Design and development of a low temperature, inductance based high frequency ac susceptometer

We report on the development of an induction based low temperature high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration have allowed a sample magnetic moment resolution of $5\times10^{-10} Am^2$ at 1 MHz. We will discuss the design and characterization of the susceptometer, and explain the calibration process. We also include some example measurements on the spin ice material CdEr$_2$S$_4$ and iron oxide based nanoparticles to illustrate functionality

Miniaturized wireless water content and conductivity soil sensor system

Obtaining more data for the research/studies of plants growing may be easier realized when suitable non-destructive detection methods are available. We are here presenting the development of a miniaturised, low-power, real-time, multi-parameter and cost-effective sensor for measurements in mini plugs (growth of seedling). The detection technique is based on measurement of electrical impedance at two frequencies for sensing two soil parameters, water content and water conductivity (dependent on e.g. total ions concentration). Electrical models were developed and comply with data at two frequencies. An easy and efficient calibration method for the sensor is established by using known liquids\u2019 properties instead of various soil types. The measurements show a good correlation between the sensor's readings and the traditional soil testing. This soil sensor can easily send data wirelessly allowing for spot checks of substrate moisture levels throughout a greenhouse/field, and/or enable sensors to be buried inside the soil/substrate for long-term consecutive measurements

Effective particle magnetic moment of multi-core particles

In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems - BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm

Effective particle magnetic moment of multi-core particles

In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems BNF Starch from Micromod with a median particle diameter of 100 am and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm

Giant Magnetoresistive Biosensors for Time-Domain Magnetorelaxometry: A Theoretical Investigation and Progress Toward an Immunoassay

Magnetorelaxometry (MRX) is a promising new biosensing technique for point-of-care diagnostics. Historically, magnetic sensors have been primarily used to monitor the stray field of magnetic nanoparticles bound to analytes of interest for immunoassays and flow cytometers. In MRX, the magnetic nanoparticles (MNPs) are first magnetized and then the temporal response is monitored after removing the magnetic field. This new sensing modality is insensitive to the magnetic field homogeneity making it more amenable to low-power portable applications. In this work, we systematically investigated time-domain MRX by measuring the signal dependence on the applied field, magnetization time, and magnetic core size. The extracted characteristic times varied for different magnetic MNPs, exhibiting unique magnetic signatures. We also measured the signal contribution based on the MNP location and correlated the coverage with measured signal amplitude. Lastly, we demonstrated, for the first time, a GMR-based time-domain MRX bioassay. This approach validates the feasibility of immunoassays using GMR-based MRX and provides an alternative platform for point-of-care diagnostics

Doxorubicin Loaded Magnetic Polymersomes: Theranostic Nanocarriers for MR Imaging and Magneto-Chemotherapy

Hydrophobically modified magnetic nanoparticles (MNPs) were encapsulated within the membrane of poly(trimethylene carbonate)-b-poly(L-glutamic acid) (PTMC-b-PGA) block copolymer vesicles using a nanoprecipitation process. This formulation method provides a high loading of MNPs (up to 70 wt %) together with a good control over the sizes of the vesicles (100 - 400 nm). The deformation of the vesicle membrane under an applied magnetic field was evidenced by anisotropic SANS. These hybrid objects display contrast enhancement properties in Magnetic Resonance Imaging, a diagnostic method routinely used for three-dimensional and non-invasive scans of the human body. They can also be guided in a magnetic field gradient. The feasibility of drug release triggered by magnetic induction was evidenced using the anticancer drug doxorubicin (DOX), which is co-encapsulated in the membrane. Magnetic polymersomes are thus proposed as multimodal drug nanocarriers for bio-imaging and magneto-chemotherapy.FP7 CP-IP 213631-2 NANOTHE