In many bedside procedures, surgeons must rely on their spatiotemporal reasoning to estimate the position of an internal target by manually measuring external anatomical landmarks. One example of such a procedure is ventriculostomy, where the surgeon inserts the catheter in the patient's skull to divert the cerebrospinal fluid and alleviate the intracranial pressure. However, one-quarter to one-third of the insertions miss the target which can ultimately lead to undesirable surgical outcomes. We have developed an interactive navigation system using mixed reality on a head-mounted display that overlays the target directly on the patient's anatomy and provides visual guidance for the surgeon to insert the catheter on the correct path to the target.

In many bedside procedures, surgeons must rely on their spatiotemporal reasoning to estimate the position of an internal target by manually measuring external anatomical landmarks. One particular example that is performed frequently in neurosurgery is ventriculostomy, where the surgeon inserts a catheter into the patient’s skull to divert the cerebrospinal fluid and alleviate the intracranial pressure. However, about one-third of the insertions miss the target.

DNA nanotechnology offers a means to synthesize custom nano-structured materials from the ground up in a hierarchical fashion. While the assembly of DNA nanostructures from small (nanometer-scale) monomeric components has been studied extensively, a general model for the hierarchical assembly of rigid or semiflexible units into multimicron-scale structures remains elusive. To study such hierarchical assembly, we have developed a system for assembling extend networks of semiflexible DNA nanotubes. These nanotubes assemble from nanometer scale tiles into materials via the nucleated growth from sites on rigid, Y-shaped nanotube seeds. In this process, nanotubes first grow from these Y-shaped seeds to form 3-armed nanotube architectures. These architectures then in turn assemble into networks that include as many as 80 seeds and can extend over areas as large as 900 μm2. We measure the kinetics of network growth and find that the assembly of these networks can be explained by a stochastic model of hierarchical assembly that assumes a single joining rate between DNA nanotube ends. Because the number of nucleation sites on the seeds and their spatial arrangement can be systematically varied by design, this system allows the assembly of a wide variety of networks and characterization of the assembly mechanisms that lead to different types of material architectures at length scales of tens to hundreds of microns. Further, by activating/deactivating the incorporated Y-shaped DNA origami junctions via strand displacement we are also able to direct networks to change form, suggesting a model system for understanding not only the formation of filament networks at this length-scale but also their reconfiguration.