Floating magnetic microrobots for fiber functionalization

Abstract

Because minimally invasive surgery is increasingly used to target small lesions, demand is growing for miniaturized tools—such as microcatheters, articulated microforceps, or tweezers—that incorporate sensing and actuation for precision surgery. Although existing microfabrication techniques have addressed the construction of these devices, accurate integration and functionalization of chemical and physical sensors represent major challenges. This paper presents a microrobotic platform for the functionalization of fibers of diameters from 140 to 830 micrometers, with a patterning precision of 5 micrometers and an orientation error below 0.4°. To achieve this, we developed two 2 millimeter–by–3 millimeter, 200-micrometer-thick microrobots to align floating electronic circuits on a fiber during a wet transfer process. The position and orientation of the microrobots were controlled at the air/water interface by a permanent magnet. The stiffness of the position controlled was 0.2 newton millimeter, leading to an average force of 0.5 newton. The nonhomogeneous magnetic field of the magnet, associated with different preferred magnetization directions recorded in the microrobots, allowed the distance between the two microrobots to be precisely controlled. This extra degree of freedom was used to control the microrobot pair as a tweezer to grab and release floating electronic patterns, whereas the others were used to align the pattern position and orientation with the fiber. A model of this control, as well as the microrobots’ interaction through surface tension, is proposed. Detailed performance validation is provided, and various exemplar sensor embodiments on a 200-micrometer-diameter fiber and three-dimensional devices are demonstrated.

Towards a Functional Atraumatic Self‐Shaping Cochlear Implant

“…This ratio will be studied to understand how many electrodes an implant can accommodate and the diameter of these electrodes to allow the implant to fully recover shape. Conversely, we can explore other alternatives to include electrodes in our SMP‐based CI, such as co‐drawing SMP and low temperature melting metal or introducing electrodes in the implant as suggested by Barbot et al [ 32 ] The results also showed a degree of variability that can be explained in part by how the material molds or collapses around the metal electrode during the molding stage, as shown by the implants tested to assess the stiction effect, which laid closer to the calculated fit line. The effect of the electrode during molding was also noticed when we compared the average initial angle after molding for the implants with and without an electrode used in this work experiments, which was 320° ( n = 30) and 282° ( n = 9), respectively.…”

A Tumbling Magnetic Microrobot System for Biomedical Applications

“…The actuating magnetic field itself can be supplied using electromagnetic coils or permanent magnets, but the latter option was incorporated into our system due to space constraints and its simplicity of implementation. Permanent magnets have been used for actuation in a variety of other robotic systems, including helical microrobot platforms [ 47 , 48 , 49 ], a microrobotic system for aligning floating electronic circuits to fibers in a wet transfer process [ 50 ], and a larger system involving magnetic capsule endoscopes [ 51 ]. More recently, point-to-point closed-loop motion control of magnetically driven screws actuated using permanent magnets was demonstrated within an agar gel tissue phantom [ 52 ].…”

Intelligent Soft Surgical Robots for Next‐Generation Minimally Invasive Surgery

“…In addition to these approaches, there are also some other techniques specifically for integrating sensors on readymade soft devices, e.g., laser‐tuned selective transfer printing [ 306 ] and wet transfer process. [ 307 ] Among them, the laser‐tuned selective transfer printing technology can also be used for the assembly and reconstruction of soft magnetic robots, [ 308 ] through which we can perceive its potential of being used to construct complex 3D soft structures in a layer‐by‐layer manner. Introducing them as a postprocessing step or directly integrating them with other methods can be considered in future.…”