Ernest Orlando Lawrence Berkeley National Laboratory

APPLICATIONS OF TECHNOLOGY: Medical imaging Magnetocardiography Magnetoencephalography Geophysical studies Magnetotellurics Controlled-source electromagnet

ADVANTAGES:

• Eliminates excess low-frequency noise inherent in SQUID devices

ABSTRACT: John Clarke and colleagues at Berkeley Lab have eliminated excess low frequency noise in high-transition temperature (Tc) superconducting quantum interference devices (SQUIDs) and SQUID-based magnetometers operating in ambient magnetic fields. Using SQUIDs fabricated with precise slots and holes, researchers have reduced the problem of intrinsic magnetic noise, previously a major impediment to the application of high-Tc SQUIDs in the earth's magnetic field, to an artifact of design. This new innovation improves operation of both single-layer and superconducting multilayer SQUID devices, with the low noise, multilayer magnetometer offering the highest sensitivity for a given size. This invention is an essential ingredient for operation of SQUID-based devices in medical applications, such as magnetocardiography and magnetoencephalography. It obviates the need for expensive, magnetically shielded rooms. Other applications include geophysical studies, for example, magnetotellurics (MT) and controlled-source electromagnetics (CSEM), in which it is essential to operate the magnetometers in an unshielded environment.

STATUS: U.S. Patent #6,023,161. Available for licensing

FOR MORE INFORMATION PLEASE SEE:

• Dantsker E.,Tanaka S., Nilsson PA, Kleiner R., Clarke J., "Reduction of 1/f noise in high-Tc dc superconducting quantum interference devices cooled in an ambient magnetic field," Applied Physics Letters, 1996, 69, 4099.
• Dantsker E., Tanaka S., Clarke J., "High-Tc super conducting quantum interference devices with slots or holes: Low 1/f noise in ambient magnetic fields," Applied Physics Letters, 1997, 70, 2037.
• Dantsker E.,Tanaka S., Nilsson PA, Kleiner R., Clarke J., "Low Excess Flux Noise in YBa2Cu3O7-x dc SQUIDs Cooled in Static Magnetic Fields," IEEE, Applied Superconductivity, Vol. 7, No. 2, June 1997

REFERENCE NUMBER: IB-1221

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

• Superconducting Multilayer Interconnect (IB-797)
• SQUID-Based, Asymmetric, Planar Gradiometer Suppresses Ambient Magnetic Field Noise (IB-1298)
• NMR/MRI with Hyperpolarized Inert Gas and High Tc SQUID for
  Signal Enhancement and Detection (IB-1441)