Hybrid helical magnetic microrobots are achieved by sequential electrodeposition of a CoNi alloy and PPy inside a photoresist template patterned by 3D laser lithography. A controlled actuation of the microrobots by a rotating magnetic field is demonstrated in a fluidic environment.
Magnetic tubular implantable micro-robots are batch fabricated by electroforming. These microdevices can be used in targeted drug delivery and minimally invasive surgery for ophthalmologic applications. These tubular shapes are fitted into a 23-gauge needle enabling sutureless injections. Using a 5-degree-of-freedom magnetic manipulation system, the microimplants are conveniently maneuvered in biological environments. To increase their functionality, the tubes are coated with biocompatible films and can be successfully filled with drugs.
A method to functionalize steerable magnetic microdevices through the co-electrodeposition of drug loaded chitosan hydrogels is presented. The characteristics of the polymer matrix have been investigated in terms of fabrication, morphology, drug release and response to different environmental conditions. Modifications of the matrix behavior could be achieved by simple chemical post processing. The system is able to load and deliver 40-80 μg cm(-2) of a model drug (Brilliant Green) in a sustained manner with different profiles. Chitosan allows a pH responsive behavior with faster and more efficient release under slightly acidic conditions as can be present in tumor or inflamed tissue. A prototype of a microrobot functionalized with the hydrogel is presented and proposed for the treatment of posterior eye diseases.
The surface properties of electrodeposited poly(pyrrole) (Ppy) doped with sodium dodecylbenzenesulphonate (NaDBS) are modified by two methods: addition of poly(ethylene glycol) (PEG) during the electrodeposition and through redox cycling post electrodeposition. X-ray photoelectron spectroscopy (XPS) was used to ascertain PEG incorporation and to analyze the change in the oxidation state of the polymer. Anodic cycling resulted in the formation of micrometer-sized surface cracks which increased the amount of Rhodamine-B dye adsorbed onto the surface, and played a role in decreasing the wettability of the surface. The change in surface wettability caused by these cracks was mitigated by the presence of PEG in the Ppy matrix. Compared to the incorporation of PEG, redox cycling was more effective in passively modulating the adhesion of NIH 3T3 fibroblast cells on the Ppy surface. Based on the attenuation of surface polarity of the Ppy surfaces by the incorporated PEG, a mechanism is proposed to explain the observed cell adhesion behavior.
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