A magnetic force sensor on a catheter tip for minimally invasive surgery.

This paper presents a magnetically guided catheter for minimally invasive surgery (MIS) with a magnetic force sensing tip. The force sensing element utilizes a magnetic Hall sensor and a miniature permanent magnet mounted on a flexible encapsulation acting as the sensing membrane. It is capable of high sensitivity and robust force measurements suitable for in-vivo applications. A second larger magnet placed on the catheter allows the catheter to be guided by applying magnetic fields. Precise orientation control can be achieved with an external magnetic manipulation system. The proposed device can be used in many applications of minimally invasive surgery (MIS) to detect forces applied on tissue during procedures or to characterize different types of tissue for diagnosis.

Electroplated porous polypyrrole nanostructures patterned by colloidal lithography for drug-delivery applications.

Porous nanostructures of polypyrrole (Ppy) were fabricated using colloidal lithography and electrochemical techniques for potential applications in drug delivery. A sequential fabrication method was developed and optimized to maximize the coverage of the Ppy nanostructures and to obtain a homogeneous layer over the substrate. This was realized by masking with electrophoretically-assembled polystyrene (PS) nanospheres and then electroplating. Drug/biomolecule adsorption and the release characteristics for the porous nanostructures of Ppy were investigated using rhodamine B (Rh-B). Rh-B is an easily detectable small hydrophobic molecule that is used as a model for many drugs or biological substances. The porous Ppy nanostructures with an enhanced surface area exhibited higher Rh-B loading capacity than bulk planar films of Ppy. Moreover, tunability of surface morphology for further applications (e.g., sensing, cell adhesion) was demonstrated.