fabricated by coating an Mg microparticle (diameter 20-25 μm) with an insulating material using atomic layer deposition (Fig.…”

Efficient Navigation of Colloidal Robots in an Unknown Environment via Deep Reinforcement Learning

“…Ultimately, our DRL algorithm allows to be integrated with experimental systems as it can directly process raw sensor inputs of microrobot systems (e.g., microscope) . Possible data scarcity and noisy‐state estimation issues in real experiments can be addressed by techniques such as imitation learning, transfer learning, and the usage of memory module …”

“…In potential real‐world applications (e.g., nanodrug delivery, precision surgery, environmental remediation, and machines), micro‐/nanorobots are confronted with navigation challenges, including long‐distance travel (e.g., travel in tissue, soil, and vasculature), unknown or spatiotemporally changing environment abundant with obstacles and dead ends, and additional time and fuel constraints. Beyond developing sophisticated micro‐/nanorobot systems that have more efficient transport mechanisms and sensing capabilities, efforts have also been directed toward developing better navigation strategies . Examples include the application of a Markov decision process framework and a variational Fermat's principle to compute optimal navigation paths in mazes and flow fields.…”

In vivo super-resolution photoacoustic computed tomography by localization of single dyed droplets

“…The penetration depth of OR-PAM is generally limited to ~1-2 mm, because its high spatial resolution depends on the tight optical focus of ballistic photons [11,12]. Photoacoustic computed tomography (PACT) detects acoustic waves generated by both ballistic and diffused photons and retrieves the optical absorption distribution through an inverse algorithm, allowing high-resolution imaging at a depth up to several centimeters [13][14][15]. PACT has been used for imaging small-animal whole-body dynamics, functional whole mouse brain hemodynamics, and human breast tumors at high spatiotemporal resolutions [16][17][18][19][20].…”