1H NMR Detection of superparamagnetic nanoparticles at 1T using a microcoil and novel tuning circuit

Sensitive NMR Sensors Detect Antibodies to Influenza

“…[3] MR relaxometers are practical as POC sensors because their requirements for magnetic-field strength, volume, and homogeneity are minimal. [4][5][6] To date, MRSws have used magnetic nanoparticles (NPs) that react with molecular targets to form aggregates and decrease the transverse relaxation time (T 2 ). Although MRSws detect highly multivalent viruses or bacteria with high sensitivity, [7,8] their sensitivity for proteins is far lower.…”

Musings on Hardware Advances and New Directions

“…For identical windings, the quality factor Q = ω L / r can be maximized to limit the bandwidth, although the bandwidth does not have to be set by the NMR coil. Andrew McDowell has a scheme to tune microcoils with terrible Q -values due to thin wires that have substantial resistivity [2] at frequencies that are too low to deal with convenient values of tuning capacitors. He obtains excellent SNRs by connecting the microcoils in series with large, high -Q dummy coils.…”

“…Andrew McDowell has pioneered the use of microcoils (coils smaller than 500 μ m) with permanent magnets [2,5] . As already mentioned, a major challenge here was in determining how to tune a coil with such a small inductance at low frequency, but this was overcome nicely with an auxiliary (normal size) coil that set the resonance condition with a normal tuning capacitor [2] .…”

“…As already mentioned, a major challenge here was in determining how to tune a coil with such a small inductance at low frequency, but this was overcome nicely with an auxiliary (normal size) coil that set the resonance condition with a normal tuning capacitor [2] . Figure 1.6 shows the fi rst proton spectrum acquired using the smallest magnet in Figure 1.4 .…”

NMR with excitation modulated by Frank sequences

“…These are advantages in miniaturizing NMR spectrometers for use at the site of interest, such as in bio-sensing applications [1][2][3], in sensing and control of chemical processes, in airport security applications such as NMR fluid screening and NQR explosives and drug detection [4,5], in conducting NMR at contaminated sites, in single-sided NMR of large or precious objects, and in NMR imaging in an emergency vehicle. Low excitation power also promises to ease SAR limitations in medical imaging, opening the door for high-field imaging in medical patient care.…”