Metastasis accounts for the vast majority of cancer deaths. The unique challenges for treating metastases include their small size, high multiplicity and dispersion to diverse organ environments. Nanoparticles have many potential benefits for diagnosing and treating metastatic cancer, including the ability to transport complex molecular cargoes to the major sites of metastasis, such as the lungs, liver and lymph nodes, as well as targeting to specific cell populations within these organs. This Review highlights the research, opportunities and challenges for integrating engineering sciences with cancer biology and medicine to develop nanotechnology-based tools for treating metastatic disease.

Treating metastatic cancer with nanotechnology

THIS paper explores opportunities and challenges in power conversion in the VHF frequency range of 30-300 MHz. The scaling of magnetic component size with frequency is investigated, and it is shown that substantial miniaturization is possible with increased frequencies even considering material and heat transfer limitations. Likewise, dramatic frequency increases are possible with existing and emerging semiconductor devices, but necessitate circuit designs that either compensate for or utilize device parasitics. We outline the characteristics of topologies and control methods that can meet the requirements of VHF power conversion, and present supporting examples from power converters operating at frequencies of up to 110 MHz.

/pdf/opportunities-and-challenges-in-very-high-frequency-power-2j4vslax8q.pdf

Opportunities and Challenges in Very High Frequency Power Conversion

A comparison of on-chip inductors with magnetic materials from previous studies is presented and examined. Results from on-chip inductors with magnetic material integrated into a 90 nm CMOS processes are presented. The inductors use copper metallization and amorphous Co-Zr-Ta magnetic material. Inductance densities of up to 1700 nH/mm2 were obtained thanks to inductance increases of up to 31 times, significantly greater than previously published on-chip inductors. With such improvements, the effects of eddy currents, skin effect, and proximity effect become clearly visible at higher frequencies. Co-Zr-Ta was chosen for its good combination of high permeability, good stability at high temperature (> 250degC), high saturation magnetization, low magnetostriction, high resistivity, minimal hysteretic loss, and compatibility with silicon technology. The Co-Zr-Ta alloy can operate at frequencies up to 9.8 GHz, but trade-offs exist between frequency, inductance, and quality factor. Our inductors with thick copper and thicker magnetic films have dc resistances as low as 0.04 Omega, and quality factors of up to 8 at frequencies as low as 40 MHz.

Review of On-Chip Inductor Structures With Magnetic Films

The activation of magnetic nanoparticles (mNPs) by an alternating magnetic field (AMF) is currently being explored as technique for targeted therapeutic heating of tumors. Various types of superparamagnetic and ferromagnetic particles, with different coatings and targeting agents, allow for tumor site and type specificity. Magnetic nanoparticle hyperthermia is also being studied as an adjuvant to conventional chemotherapy and radiation therapy. This review provides an introduction to some of the relevant biology and materials science involved in the technical development and current and future use of mNP hyperthermia as clinical cancer therapy.

/pdf/magnetic-nanoparticle-hyperthermia-in-cancer-treatment-4n2bfhtqwc.pdf

Magnetic nanoparticle hyperthermia in cancer treatment.

This paper reviews the current state of power supply technology platforms and highlights future trends and challenges toward realizing fully monolithic power converters. This paper presents a detailed survey of relevant power converter technologies, namely power supply in package and power supply on chip (PwrSoC). The performance of different power converter solutions reported in the literature is benchmarked against existing commercial products. This paper presents a detailed review of integrated magnetics technologies, primarily microinductors, a key component in realizing a monolithic power converter. A detailed review and comparison of different microinductor structures and the magnetic materials used as inductor cores is presented. The deposition techniques for integrating the magnetic materials in the microinductor structures are discussed. This paper proposes the use of two performance metrics or figures of merit in order to compare the dc and ac performance of individual microinductor structures. Finally, the authors discuss future trends, key challenges, and potential solutions in the realization of the “holy grail” of monolithically integrated power supplies (PwrSoC).

Review of Integrated Magnetics for Power Supply on Chip (PwrSoC)

Thin-film inductors for 1 GHz-drive mobile communication handset application has been demonstrated. This is the possible practical application of soft magnetic films in 1 GHz range. Fe61Al13O26 with Ms=1.2 T, ρ=500 μΩ cm, fr=2 GHz were used for the inductors. L=7.6 nH, R=6.5 Ω, and Q=7.4 were obtained at 1 GHz in a 370 μm×370 μm square four turn spiral of line/space=11 μm/11 μm covered with 0.1-μm-thick slitted Fe61Al13O26 film with Cr underlayer. The L was increased over the flux saturated inductor by 8.6% without any degrade of quality factor.

Microfabrication and characteristics of magnetic thin-film inductors in the ultrahigh frequency region

The design and fabrication of high-Q air-core toroidal inductors are described. Designs are optimized for maximum Q for a given size and inductance, independent any particular fabrication process. A fabrication process using a combination of thin-film processes and conventional machining has been used to make prototypes. Measurements performed on the first prototypes confirm the predicted Q of 115 at 50 MHz.

/pdf/design-and-fabrication-of-low-loss-toroidal-air-core-3tpr52zhxr.pdf

Design and Fabrication of Low-Loss Toroidal Air-Core Inductors

The structural and magnetic properties of four different iron oxide and iron nanoparticles were investigated with respect to the possible application for magnetic hyperthermia treatments. The specific power absorption rates were measured in alternating magnetic fields of 75–150 Oe at frequencies of 10–300 kHz. The heating behavior is discussed in relation to the magnetic behavior of the nanoparticles. It was found that the largest specific absorption rate of 2.8W∕g occurred for the 20–30-nm-diam Fe2O3 nanoparticles.

Heat deposition in iron oxide and iron nanoparticles for localized hyperthermia

We have investigated the uniaxial magnetic anisotropy of the high resistivity Fe–Al–O granular films prepared by sputtering. It is found that application of external dc field during film deposition and post-annealing treatments give rise to no serious effects on the magnetic anisotropy. In contrast, the incident angle of sputtered particles to the substrate greatly affects the strength and the direction of the anisotropy. These results suggest that the magnetic anisotropy is induced by a shape anisotropy due to anisotropic morphology in the films. The temperature dependence of the anisotropy constant, however, does not obey the usual shape anisotropy relationship Ku(T)∝Ms(T)2. In the present article, we propose an anisotropic coupling model in order to explain the uniaxial anisotropy found in these granular films, where the magnetic coupling between Fe grains is assumed to be anisotropic in the film plane due to the presence of low Tc intergranular phase which bridges the gap between Fe grains in one dire...

Study on the in-plane uniaxial anisotropy of high permeability granular films

Owing to high resistivity and high inplane uniaxial anisotropy, granular films are known to exhibit high permeability at radio frequencies. But this granular resistivity is not high enough to suppress eddy current when they are used at gigahertz frequencies. Recent developments to solve this problem are described. One is patterning the granular films. It is effective to control the inplane anisotropy and to suppress inplane eddy current. Another is deposition of granular films by evaporation. A peculiar fiber structure is formed for which very high resistivity and anisotropy are realized. Finally, a study of using these films as near-field electromagnetic noise absorbers is described, and it is demonstrated that they have high potential as micrometer-scale noise absorbing elements in the gigahertz frequency range.

Weidong Li

Papers

Microfabrication and characteristics of magnetic thin-film inductors in the ultrahigh frequency region

Design and Fabrication of Low-Loss Toroidal Air-Core Inductors

Heat deposition in iron oxide and iron nanoparticles for localized hyperthermia

Study on the in-plane uniaxial anisotropy of high permeability granular films

Granular thin films with high RF permeability