Magnetic nanoparticles (MNPs) are widely used in biomedical and clinical applications, including medical imaging, therapeutics, and biological sample processing. Rapid characterization of MNPs, notably their magnetic moments, should facilitate optimization of particle synthesis and accelerate assay development. Here, we report a compact and low-cost magnetometer for fast, on-site MNP characterization. Termed integrated microHall magnetometer (iHM), our device was fabricated using standard semiconductor processes: an array of Hall sensors, transistor switches, and amplifiers were integrated into a single chip, thus improving detection sensitivity and facilitating chip operation. By applying the iHM, we demonstrate versatile magnetic assays. We measured magnetic susceptibility and moments of MNPs using small sample amounts (~10 pL), identified different MNP compositions in mixtures, and detected MNP-labeled single cells.

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This article describes the successful development and the performance of X‐band 100 W pulsed SSPA using a 25 W GaN‐on‐SiC high electron mobility transistor (HEMT). The GaN HEMT with a gate length of 0.25 µm and a total gate width of 8 mm were fabricated. The GaN HEMT provide a linear gain of 8 dB with 25 W output power operated at 30 V drain voltage in continuous wave (CW)‐operation with a power added efficiency of 43% at X‐band. It also shows a maximum output power density of 3 W/mm. The X‐band pulsed SSPA exhibited an output power of 100 W (50 dBm) with a power gain of 53 dB in a frequency range of 9.2–9.5 GHz. This 25 W GaN HEMT and X‐band 100 W pulsed SSPA are suitable for the radar systems and related applications in X‐band. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:212–216, 2015