Objective: Magnetic nanoparticles conjugated to a monoclonal antibody can be i.v. injected to target cancer tissue and will rapidly heat when activated by an external alternating magnetic field (AMF). The result is necrosis of the microenvironment provided the concentration of particles and AMF amplitude are sufficient. High-amplitude AMF causes nonspecific heating in tissues through induced eddy currents, which must be minimized. In this study, application of highamplitude, confined, pulsed AMF to a mouse model is explored with the goal to provide data for a concomitant efficacy study of heating i.v. injected magnetic nanoparticles. Methods: Thirty-seven female BALB/c athymic nude mice (5-8 weeks) were exposed to an AMF with frequency of 153 kHz, and amplitude (400-1,300 Oe), duration (1-20 minutes), duty (15-100%), and pulse ON time (2-1,200 seconds). Mice were placed in a water-cooled four-turn helical induction coil. Two additional mice, used as controls, were placed in the coil but received no AMF exposure. Tissue and core temperatures as the response were measured in situ and recorded at 1-second intervals. Results: No adverse effects were observed for AMF amplitudes of V700 Oe, even at continuous power application (100% duty) for up to 20 minutes. Mice exposed to AMF amplitudes in excess of 950 Oe experienced morbidity and injury when the duty exceeded 50%. Conclusion: High-amplitude AMF (up to 1,300 Oe) was well tolerated provided the duty was adjusted to dissipate heat. Results presented suggest that further tissue temperature regulation can be achieved with suitable variations of pulse width for a given amplitude and duty combination.These results suggest that it is possible to apply high-amplitude AMF (>500 Oe) with pulsing for a time sufficient to treat cancer tissue in which magnetic nanoparticles have been embedded.
We introduce here a new transformer/inductor technology which is suitable for integrated power for multichip modules (MCM), microprocessors and chip sets. The transformer/inductor is embedded within the ceramic substrate, as are the chips and other components. It provides for extremely tight secondary side circuit layouts with very low and fixed leakage inductance. The core is a new multipole structure which can be considered as a number of transformers integrated into one monolithic structure. The core consists of a bottom ferrite plate, and the winding is constructed using high density interconnect techniques (HDI), such as laminating dielectric layers and depositing winding metals using sputtering followed by electroplating. Winding patterns are etched using photo-resist and wet etching techniques. Multiple vias are used to connect different primary and secondary winding layers. A conformal metal mask is used to laser-drill through (large) holes for the posts of the top part of the core. An experimental 50-W, six-pole transformer has been built using these techniques. It operates at 1.0 MHz with efficiency approaching 98.7% and has a net height of about 0.09 in ( 2.3 mm). It has a power density of 71 W/cc (or 1170 W/in 3 ) and a surface power density of 17 W/cm 2 .
Index Terms-High density interconnect (HDI), multichip modules (MCM).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.