Radio Frequency Planar Coil-Based On-Chip Probe for Portable Nuclear Magnetic Resonance (original) (raw)
Related papers
Saw-Tooth Shaped Legs Birdcage RF Coil for Small Animal NMR Imaging at 1.5T MRI System
— In this paper we are demonstrating a novel method of designing and implementing a modified birdcage type Radio Frequency (RF) coil for small animal Nuclear Magnetic Resonance (NMR) imaging. This RF coil is basically a band pass type birdcage coil which is specifically designed to perform the whole body NMR imaging of small animal at 1.5T MRI systems. The designed RF coil contains the saw tooth shaped pattern as the leg conductors. The magnetic field produced at 63.85 MHz resonance frequency by this designed saw toothed shape leg pattern RF coil is significantly stronger than the magnetic field produced by a conventional straight leg band pass type birdcage coil designed with the same dimension. A full wave 3D electromagnetic simulation is carried out to optimize the RF coil dimensions, capacitor values and to study the RF coil electromagnetic characteristics.
2014 IEEE Asia Pacific Conference on Circuits and Systems (APCCAS), 2014
This paper reports the co-design of a low-noise receiver front-end and its exciting-sensing coil for portable nuclear magnetic resonance (NMR) screening of chemical/biological droplets operating at 21.3MHz (0.5T magnet). To minimize the noise contribution of the receiver front-end and its coil compared to the induced signal, EM analysis is involved to optimize the geometry of the off-chip coil with the input-referred noise of the receiver front-end taken into account. By choosing a proper geometry of the coil, the resulted SNR of the receiver front-end was shown to be maximized with the dedicated input-referred noise of the receiver. Simulated in 180nm CMOS, the receiver front-end shows an input-referred noise as low as 920.11pV/ at 25.2mW of power, and the estimated die area is ~2mm 2. I.
Birdcage Type NMR Receiver Coil Sensor with Integrated Detuning Circuit for 3T MRI System
— A novel birdcage type Radio Frequency (RF) receiver coil sensor with passive type detuning circuits integrated on the end-rings of the coil sensor has been implemented. A simulation model of the RF receiver coil sensor with the passive type detuning circuits has also been proposed. The simulation model completely explains the working principle of the RF receiver coil sensor with the passive type detuning circuits. The RF coil sensor was designed to perform the Nuclear Magnetic Resonance (NMR) imaging of small animal at 3T Magnetic Resonance Imaging (MRI) system. The integrated detuning circuits of the RF coil sensor eliminate the noises induced by the mutual inductance between receiving and transmitting coils. We have confirmed the performances of the RF coil sensor through experiments, which agreed well with those of the simulations.
Magnetic resonance microsystems for life science applications
The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05.
Nuclear magnetic (MR) resonance spectroscopy and imaging technique are powerful methods available for determining molecular structures and non-invasive 3D imaging. In the effort of developing a nanoMRl microsystem, we have designed, fabricated, assembled and did preliminary characterization of the nanoMRI probe. A multilayer high aspect ratio metal process has been developed for this project. NanoMRI probes are designed through multi-physics finite element 3D analysis, integrated using the high aspect ratio process, assembled, and the RF coils are matched and tuned to a 5OOMHz system. Due to the large magnetic field gradients and fast switching gradient coils, the high mass-sensitivity and additional orthogonal RF signal channels, special MR pulse sequencies [5] can be developed for imaging and molecular structural analysis.
SINGLE CHIP PROBE FOR HIGH RESOLUTION MAGIC ANGLE COIL SPINNING NMR OF BIOLOGICAL SAMPLES
ABSTRACT We report a single-chip probe for “magic angle coil spinning”-MACS nuclear magnetic resonance (NMR) spectroscopy. The probe consists in a wirebonded microcoil integrated with an on-chip interdigitated capacitor. This LC-circuit is resonant at 500 MHz (1H Larmor frequency at 11.7 T) enabling wireless inductive coupling of the NMR signal and spinning for high resolution NMR. We demonstrate stable spinning up to 110 Hz of the probe containing 330 nl water sample.
Journal of Magnetic …, 2007
A novel coil, called Z coil, is presented. Its function is to reduce the strong thermal effects produced by rf heating at high frequencies. The results obtained at 500 MHz in a 50 μl sample prove that the Z coil can cope with salt concentrations that are one order of magnitude higher than in traditional solenoidal coils. The evaluation of the rf field is performed by numerical analysis based on first principles and by carrying out rf field measurements. Reduction of rf heating is probed with a DMPC/DHPC membrane prepared in buffers of increasing salt concentrations. The intricate correlation that exists between the magnetic and electric field is presented. It is demonstrated that, in a multiply tuned traditional MAS coil, the rf electric field E1 cannot be reduced without altering the rf magnetic field. Since the detailed distribution differs when changing the coil geometry, a comparison involving the following three distinct designs is discussed: (1) a regular coil of 5.5 turns, (2) a variable pitch coil with the same number of turns, (3) the new Z coil structure. For each of these coils loaded with samples of different salt concentrations, the nutation fields obtained at a certain power level provide a basis to discuss the impact of the dielectric and conductive losses on the rf efficiency.
Design and fabrication of micro-coils for NMR micro probes
2018
The miniaturization of probes for Magnetic Resonance (MR) analytical methods -Nuclear Magnetic Resonance (NMR), Magnetic Resonance Imaging (MRI), or relaxometryhas been the latest trend which allows portability and analysis of the chemical composition of minute (in the range of nL to μL) volumes of sample. MR analyses typically require that such a probe is used in an external setup with a very strong constant magnetic field with no temporal variation and external detector circuits. A critical aspect for the success of such an experiment is to ensure a high signal-to-noise ratio (SNR). However, the resulting value of the SNR delivered by a miniature probe has a complicated dependence on both the external measurement setup, chemical composition of the sample and the probe design. For probe designers, there are no clear guidelines to suggest how a given probe will behave under any external measurement setup or chemical composition of the sample under test, or how to approach a probe de...
Dual Resonant RF Coil for 1.5T and 3T MRI Systems Employing FPCB Etched Sub-legs
— Radio frequency coil is the core component used in the detection of nuclear magnetic resonance signal. Usually the radio frequency coil is designed for operation on a specific magnetic field strength based magnetic resonance imaging system. This paper describes the method of implementing a modified birdcage type receive only radio frequency coil which has the ability to detect the nuclear magnetic resonance signal of 1 H nuclei at 64 MHz and 128 MHz resonance frequency for 1.5T and 3T magnetic resonance imaging systems respectively. This dual resonance is achieved by dividing each coil leg into pair of sub-legs. This radio frequency coil is designed to perform the whole body nuclear magnetic resonance imaging of small animal. The coil performance has been verified via simulation and electrical parameter measurements.
Variable angle spinning (VAS) experiments can be used to measure long-range dipolar couplings and provide structural information about molecules in oriented media. We present a probe design for this type of experiment using a contactless resonator. In this circuit, RF power is transmitted wirelessly via coaxial capacitive coupling where the coupling efficiency is improved by replacing the ordinary sample coil with a double frequency resonator. Our probe constructed out of this design principle has shown favorable properties at variable angle conditions. Moreover, a switched angle spinning correlation experiment is performed to demonstrate the probe’s capability to resolve dipolar couplings in strongly aligned molecules.
Lithographic RF Coil Design Study for a Sub-Surface MRI System
2005
The materials used in organic light emitting diodes (OLED) and liquid crystal displays (LCD) are subject to deterioration in performance from moisture egress, but little is known about the process. Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are well suited to study these display materials. We are exploring various coil designs for a sub-surface MRI system suitable for imaging these displays and other objects to a depth of 10 mm in nonferromagnetic proton-rich media. Using an iterative development process for our RF surface coils, we have hand-wound five different embodiments. With each embodiment iteration, sensitivity and Q were improved. However, the coil geometries that we have developed so far have been limited to those obtainable with hand-winding construction techniques. Moreover, coupling of our RF coil designs with our acquisition host has posed an engineering challenge that we have reasonably addressed to achieve our preliminary results. Use of li...