Digital SQUID (Superconducting Quantum Interference Devices)-based Systems for Magnetic Resonance (MR) and Magnetic Source (MS) Imaging
Magnetic fields can be measured with induction coils and fluxgate magnetometers. However, in certain cases, the magnet field signals are so weak that more sensitive magnetometers are needed to properly measure magnetic field from biological samples. In addition, there are no established techniques or systems, which can measure both intrinsic and induced magnetic signals from biological samples. This SBIR program addresses the development of a prototype MR/MS Imaging system for biological applications. While we will focus on the imaging applications, the system can also be utilized for NMR (Nuclear Magnetic Resonance) spectroscopy. The proposed system uses digital SQUIDs (Superconducting QUantum Interference Devices) as its imaging sensors. SQUIDs are extremely sensitive detectors of magnetic flux and have been used extensively to detect weak biomagnetic signals in MSI. All recent measurements of weak magnetic fields utilize SQUID magnetometers. Inductive coils measure the rate of change of flux with time, and therefore, have vanishing sensitivity as the frequency goes to zero. By contrast, SQUIDs measure flux directly and can detect changes in flux at any rate including extremely low frequencies. Recent research has shown that these SQUID-based sensors may also be used to measure the very weak magnetic signals in MRI systems. The imaging system consists of a liquid helium dewar, which cools down the digital SQUID to ~4 K, and a separate cooler to cool down the pickup coil to 50 K. A single pickup coil which is superconducting at low magnetic field for MSI and highly conductive for MRI applications at high magnetic field is utilized as the magnetic sensor. A novel 4-channel digital SQUID magnetometer whose front-end analog SQUIDs are amplified by an on-chip SQUID amplifier is used as the front-end of the receiver. The digital SQUID outputs, which are measure of the applied signal, are tracked by a standard off-the-shelf counter. A magnet, which is tunable between 0.1 T to 3 T is used for the MR imaging. Data acquisition and imaging software are designed for operation of the digital SQUIDs. We utilize as many standard parts as possible to cost-effectively demonstrate the two imaging technologies (MSI and MRI) in a single system producing an unparalleled functional imagery for biological systems. The system will be optimized for imaging of magnetic fields at the scale of 50 m. The compact magnetic imaging system with the new advanced SQUID allows Hypres to extend its capabilities and establish the instrumentation techniques required for a rapid-cycle commercial capability to develop low-noise, integrated digital SQUID magnetometers and gradiometers for biomedical instrumentation, which will lead to new insights into cellular biology. The system can be easily can be easily adapted for many applications such as sensors for energy and nuclear physics applications, in addition to biomedical applications.
- Research Organization:
- HYPRES, Inc., Elmsford, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- DOE Contract Number:
- SC0019571
- OSTI ID:
- 1577327
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-SC0019571; 9145921190
- Country of Publication:
- United States
- Language:
- English
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